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Citation analysis of orthopaedic literature; 18 major orthopaedic journals compared for Impact Factor and SCImago

Citation analysis of orthopaedic literature; 18 major orthopaedic journals compared for Impact... Background: One of the disadvantages of the Impact Factor (IF) is self-citation. The SCImago Journal Rank (SJR) indicator excludes self-citations and considers the quality, rather than absolute numbers, of citations of a journal by other journals. The present study re-evaluated the influence of self-citation on the 2007 IF for 18 major orthopaedic journals and investigated the difference in ranking between IF and SJR. Methods: The journals were analysed for self-citation both overall and divided into a general group (n = 8) and a specialized group (n = 10). Self-cited and self-citing rates, as well as citation densities and IFs corrected for self- citation (cIF), were calculated. The rankings of the 18 journals by IF and by SJR were compared and the absolute difference between these rankings (ΔR) was determined. Results: Specialized journals had higher self-citing rates (p = 0.01, Δmedian = 9.50, 95%CI -19.42 to 0.42), higher self-cited rates (p = 0.0004, Δmedian = -10.50, 95%CI -15.28 to -5.72) and greater differences between IF and cIF (p = 0.003, Δmedian = 3.50, 95%CI -6.1 to 13.1). There was no significant correlation between self-citing rate and IF for both groups (general: r = 0.46, p = 0.27; specialized: r = 0.21, p = 0.56). When the difference in ranking between IF and SJR was compared between both groups, sub-specialist journals were ranked lower compared to their general counterparts (ΔR: p = 0.006, Δmedian = 2.0, 95%CI -0.39 to 4.39). Conclusions: Citation analysis shows that specialized orthopaedic journals have specific self-citation tendencies. The correlation between self-cited rate and IF in our sample was large but, due to small sample size, not significant. The SJR excludes self-citations in its calculation and therefore enhances the underestimation in ranking of specialized journals. Background to manipulate it. A journal’s IF can be increased artifi- The IF [1] is considered the best reference utensil for cially by using self-citations, publishing relatively many evaluation of scientific journals although its limitations review articles and limiting the number of articles have already been described extensively [2-7]. Major included. points of criticism are the lack of quality assessment for The internet search engine Google™ uses a PageRank citations [5], poor comparability between different algorithm to determine page ranking after a specific domains of interest per journal [6] and the mainly Eng- search query. Several authors have advocated a similar lish language in publications. A major problem with the algorithm for the evaluation of scientific journals. Fala- IF for journals is self-citation, defined in Journal Cita- gas et al. [5] recently described the application of a tion Reports as referring to articles from the same jour- PageRank algorithm to the Scopus database to produce nal [1]. Due to these limitations and the simplicity of the SCImago Journal Rank (SJR) indicator. The SJR calculating the IF, it would be relatively easy for editors represents awarded prestige per article in the analysed year and is calculated using a complicated iterative for- * Correspondence: [email protected] mula. Self-citations do not contribute to the SJR, since a † Contributed equally journal can receive prestige only from other journals, Department of Orthopedic Surgery, Reinier de Graaf Groep, P.O. Box 5501, not from itself [8]. The SJR has several other benefits 2600 GA Delft, The Netherlands © 2010 Siebelt et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Siebelt et al. BMC Musculoskeletal Disorders 2010, 11:4 Page 2 of 7 http://www.biomedcentral.com/1471-2474/11/4 [5], such as the greater number of journals and lan- AJSM articles on a total of 8089 citations; the self-citing guages included in its database and the fact that it is rate was 1542/8089 = 19% (Table 1). open-source software (free of charge). The ratio between the number of self-cited articles in In thepresent studywefirst aimedtoevaluatethe journal X in 2007 and the total amount of citations influence of self-citations on the 2007 IF for 18 major received in 2007 for articles in journal X is the self- orthopaedic journals, including sub-specialist journals. cited rate [1]. For example, AJSM was cited 10,711 These journals publish specialized articles concerning a times in total, of which 1542 by itself; the self-cited rate narrow field of interest and as such are expected to was 1542/10711 = 14% (Table 1). receive relatively few citations from other journals. We The citation density [1] was determined by dividing therefore hypothesized that self-citation rates are higher the total number of references in journal X in 2007 by for specialized journals than for the general orthopaedic the total number of articles published in that journal in literature. Secondly, we investigated ranking of ortho- 2007. For example, the 239 articles published in AJSM paedic journals with the SJR. This indicator excludes in 2007 contained a total of 8089 references; the citation self-citations, therefore we hypothesized that the SJR density was 8089/239 = 34 citations per article (Table ranks specialized journals comparatively lower than does 1). the IF. We retrieved information regarding ranking by SJR via the SCImago journal- and country-rank website devel- Methods oped by the SCImago research group [8]; the journals We included and analyzed 18 orthopaedic journals, were selected by matching international standard serial making a distinction between general and specialized number (ISSN) found in the JCR. Since the IF ranks orthopaedic journals. Two orthopaedic clinicians partici- 6426 journals and the SJR 15,922, absolute rankings by pating in this study individually allocated journals to IF and SJR are not comparable. Therefore only the 18 either the general or the specialized group. journals included in our analysis were mutually ranked The general group included the following journals: for IF (R )and SJR(R ). Thedifferencebetween R IF SJR IF Acta Orthopaedica (Acta), Archives of Orthopaedics and and R , expressed as ΔR, was calculated to check for a SJR Trauma (AOTS), BMC Musculoskeleletal Disorders possible difference between both rankings. (BMCMD), Clinical Orthopaedics and Related Research Statistical analysis (CORR), International Orthopaedics (Int Orthop), the Statistical analysis was performed using Prism v5.00 for American Volume of Journal of Bone and Joint Surgery Windows (Graphpad Software Inc, San Diego, CA, (JBJS [Am]), the British volume of Journal of Bone and USA). Analysing differences between general and specia- Joint Surgery (JBJS [Br]) and Orthopaedic Clinics of lized journals for the IF, the following specifics were North America (OCNA). compared using a Mann-Whitney test: self-citing rate, The specialized orthopaedic journals included in the self-cited rate, citation density, ΔIF, R ,R and ΔR. IF SJR study were: American Journal of Sports Medicine We determined the medians, the first- and third-quartile (AJSM), Arthroscopy, European Spine Journal (ESJ), Foot values, and the difference between the medians (Δmed- and Ankle International (FAI), Journal of Arthroplasty ian = median -median )and theirconfi- general specialized (JOA), Journal of Orthopaedic Trauma (JOT), Journal of dence intervals. A Spearman rank correlation coefficient Pediatric Orthopaedics (JPO), Journal of shoulder and was computed to estimate the correlation between self- elbow surgery (JSES), Knee surgery sports traumatology citing rates and IF, as well as between the journal rank- arthroscopy (KSSTA) and Spine. ings by IF and by SJR. For all tests, p values < 0.05 were For both groups self-citation was analysed for the considered significant. 2007 IF. The self-citing rate, self-cited rate and citation density, parameters known to influence the IF [2], were Results calculated for each of these journals as defined by the Self-citation rates ISI Web of Science [1]. Also, all IF were corrected for The journals with the highest self-citing rates were the influence of self-citations (cIF) [1]; for individual CORR in the general group (15%) and Spine in the spe- journal evaluation, an absolute change of >0.5 in IF (ΔIF cialized group (29%) (Table 1); the lowest rates were for = IF - cIF) was considered substantial. To estimate the BMC MD/OCNA (general group, 1%) and KSSTA/ESJ influence of self-citation on the IF, journals in both (specialized group, 5%). The highest self-cited rates were groups were correlated for self-citing rate and IF. for CORR/Int Orthop (general, 14%) and FAI (specia- The self-citing rate [1] was calculated by dividing the lized, 38%), the lowest rates for OCNA (1%) and JPO number of self-cited articles in journal X in 2007 by the (9%). Arthroscopy (0.75), AJSM (0.67) and Spine (0.63), total amount of citations by that journal in 2007. For all experience substantial declines in IF when corrected example, in 2007 AJSM contained 1542 citations of for self-citation (cIF). Siebelt et al. BMC Musculoskeletal Disorders 2010, 11:4 Page 3 of 7 http://www.biomedcentral.com/1471-2474/11/4 Table 1 Self-citing rate, self-cited rate, citation density and IF 2007 a b c Journal* Self-citing (%) Self-cited (%) Citation density (%) Impact Factor 2007 Corrected IF (cIF) Difference (ΔIF = IF – cIF) General orthopaedic journals Acta 7 5 31 1.285 1.122 0.163 AOTS 2 4 23 0.913 0.873 0.040 BMC MD 1 6 38 1.323 1,226 0.097 CORR 15 8 31 1.891 1.626 0.265 Int Orthop 4 8 22 0.903 0.796 0.107 JBJS [Am] 7 6 36 2.487 2.363 0.124 JBJS [Br] 6 7 28 1.868 1.664 0.204 OCNA 1 1 53 1.692 1.692 0.000 Specialized orthopaedic journals AJSM 19 14 34 3.397 2.731 0.666 Arthroscopy 27 23 22 2.296 1.550 0.746 ESJ 5 17 34 2.021 1.545 0.476 FAI 24 38 23 0.956 0.581 0.375 JoA 14 15 21 1.609 1.403 0.206 JOT 11 13 29 1.429 1.199 0.230 JPO 15 9 34 1.036 0.927 0.109 JSES 14 21 24 1.348 1.158 0.190 KSSTA 5 16 26 1.626 1.314 0.312 Spine 29 20 32 2.499 1.871 0.628 Acta Orthopaedica (Acta), American Journal of Sports Medicine (AJSM), Arthroscopy, Archives of Orthopaedics and Trauma (AOTS), BMC Musculoskeleletal Disorders (BMC MD), Clinical Orthopaedics and Related Research (CORR), European Spine Journal (ESJ), Foot and Ankle International (FAI), International Orthopaedics (Int Orthop), Journal of Arthroplasty (JOA), the American Volume of Journal of Bone and Joint Surgery (JBJS [Am]), the British volume of Journal of Bone and Joint Surgery (JBJS [Br]), Journal of Orthopaedic Trauma (JOT), Journal of Pediatric Orthopaedics (JPO), Journal of shoulder and elbow surgery (JSES), Knee surgery sports traumatology arthroscopy (KSSTA), Orthopaedic Clinics of North America (OCNA),and Spine. p = 0.01, Mann–Whitney between general and specialized journals. p = 0.0004, Mann–Whitney between general and specialized journals. p = 0.003, Mann–Whitney between general and specialized journals. Comparative Ranking: IF versus SCImago (Table 3) Table 2 shows the medians and first- and third-quar- TherankingsbyIFand SJRfor the18 journalsinour tile values of the citation analysis. Specialized journals have significantly higher self-citing rates (Δmedian = analysis are presented in Table 3. For the SJR, an ortho- 9.50, 95%CI -19.42 to 0.42, p = 0.01) and self-cited rates paedic ranking is possible for the sixteen journals repre- (Δmedian = -10.50, 95%CI -15.28 to -5.72, p = 0.0004). sented in the subcategory Medicine: Orthopaedics and Both types of journal tend to use similar numbers of Sport Medicine in the SJR database, but not for BMC citations per published article (Δmedian = 3.50; 95%CI MD (included in the subcategory Medicine: Miscella- -6.1 to 13.1, p = 0.35). The absolute difference between neous)and Spine (included in the subcategory Biochem- IF and cIF proved to be greater for specialized journals istry, Genetics and Molecular Biology). (Δmedian = -0.22; 95%CI -0.45 to -0.01; p = 0.003). In comparing SJR rank relative to IF rank, seven jour- There was no significant correlation between the self- nals maintained their rank (OCNA, JOT, JSES, JPO, FAI, cited rate and the IF for either the general (r = 0.46; p = AOTS, Int Orthop), six improved their rank (JBJS [Am], 0.27) or the specialized group (r = 0.21; p = 0.56) (figure CORR, JBJS [Br], JoA, Acta, BMC MD)and five experi- 1A). enced a decline in rank (AJSM, Spine, Arthroscopy, ESJ, Table 2 Citation analysis for general and specialized journal groups General (n = 8) Specialized (n = 10) 1st Quartile Median 3rd Quartile 1st Quartile Median 3rd Quartile Self-citing rate 1.25 5.00 7.00 9.50 14.50 24.75 Self-cited rate 4.25 6.00 7.75 13.75 16.50 21.50 Citation density 24.25 31.00 37.50 22.75 27.50 34.00 ΔIF 0.05 0.12 0.19 0.20 0.34 0.64 Siebelt et al. BMC Musculoskeletal Disorders 2010, 11:4 Page 4 of 7 http://www.biomedcentral.com/1471-2474/11/4 Figure 1 Correlation Analysis. A: Correlation between self-cited rate (%) and impact factor B: Correlation between IF and SJR KSSTA). The greatest differences between SJR and IF orthopaedic journals. Hakkalamani et al. [9] excluded rank were seen for BMC MD (seven places up in SJR) several journals because of a suspected increased self- and ESJ/KSSTA (four places down). Despite these citation because of subject subspecialty. Applying stan- changes, a strong correlation was found between IF and dard definitions for self-citing rate, self-cited rate and SJR (general: r = 0,98, p < 0.0001) (specialized: r = 0.93, citation index from the ISI Web of Science to these jour- p < 0.0001) (figure 1B). nals, we were able to identify specific citation patterns for Table 4 presents the differences in ranking between specialized journals. Comparison of the Impact Factor both groups, IF (Δmedian = 1.00, 95%CI -7.13 to 9.13, p with the newly introduced SCImago journal rank indica- = 0.41) and for SJR (Δmedian = -3.50, 95%CI -12.2 to tor elucidated whether citation analysis based on a 5.2, p = 0.76). There was a significant difference in ΔR PageRank algorithm provides improved quality assess- between both groups (Δmedian = 2.0, 95%CI -0.39 to ment of orthopaedic literature over journal indicators. 4.39, p = 0.006). A limitation of this study is the evaluation of journal citations for 2007 only, and not for other years of publi- Discussion cation. Furthermore, the distinction made between gen- Key findings eral and specialized journals is arbitrary; however, Our study revealed the following: (1) Specialized jour- distinguishing journal categories by domain of interest is nals receive proportionally more self-citations with a plausible and is coherent with work published previously strong influence on the IF. (2) The SJR shows a strong [9]. Therefore, we believe that applying widely accepted relation with the IF. (3) Correcting for self-citation with methods for citation analysis to our analysis groups gen- the newly introduced SJR results in substantial indivi- erated reliable data. dual changes for journal ranking. (4) Specialized journals Previous Literature tend to drop, whereas general journals will climb, in Self-citation indicators that affect the IF are not limited rank when the SJR is applied instead of IF. to the orthopaedic literature [9]. Similar relations have Group-specific characteristics were clearly visible. Sub- been demonstrated for anaesthesia [10] and radiology specialist journals have higher self-citing (p = 0.01) and [11]. The high self-citation indexes found within these self-cited rates (p = 0.0004), also expressed in a greater specialized fields of medical science prompted sugges- difference between IF and corrected IF for self-citations tions that self-citations should be eliminated from the (p = 0.003). Despite the elaborate iterative calculation of calculation of the IF. However for the 2007 IF in ortho- the SJR, there exists a very strong correlation between paedic literature we did not find a similar distinct influ- IF and SJR ranking (general: r = 0.98, p < 0.0001) (spe- ence of self-citations. The high self-citation indexes for cialized: r = 0.93, p < 0.0001). Comparing the mutual specialized journals relative to general journals rather difference in ranking for SJR and IF between both indicate that these journals serve a small and isolated groups showed an increased contrast (p = 0.003). field within the orthopaedic literature [10]. The question Strength and weaknesses of our study can be posed whether high self-citation rates within a Our study is strengthened by the analysis of two separate specialized domain of interest are indications for low- groups of orthopaedic literature: general and specialized quality publications or rather reflect overall high quality? Siebelt et al. BMC Musculoskeletal Disorders 2010, 11:4 Page 5 of 7 http://www.biomedcentral.com/1471-2474/11/4 Table 3 Comparative rankings of orthopaedic journals by journal impact factor and SCImago journal rank indicator Journal Impact Factor SCImago journal rank indicator Study rank Total rank Orthopaedic rank Value Journal Value Orthopaedic rank Total rank Study rank (n = 18) (n = 6426) (n = 48) (n = 120) (n = 15922) (n = 18) 1 785 2 3.397 *AJSM 0.220 8 788 2 2 1323 3 2.499 *Spine 0.203 - - 3 3 1330 4 2.487 JBJS [Am] 0.237 7 724 1 4 1514 6 2.296 *Arthroscopy 0.164 13 1080 7 5 1818 10 2.021 *ESJ 0.138 22 1281 10 6 1999 11 1.891 CORR 0.177 11 994 4 7 2023 12 1.868 JBJS [Br] 0.174 12 1017 5 8 2280 13 1.692 OCNA 0.162 15 1101 8 9 2376 16 1.626 *KSSTA 0.111 34 1589 14 10 2406 17 1.609 *JoA 0.141 21 1246 9 11 2719 20 1.429 *JOT 0.129 24 1364 11 12 2868 21 1.348 *JSES 0.116 29 1515 12 13 2907 22 1.323 BMC MD 0.169 - 2907 6 14 2996 25 1.285 Acta 0.113 31 1540 13 15 3541 28 1.036 *JPO 0.103 40 1679 15 16 3757 29 0.956 *FAI 0.093 44 1792 16 17 3856 30 0.913 AOTS 0.089 45 1838 17 18 3882 31 0.903 Int Orthop 0.081 50 1965 18 3 1330 4 2.487 JBJS [Am] 0.237 7 1684 1 1 785 2 3.397 *AJSM 0.220 8 1815 2 2 1323 3 2.499 *Spine 0.203 - 1954 3 6 1999 11 1.891 CORR 0.177 11 2217 4 7 2023 12 1.868 JBJS [Br] 0.174 12 2258 5 13 2907 22 1.323 BMC MD 0.169 - 2907 6 4 1514 6 2.296 *Arthroscopy 0.164 13 2394 7 8 2280 13 1.692 OCNA 0.162 15 2431 8 10 2406 17 1.609 *JoA 0.141 21 2743 9 5 1818 10 2.021 *ESJ 0.138 22 2802 10 11 2719 20 1.429 *JOT 0.129 24 2985 11 12 2868 21 1.348 *JSES 0.116 29 3284 12 14 2996 25 1.285 Acta 0.113 31 3338 13 9 2376 16 1.626 *KSSTA 0.111 34 3432 14 15 3541 28 1.036 *JPO 0.103 40 3655 15 16 3757 29 0.956 *FAI 0.093 44 3979 16 17 3856 30 0.913 AOTS 0.089 45 4121 17 18 3882 31 0.903 Int Orthop 0.081 50 4459 18 Acta Orthopaedica (Acta), American Journal of Sports Medicine (AJSM), Arthroscopy, Archives of Orthopaedics and Trauma (AOTS), BMC Musculoskeleletal Disorders (BMC MD), Clinical Orthopaedics and Related Research (CORR), European Spine Journal (ESJ), Foot and Ankle International (FAI), International Orthopaedics (Int Orthop), Journal of Arthroplasty (JOA), the American Volume of Journal of Bone and Joint Surgery (JBJS [Am]), the British volume of Journal of Bone and Joint Surgery (JBJS [Br]), Journal of Orthopaedic Trauma (JOT), Journal of Pediatric Orthopaedics (JPO), Journal of shoulder and elbow surgery (JSES), Knee surgery sports traumatology arthroscopy (KSSTA), Orthopaedic Clinics of North America (OCNA),and Spine. *: Specialized journals are marked with an asterisk. a: Orthopaedic rankings for BMC MD and Spine are not available, as they are not in the same sub-category as the other 16 journals. Siebelt et al. BMC Musculoskeletal Disorders 2010, 11:4 Page 6 of 7 http://www.biomedcentral.com/1471-2474/11/4 Table 4 Comparison of IF and SJR rankings General (n = 8) Specialized (n = 10) st rd st rd 1 Quartile Median 3 Quartile 1 Quartile Median 3 Quartile R 6.25 10.50 16.25 3.50 9.50 12.75 IF R 4.25 7.00 16.00 6.00 10.50 14.25 SJR ΔR=R -R 0.0 1.50 2.00 -3.50 -0.50 0.0 IF SJR Papers published in these specialized journals are likely [Am]: the American Volume of Journal of Bone and to have a high impact in their field of interest [6]. Joint Surgery; JBJS [Br]: the British volume of Journal of Implications of our study Bone and Joint Surgery; JOA: Journal of Arthroplasty; Postma has stated that the impact of evolutionary JOT: Journal of Orthopaedic Trauma; JPO: Journal of papers published in multidisciplinary journals is sub- Pediatric Orthopaedics; JSES: Journal of shoulder and stantially overestimated by their overall impact factor elbow surgery; KSSTA: Knee surgery sports traumatol- and, on the other hand, that the impact of papers in ogy arthroscopy; R :IF ranking; R :SJR ranking; ΔR: IF SJR more specialized journals is significantly underestimated difference between IF and SJR ranking [6]. We agree that the IF has evolved for many users into an indicator of quality for articles, but one should Author details always be aware of the fact that article citation rates 1 Department of Orthopedic Surgery, Reinier de Graaf Groep, P.O. Box 5501, determine the journal impact factor, not vice versa [3]. 2600 GA Delft, The Netherlands. Division of Orthopedic Surgery, McMaster University, Ontario, Canada. Department of Orthopedic Surgery, Onze Lieve The differences found in our analysis of two groups of Vrouwe Gasthuis, Amsterdam, The Netherlands. orthopaedic journals do not represent a difference in quality of articles published in these journals. They con- Authors’ contributions MS: study design; acquisition, analysis and interpretation of data; statistical firm that these groups publish different types of analysis; drafting and revising of the manuscript, read and approved final research, that is, either multidisciplinary or sub-specia- manuscript. TS: study design; acquisition, analysis and interpretation of data; lized orthopaedic literature. statistical analysis; drafting and revising of the manuscript, read and approved final manuscript. PP: study design, data interpretation; revising of The SJR, based on an PageRank algorithm, provides a the manuscript, read and approved final manuscript. RMB: study design, data more sophisticated alternative for the IF and eliminates interpretation; revising of the manuscript, read and approved final the effect of self-citations, which might be desirable if manuscript. MB: study design, data interpretation; revising of the manuscript, read and approved final manuscript. RWP: study design, data interpretation; self-citation is seen as a negative aspect. Our analysis revising of the manuscript, read and approved final manuscript. showed that the SJR bears a high resemblance with the IF, but further enhances differences between general Competing interests The authors declare that they have no competing interests. and specialized literature. As a result of the iterative cal- culation of the SJR, the contrast between both groups of Received: 20 April 2009 literature will increase over time. Accepted: 4 January 2010 Published: 4 January 2010 References Conclusions 1. Science Citation Index, Journal Citation Reports. Institute for Scientific Even though there was no significant correlation Information, Philidelphia, Pennsylvania, USA: 1997. between self-cited rate and IF, there is a strong relation 2. Garfield E: The History and Meaning of the Journal Impact Factor. JAMA 2006, 295(1):90-3. between these both indices. Self-citation indexes tended 3. Seglen PO: Why the impact factor of journals should not be used for to be higher for specialized orthopaedic journals. The evaluating research. BMJ 1997, 314(7079):498-502. SJR corrects for self-citations, which increases the gap in 4. Bosker BH, Verheyen CC: The international rank order of publications in major clinical orthopaedic journals from 2000 to 2004. J Bone Joint Surg overall ranking between specialized and general journals, Br 2006, 88(2):156-8. this reflects a difference in field of interest rather than 5. Falagas ME, Kouranos VD, Arencibia-Jorge R, Karageorgopoulos DE: quality. Comparison of SCImago journal rank indicator with journal impact factor. FASEB J 2008, 22(8):2623-8. 6. Postma E: Inflated impact factors? The true impact of evolutionary List of abbreviations papers in non-evolutionary journals. PLoS ONE 2007, 2(10):e999. IF: Impact Factor; SJR: SCImago Journal Rank Indicator; 7. Bhandari M, Busse J, Devereaux PJ, Montori VM, Swiontkowski M, Tornetta Iii P, Einhorn TA, Khera V, Schemitsch EH: Factors associated with citation Acta: Acta Orthopaedica; AJSM: American Journal of rates in the orthopedic literature. Can J Surg 2007, 50(2):119-23. Sports Medicine; AOTS: Archives of Orthopaedics and 8. SJR – SCImago Journal & Country Rank. http://www.scimagojr.com, Trauma; BMCMD: BMC Musculoskeleletal Disorders; Retrieved January 14, 2009. 9. Hakkalamani S, Rawal A, Hennessy MS, Parkinson RW: The impact factor of CORR: Clinical Orthopaedics and Related Research; ESJ: seven orthopaedic journals: factors influencing it. J Bone Joint Surg Br European Spine Journal; FAI: Foot and Ankle Interna- 2006, 88(2):159-62. tional; Int Orthop: International Orthopaedics; JBJS Siebelt et al. BMC Musculoskeletal Disorders 2010, 11:4 Page 7 of 7 http://www.biomedcentral.com/1471-2474/11/4 10. Fassoulaki A, Paraskeva A, Papilas K, Karabinis G: Self-citations in six anaesthesia journals and their significance in determining the impact factor. Br J Anaesth 2000, 84:266-9. 11. Miguel A, Martí-Bonmatí L: Self-citation: comparison between Radiología, European Radiology and Radiology for 1997-1998. Eur Radiol 2002, 12(1):248-52. 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Citation analysis of orthopaedic literature; 18 major orthopaedic journals compared for Impact Factor and SCImago

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References (17)

Publisher
Springer Journals
Copyright
Copyright © 2010 by Siebelt et al; licensee BioMed Central Ltd.
Subject
Medicine & Public Health; Orthopedics; Rehabilitation; Rheumatology; Sports Medicine; Internal Medicine; Epidemiology
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1471-2474
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10.1186/1471-2474-11-4
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20047693
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Abstract

Background: One of the disadvantages of the Impact Factor (IF) is self-citation. The SCImago Journal Rank (SJR) indicator excludes self-citations and considers the quality, rather than absolute numbers, of citations of a journal by other journals. The present study re-evaluated the influence of self-citation on the 2007 IF for 18 major orthopaedic journals and investigated the difference in ranking between IF and SJR. Methods: The journals were analysed for self-citation both overall and divided into a general group (n = 8) and a specialized group (n = 10). Self-cited and self-citing rates, as well as citation densities and IFs corrected for self- citation (cIF), were calculated. The rankings of the 18 journals by IF and by SJR were compared and the absolute difference between these rankings (ΔR) was determined. Results: Specialized journals had higher self-citing rates (p = 0.01, Δmedian = 9.50, 95%CI -19.42 to 0.42), higher self-cited rates (p = 0.0004, Δmedian = -10.50, 95%CI -15.28 to -5.72) and greater differences between IF and cIF (p = 0.003, Δmedian = 3.50, 95%CI -6.1 to 13.1). There was no significant correlation between self-citing rate and IF for both groups (general: r = 0.46, p = 0.27; specialized: r = 0.21, p = 0.56). When the difference in ranking between IF and SJR was compared between both groups, sub-specialist journals were ranked lower compared to their general counterparts (ΔR: p = 0.006, Δmedian = 2.0, 95%CI -0.39 to 4.39). Conclusions: Citation analysis shows that specialized orthopaedic journals have specific self-citation tendencies. The correlation between self-cited rate and IF in our sample was large but, due to small sample size, not significant. The SJR excludes self-citations in its calculation and therefore enhances the underestimation in ranking of specialized journals. Background to manipulate it. A journal’s IF can be increased artifi- The IF [1] is considered the best reference utensil for cially by using self-citations, publishing relatively many evaluation of scientific journals although its limitations review articles and limiting the number of articles have already been described extensively [2-7]. Major included. points of criticism are the lack of quality assessment for The internet search engine Google™ uses a PageRank citations [5], poor comparability between different algorithm to determine page ranking after a specific domains of interest per journal [6] and the mainly Eng- search query. Several authors have advocated a similar lish language in publications. A major problem with the algorithm for the evaluation of scientific journals. Fala- IF for journals is self-citation, defined in Journal Cita- gas et al. [5] recently described the application of a tion Reports as referring to articles from the same jour- PageRank algorithm to the Scopus database to produce nal [1]. Due to these limitations and the simplicity of the SCImago Journal Rank (SJR) indicator. The SJR calculating the IF, it would be relatively easy for editors represents awarded prestige per article in the analysed year and is calculated using a complicated iterative for- * Correspondence: [email protected] mula. Self-citations do not contribute to the SJR, since a † Contributed equally journal can receive prestige only from other journals, Department of Orthopedic Surgery, Reinier de Graaf Groep, P.O. Box 5501, not from itself [8]. The SJR has several other benefits 2600 GA Delft, The Netherlands © 2010 Siebelt et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Siebelt et al. BMC Musculoskeletal Disorders 2010, 11:4 Page 2 of 7 http://www.biomedcentral.com/1471-2474/11/4 [5], such as the greater number of journals and lan- AJSM articles on a total of 8089 citations; the self-citing guages included in its database and the fact that it is rate was 1542/8089 = 19% (Table 1). open-source software (free of charge). The ratio between the number of self-cited articles in In thepresent studywefirst aimedtoevaluatethe journal X in 2007 and the total amount of citations influence of self-citations on the 2007 IF for 18 major received in 2007 for articles in journal X is the self- orthopaedic journals, including sub-specialist journals. cited rate [1]. For example, AJSM was cited 10,711 These journals publish specialized articles concerning a times in total, of which 1542 by itself; the self-cited rate narrow field of interest and as such are expected to was 1542/10711 = 14% (Table 1). receive relatively few citations from other journals. We The citation density [1] was determined by dividing therefore hypothesized that self-citation rates are higher the total number of references in journal X in 2007 by for specialized journals than for the general orthopaedic the total number of articles published in that journal in literature. Secondly, we investigated ranking of ortho- 2007. For example, the 239 articles published in AJSM paedic journals with the SJR. This indicator excludes in 2007 contained a total of 8089 references; the citation self-citations, therefore we hypothesized that the SJR density was 8089/239 = 34 citations per article (Table ranks specialized journals comparatively lower than does 1). the IF. We retrieved information regarding ranking by SJR via the SCImago journal- and country-rank website devel- Methods oped by the SCImago research group [8]; the journals We included and analyzed 18 orthopaedic journals, were selected by matching international standard serial making a distinction between general and specialized number (ISSN) found in the JCR. Since the IF ranks orthopaedic journals. Two orthopaedic clinicians partici- 6426 journals and the SJR 15,922, absolute rankings by pating in this study individually allocated journals to IF and SJR are not comparable. Therefore only the 18 either the general or the specialized group. journals included in our analysis were mutually ranked The general group included the following journals: for IF (R )and SJR(R ). Thedifferencebetween R IF SJR IF Acta Orthopaedica (Acta), Archives of Orthopaedics and and R , expressed as ΔR, was calculated to check for a SJR Trauma (AOTS), BMC Musculoskeleletal Disorders possible difference between both rankings. (BMCMD), Clinical Orthopaedics and Related Research Statistical analysis (CORR), International Orthopaedics (Int Orthop), the Statistical analysis was performed using Prism v5.00 for American Volume of Journal of Bone and Joint Surgery Windows (Graphpad Software Inc, San Diego, CA, (JBJS [Am]), the British volume of Journal of Bone and USA). Analysing differences between general and specia- Joint Surgery (JBJS [Br]) and Orthopaedic Clinics of lized journals for the IF, the following specifics were North America (OCNA). compared using a Mann-Whitney test: self-citing rate, The specialized orthopaedic journals included in the self-cited rate, citation density, ΔIF, R ,R and ΔR. IF SJR study were: American Journal of Sports Medicine We determined the medians, the first- and third-quartile (AJSM), Arthroscopy, European Spine Journal (ESJ), Foot values, and the difference between the medians (Δmed- and Ankle International (FAI), Journal of Arthroplasty ian = median -median )and theirconfi- general specialized (JOA), Journal of Orthopaedic Trauma (JOT), Journal of dence intervals. A Spearman rank correlation coefficient Pediatric Orthopaedics (JPO), Journal of shoulder and was computed to estimate the correlation between self- elbow surgery (JSES), Knee surgery sports traumatology citing rates and IF, as well as between the journal rank- arthroscopy (KSSTA) and Spine. ings by IF and by SJR. For all tests, p values < 0.05 were For both groups self-citation was analysed for the considered significant. 2007 IF. The self-citing rate, self-cited rate and citation density, parameters known to influence the IF [2], were Results calculated for each of these journals as defined by the Self-citation rates ISI Web of Science [1]. Also, all IF were corrected for The journals with the highest self-citing rates were the influence of self-citations (cIF) [1]; for individual CORR in the general group (15%) and Spine in the spe- journal evaluation, an absolute change of >0.5 in IF (ΔIF cialized group (29%) (Table 1); the lowest rates were for = IF - cIF) was considered substantial. To estimate the BMC MD/OCNA (general group, 1%) and KSSTA/ESJ influence of self-citation on the IF, journals in both (specialized group, 5%). The highest self-cited rates were groups were correlated for self-citing rate and IF. for CORR/Int Orthop (general, 14%) and FAI (specia- The self-citing rate [1] was calculated by dividing the lized, 38%), the lowest rates for OCNA (1%) and JPO number of self-cited articles in journal X in 2007 by the (9%). Arthroscopy (0.75), AJSM (0.67) and Spine (0.63), total amount of citations by that journal in 2007. For all experience substantial declines in IF when corrected example, in 2007 AJSM contained 1542 citations of for self-citation (cIF). Siebelt et al. BMC Musculoskeletal Disorders 2010, 11:4 Page 3 of 7 http://www.biomedcentral.com/1471-2474/11/4 Table 1 Self-citing rate, self-cited rate, citation density and IF 2007 a b c Journal* Self-citing (%) Self-cited (%) Citation density (%) Impact Factor 2007 Corrected IF (cIF) Difference (ΔIF = IF – cIF) General orthopaedic journals Acta 7 5 31 1.285 1.122 0.163 AOTS 2 4 23 0.913 0.873 0.040 BMC MD 1 6 38 1.323 1,226 0.097 CORR 15 8 31 1.891 1.626 0.265 Int Orthop 4 8 22 0.903 0.796 0.107 JBJS [Am] 7 6 36 2.487 2.363 0.124 JBJS [Br] 6 7 28 1.868 1.664 0.204 OCNA 1 1 53 1.692 1.692 0.000 Specialized orthopaedic journals AJSM 19 14 34 3.397 2.731 0.666 Arthroscopy 27 23 22 2.296 1.550 0.746 ESJ 5 17 34 2.021 1.545 0.476 FAI 24 38 23 0.956 0.581 0.375 JoA 14 15 21 1.609 1.403 0.206 JOT 11 13 29 1.429 1.199 0.230 JPO 15 9 34 1.036 0.927 0.109 JSES 14 21 24 1.348 1.158 0.190 KSSTA 5 16 26 1.626 1.314 0.312 Spine 29 20 32 2.499 1.871 0.628 Acta Orthopaedica (Acta), American Journal of Sports Medicine (AJSM), Arthroscopy, Archives of Orthopaedics and Trauma (AOTS), BMC Musculoskeleletal Disorders (BMC MD), Clinical Orthopaedics and Related Research (CORR), European Spine Journal (ESJ), Foot and Ankle International (FAI), International Orthopaedics (Int Orthop), Journal of Arthroplasty (JOA), the American Volume of Journal of Bone and Joint Surgery (JBJS [Am]), the British volume of Journal of Bone and Joint Surgery (JBJS [Br]), Journal of Orthopaedic Trauma (JOT), Journal of Pediatric Orthopaedics (JPO), Journal of shoulder and elbow surgery (JSES), Knee surgery sports traumatology arthroscopy (KSSTA), Orthopaedic Clinics of North America (OCNA),and Spine. p = 0.01, Mann–Whitney between general and specialized journals. p = 0.0004, Mann–Whitney between general and specialized journals. p = 0.003, Mann–Whitney between general and specialized journals. Comparative Ranking: IF versus SCImago (Table 3) Table 2 shows the medians and first- and third-quar- TherankingsbyIFand SJRfor the18 journalsinour tile values of the citation analysis. Specialized journals have significantly higher self-citing rates (Δmedian = analysis are presented in Table 3. For the SJR, an ortho- 9.50, 95%CI -19.42 to 0.42, p = 0.01) and self-cited rates paedic ranking is possible for the sixteen journals repre- (Δmedian = -10.50, 95%CI -15.28 to -5.72, p = 0.0004). sented in the subcategory Medicine: Orthopaedics and Both types of journal tend to use similar numbers of Sport Medicine in the SJR database, but not for BMC citations per published article (Δmedian = 3.50; 95%CI MD (included in the subcategory Medicine: Miscella- -6.1 to 13.1, p = 0.35). The absolute difference between neous)and Spine (included in the subcategory Biochem- IF and cIF proved to be greater for specialized journals istry, Genetics and Molecular Biology). (Δmedian = -0.22; 95%CI -0.45 to -0.01; p = 0.003). In comparing SJR rank relative to IF rank, seven jour- There was no significant correlation between the self- nals maintained their rank (OCNA, JOT, JSES, JPO, FAI, cited rate and the IF for either the general (r = 0.46; p = AOTS, Int Orthop), six improved their rank (JBJS [Am], 0.27) or the specialized group (r = 0.21; p = 0.56) (figure CORR, JBJS [Br], JoA, Acta, BMC MD)and five experi- 1A). enced a decline in rank (AJSM, Spine, Arthroscopy, ESJ, Table 2 Citation analysis for general and specialized journal groups General (n = 8) Specialized (n = 10) 1st Quartile Median 3rd Quartile 1st Quartile Median 3rd Quartile Self-citing rate 1.25 5.00 7.00 9.50 14.50 24.75 Self-cited rate 4.25 6.00 7.75 13.75 16.50 21.50 Citation density 24.25 31.00 37.50 22.75 27.50 34.00 ΔIF 0.05 0.12 0.19 0.20 0.34 0.64 Siebelt et al. BMC Musculoskeletal Disorders 2010, 11:4 Page 4 of 7 http://www.biomedcentral.com/1471-2474/11/4 Figure 1 Correlation Analysis. A: Correlation between self-cited rate (%) and impact factor B: Correlation between IF and SJR KSSTA). The greatest differences between SJR and IF orthopaedic journals. Hakkalamani et al. [9] excluded rank were seen for BMC MD (seven places up in SJR) several journals because of a suspected increased self- and ESJ/KSSTA (four places down). Despite these citation because of subject subspecialty. Applying stan- changes, a strong correlation was found between IF and dard definitions for self-citing rate, self-cited rate and SJR (general: r = 0,98, p < 0.0001) (specialized: r = 0.93, citation index from the ISI Web of Science to these jour- p < 0.0001) (figure 1B). nals, we were able to identify specific citation patterns for Table 4 presents the differences in ranking between specialized journals. Comparison of the Impact Factor both groups, IF (Δmedian = 1.00, 95%CI -7.13 to 9.13, p with the newly introduced SCImago journal rank indica- = 0.41) and for SJR (Δmedian = -3.50, 95%CI -12.2 to tor elucidated whether citation analysis based on a 5.2, p = 0.76). There was a significant difference in ΔR PageRank algorithm provides improved quality assess- between both groups (Δmedian = 2.0, 95%CI -0.39 to ment of orthopaedic literature over journal indicators. 4.39, p = 0.006). A limitation of this study is the evaluation of journal citations for 2007 only, and not for other years of publi- Discussion cation. Furthermore, the distinction made between gen- Key findings eral and specialized journals is arbitrary; however, Our study revealed the following: (1) Specialized jour- distinguishing journal categories by domain of interest is nals receive proportionally more self-citations with a plausible and is coherent with work published previously strong influence on the IF. (2) The SJR shows a strong [9]. Therefore, we believe that applying widely accepted relation with the IF. (3) Correcting for self-citation with methods for citation analysis to our analysis groups gen- the newly introduced SJR results in substantial indivi- erated reliable data. dual changes for journal ranking. (4) Specialized journals Previous Literature tend to drop, whereas general journals will climb, in Self-citation indicators that affect the IF are not limited rank when the SJR is applied instead of IF. to the orthopaedic literature [9]. Similar relations have Group-specific characteristics were clearly visible. Sub- been demonstrated for anaesthesia [10] and radiology specialist journals have higher self-citing (p = 0.01) and [11]. The high self-citation indexes found within these self-cited rates (p = 0.0004), also expressed in a greater specialized fields of medical science prompted sugges- difference between IF and corrected IF for self-citations tions that self-citations should be eliminated from the (p = 0.003). Despite the elaborate iterative calculation of calculation of the IF. However for the 2007 IF in ortho- the SJR, there exists a very strong correlation between paedic literature we did not find a similar distinct influ- IF and SJR ranking (general: r = 0.98, p < 0.0001) (spe- ence of self-citations. The high self-citation indexes for cialized: r = 0.93, p < 0.0001). Comparing the mutual specialized journals relative to general journals rather difference in ranking for SJR and IF between both indicate that these journals serve a small and isolated groups showed an increased contrast (p = 0.003). field within the orthopaedic literature [10]. The question Strength and weaknesses of our study can be posed whether high self-citation rates within a Our study is strengthened by the analysis of two separate specialized domain of interest are indications for low- groups of orthopaedic literature: general and specialized quality publications or rather reflect overall high quality? Siebelt et al. BMC Musculoskeletal Disorders 2010, 11:4 Page 5 of 7 http://www.biomedcentral.com/1471-2474/11/4 Table 3 Comparative rankings of orthopaedic journals by journal impact factor and SCImago journal rank indicator Journal Impact Factor SCImago journal rank indicator Study rank Total rank Orthopaedic rank Value Journal Value Orthopaedic rank Total rank Study rank (n = 18) (n = 6426) (n = 48) (n = 120) (n = 15922) (n = 18) 1 785 2 3.397 *AJSM 0.220 8 788 2 2 1323 3 2.499 *Spine 0.203 - - 3 3 1330 4 2.487 JBJS [Am] 0.237 7 724 1 4 1514 6 2.296 *Arthroscopy 0.164 13 1080 7 5 1818 10 2.021 *ESJ 0.138 22 1281 10 6 1999 11 1.891 CORR 0.177 11 994 4 7 2023 12 1.868 JBJS [Br] 0.174 12 1017 5 8 2280 13 1.692 OCNA 0.162 15 1101 8 9 2376 16 1.626 *KSSTA 0.111 34 1589 14 10 2406 17 1.609 *JoA 0.141 21 1246 9 11 2719 20 1.429 *JOT 0.129 24 1364 11 12 2868 21 1.348 *JSES 0.116 29 1515 12 13 2907 22 1.323 BMC MD 0.169 - 2907 6 14 2996 25 1.285 Acta 0.113 31 1540 13 15 3541 28 1.036 *JPO 0.103 40 1679 15 16 3757 29 0.956 *FAI 0.093 44 1792 16 17 3856 30 0.913 AOTS 0.089 45 1838 17 18 3882 31 0.903 Int Orthop 0.081 50 1965 18 3 1330 4 2.487 JBJS [Am] 0.237 7 1684 1 1 785 2 3.397 *AJSM 0.220 8 1815 2 2 1323 3 2.499 *Spine 0.203 - 1954 3 6 1999 11 1.891 CORR 0.177 11 2217 4 7 2023 12 1.868 JBJS [Br] 0.174 12 2258 5 13 2907 22 1.323 BMC MD 0.169 - 2907 6 4 1514 6 2.296 *Arthroscopy 0.164 13 2394 7 8 2280 13 1.692 OCNA 0.162 15 2431 8 10 2406 17 1.609 *JoA 0.141 21 2743 9 5 1818 10 2.021 *ESJ 0.138 22 2802 10 11 2719 20 1.429 *JOT 0.129 24 2985 11 12 2868 21 1.348 *JSES 0.116 29 3284 12 14 2996 25 1.285 Acta 0.113 31 3338 13 9 2376 16 1.626 *KSSTA 0.111 34 3432 14 15 3541 28 1.036 *JPO 0.103 40 3655 15 16 3757 29 0.956 *FAI 0.093 44 3979 16 17 3856 30 0.913 AOTS 0.089 45 4121 17 18 3882 31 0.903 Int Orthop 0.081 50 4459 18 Acta Orthopaedica (Acta), American Journal of Sports Medicine (AJSM), Arthroscopy, Archives of Orthopaedics and Trauma (AOTS), BMC Musculoskeleletal Disorders (BMC MD), Clinical Orthopaedics and Related Research (CORR), European Spine Journal (ESJ), Foot and Ankle International (FAI), International Orthopaedics (Int Orthop), Journal of Arthroplasty (JOA), the American Volume of Journal of Bone and Joint Surgery (JBJS [Am]), the British volume of Journal of Bone and Joint Surgery (JBJS [Br]), Journal of Orthopaedic Trauma (JOT), Journal of Pediatric Orthopaedics (JPO), Journal of shoulder and elbow surgery (JSES), Knee surgery sports traumatology arthroscopy (KSSTA), Orthopaedic Clinics of North America (OCNA),and Spine. *: Specialized journals are marked with an asterisk. a: Orthopaedic rankings for BMC MD and Spine are not available, as they are not in the same sub-category as the other 16 journals. Siebelt et al. BMC Musculoskeletal Disorders 2010, 11:4 Page 6 of 7 http://www.biomedcentral.com/1471-2474/11/4 Table 4 Comparison of IF and SJR rankings General (n = 8) Specialized (n = 10) st rd st rd 1 Quartile Median 3 Quartile 1 Quartile Median 3 Quartile R 6.25 10.50 16.25 3.50 9.50 12.75 IF R 4.25 7.00 16.00 6.00 10.50 14.25 SJR ΔR=R -R 0.0 1.50 2.00 -3.50 -0.50 0.0 IF SJR Papers published in these specialized journals are likely [Am]: the American Volume of Journal of Bone and to have a high impact in their field of interest [6]. Joint Surgery; JBJS [Br]: the British volume of Journal of Implications of our study Bone and Joint Surgery; JOA: Journal of Arthroplasty; Postma has stated that the impact of evolutionary JOT: Journal of Orthopaedic Trauma; JPO: Journal of papers published in multidisciplinary journals is sub- Pediatric Orthopaedics; JSES: Journal of shoulder and stantially overestimated by their overall impact factor elbow surgery; KSSTA: Knee surgery sports traumatol- and, on the other hand, that the impact of papers in ogy arthroscopy; R :IF ranking; R :SJR ranking; ΔR: IF SJR more specialized journals is significantly underestimated difference between IF and SJR ranking [6]. We agree that the IF has evolved for many users into an indicator of quality for articles, but one should Author details always be aware of the fact that article citation rates 1 Department of Orthopedic Surgery, Reinier de Graaf Groep, P.O. Box 5501, determine the journal impact factor, not vice versa [3]. 2600 GA Delft, The Netherlands. Division of Orthopedic Surgery, McMaster University, Ontario, Canada. Department of Orthopedic Surgery, Onze Lieve The differences found in our analysis of two groups of Vrouwe Gasthuis, Amsterdam, The Netherlands. orthopaedic journals do not represent a difference in quality of articles published in these journals. They con- Authors’ contributions MS: study design; acquisition, analysis and interpretation of data; statistical firm that these groups publish different types of analysis; drafting and revising of the manuscript, read and approved final research, that is, either multidisciplinary or sub-specia- manuscript. TS: study design; acquisition, analysis and interpretation of data; lized orthopaedic literature. statistical analysis; drafting and revising of the manuscript, read and approved final manuscript. PP: study design, data interpretation; revising of The SJR, based on an PageRank algorithm, provides a the manuscript, read and approved final manuscript. RMB: study design, data more sophisticated alternative for the IF and eliminates interpretation; revising of the manuscript, read and approved final the effect of self-citations, which might be desirable if manuscript. MB: study design, data interpretation; revising of the manuscript, read and approved final manuscript. RWP: study design, data interpretation; self-citation is seen as a negative aspect. Our analysis revising of the manuscript, read and approved final manuscript. showed that the SJR bears a high resemblance with the IF, but further enhances differences between general Competing interests The authors declare that they have no competing interests. and specialized literature. As a result of the iterative cal- culation of the SJR, the contrast between both groups of Received: 20 April 2009 literature will increase over time. Accepted: 4 January 2010 Published: 4 January 2010 References Conclusions 1. Science Citation Index, Journal Citation Reports. Institute for Scientific Even though there was no significant correlation Information, Philidelphia, Pennsylvania, USA: 1997. between self-cited rate and IF, there is a strong relation 2. Garfield E: The History and Meaning of the Journal Impact Factor. JAMA 2006, 295(1):90-3. between these both indices. Self-citation indexes tended 3. Seglen PO: Why the impact factor of journals should not be used for to be higher for specialized orthopaedic journals. The evaluating research. BMJ 1997, 314(7079):498-502. SJR corrects for self-citations, which increases the gap in 4. Bosker BH, Verheyen CC: The international rank order of publications in major clinical orthopaedic journals from 2000 to 2004. J Bone Joint Surg overall ranking between specialized and general journals, Br 2006, 88(2):156-8. this reflects a difference in field of interest rather than 5. Falagas ME, Kouranos VD, Arencibia-Jorge R, Karageorgopoulos DE: quality. Comparison of SCImago journal rank indicator with journal impact factor. FASEB J 2008, 22(8):2623-8. 6. Postma E: Inflated impact factors? The true impact of evolutionary List of abbreviations papers in non-evolutionary journals. PLoS ONE 2007, 2(10):e999. IF: Impact Factor; SJR: SCImago Journal Rank Indicator; 7. Bhandari M, Busse J, Devereaux PJ, Montori VM, Swiontkowski M, Tornetta Iii P, Einhorn TA, Khera V, Schemitsch EH: Factors associated with citation Acta: Acta Orthopaedica; AJSM: American Journal of rates in the orthopedic literature. Can J Surg 2007, 50(2):119-23. Sports Medicine; AOTS: Archives of Orthopaedics and 8. SJR – SCImago Journal & Country Rank. http://www.scimagojr.com, Trauma; BMCMD: BMC Musculoskeleletal Disorders; Retrieved January 14, 2009. 9. Hakkalamani S, Rawal A, Hennessy MS, Parkinson RW: The impact factor of CORR: Clinical Orthopaedics and Related Research; ESJ: seven orthopaedic journals: factors influencing it. J Bone Joint Surg Br European Spine Journal; FAI: Foot and Ankle Interna- 2006, 88(2):159-62. tional; Int Orthop: International Orthopaedics; JBJS Siebelt et al. BMC Musculoskeletal Disorders 2010, 11:4 Page 7 of 7 http://www.biomedcentral.com/1471-2474/11/4 10. Fassoulaki A, Paraskeva A, Papilas K, Karabinis G: Self-citations in six anaesthesia journals and their significance in determining the impact factor. Br J Anaesth 2000, 84:266-9. 11. Miguel A, Martí-Bonmatí L: Self-citation: comparison between Radiología, European Radiology and Radiology for 1997-1998. Eur Radiol 2002, 12(1):248-52. Pre-publication history The pre-publication history for this paper can be accessed here:http://www. biomedcentral.com/1471-2474/11/4/prepub doi:10.1186/1471-2474-11-4 Cite this article as: Siebelt et al.: Citation analysis of orthopaedic literature; 18 major orthopaedic journals compared for Impact Factor and SCImago. BMC Musculoskeletal Disorders 2010 11:4. Publish with Bio Med Central and every scientist can read your work free of charge "BioMed Central will be the most significant development for disseminating the results of biomedical researc h in our lifetime." Sir Paul Nurse, Cancer Research UK Your research papers will be: available free of charge to the entire biomedical community peer reviewed and published immediately upon acceptance cited in PubMed and archived on PubMed Central yours — you keep the copyright BioMedcentral Submit your manuscript here: http://www.biomedcentral.com/info/publishing_adv.asp

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