TY - JOUR
AU - Apple, Fred, S
AB - To the Editor: We previously reported on the use of B-type natriuretic peptide (BNP) testing in the 400-bed Hennepin County Medical Center at the inception of testing in August 2001 (1). We now describe its use and report the agreement of the results with diagnoses in the patient records in this urban teaching hospital 4 years later. We queried all BNP orders for June through August 2005 and found 975 test orders on 608 patients. To determine a diagnosis of heart failure, physician discharge dictations and ICD-9 codings were reviewed after Institutional Review Board approval. Final diagnoses were likely influenced by the BNP concentrations in some cases, potentially leading to overestimation of apparent diagnostic accuracy. The Biosite Triage and Beckman Coulter Access BNP assays were performed according to the manufacturers’ guidelines and were highly correlated (r = 0.99; n = 50), with Bland–Altman analysis demonstrating a mean (SD) difference of 16 (23) ng/L. Total imprecision (CV) near the 100 ng/L cutoff was <12% for both assays. In 2001, most BNP tests were requested by the emergency department (44%) and cardiology units (41%), noncardiac intensive care unit (ICU; 3.6%), general medicine (3.5%), and miscellaneous clinics (4.1%) (1). In 2005, the emergency department ordered 41% and the cardiology units only 10%, diluted by the increase in test utilization by noncardiac ICUs (16%), general medicine units (15%), miscellaneous clinics (13%), cardiology clinics (3.5%), and miscellaneous inpatient services (1.2%; Table 11 ). Thirty percent of patients had a diagnosis of heart failure, and 70% did not. One half (50%) of the group were female. The mean (SD) ages of the heart failure and non-heart failure groups were 63 (15) and 58 (16) years, respectively (P <0.01). The median (interquartile range) BNP concentration was significantly greater for heart failure patients than for non-heart failure patients [482 (13–1024) ng/L vs 61 (5–161) ng/L, respectively; P <0.01]. BNP was increased (≥100 ng/L) in 92.8% of patients with a diagnosis of heart failure and was within reference values in 53.6% of those without heart failure. In patients without a diagnosis of heart failure, 272 BNP tests had values ≥100 ng/L, representing 28% of ordered tests in these patients (without heart failure). Many of these patients had renal, other cardiovascular, pulmonary, or liver disease and/or multisystem pathology, which can also increase BNP. In patients with a diagnosis of heart failure, 28 BNP results were <100 ng/L. Possible explanations include confounding variables such as vasodilator administration, acute dehydration, and/or intravenous diuresis. In addition, age- and sex-specific reference cutoffs were not used. A variety of in- and outpatient services now use BNP to assist in decision-making (Table 11 ). When the diagnostic accuracy of BNP testing in a large prospective trial was first reported in 2002, the overall test sensitivity and specificity were 90% and 76%, respectively (2). Similarly, we reported an apparent sensitivity and specificity of 94.8% and 77.1%, respectively (1). In the present report, BNP was increased in 92.8% of patients with a diagnosis of heart failure, suggesting that the sensitivity of the test remains high, but BNP was also high in >28% of patients who did not carry a heart failure diagnosis, suggesting that test specificity was much lower than 76%–77%. Although BNP was ≥100 ng/L in most patients with heart failure regardless of ordering location, it was also ≥100 ng/L in many patients without diagnosed heart failure, and this rate varied among locations (Table 11 ). Most astounding was the noncardiac ICU, where the test was positive in >90% of patients without a discharge diagnosis of heart failure. Many of the patients in the ICU had acute and/or chronic renal failure, volume overload, and/or multisystem organ failure, which increased BNP test results in the absence of CHF. Many BNP tests were ordered on ICU patients whose admission notes indicated a history of renal failure. Our previous study examined test utilization during a familiarization period, when a majority of physicians ordering tests likely had formal interactions with laboratory medicine and/or cardiology staff to guide appropriate use and interpretation of the newly implemented test (1). In the current study period, fewer physicians ordering tests had formal opportunities to review test utilization criteria. Thus, we suggest that physician education is an important component for maintaining test accuracy and appropriate use. Given that our hospital trains resident physicians, leading to a high annual provider turnover, we propose periodic utilization reviews and refresher training for BNP and other tests. These measures could serve to maximize test accuracy, mitigate test overuse, enhance physician education, and improve patient care. Table 1. Results of BNP testing in a community hospital. Physician orders . Patients with HF,1 n . CHF patients with BNP ≥100 ng/L,2 . Patients without CHF, n . Non-CHF patients with BNP <100 ng/L,2% . Year  2001 (n = 430; 54 tests/month) 172 94.8 (91.3–96.9) 162 77.1 (70.6–82.7)  2005 (n = 975; 325 tests/month) 186 92.8 (89.8–95.0) 422 53.6 (49.5–57.6) Location  Emergency department (n = 396) 89 92.6 (87.2–95.8) 209 68.1 (62.1–73.6)  Cardiology (n = 100) 22 93.9 (85.4–97.5) 24 44.1 (28.8–60.6)  Noncardiac ICU (n = 158) 10 92.1 (79.1–97.1) 42 9.2 (5.2–15.7)  General medicine (n = 148) 27 94.9 (87.7–97.9) 50 46.4 (35.1–58.0)  Miscellaneous clinics (n = 127) 21 90.3 (75.0–96.5) 82 79.2 (70.0–86.1)  Cardiology clinic (n = 34) 14 87.0 (67.6–95.3) 10 72.7 (42.8–90.0)  Miscellaneous inpatient services (n = 12) 3 100.0 (54.1–99.6) 5 28.6 (8.5–65.1) Physician orders . Patients with HF,1 n . CHF patients with BNP ≥100 ng/L,2 . Patients without CHF, n . Non-CHF patients with BNP <100 ng/L,2% . Year  2001 (n = 430; 54 tests/month) 172 94.8 (91.3–96.9) 162 77.1 (70.6–82.7)  2005 (n = 975; 325 tests/month) 186 92.8 (89.8–95.0) 422 53.6 (49.5–57.6) Location  Emergency department (n = 396) 89 92.6 (87.2–95.8) 209 68.1 (62.1–73.6)  Cardiology (n = 100) 22 93.9 (85.4–97.5) 24 44.1 (28.8–60.6)  Noncardiac ICU (n = 158) 10 92.1 (79.1–97.1) 42 9.2 (5.2–15.7)  General medicine (n = 148) 27 94.9 (87.7–97.9) 50 46.4 (35.1–58.0)  Miscellaneous clinics (n = 127) 21 90.3 (75.0–96.5) 82 79.2 (70.0–86.1)  Cardiology clinic (n = 34) 14 87.0 (67.6–95.3) 10 72.7 (42.8–90.0)  Miscellaneous inpatient services (n = 12) 3 100.0 (54.1–99.6) 5 28.6 (8.5–65.1) 1 HF, heart failure; CHF, congestive heart failure. 2 Values in parentheses are the 95% confidence interval. Table 1. Results of BNP testing in a community hospital. Physician orders . Patients with HF,1 n . CHF patients with BNP ≥100 ng/L,2 . Patients without CHF, n . Non-CHF patients with BNP <100 ng/L,2% . Year  2001 (n = 430; 54 tests/month) 172 94.8 (91.3–96.9) 162 77.1 (70.6–82.7)  2005 (n = 975; 325 tests/month) 186 92.8 (89.8–95.0) 422 53.6 (49.5–57.6) Location  Emergency department (n = 396) 89 92.6 (87.2–95.8) 209 68.1 (62.1–73.6)  Cardiology (n = 100) 22 93.9 (85.4–97.5) 24 44.1 (28.8–60.6)  Noncardiac ICU (n = 158) 10 92.1 (79.1–97.1) 42 9.2 (5.2–15.7)  General medicine (n = 148) 27 94.9 (87.7–97.9) 50 46.4 (35.1–58.0)  Miscellaneous clinics (n = 127) 21 90.3 (75.0–96.5) 82 79.2 (70.0–86.1)  Cardiology clinic (n = 34) 14 87.0 (67.6–95.3) 10 72.7 (42.8–90.0)  Miscellaneous inpatient services (n = 12) 3 100.0 (54.1–99.6) 5 28.6 (8.5–65.1) Physician orders . Patients with HF,1 n . CHF patients with BNP ≥100 ng/L,2 . Patients without CHF, n . Non-CHF patients with BNP <100 ng/L,2% . Year  2001 (n = 430; 54 tests/month) 172 94.8 (91.3–96.9) 162 77.1 (70.6–82.7)  2005 (n = 975; 325 tests/month) 186 92.8 (89.8–95.0) 422 53.6 (49.5–57.6) Location  Emergency department (n = 396) 89 92.6 (87.2–95.8) 209 68.1 (62.1–73.6)  Cardiology (n = 100) 22 93.9 (85.4–97.5) 24 44.1 (28.8–60.6)  Noncardiac ICU (n = 158) 10 92.1 (79.1–97.1) 42 9.2 (5.2–15.7)  General medicine (n = 148) 27 94.9 (87.7–97.9) 50 46.4 (35.1–58.0)  Miscellaneous clinics (n = 127) 21 90.3 (75.0–96.5) 82 79.2 (70.0–86.1)  Cardiology clinic (n = 34) 14 87.0 (67.6–95.3) 10 72.7 (42.8–90.0)  Miscellaneous inpatient services (n = 12) 3 100.0 (54.1–99.6) 5 28.6 (8.5–65.1) 1 HF, heart failure; CHF, congestive heart failure. 2 Values in parentheses are the 95% confidence interval. M.L. received funding from the Mayo Endowment. F.A. has received honoraria and research funding from Biosite and Beckman Coulter. 1 Apple FS, Trinity E, Steen J, Prawer S, Wu AH. BNP test utilization for CHF in community hospital practice. Clin Chim Acta 2003 ; 328 : 191 -193. 2 Maisel AS, Krishnaswamy P, Nowak RM, McCord J, Hollander JE, Duc P, et al. Rapid measurement of B-type natriuretic peptide in the emergency diagnosis of heart failure. N Engl J Med 2002 ; 347 : 161 -167. © 2006 The American Association for Clinical Chemistry This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model)
TI - Use of B-Type Natriuretic Peptide Testing in a Community Teaching Hospital 4 Years After Implementation and Agreement of Results with Discharge Diagnoses
JF - Clinical Chemistry
DO - 10.1373/clinchem.2005.063404
DA - 2006-04-01
UR - https://www.deepdyve.com/lp/oxford-university-press/use-of-b-type-natriuretic-peptide-testing-in-a-community-teaching-V0tOVfreZn
SP - 767
VL - 52
IS - 4
DP - DeepDyve
ER -