Incidence of cardiovascular events in polymyalgia
rheumatica and giant cell arteritis amongst an Asian
population: Propensity score matched cohort study
and Nagato KURIYAMA
Division of General Internal Medicine, Department of Medicine,
Center for Clinical Epidemiology, St. Luke’s International
Fujita Health University, Toyoake,
Division of Rheumatology, JR Tokyo General Hospital, Tokyo, and
Department of Epidemiology for Community Health and Medicine, Kyoto Prefectural University of Medicine, Kyoto, Japan
Background: The hypothesis that patients with polymyalgia rheumatica (PMR) or giant cell arteritis (GCA) have
a high risk for future cardiovascular diseases has not been adequately tested. The aim of this study is to evaluate
this hypothesis in Japan, where the prevalence and severity of PMR and GCA are the lowest.
Methods: A propensity score matched cohort study was conducted at St. Luke’s International Hospital, Tokyo,
Japan, from 2003 to 2016. We included all patients who were diagnosed as PMR or GCA cases and matched
comparators with a proportion of 1 : 2. Our primary outcome was newly diagnosed cardiovascular disease. The
propensity score was calculated using logistic regression with forward stepwise selection in 30 variables. Kaplan–
Meier curves were drawn and the log-rank test and Cox proportional hazard model were performed for survival
analyses. Two types of sensitivity analyses were conducted to conﬁrm the results.
Results: Among 2461 potential patients, the propensity score identiﬁed 504 (168 cases and 336 comparators)
patients. During follow up (median 839.5 days), 110 (21.8%) developed cardiovascular diseases. The Kaplan–
Meier curves between those with and without PMR or GCA were not signiﬁcantly different (P = 0.85). The Cox
proportional hazard model calculated the hazard ratio (HR) of those with PMR or GCA compared to those with-
out as 0.96 (95% CI: 0.64–1.46). The results from sensitivity analyses were consistent (HR 0.70–1.06).
Conclusion: Patients with PMR or GCA may not have a higher risk of future cardiovascular diseases among the
Japanese population. The sensitivity analyses and sample size calculation supported the results.
Key words: cardiovascular events, GCA, PMR, propensity score.
Polymyalgia rheumatica (PMR) is a relatively common
disease worldwide. In the USA, more than 700 million
patients suffer from PMR
and the lifetime risks for
developing PMR were estimated at approximately 1.7%
for men and 2.4% for women, respectively.
the number of patients in Japan is less than those of
the number of patients with
PMR is still considerable. It was reported that the inci-
dence rate in Japan was the lowest in the world,
that in other countries it was 12.7–68.3 per 100 000
Giant cell arteritis (GCA) is a well-known
comorbidity for PMR, and it was reported that approxi-
mately 20% of those with PMR had GCA, whereas 50%
of those with GCA had PMR.
Similar to PMR, the
incidence rate of GCA in Japan is quite low at the level
of 1.47 per 100 000 people and only 30.6% of those
Correspondence: Daiki Kobayashi, MD, MPH, MBA, Division of
General Internal Medicine, Department of Medicine, St. Luke’s
International Hospital, Tokyo, Japan. Email: email@example.com
© 2018 Asia Paciﬁc League of Associations for Rheumatology and John Wiley & Sons Australia, Ltd
International Journal of Rheumatic Diseases 2018; 21: 1314–1321