Racial and ethnic variation in the prevalence of knee osteoarthritis among older U.S. adults, including Asian ethnic populations

Objective: National surveys suggest that US Asian adults have lower prevalence of osteoarthritis compared to White and Black adults, but disaggregated subgroup data are limited. This study examined the burden of knee osteoarthritis among older US adults by race and ethnicity, including Asian subgroup differences. Design: Data from a large integrated healthcare delivery system in northern California were used to identify adults aged 50-89 years during 2017-2019 who had body mass index (BMI) measured. Knee osteoarthritis was defined by ≥ 2 diagnoses (ICD-10 M17.x) during 2017-2019. The association of race/ethnicity and prevalence of knee osteoarthritis was examined using modified Poisson regression, adjusting for age and BMI level. Results: Among 1,183,576 adults (mean age 64.3 ± 9.6 years; 54.3 % female; 54.7 % White, 17.8 % Asian/Pacific Islander, 11.9 % Hispanic, and 6.7 % Black), 101,959 (8.6 %) had diagnosed knee osteoarthritis. For males, prevalence of knee osteoarthritis was higher for South Asian (adjusted prevalence ratio, aPR 1.51), modestly higher for Black (aPR 1.16), and similar or lower for Vietnamese, Chinese, Japanese, Filipino, Hispanic, and Native Hawaiian/Pacific Islander (NHPI) (aPRs 0.70-1.05) versus White males. For females, prevalence was higher for South Asian (aPR 2.15), modestly or somewhat higher for Hispanic, Filipina, Vietnamese, and Black (aPRs 1.14-1.32), and similar or lower for Japanese, Chinese, and NHPI (aPRs 0.77-1.05) versus White females. Conclusions: Knee osteoarthritis prevalence varied substantially by race/ethnicity with marked differences among Asian subgroups. Notably, prevalence was 1.5-to-2-fold higher for South Asian compared to White adults, surpassing Black adults. Delineation of reasons underlying higher knee osteoarthritis burden among high-risk ethnic populations is needed.