The incidence and characteristics of accelerated knee osteoarthritis among women: the Chingford cohort

Background Prior research on accelerated knee osteoarthritis (AKOA) was primarily confined to the Osteoarthritis Initiative, which was enriched with people with risk factors for knee osteoarthritis (KOA). It is unclear how often AKOA develops in a community-based cohort and whether we can replicate prior findings from the Osteoarthritis Initiative in another cohort. Hence, we determined the incidence and characteristics of AKOA among women in the Chingford Study, which is a prospective community-based cohort. Methods The Chingford Study had 1003 women with quinquennial knee radiographs over 15 years. We divided the 15-year observation period into three consecutive 5-year phases. Within each 5-year phase, we selected 3 groups of participants among women who started a phase without KOA (Kellgren-Lawrence [KL] < 2): 1) incident AKOA developed KL grade >= 3, 2) typical KOA increased radiographic scoring (excluding AKOA), and 3) no KOA had the same KL grade over time. Study staff recorded each participant's age, body mass index (BMI), and blood pressure at baseline, 5-year, and 10-year study visits. We used multinomial logistic regression models to test the association between groups (outcome) and age, BMI, and blood pressure at the start of each phase. The cumulative incidences and odds ratios (OR) from each phase were pooled using a fixed-effect meta-analysis model. Results The person-based cumulative incidence of AKOA was 3.9% over 5 years (pooled estimate across the three 5-year phases). Among incident cases of KOA, AKOA represented similar to 15% of women with incident KOA. Women with AKOA were older than those with typical (OR = 1.56, 95%CI = 1.16-2.11) or no KOA (OR = 1.84, 95%CI = 1.40-2.43). Women with AKOA had a greater BMI than those without KOA (OR = 1.52, 95%CI = 1.17-1.97). We observed no association between group and blood pressure. Conclusions In a community-based cohort, > 1 in 7 women with incident KOA had AKOA. Like the Osteoarthritis Initiative, people with AKOA were more likely to have greater age and BMI.