Hormone therapy and oral contraceptives in the risk of knee osteoarthritis: a prospective cohort study.

OBJECTIVE

To evaluate the association of hormone therapy (HT) and oral contraceptives (OC) with the risk of knee osteoarthritis (KOA).

METHODS

Using data from the UK Biobank, we included 211,345 women (mean 56.5 y) who were free of KOA and had self-reported data on the use of HT and OC at baseline. The outcome was an incident KOA during the follow-up. Cox regression models were used to evaluate the association of the status (never, former, current) and duration of HT and OC use with the risk of KOA. We also assessed the association between specific exogenous sex hormones and the risk of KOA.

RESULTS

During a median follow-up of 13.6 years, 14,878 (7.0%) women developed KOA. Compared with women who had never used HT, both former and current users had an increased risk of KOA [former: hazard ratio (HR)=1.25, 95% CI: 1.20-1.31; current: HR=1.46, 95% CI: 1.35-1.58; Ptrend <0.001). There was a dose-responsive association between the duration of HT use and the risk of KOA (HR=1.20-1.43, Ptrend <0.001). Former use of OC increased KOA risk only in women <60 years (HR=1.15, 95% CI: 1.04-1.27). In addition, both estrogen and progestogen and their combination were associated with an increased risk of KOA (HR=1.33-1.47).

CONCLUSIONS

There is a dose-responsive association between the duration of HT use and the risk of KOA among middle-aged and older women. History of OC use may increase the risk of KOA in women younger than 60 years.