ESTROGEN REPLACEMENT THERAPY AND WORSENING OF RADIOGRAPHIC KNEE OSTEOARTHRITIS

Objective. To examine whether estrogen replacement therapy (ERT) preve nts worsening of radiographic knee osteoarthritis (OA) in elderly wome n, Methods. A total of 551 women ages 63-91 years (mean age 71) in the Framingham Study were followed up from biennial examination 18 (1983- 1985) to examination 22 (1992-1993), Data on postmenopausal ERT were o btained every 2 a-ears. Subjects were classified into 3 groups accordi ng to their estrogen use at biennial examination 18: never users (n = 349), past users (n 162), and current users (n = 40), Women received a nteroposterior weight-bearing knee radiographs at examinations 18 and 22, Using the Kellgren and Lawrence criteria, global radiographic knee OA was assessed, (grade range 0-4) and individual radiographic featur es, such as osteophytes and joint space narrowing, were scored from 0 to 3, Worsening was defined as either development of radiographic OA t hat was not present at baseline (incident OA) or progression of baseli ne radiographic OA by greater than or equal to 1 Kellgren and Lawrence grade (progressive OA). Potential confounding factors included age, b ody mass index, weight change, smoking, knee injury, physical activity level, and bone mineral density at the femoral neck. Results. During 8 Sears of followup, 17.4% of knee radiographic scores worsened by I g rade and 5.8% by 2 or 3 grades among never users of ERT, Among current estrogen users, only 11.7% of knee radiographic scores worsened by 1 grade and none worsened by more than I grade. After adjusting for age and other potential confounding factors, the relative risk of incident radiographic knee OA in comparison with never users of estrogen was 0 .8 (95% confidence interval [95% CI] 0.5-1.4) in past users and 0.4 (9 5% 0.1-3.0) in current users. Current use of estrogen also showed a tr end toward decreased risk of progressive knee OA compared with never u se (odds ratio [OR] 0.5, 95% CI 0.1-2.9), When both incident and progr essive radiographic knee OA cases were combined, current ERT use had a 60% decreased risk compared with never use (OR 0.4, 95% CI 0.1-1.5), Conclusion. This is the first prospective cohort study to examine the effects of ERT on radiographic knee OA, The results indicate that curr ent use of ERT had a moderate, but not statistically significant, prot ective effect against worsening of radiographic knee OA among elderly white women. These findings corroborate those of cross-sectional studi es and point further to a potential benefit of female hormones in OA.