The effect of patients' sex on physicians' recommendations for total knee arthroplasty.

BACKGROUND The underuse of total joint arthroplasty in appropriate candidates is more than 3 times greater among women than among men. When surveyed, physicians report that the patient's sex has no effect on their decision-making; however, what occurs in clinical practice may be different. The purpose of our study was to determine whether patients' sex affects physicians' decisions to refer a patient for, or to perform, total knee arthroplasty. METHODS Seventy-one physicians (38 family physicians and 33 orthopedic surgeons) in Ontario performed blinded assessments of 2 standardized patients (1 man and 1 woman) with moderate knee osteoarthritis who differed only by sex. The standardized patients recorded the physicians' final recommendations about total knee arthroplasty. Four surgeons did not consent to the inclusion of their data. After detecting an overall main effect, we tested for an interaction with physician type (family physician v. orthopedic surgeon). We used a binary logistic regression analysis with a generalized estimating equation approach to assess the effect of patients' sex on physicians' recommendations for total knee arthroplasty. RESULTS In total, 42% of physicians recommended total knee arthroplasty to the male but not the female standardized patient, and 8% of physicians recommended total knee arthroplasty to the female but not the male standardized patient (odds ratio [OR] 4.2, 95% confidence interval [CI] 2.4-7.3, p < 0.001; risk ratio [RR] 2.1, 95% CI 1.5-2.8, p < 0.001). The odds of an orthopedic surgeon recommending total knee arthroplasty to a male patient was 22 times (95% CI 6.4-76.0, p < 0.001) that for a female patient. The odds of a family physician recommending total knee arthroplasty to a male patient was 2 times (95% CI 1.04-4.71, p = 0.04) that for a female patient. INTERPRETATION Physicians were more likely to recommend total knee arthroplasty to a male patient than to a female patient, suggesting that gender bias may contribute to the sex-based disparity in the rates of use of total knee arthroplasty.