LOS ANGELES — Physicians and patients are less likely to favor bisphosphonate therapy for osteoporosis when efficacy is expressed in terms of absolute risk reduction, as health literacy experts recommend, rather than relative risk reduction, Dr. Christine A. Sinsky reported at the annual meeting of the Society of General Internal Medicine.
Despite the widespread use of relative risk reduction (RRR) values to describe the benefits of osteoporosis therapy, health literacy experts favor focusing on absolute risk reduction (ARR). That's because RRR tends to overstate risk reduction when there is a low baseline frequency of a condition, such as hip fracture in osteoporosis, said Dr. Sinsky, an internist in private practice in Dubuque, Iowa.
Data cited by the U.S. Preventive Services Task Force (USPSTF) suggest that after 5 years of treatment with bisphosphonates, the RRR for hip fracture is 35%, while the absolute risk of fracture in the at-risk population decreases from 3% to 2%, yielding a 1% ARR (Ann. Int. Med. 2002;137:526–8).
Investigators administered a 10-item questionnaire to 641 consecutive female patients (aged 50 years or older) and all general medicine physicians at a university-based practice and a community practice. The patients were asked: “You have a bone density test that indicates osteoporosis. You have full drug coverage. Are you interested in treatment?” The physicians were asked: “Your 65-year-old patient has a [dual-energy x-ray absorptiometry] scan that indicates osteoporosis. The patient has full drug coverage. Would you recommend treatment?” Other scenarios presented out-of-pocket costs to the patient ranging from 0% to 90%. Subsequent questions presented similar scenarios but with efficacy of treatment presented as either RRR or ARR.
When treatment benefit was presented as RRR, 86% of patients expressed interest, which was significantly higher than the 57% rate when benefit was expressed as ARR. Similarly, physicians were significantly more likely to recommend osteoporosis treatment for their patients when treatment benefits were presented as RRR (97%) as opposed to ARR (53%). One limitation of the study is that patients may not have understood the clinical consequences of hip fractures, Dr. Sinsky noted.