A REVIEW OF POSTMENOPAUSAL HORMONE-THERAPY RECOMMENDATIONS - POTENTIAL FOR SELECTION BIAS

Objective: To survey the advice given to physicians in regard to postm enopausal hormone therapy, and thus to find out indirectly whether sel ective prescribing may have contributed to the findings of health effe cts. Data sources: Surveys on the health benefits of postmenopausal th erapy were identified from previous reviews. Experts in various fields were consulted regarding relevant textbooks, and recommended booklist s were used. Methods of study selection: Most of the surveys were cond ucted in the United States and concerned only estrogens; therefore, we focused on these data. Advice given to United States physicians on es trogen prescribing was abstracted from the Physicians' Desk Reference, five textbooks, and other sources written between 1945-1990. Data ext raction and synthesis: In advice given to physicians, there was concer n that estrogens could cause cancer. In addition, it was not recommend ed to give estrogens to women in poor general health. Advice concernin g cardiovascular diseases and estrogens was contradictory and variable . Conclusions: If the advice observed reflects the prescribing practic es of physicians, then surveys on the health impact of estrogen therap y may have underestimated the risk of breast cancer and overestimated the prevention of fractures. The impact on studies of cardiovascular d iseases is less clear, and other mechanisms of selection bias may have been more important.