Cohort study of the association of hypnotic use with mortality in postmenopausal women

OBJECTIVE Previous studies found an association between hypnotic use and mortality risk. The prospective outcome data and the many baseline risk factors included in the Women's Health Initiative (WHI) provide an opportunity to better understand the reasons for this association. SETTING The WHI is a long-term national health study that focused on strategies for preventing disease in postmenopausal women. Participants were enrolled from 1993 to 1998. DESIGN Baseline hypnotic use was evaluated for an association with subsequent mortality or disease after adjusting for baseline risk. SUBJECTS 148 938 postmenopausal women between the ages of 50 and 79 throughout the USA. The median follow-up was 8 years. MAIN OUTCOME MEASURES Mortality. Secondary outcomes included myocardial infarction, stroke, diabetes and seven types of cancer. RESULTS For persons who use hypnotic medications almost daily the age-adjusted hazard ratio (HR) for mortality was 1.62 (95% CI 1.50 to 1.74). Greater hypnotic use was associated with less healthy levels of physical function, general health and smoking at baseline. After adjustment for these factors the HR for almost daily hypnotic use was 1.14 (1.06 to 1.23) for mortality and 1.53 (1.18 to 1.99) for melanoma; it was not significantly associated with increased incidence of other diseases tested. Less frequent hypnotic use and several types of sleeping difficulties were not associated with mortality, but sleeping more than 10 h a night had a risk-adjusted HR for mortality of 1.28 (1.01 to 1.61). CONCLUSIONS The association of hypnotic use with mortality and incident disease was greatly reduced after adjusting for baseline risk factors. These findings do not support a strong independent association of hypnotic use with most health outcomes.