Abstract
Abstract: :
Purpose: To examine the incidence of age-related cataract in a randomized trial of beta-carotene (50 mg every other day) in women. Methods: The Women's Health Study is a randomized, double-blind, placebo-controlled trial originally testing aspirin, vitamin E, and beta-carotene in the prevention of cancer and cardiovascular disease among 39,876 women aged 45 years or older. The beta-carotene component was terminated early after a median treatment duration of 2.1 years. A total of 37,253 participants did not report cataract at baseline and are included in this analysis. Age-related cataract was defined as an incident, age-related lens opacity, responsible for a reduction in best-corrected visual acuity to 20/30 or worse, based on self-report confirmed by medical record review. At the time of randomization, 13% of women in both treatment groups were current smokers. Results: Overall, there were 111 cataracts in the beta-carotene group and 122 cataracts in the placebo group (relative risk [RR], 0.89; 95% confidence interval [CI], 0.69-1.15). Cigarette smoking is a risk factor for cataract, and the effect of beta-carotene supplementation seemed to be modified by smoking status at baseline (p for interaction = 0.065). Among the subgroup of current smokers, there were 16 cases of cataract in the beta-carotene group compared to 29 in the placebo group (RR, 0.50; CI, 0.27 to 0.92). Among current nonsmokers, there was no significant difference in the number of cases in the two treatment groups (95 vs. 93; RR, 1.00; CI, 0.75 to 1.33). Conclusion: Two years of beta-carotene treatment has no large beneficial or harmful effect on cataract during the treatment period. However, among the subgroup of women who were current smokers at baseline, beta-carotene appeared to attenuate their risk of cataract by about one-half.
Keywords: 338 cataract • 321 antioxidants • 357 clinical (human) or epidemiologic studies: treatment/prevention assessment/controlled clinical trials