Incidence of cataract operations in Finnish male smokers unaffected by α tocopherol or β carotene supplements

Abstract

Objective - To examine the effect of α tocopherol and β carotene supplementation on the incidence of age related cataract extraction. Setting - The Alpha-tocopherol Beta-carotene (ATBC) Study was a randomised, double blind, placebo controlled, 2 x 2 factorial trial conducted in south western Finland. The cataract surgery study population of 28,934 male smokers 50-69 years of age at the start. Intervention - Random assignment to one of four regimens: α tocopherol 50 mg per day, β carotene 20 mg per day, both α tocopherol and β carotene, or placebo. Follow up continued for five to eight years (median 5.7 years) with a total of 159,199 person years. Outcome measure - Cataract extraction, ascertained from the National Hospital Discharge Registry. Results - 425 men had cataract surgery because of senile or presenile cataract during the follow up. Of these, 112 men were in the α tocopherol alone group, 112 men in the β carotene alone group, 96 men in the α tocopherol and β carotene group, and 105 men in the placebo group. When supplementation with α tocopherol and with β carotene were introduced to a Cox proportional hazards model with baseline characteristics (age, education, history of diabetes, body mass index, alcohol consumption, number of cigarettes smoked daily, smoking duration, visual acuity, and total cholesterol), neither α tocopherol (relative risk, RR, 0.91, 95% confidence intervals, CI, 0.74, 1.11) nor β carotene (RR 0.97, 95% CI 0.79, 1.19) supplementation affected the incidence of cataract surgery. Conclusion - Supplementation with α tocopherol or β carotene does not affect the incidence of cataract extractions among male smokers.