Vitamin D supplementation and the incidence of cataract surgery in older Australian adults
Ophthalmology. 2022 Sep 26;S0161-6420(22)00753-9. doi: 10.1016/j.ophtha.2022.09.015 PDF is behind a $36 paywall
Sabbir T Rahman 1 , Mary Waterhouse 1 , Briony Duarte Romero 1 , Catherine Baxter 1 , Dallas English 2 , David A Mackey 3 , Peter R Ebeling 4 , Bruce K Armstrong 5 , Donald S A McLeod 6 , Gunter Hartel 1 , Rachel L O'Connell 7 , Jolieke C van der Pols 8 , Alison J Venn 9 , Penelope M Webb 10 , David C Whiteman 1 , Rachel E Neale 11
Objective: Observational studies suggest that higher serum 25-hydroxyvitamin D concentration may be associated with lower risk of cataract. However, no randomized controlled trials (RCTs) have assessed the effect of vitamin D supplementation on the incidence of cataract. We aimed to assess whether vitamin D supplementation reduces the incidence of cataract surgery.
Design: We conducted an ancillary study of D-Health Trial, a randomized, double-masked, placebo-controlled trial of monthly vitamin D for the prevention of all-cause mortality conducted from 2014 to 2020 within the Australian general population.
Participants: We invited 421,207 men and women aged 60-84 years to participate; including an additional 1,896 volunteers, 40,824 expressed interest. Those with hypercalcemia, hyperparathyroidism, kidney stones, osteomalacia or sarcoidosis, or who were taking >500 international units (IU) supplemental vitamin D per day were excluded. 21,315 people were randomized. 1,390 participants did not fulfil the eligibility criteria for this analysis (linked data available, no cataract within first 6 months) leaving 19,925 included. The median follow-up was 5 years. .
Intervention: 60,000 IU of vitamin D3 (n=10,662) or placebo (n=10,653) taken orally once per month for a maximum of 5 years.s
Main outcomes measures: The primary outcome for this analysis was the first surgical treatment for cataract, ascertained through linkage to universal health insurance records and hospital data.
Results: Among 19,925 participants eligible for the analysis of incident cataract (mean age 69.3 years, 46% women) 3,668 (18.4%) underwent cataract surgery during follow-up (n=1,841 (18.5%) of the vitamin D group and n=1,827 (18.3%) of the placebo group). The incidence of cataract surgery was similar between the two groups (incidence rate 41.6 and 41.1 per 1,000 person-years in the vitamin D and placebo groups, respectively; hazard ratio 1.02; 95% CI 0.95 to 1.09). In pre-specified subgroup analyses, the effect of vitamin D supplementation on the incidence of cataract surgery was not modified by age, sex, body mass index, predicted serum 25-hydroxyvitamin D concentration, or ambient ultraviolet radiation.
Conclusions: Routinely supplementing older adults who live in an area with a low prevalence of vitamin D deficiency with high-dose vitamin D is unlikely to reduce the need for cataract surgery.