Objective: To determine whether exposure to allopurinol is associated with
an increased risk of cataract extraction in elderly patients.
Methods: We conducted a case-control study using data from the Quebec unive
rsal health insurance program for all elderly patients. The 3677 cases were
patients with a cataract extraction between 1992 and 1994. The 21 868 cont
rols were randomly selected among patients not diagnosed with cataract and
matched to cases on the date of the extraction. We determined the odds rati
o of cataract extraction according to the cumulative dose and duration of a
llopurinol use relative to nonusers, using conditional logistic regression
analysis. The analysis was adjusted for the effects of age, sex, diabetes m
ellitus, hypertension, glaucoma, and ophthalmic and oral corticosteroid exp
osure.
Results: A cumulative dose of allopurinol of more than 400 g or a duration
of use of longer than 3 years were associated with an increased risk of-cat
aract extraction, with odds ratios of 1.82 (95% confidence interval [CI], 1
.18-2.80) and 1.53 (95% CI, 1.12-2.08), respectively. No increase in risk w
as observed for lower cumulative doses or shorter exposure periods.
Conclusion: Long-term administration of allopurinol increases the risk of c
ataract extraction in elderly patients.