SSRIs linked to cataract development
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Researchers found a possible association between current use of selective serotonin reuptake inhibitors (SSRIs), especially fluvoxamine and venlafaxine, and a future diagnosis of cataracts.
Researchers conducted a nested, case-control study of subjects within a previous study of patients who had received a coronary revascularization procedure between 1995 through 2004 in Quebec, Canada. Linked administrative databases of the health insurance system provided the data for all residents 65 years or older who are part of Canada's universal health care plan. Results appeared in the June issue of Ophthalmology.
Available SSRIs included citalopram, fluoxetine, fluvoxamine, paroxetine, and sertraline, and researchers also looked at venlafaxine, a serotonin and norepinephrine reuptake inhibitor (SNRI). Researchers identified patients prescribed SSRIs or venlafaxine one year before the index date. Current users had received an SSRI or venlafaxine within 30 days of the index date, or were defined as past users. Cataracts were identified by an ophthalmologist.
For each case, 10 controls were selected and matched by index date, age and cohort entry. Crude and adjusted rate ratios (RRs) and corresponding confidence intervals (CIs) were computed for current SSRI use. Rate ratios were adjusted for gender, corticosteroid use, statins, high blood pressure, antihypertensives and antidiabetics.
From the data, 18,784 cases and 187,840 controls met inclusion criteria. The adjusted RR for cataracts among current users of SSRIs was 1.15 (95% CI, 1.08 to 1.23). The risk of cataracts was highest with fluvoxamine (RR, 1.39; 95% CI, 1.07 to 1.80), followed by venlafaxine (RR, 1.33; 95% CI, 1.14 to 1.55) and paroxetine for cataract surgery (RR, 1.23; 95% CI, 1.05 to 1.45).
The average time to diagnosis of cataracts while on SSRI therapy was 656 days for the first analysis and 690 days for a second analysis. The two analyses were generally concordant, except when cases were restricted to outpatient surgery. Then, paroxetine was associated with cataracts (RR, 1.23; 95% CI, 1.05 to 1.45). Past use did not pose a risk (RR, 1.06; 95% CI, 0.97 to 1.17).
The strength of this study is the large sample size and the detailed prescription drug information, which allowed researchers to look at the time of onset of cataracts, as well as the risk of individual SSRIs. Limitations include cataract diagnosis by ICD-9 codes, which does not confirm surgery. Detailed work-ups for cataract diagnosis were not available. Not all confounders, including smoking, could be assessed. Finally, because cataracts may take years to develop, subjects could have had undiagnosed cataracts.
Up to 10% of U.S. residents take an antidepressant, mainly SSRIs and SNRIs. Using a relative risk of 1.15 for SSRI users, a population attributable risk of 1.5%, and a 10% prevalence of use, researchers estimated 22,000 cases of cataracts may be avoided secondary to SSRI use. However, more study is needed to confirm the link in other populations, authors wrote.