Bisphosphonates associated with scleritis, uveitis

First-time use of oral bisphosphonates is associated with increased risk for uveitis and scleritis, according to a retrospective cohort study.

Because of published reports of ocular inflammation with bisphosphonate use, researchers conducted a retrospective cohort study among residents of British Columbia who had visited an ophthalmologist from 2000 to 2007. The cohort included 10,827 first-time users of bisphosphonates and 923,320 nonusers who were followed for scleritis or uveitis to the time of their first inflammatory ocular adverse event, death, termination of insurance or the end of the study period.

Results appeared early online April 2 at CMAJ.

First-time users of bisphosphonates had an elevated risk of uveitis (adjusted relative risk [RR], 1.45, 95% CI, 1.25 to 1.68) and scleritis (adjusted RR, 1.51; 95% CI, 1.34 to 1.68) compared with nonusers. The results of the sensitivity analysis in which use of nonsteroidal anti-inflammatory drugs was added to the definition for scleritis did not change the results. Numbers needed to harm were 1,100 for uveitis and 370 for scleritis.

The authors noted that the release of inflammatory mediators is believed to be the possible mechanism for bisphosphonate-induced inflammatory events. Alendronate and risedronate are nitrogen-based aminobisphosphonates and are considered more potent than non-aminobisphosphonates.

“The risk of inflammatory ocular adverse events, including scleritis and uveitis, is not highlighted in most package inserts included with oral bisphosphonates,” the authors wrote. “Our study highlights the need for clinicians to inform their patients about the signs and symptoms of scleritis and uveitis, so that prompt treatment may be sought and further complications averted. Patients taking oral bisphosphonates must be familiar with the signs and symptoms of these conditions, so that they can seek immediate assessment by an ophthalmologist.”