Risk of suicide among users of calcium channel blockers: population based, nested case-control study.

Lindberg et al reported the results of two studies, which they interpreted as showing that calcium channel blockers may increase the risk of suicide. They found a significant correlation between rates of suicide and use of calcium channel blockers (r = 0.29, P < 0.001) in a cross sectional ecological study and an increased risk of suicide (relative risk 5.4, 95% confidence interval 1.4 to 20.5) in users of calcium channel blockers compared with non-users. But they did not control for important independent risk factors such as depression and did not validate diagnoses of suicide. We aimed at investigating further the possible association between use of calcium channel blockers and risk of suicide among people with hypertension, given the limitations of Lindberg et al’s study.