Calcium channel blockers (CCBs) are known to reduce the availability of iron-an important mineral for intracellular pathogens. Nonetheless, whether the use of CCBs modifies the risk of active tuberculosis in the clinical setting remains unclear. To determine whether CCBs may modify the risk of active tuberculosis disease, we conducted a nested case-control study using the National Health Insurance Research Database of Taiwan between January 1999 and December 2011. Conditional logistic regression and disease risk score adjustment were used to calculate the risk of active tuberculosis disease associated with CCB use. Subgroup analyses investigated the effect of different types of CCBs and potential effect modification in different subpopulations. A total of 8164 new active tuberculosis cases and 816 400 controls were examined. Use of CCBs was associated with a 32% decrease in the risk of active tuberculosis (relative risk [RR], 0.68 [95% CI, 0.58-0.78]) after adjustment with disease risk score. Compared with nonuse of CCBs, the use of dihydropyridine CCBs was associated with a lower risk of tuberculosis (RR, 0.63 [95% CI, 0.53-0.79]) than nondihydropyridine CCBs (RR, 0.73 [95% CI, 0.57-0.94]). In contrast, use of β-blockers (RR, 0.99 [95% CI, 0.83-1.12]) or loop diuretics (RR, 0.88 [95% CI, 0.62-1.26]) was not associated with lower risk of tuberculosis. In subgroup analyses, the risk of tuberculosis associated with the use of CCBs was similar among patients with heart failure or cerebrovascular diseases. Our study confirms that use of dihydropyridine CCBs decreases the risk of active tuberculosis.
Keywords: calcium channel blockers; heart failure; hypertension; pharmacoepidemiology; tuberculosis.