Use of calcium channel blockers and risk of hospitalized gastrointestinal tract bleeding

Background: We conducted a case-control study of the association between ca lcium channel blocker use and gastrointestinal (GI) tract bleeding in hyper tensive members of a health maintenance organization. Methods: Case patients (n=174) were treated hypertensive health maintenance organization members hospitalized for GI tract bleeding between January 19 92 and December 1994. Case patients were identified using computerized diag nosis codes and were confirmed by medical record review. Control subjects ( n=771) were treated hypertensive members selected from ongoing studies at t he health maintenance organization. Computerized pharmacy data and medical records were used to assess medication use and other risk factors for GI tr act bleeding. Results: Compared with P-blocker users, calcium channel blocker users had a n age-, sex- and calendar year-adjusted relative risk (RR) of GI tract blee ding of 2.60 (95% confidence interval [CI], 1.71-3.96). The RR associated w ith calcium channel blocker use was 2.05 (95% CI, 1.33-3.17) after further adjustment for number of recent visits, diastolic blood pressure, chronic c ongestive heart failure, and duration of hypertension. No significant dose- response relationship was observed. Compared with P-blocker users, angioten sin-converting enzyme inhibitor users had an RR of 1.22 (95% CI, 0.75-1.97) . Calcium channel blocker use tended to be more strongly associated with ri sk of lower GI tract bleeding (RR, 2.56; 95% CI, 1.08-6.05) than with risk of upper GI tract bleeding (RR, 1.54; 95% CI, 0.91-2.59) or peptic ulcer-re lated bleeding (RR, 1.17; 95% CI, 0.62-2.21), although these results were c ompatible with chance. Conclusions: Calcium channel blocker use might be associated with an elevat ed risk of GI tract bleeding. These findings require confirmation in random ized studies.