Increase in mortality rate following coprescription of cisapride and contraindicated drugs

BACKGROUND: No epidemiologic study, as of this writing, has been published on the use of cisapride with contraindicated drugs and its relation to mortality rates in a population-based setting. OBJECTIVE: To estimate the prevalence of concomitant use of cisapride with contraindicated drugs and evaluate the association between this and the risk of mortality. METHODS: Claims data were obtained from the Health Insurance Review Agency of Korea. The study population consisted of patients younger than 85 years who visited clinics or hospitals in the city of Busan as new users of cisapride between November 1, 2000, and April 30, 2002. The coprescription of cisapride was defined as prescribing cisapride with one or more contraindicated drugs with the same prescription. Nationwide mortality data were also used. The prevalence of coprescribing cisapride was estimated and the association between this and the risk of mortality was assessed by rate ratios (RRs). The RRs were estimated using Cox's regression model with time-dependent covariate, adjusted for age, sex, and comorbidities. RESULTS: A total of 36 865 patients out of 56 012 claims were newly prescribed cisapride; of these, 1175 patients (35%) were concomitantly prescribed at least one contraindicated drug, which suggested adjusted mortality RRs of 14.08 (95% CI 7.41 to 26.76) for recent users and 1.33 (95% CI 0.92 to 1.93) for past users of cisapride. CONCLUSIONS: Despite the discontinuation of the drug's commercial marketing, cisapride was still in use in clinics and hospitals in Busan. In many cases, cisapride was co-prescribed with contraindicated drugs, which is associated with increased mortality rates.