Fluoroquinolones and the Risk of Serious Arrhythmia: A Population-Based Study

Background. Fluoroquinolones have been suspected to cause cardiac arrhythmia but data are lacking, particularly for the individual fluoroquinolones. We assessed the risk of serious arrhythmia, defined as ventricular arrhythmia or sudden/unattended death identified in hospital discharge diagnoses, related to fluoroquinolones as a class as well as for each individual molecule. Methods. We used a cohort of patients treated for respiratory conditions from 1 January 1990 to 31 December 2005, identified using the healthcare databases from the province of Quebec (Canada), with follow-up until 31 March 2007. A nested case-control analysis was performed within this cohort, with all cases of serious arrhythmia occurring during follow-up identified from hospitalization records. These cases were matched with up to 20 controls. Conditional logistic regression was used to compute adjusted rate ratios (RRs) of serious arrhythmia associated with fluoroquinolone use. Results. Within the cohort of 605 127 subjects, 1838 cases were identified (incidence rate = 4.7/10 000 person-years). The rate of serious arrhythmia was elevated with current fluoroquinolone use (RR = 1.76; 95% confidence interval [CI], 1.19-2.59), in particular with new current use (RR = 2.23; 95% CI, 1.31-3.80). Gatifloxacin use was associated with the highest rate (RR = 7.38; 95% CI, 2.30-23.70); moxifloxacin and ciprofloxacin were also associated with elevated rates of serious arrhythmia (RR = 3.30; 95% CI, 1.47-7.37 and RR = 2.15; 95% CI, 1.34-3.46, respectively). Conclusions. The use fluoroquinolones is associated with an elevated risk of serious arrhythmia, with some differences among molecules. Given that the individual fluoroquinolones share various indications, the relative risks of serious arrhythmia could inform the choice of different molecules in high-risk patients.