Oral fluoroquinolones may not be associated with increased arrhythmia risk
Researchers detected a significant difference according to age group, but no statistically significant differences in rate ratios in subanalyses of underlying cardiovascular disease, co-treatment with drugs known to increase the risk of torsades de points, country of residence, or sex or across levels of arrhythmia risk score.
Treatment with oral fluoroquinolones does not appear to put patients at increased risk of serious arrhythmia, a new study suggests.
The study compared fluoroquinolones with phenoxymethylpenicillin (penicillin V), an antibiotic without proarrhythmic effects. Results were published online on Feb. 26 by The BMJ.
Researchers derived the study cohort from several years of register data on Danish and Swedish adults ages 40 to 79 years, which included filled prescriptions, cases of serious arrhythmia, and patient characteristics. After propensity score matching in a 1:1 ratio, they looked at 909,656 courses of oral fluoroquinolones and penicillin V (309,995 in Denmark, 599,661 in Sweden). Prescribed fluoroquinolones included ciprofloxacin (82.6%), norfloxacin (12.1%), ofloxacin (3.2%), moxifloxacin (1.2%), and others (0.9%).
A total of 144 cases of serious arrhythmia, defined as a diagnosis of ventricular tachycardia or flutter, occurred during follow-up (66 in current fluoroquinolone users, 78 in current penicillin V users). Incidence rates were 3.4 per 1,000 person-years in fluoroquinolone users and 4.0 per 1,000 person-years in penicillin users (rate ratio, 0.85; 95% CI, 0.61 to 1.18). Compared with current penicillin V use (i.e., 0 to 7 days after prescription), the absolute risk difference for current fluoroquinolone use was −13 (95% CI, −35 to 16) cases per 1,000,000 courses of fluoroquinolones.
In addition to the findings related to current use, researchers found no increased risk associated with fluoroquinolones in periods of indeterminate use (i.e., 8 to 14 days after prescription) or past use (i.e., 15 to 44 days after prescription). The respective rate ratios were 1.13 (95% CI, 0.71 to 1.78) and 1.08 (95% CI, 0.83 to 1.42) for fluoroquinolones compared to penicillin V.
Researchers detected no statistically significant differences in rate ratios in subanalyses of underlying cardiovascular disease, co-treatment with drugs known to increase the risk of torsades de points, country of residence, or sex or across levels of arrhythmia risk score. However, there was a significant difference according to age group: The rate ratio for arrhythmia was 0.45 (95% CI, 0.23 to 0.88) among current fluoroquinolones users ages 40 to 64 years and 1.07 (95% CI, 0.73 to 1.57) among those ages 65 to 79 years (P=0.02), both compared to penicillin V users.
“We cannot exclude that in some situations fluoroquinolones can cause torsades de pointes,” the study authors wrote. “However, we did not find support for an increased risk of serious arrhythmia associated with oral fluoroquinolone use in a general adult outpatient population.” They noted certain limitations to the study, such as lack of information on both the indication for and the actual duration of treatment. Additionally, since most prescriptions in the study were for ciprofloxacin, it's possible that other fluoroquinolones may pose different risks, they noted.