A paper in the British Medical Journal reported an association between use of the antibiotic clarithromycin and a small increased risk of cardiac deaths. The authors suggest that more research should be carried out before changing prescription practices. Roundup comments accompanied this before the headlines analysis.
Title, Date of Publication & Journal
Use of clarithromycin and roxithromycin and risk of cardiac death: cohort study
August 19th 2014
British Medical Journal
Claim supported by evidence?
Clarithromycin is a common antibiotic, used in a range of similar settings to penicillin. This paper identifies an apparent small but significant increase in the risk of cardiac death in a historical cohort study of Danish adults (40—74 years). There is no suggestion that current prescribing practice should change other than perhaps among those at high risk.
This study supports previous research indicating an increased risk of cardiac death for this class of drug (the absolute risk difference is 37 cardiac deaths per 1 million courses for clarithromycin compared to penicillin; equivalent 95% confidence interval is 4 to 90), as evidenced by QT prolongation.
The authors highlighted the weaknesses of their study and are suitably cautious in their conclusions, emphasising the need for further research to confirm these findings.
Detecting potential differences in low risk requires large studies such as this. Even then there is potential for such findings to be due to unidentified cofounders. For an excellent summary of strengths and limitations read this section of the paper. In brief:
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