The association between benzodiazepines and influenza-like illness-related pneumonia and mortality: a survival analysis using UK Primary Care data.

PURPOSE: Bacterial superinfections, including pneumonia, are frequent complications of influenza-like illness (ILI). Clinical and laboratory evidence suggests that benzodiazepines and Z-drugs may influence susceptibility to infections and mortality. We investigated whether benzodiazepines and zopiclone modify the occurrence of ILI-related pneumonia and mortality.
METHODS: We obtained data on 804 051 ILI patients from a comprehensive primary care database, the Clinical Practice Research Datalink. The follow-up period started from the diagnosis of ILI for 30 days. Pneumonia and deaths occurring within the 30-day follow-up period were considered as potentially 'ILI related'. Exposure to benzodiazepines and zopiclone was determined in the period preceding a diagnosis of ILI with current use defined as a prescription for benzodiazepines in the month prior to ILI diagnosis. Cox regression was used for the analyses. Adjusted hazard ratios (HRs) with 95% confidence intervals (CIs) are presented.
RESULTS: Influenza-like illness-related pneumonia and mortality were noted in 1117 and 707 ILI patients, respectively. Current exposure to benzodiazepines was associated with increased occurrence of both ILI-related pneumonia and mortality (ILI-related pneumonia adjusted HR 4.24, 95%CI [2.27, 7.95]; ILI-related mortality adjusted HR 20.69, 95%CI [15.54, 27.54]). A similar increase in ILI-related mortality but not pneumonia was observed with current zopiclone use (ILI-related mortality adjusted HR 10.86, 95%CI [6.93, 17.02]; ILI-related pneumonia adjusted HR 1.97, 95%CI [0.63, 6.12]).
CONCLUSION: Benzodiazepines may increase the likelihood of pneumonia and mortality related to ILI. A cautionary approach to prescribing benzodiazepine is suggested in people known to be at increased risk of pneumonia or mortality.