Association between infection rates and sleeping pill use

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By Dr. Simon Kyle

While it is well known that sleeping pills can lead to next-day drowsiness and impaired vigilance, emerging research aims to quantify the potential for longer-term health consequences. In a new study published in the Journal of Psychiatric Research, a team of researchers from Taiwan investigate whether use of zolpidem, a short-acting nonbenzodiazepine hypnotic of the imidazopyridine class, is linked to increased risk of infection.

The research team analyzed data from Taiwan’s National Health Insurance Program, a database containing extensive information on insured participants – including details of prescriptions, clinician visits and diagnostic codes to index health conditions. The authors investigated patients who had been diagnosed with a sleep-related condition (according to the International Classification of Diseases) and who had not previously taken zolpidem or had been diagnosed with an infectious disease. A total of 17,474 patients with sleep disturbance were identified, of whom nearly six thousand were prescribed zolpidem. All participants were followed-up over three years and number of participants admitted to hospital following an infectious event (e.g. pneumonia, bronchitis) was recorded.

The main finding was that 5.6% of patients taking zolpidem were hospitalized for an infectious event while only 2.7% of those not taking zolpidem were hospitalized. There was also a dose-related effect, whereby those who had taken zolpidem for longer were at greatest risk of infection. Those who were prescribed zolpidem were also older, had poorer overall physical health and were more likely to be taking additional medications. Recognizing that these factors may also influence probability of infectious events, the authors controlled for these variables in a second round of analyses, and observed that zolpidem use still raised risk of infection by approximately 70%.

The authors acknowledge that other factors were not assessed which may have influenced the relationship, chief amongst which are mental disorders like anxiety and depression. Level, type and severity of sleep disturbance was also not accounted for. Nevertheless, the link between classic benzodiazepines and depressed immune function is well known and thus further work linking zolpidem to immune markers may prove fruitful.

Chih-Yuan, H., et al. (2014). The association between zolpidem and infection in patients with sleep disturbance. Journal of Psychiatric Research, published online 4 April, doi:10.1016/j.jpsychires.2014.03.017

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