Factors associated with hypnotics polypharmacy in the Japanese population

Insomnia disorder is a global public health issue, commonly treated with hypnotics. However, long-term use of benzodiazepine derivatives (BZDs), especially polypharmacy with this kind of drug, carries risks for dependence and abuse. This study using large-scale medical insurance records investigated the causes of polypharmacy through the treatment of insomnia disorder.

A cross-sectional study analyzed anonymized medical record data from July 2014 to March 2018 provided by a nationwide Japanese health insurance association covering 405,952 individuals. Outpatients prescribed at least one sleep medication were included. Demographic data, pharmacological classification of the drugs, and comorbidities were assessed using hierarchical logistic regression analysis to explore their associations with polypharmacy.

Of the 33,212 outpatients who were prescribed sleep medications, 32.5 % were prescribed multiple types. After adjusting for demographics and type of sleep medications as covariates, hypnotic polypharmacy was significantly associated with younger age, the presence of certain kinds of comorbidities, and using BZD anxiolytics before bedtime with the highest adjusted odds ratios (8.01-9.39) when referenced with BZD hypnotics. On the other hand, usage of orexin receptor antagonists, melatonin receptor agonists, and Z-drugs indicated lower odds ratios (0.74-0.87).

Hypnotic polypharmacy is relatively common in the Japanese general population. With the introduction of non-pharmacological therapy in mind, assessing patients' comorbidities and avoiding the use of benzodiazepines, especially BZD anxiolytics, before bedtime would be recommended to prevent polypharmacy.