Association of zolpidem use and subsequent increased risk of epilepsy: a population-based, case-control study.
OBJECTIVE
To evaluate the impact of long-term zolpidem use on the subsequent risk of epilepsy.


METHODS
We used data from the National Health Insurance system of Taiwan to conduct a population-based case-control study. We identified 4,972 newly diagnosed epilepsy patients (ICD-9-CM code 345) for the period of 2005-2010 as cases. For each epilepsy case, 4 controls without a history of epilepsy were randomly selected from the rest of the population. Zolpidem was used as a predictor of epilepsy.


RESULTS
Patients with epilepsy exhibited an adjusted odds ratio (OR) of 1.86 (95% CI, 1.70-2.03) and were, therefore, more strongly associated with zolpidem exposure than control patients were. The adjusted OR of epilepsy increased with the increase of mean zolpidem exposure (g/y). Compared with the OR of nonusers, the adjusted OR was 1.64 (95% CI, 1.44-1.86) for those who had taken < 1.0 g/y of zolpidem and 2.38 (95% CI, 2.06-2.74) for those who had taken ≥ 20.0 g/y of zolpidem. An adjusted OR of 3.55 (95% CI, 2.94-4.28) was noted to be associated with epilepsy when users had stopped taking the drug less than 7 days earlier. The estimated risk declined to an OR of 1.62 (95% CI, 1.47-1.78) when users had stopped taking the drug more than 90 days earlier.


CONCLUSIONS
This population-based, retrospective case-control study revealed a possible increase in epilepsy risk with zolpidem use, at either typical or supratherapeutic doses. These findings might stimulate public interest in safety issues regarding zolpidem use.
Department of Neurosurgery, Buddhist Tzu Chi General Hospital and College of Medicine, Tzu Chi University, Hualien Taiwan.
Tomor
T
Harnod
Yu-Chiao
YC
Wang
Fung-Chang
FC
Sung
Chia-Hung
CH
Kao
D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D004827:Epilepsy / Q000139:chemically induced* / Q000453:epidemiology; D005260:Female; D006801:Humans; D006993:Hypnotics and Sedatives / Q000009:adverse effects* / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D011725:Pyridines / Q000009:adverse effects* / Q000627:therapeutic use; D012306:Risk; D013624:Taiwan / Q000453:epidemiology; D055815:Young Adult; D000077334:Zolpidem
D006993:Hypnotics and Sedatives; D011725:Pyridines; D000077334:Zolpidem