Use of Zolpidem and Risk of Acute Pyelonephritis in Women: A Population-Based Case-Control Study in Taiwan

The aim of this study was to assess a possible correlation between zolpidem use and acute pyelonephritis (APN) in women in Taiwan. Therefore, we performed a case-control study involving the Taiwan's National Health Insurance Research Database between 2000 and 2011. This study included 3151 female participants aged 20 to 84 years who experienced the first bout of APN (case group) and 6015 randomly selected female participants without APN (control group). Zolpidem use was defined as "current," "early," or "late," if the last remaining 1 tablet for zolpidem was detected within 7 days, between 8 and 14 days, or ≥15 days before the date of APN diagnosis, respectively. The multivariable unconditional logistic regression model was used to calculate the odds ratios (ORs) with 95% confidence intervals (CIs) to assess the correlation between zolpidem use and APN. After adjusting for confounders, the multivariable analysis yielded an adjusted APN OR of 2.2 for participants with current zolpidem use (95%CI 1.7-2.8) compared with participants who never used zolpidem. The adjusted ORs gradually decreased to 1.4 for participants with early zolpidem use (95%CI 0.8-2.5) and 1.1 for participants with late zolpidem use (95%CI 0.9-1.2), but without statistical significance. Only patients with current zolpidem use had a significantly increased relative risk of APN. Additional large confirmatory studies are needed to illustrate a causal relationship. Meanwhile, physicians and pharmacists should be more cautious about the risk of APN when prescribing and dispensing zolpidem in women.