Association Between Oral Fluoroquinolones and Neuropsychiatric Events: Self‐Controlled Case Series With Active Comparator Design

Purpose: The evidence of the neuropsychiatric effects associated with fluoroquinolones is mainly supported by case reports. Population‐based evidence remains largely limited. We aimed to investigate the association between the use of fluoroquinolones and hospitalization or Accident & Emergency department visits for acute neuropsychiatric events using a self‐controlled case series (SCCS) and active comparator to reduce confounding. Methods: We conducted a SCCS with a recently described active comparator design using all public outpatient clinics, hospitalization, and Accident and Emergency department records from the Clinical Data Analysis and Reporting System, Hong Kong from 2001 to 2013. Among 166 325 people with an oral fluoroquinolone prescription, 4287 people who had an incident neuropsychiatric event were included. We then estimated the incidence rate ratio (IRR) of acute neuropsychiatric events during periods before and after fluoroquinolone prescription, versus baseline. We repeated the analysis for amoxicillin/clavulanic acid users as an active comparator. We then estimated the comparator‐adjusted estimates by dividing the IRR for fluoroquinolone by the IRR for amoxicillin/clavulanic acid. The primary outcome was neuropsychiatric events. Secondary outcomes were psychotic events and cognitive impairment. Results: An increased risk of neuropsychiatric events was observed in the current use of fluoroquinolone [IRR: 2.11 (95% confidence interval (CI): 1.58–2.83)] and 1–7 days after the end of fluoroquinolone prescription [IRR: 1.90 (95% CI: 1.30–2.75)] versus baseline. No increased risk was observed in other risk periods versus baseline. Similar patterns were observed in the current use of amoxicillin/clavulanic acid [IRR: 1.92 (95% CI: 1.19–3.11)] and 1–7 days after the end of fluoroquinolone prescription [IRR: 1.81 (95% CI: 1.11–2.97)] versus baseline. Similar results were found for secondary outcomes. Using the active comparator design, comparator‐adjusted estimates were 1.10 (95% CI: 0.63–1.93) in current use of fluoroquinolones and 1.05 (95% CI: 0.57–1.95) in 1–7 days postexposure to fluoroquinolones versus baseline. Conclusions: Although our study showed a higher incidence of neuropsychiatric events in the current use of fluoroquinolones and 7 days after the end of fluoroquinolones prescriptions compared with baseline, a similar temporal pattern was also found for amoxicillin/clavulanic acid users. Using amoxicillin/clavulanic acid as the active comparator, we found no difference in the risk of neuropsychiatric events associated with fluoroquinolone compared with baseline. Therefore, the risk of neuropsychiatric events may not need to influence the decision to prescribe either fluoroquinolones or amoxicillin/clavulanic acid based on the evidence in this study.