Fluoroquinolone-Related Neuropsychiatric Events in Hospitalized Veterans

Objective: To measure the incidence and risk factors for fluoroquinolone (ciprofloxacin, moxifloxacin, and levofloxacin)-associated psychosis or delirium in a veteran population. Methods: A retrospective study was conducted in the Western New York Veterans Affairs Health System (2005–2013). Participants were hospitalized veterans receiving a fluoroquinolone for at least 48 hours (n = 631). Cases of delirium or psychosis were defined by the Diagnostic and Statistical Manual of Mental Disorders-IV criteria, and the Naranjo scale (score ≥ 1) was used to determine the probability of the adverse drug reaction being related to fluoroquinolones. A bivariate analysis of covariates followed by a multivariate logistic regression was used to determine predisposing factors to the development of delirium/psychosis. Results: The mean age of the population was 71.5 years (range: 22–95). Fluoroquinolone-associated delirium/psychosis occurred in 3.7% of the inpatients studied (n = 23). The median Naranjo score was 3 indicating a possible association. Psychosis/delirium occurred in 3.6% of ciprofloxacin-treated patients (n = 14/391), 4.5% of patients-treated with moxifloxacin (n = 9/200), and 0% of those receiving levofloxacin (n = 0/40); p = 0.4. Significant risk factors for development of delirium/psychosis in patients receiving a fluoroquinolone in the multivariate logistical regression included typical antipsychotic use (OR, 5.4; 95% CI: 1.4–16.7) and age. A 10-year increase in age was associated with a 1.8-fold greater odds of a neuropsychiatric event. Conclusions: Fluoroquinolones may be more commonly associated with delirium/psychosis than originally reported in this veteran population. Caution should be used when prescribing a fluoroquinolone for patients on typical antipsychotics and those of advanced age.