Antipsychotics and the Risk of Aspiration Pneumonia in Individuals Hospitalized for Nonpsychiatric Conditions: A Cohort Study

Abstract

Background/objectives: Off-label use of antipsychotics is common in hospitals, most often for delirium management. Antipsychotics have been associated with aspiration pneumonia in community and nursing home settings, but the association in hospitalized individuals is unexplored. We aimed to investigate the association between antipsychotic exposure and aspiration pneumonia during hospitalization.

Design: Retrospective cohort study.

Setting: Large academic medical center.

Participants: All adult hospitalizations between January 2007 and July 2013. We excluded outside hospital transfers, hospitalizations shorter than 48 hours, and psychiatric hospitalizations.

Measurements: Antipsychotic use defined as any pharmacy charge for an antipsychotic medication. Aspiration pneumonia was defined according to a discharge diagnosis code for aspiration pneumonia not present on admission and validated using chart review. A generalized estimating equation was used to control for 43 potential confounders.

Results: Our cohort included 146,552 hospitalizations (median age 56; 39% male). Antipsychotics were used in 10,377 (7.1%) hospitalizations (80% atypical, 35% typical, 15% both). Aspiration pneumonia occurred in 557 (0.4%) hospitalizations. The incidence of aspiration pneumonia was 0.3% in unexposed individuals and 1.2% in those with antipsychotic exposure (odds ratio (OR) = 3.9, 95% confidence interval (CI) = 3.2-4.8). After adjustment, antipsychotic exposure was significantly associated with aspiration pneumonia (adjusted OR = (aOR) = 1.5, 95% CI = 1.2-1.9). Similar results were demonstrated in a propensity-matched analysis and in an analysis restricted to those with delirium or dementia. The magnitude of the association was similar for typical (aOR = 1.4, 95% CI = 0.94-2.2) and atypical (aOR = 1.5, 95% CI = 1.1-2.0) antipsychotics.

Conclusion: Antipsychotics were associated with greater odds of aspiration pneumonia after extensive adjustment for participant characteristics. This risk should be considered when prescribing antipsychotics in the hospital.

Keywords: antipsychotics; aspiration; hospitalization; pneumonia.

Figure 1

a) Adjusted association between antipsychotic exposure and aspiration pneumonia, by age category. We used a multivariable GEE to adjust for all variables listed in Table 1 except insomnia, plus the Healthcare Cost and Utilization Project comorbidities with the exception of peptic ulcer disease without bleeding, acquired immune deficiency syndrome (AIDS), solid tumor without metastasis, and drug abuse. b) Adjusted absolute incidence of aspiration pneumonia attributable to antipsychotic exposure (attributable risk), calculated as the difference between the adjusted incidence of aspiration pneumonia among exposed and unexposed, derived using Bayes theorem. Number-needed-to-harm calculated by taking the inverse of the attributable risk. Antipsychotic exposure and aspiration pneumonia incidence both increased with age (5.2%, 7.3%, and 12.5% exposed and 0.2%, 0.6%, and 0.7% aspiration pneumonia incidence for age <65, 65–74, and ≥75, respectively).