Mental illness and hospitalization for ambulatory care sensitive medical conditions.

BACKGROUND: Hospitalization due to ambulatory care sensitive (ACS) medical conditions is widely used as an indicator of poor primary care access and effectiveness. It is unknown whether patients with mental disorders have higher ACS admission rate, compared with patients without mental disorders.
OBJECTIVE: To compare the ACS admission pattern and its resultant hospital cost and length of stay (LOS) between medical patients with and without coexisting mental disorders.
METHODS: Using New York State hospital discharge data for 2004, we conducted a retrospective cohort study on inpatient cases who were aged 20-64 years and hospitalized due to either ACS condition or non-ACS "marker" condition. Multivariate regression was used to estimate the relative odds of ACS admissions and the incremental resource use for mentally ill patients during ACS hospitalization.
RESULTS: Inpatient cases with mental disorders (N = 38,514) were more likely than others (N = 116,798) to have ACS admission [adjusted odds ratio (AOR), 2.30; 95% confidence interval (CI), 2.17-2.43] relative to admission due to marker conditions. During ACS hospitalization, mentally ill cases showed an average incremental cost of $556 (95% CI, $340-$778), and an average incremental LOS of 0.7 days (95% CI, 0.6-0.8 days). The higher ACS admission rate and hospital resource consumption were most pronounced for those with major depression, other psychoses, and combined psychiatric and substance-abuse disorders.
CONCLUSIONS: Patients with mental disorders experience higher risk of hospitalization due to ACS medical conditions than the general population. During an ACS hospitalization, patients with mental disorders have longer length of stay and higher hospital cost than other patients.