Objective: Among HIV-infected individuals, we examined whether having co-occurring serious mental illness (SMI) and injection drug use (IDU) impacts: (a) receipt of highly active antiretroviral therapy (HAART), and (b) utilization of inpatient HIV services, compared to those who have SMI only, IDU only or neither SMI nor IDU.
Method: Demographic, clinical and resource utilization data were collected from medical records of 5119 patients in HIV primary care at four US HIV care sites in different geographic regions with on-site mental health services in 2001. We analyzed receipt of HAART using multivariate logistic regression and the number of medical hospital admissions using multivariate logistic and Poisson regression analyses, which controlled for demographic factors, receipt of HAART, CD4 count and HIV-1 RNA.
Results: Those with co-occurring SMI and IDU [adjusted odds ratio (AOR)=0.52; 95% confidence interval (95% CI)=0.41-0.81] and those with IDU alone (AOR=0.64; 95% CI=0.58-0.85) were significantly less likely to receive HAART than those with neither SMI nor IDU, controlling for demographic and clinical factors. Those with co-occurring SMI and IDU were more likely to use any inpatient medical services (AOR=2.22; 95% CI=1.64-3.01) and were significantly more likely to use them more frequently (incidence rate ratio=1.33; 95% CI=1.13-1.55) than those with neither SMI nor IDU, SMI only or IDU only.
Conclusion: HIV-infected individuals with co-occurring SMI and IDU are significantly more likely to utilize HIV-related medical inpatient services than individuals with no comorbidity or with only one comorbidity. Individuals with both SMI and IDU did not differ from those with IDU only in receipt of HAART. Inpatient hospitalizations are expensive, and efforts should be targeted towards these populations to reduce potentially avoidable inpatient care.