John A. Fleishman, PhD, Kelly A. Gebo, MD, MPH, Erin D. Reilly, MPH, Richard Conviser, PhD, W. Christopher Mathews, MSPH, P. Todd Korthuis, MD, James Hellinger, PhD,_ Richard Rutstein, MD, Philip Keiser, MD, Haya Rubin, MD, and Richard D. Moore, MD, MHS for the HIV Research Network  

Med Care 2005;43: III-40 –III-52

Background
Rapid changes in HIV epidemiology and antiretroviral therapy may have resulted in recent changes in patterns of healthcare utilization.

Objectives
The objective of this study was to examine sociodemographic and clinical correlates of inpatient and outpatient HIVrelated health service utilization in a multistate sample of patients with HIV.

Design
Demographic, clinical, and resource utilization data were collected from medical records for 2000, 2001, and 2002. Setting: This study was conducted at 11 U.S. HIV primary and specialty care sites in different geographic regions. Patients: In each year, HIV-positive patients with at least one CD4 count and any use of inpatient, outpatient, or emergency room services. Sample sizes were 13,392 in 2000, 15,211 in 2001, and 14,403 in 2002.

Main Outcome Measures
Main outcome measures were number of hospital admissions, total days in hospital, and number of outpatient clinic/office visits per year. Inpatient and outpatient costs were estimated by applying unit costs to numbers of inpatient days and outpatient visits.

Results
Mean numbers of admissions per person per year decreased from 2000 (0.40) to 2002 (0.35), but this difference was not significant in multivariate analyses. Hospitalization rates were significantly higher among patients with greater immunosuppression, women, blacks, patients who acquired HIV through drug use, those 50 years of age and over, and those with Medicaid or Medicare. Mean annual outpatient visits decreased significantly between 2000 and 2002, from 6.06 to 5.66 visits per person per year. Whites, Hispanics, those 30 years of age and over, those on highly active antiretroviral therapy (HAART), and those with Medicaid or Medicare had significantly higher outpatient utilization. Inpatient costs per patient per month (PPPM) were estimated to be $514 in 2000, $472 in 2001, and $424 in 2002; outpatient costs PPPM were estimated at $108 in 2000, $100 in 2001, and $101 in 2002.

Conclusion
Changes in utilization over this 3-year period, although statistically significant in some cases, were not substantial. Hospitalization rates remain relatively high among minority or disadvantaged groups, suggesting persistent disparities in care. Combined inpatient and outpatient costs for patients on HAART were not significantly lower than for patients not on HAART.

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