The Relationship between Outpatient Drug Costs and Disease Progression in the Human Immunodeficiency Virus-Infected Population

As the focus of the management of human immunodeficiency virus (HIV) infection turns from the treatment of AIDS to the entire continuum of the disease, projection of long-term healthcare costs becomes increasingly important. Rather than a fulminant disease treated primarily inside the hospital, HIV infection will become a chronic condition requiring years of outpatient monitoring and pharmacologic intervention with attending increases in pharmacy costs. The objective of this study was to characterize outpatient drug costs by Walter Reed (WR) disease stage in order to estimate the association of disease progression and outpatient prescription drug costs. We hypothesized that there was an association between HIV disease progression, measured by the WR Staging Classification System, and outpatient prescription drug costs. Outpatient drug costs were summarized for 190 HIV-positive patients during a three-month period who presented at Walter Reed Army Medical Center for staging and follow-up. The overall median cost per day per patient for all stages was $3.21 (range $0.01–53.45) with wide variation between patients. Daily costs for patients in WR stage V were the greatest (median $9.26). There was a significant association between WR stage of disease and outpatient drug costs (Spearman rho = 0.51, t = 6.9, df = 188, p<0.001). The association was not completely linear because costs in WR stage VI were less than WR stages IV or V. Annual extrapolated outpatient drug costs for these 190 patients would be nearly $0.5 million.