Differences among U.S. States in Estimating the Number of People Living with HIV/AIDS: Impact on Allocation of Federal Ryan White Funding

Abstract

Objective. We assessed the impact of differing laboratory reporting scenarios on the completeness of estimates of people living with human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS) (PLWHA) in the U.S., which are used to guide allocation of federal Ryan White funds. Methods. We conducted a four-year simulation study using clinical and laboratory data on 1,337 HIV-positive women, including 477 (36%) who did not have AIDS at baseline. We estimated the completeness of HIV (non-AIDS) case ascertainment for three laboratory reporting scenarios: CD4<200 cells/μL and detectable viral load (Scenario A); CD4<500 cells/μL and no viral load reporting (Scenario B); and CD4<500 cells/μL and detectable viral load (Scenario C). Results. Each scenario resulted in an increasing proportion of HIV (non-AIDS) cases being ascertained over time, with Scenario C yielding the highest by Year 4 (Year 1: 69.0%, Year 4: 88.1%), followed by Scenario A (Year 1: 63.3%, Year 4: 84.5%), and Scenario B (Year 1: 43.0%, Year 4: 67.7%). Overall completeness of PLWHA ascertainment after four years was highest for Scenario C (95.8%), followed by Scenario A (94.5%), and Scenario B (88.5%). Conclusions. Differences in laboratory reporting regulations lead to substantial variations in the completeness of PLWHA estimates, and may penalize jurisdictions that are most successful at treating HIV/AIDS patients or those with weak or incomplete HIV/AIDS surveillance systems.