A two-stage sampling method for clinical surveillance of individuals in care for HIV infection in the United States.

OBJECTIVES: The goals of this study were two-fold: (1) to describe methods for drawing a population-based sample of individuals in care for HIV infection and (2) to compare data from the sample with data from existing surveillance systems that describe care for HIV. METHODS: The authors implemented a two-stage sampling method, using local HIV/AIDS surveillance data as a sampling frame of HIV care providers in three states. At selected providers, medical records of a random sample of patients were abstracted. RESULTS: The medical records of a number of patients, ranging from 253 to 374 individuals per state, were abstracted. The demographics of sampled individuals and of individuals reported to the local HIV/AIDS surveillance program were similar; however, differences existed in the proportion of individuals receiving HIV care consistent with treatment guidelines between the sample and a contemporary facility-based supplemental surveillance project. The median design effect for outcomes collected in the sample was 1.8 (range=0.5-29.6). CONCLUSIONS: This survey method is feasible for collecting population-based data on patients in care for HIV. Sample size and some design elements should be changed in future studies to increase precision of estimates and usefulness of data for local planning and evaluation.