PHACS uses a “trigger-based” approach in its studies. We want to estimate the prevalence of major abnormalities, or adverse events (AEs), that are potentially related to antiretroviral exposure. However, evaluations are often expensive, invasive to subjects, require specially trained personnel, or may require additional clinic visits.
We use a trigger-based approach because it allows us to select a targeted “high-risk” subset of all participants and conduct detailed evaluations. This trigger approach improves our ability to detect AEs, and focuses more extensive evaluations on those who might benefit most from identifying AEs.