"Measuring the gap": advances and practical considerations in assessment of adoption, penetration, and sustainment of HIV prevention services.

Purpose of review: Prior reviews have documented lack of consistency around implementation outcome measurement and gaps in assessing adoption, penetration or reach, and sustainment in HIV research. Our review sought to summarize approaches to measuring adoption, penetration, and sustainment in the HIV research literature, with a focus on the preexposure prophylaxis (PrEP) field which is ripe for exploration as long-acting PrEP formulations become available and oral PrEP programs become increasingly sustained.

Recent findings: Our literature search of adoption, penetration, and sustainment measurement in HIV research identified 250 manuscripts. We developed a conceptual heuristic of latent and manifest measures for HIV implementation research. Few PrEP studies measured adoption according to our heuristic and latent adoption measurements were often conflated with acceptability, while manifest measurements were conflated with penetration. Most PrEP studies measuring penetration focused on the client level, with fewer measuring penetration among organizations or providers. Sustainment measurement across studies was diverse and included mixed methods assessment at organization, provider, and client levels.

Summary: Heterogeneity persists in operationalizing adoption, penetration, and sustainment. Future work is needed to develop and validate pragmatic and robust measures of these constructs that can be used in evolving HIV implementation contexts.