The Index of Engagement in PrEP Care: Evaluation of Psychometric Properties and Predictive Potential.

Background: The Index of Engagement in HIV Care is a psychometrically valid 10-item self-report measure with predictive power to classify individuals to higher and lower odds of disengaging from HIV care. Given high rates of disengagement from preexposure prophylaxis (PrEP) care, we adapted the HIV Index to PrEP.

Methods: We evaluated the psychometric properties of the PrEP-Index in a cross-sectional validation among PrEP-eligible persons seen in an HIV Prevention Program and conducted exploratory analysis to assess its potential utility as a prognostic tool. The PrEP Index contains 10 items with answers ranging from (1) not at all to (5) extremely. Possible PrEP-Index scores ranged from 10 to 50, with higher sum scores representing higher levels of engagement.

Results: Study participants were cisgender men who have sex with men, and racially and ethnically diverse (non-Hispanic White = 39.2%). Factor analyses supported the 1-factor structure. Among 347 respondents, 118 individuals (34.0%) were available for predictive validity analysis. The PrEP Index score was positively associated with visit constancy at 6 months ( = 0.2261; 95% confidence interval: 0.0363 to 0.4051). Finally, a patient scoring 45 on the PrEP-Index will be classified as not returning within 6 months (sensitivity = 0.73, specificity = 0.65).

Conclusions: The PrEP-Index is a psychometrically valid and reliable scale that demonstrates potential utility in identifying individuals at elevated risk of falling out of PrEP care by 6 months, the time point by which the majority of PrEP discontinuations occur. The PrEP-Index could be a useful clinical prognostic tool to allow for efficient resource targeting by clinics to improve engagement in PrEP care.