Development and psychometric validation of SADAR-PrEP, an Indonesian PrEP knowledge and attitudes instrument

The use of pre-exposure prophylaxis (PrEP) in Indonesia remains limited despite its proven effectiveness in HIV prevention, partly due to low public awareness and knowledge and the absence of validated measurement instruments for the general population. This study developed and psychometrically validated the SADAR-PrEP (Skala pengetAhuan DAn Respon terhadap PrEP) instrument through (i) forward-backward translation and cultural adaptation; (ii) content validity through multidisciplinary expert panel review (n = 25); (iii) face validity through structured cognitive interviews across regional groups; (iv) construct validity using exploratory factor analysis (EFA); (v) internal consistency reliability; and (vi) known-groups validity with effect sizes. A total of 1,150 adults from six regions in Indonesia completed the instrument. EFA revealed a unidimensional structure (KMO = 0.928; single factor eigenvalue = 4.959, explaining 49.6% of the variance; factor loadings 0.618-0.766). Internal consistency was excellent (Cronbach's α = 0.874; corrected item-total correlations 0.538-0.676). Known-groups comparisons confirmed significant differences in scores across education, health background, and workshop attendance groups (p ≤ 0.003; Cohen's d = 0.24-0.63). Although 74.3% expressed willingness to use PrEP, only 16.1% knew how to access services. SADAR-PrEP is the first validated PrEP knowledge and attitude instrument for the general Indonesian population, providing a scalable tool for evidence-based HIV prevention education, programme planning, and policy development.