Validity of a common measure of intimate partner violence perpetration: Impact on study inference in trials in low- and middle-income countries.

Background: In lower-and middle-income countries (LMICs), studies of interventions to reduce intimate partner violence (IPV) perpetration are expanding yet measurement equivalence of the construct has not been established. We assessed the measurement equivalence of physical and sexual IPV perpetration used in recent trials in LMICs and tested the impact of non-invariance on trial inference. Methods: With data from three recent intervention trials among men (sample size 505-1537 across studies), we calculated tetrachoric correlations among items and used multiple-group confirmatory factor analysis to assess invariance across arms and over time. We also assessed treatment effects adjusting for covariate imbalance and using inverse probability to treatment weights to assess concordance of invariant measures with published results, where warranted. Findings: The average correlation among items was high and increased over time with several items in two studies showing correlations ≥0.85 at endline. Increases in correlation for physical IPV were concentrated in the treatment arm in two of the studies. The increase in correlation in sexual IPV differed by arm across studies. Across all studies, a correlated two-factor solution was the best fitting model according to the EFAs and CFAs. One study demonstrated measurement invariance across arms and over time. In two of the studies, longitudinal measurement non-invariance was detected in the intervention arms. In post hoc testing, one study attained invariance with a one-factor model and study inference was concordant with published findings. The other study did not attain even partial invariance. Conclusion: Common measures of physical and sexual IPV perpetration cannot be used for valid effect estimation without further refinement. The study highlights the need for an expanded item set, content validity assessments, further measurement invariance testing, and then consistent use of the item sets in future intervention trials to support accurate inference on the effectiveness of IPV perpetration prevention interventions.