Longitudinal relationship between pre-exposure prophylaxis motivation and change in adherence among men who have sex with men in Western China.

Introduction: The efficacy of pre-exposure prophylaxis (PrEP) is highly dependent on adherence, and adherence behavior is influenced by motivation. The aim of this study was to explore the longitudinal relationship between PrEP motivation and change in adherence among men who have sex with men (MSM) in Western China.

Methods: From November 2019 to June 2021, we conducted a PrEP prospective cohort study. Motivation to take medicine was measured by the PrEP Motivation Scale at baseline, and was grouped into different levels of latent categories by Latent Profile Analysis (LPA). A multinomial logistic regression model was used to explore the longitudinal relationship between change in adherence (improvement, decline, no change) and different levels of PrEP motivation.

Results: MSM were divided into two categories of PrEP motivation, a "high motivation group" (n = 506, 69.89%) and a "low motivation group" (n = 218, 30.11%). High PrEP motivation had no significant effect on the change in short-term adherence, however, it contributed to the improvement in long-term adherence [odds ratio (OR) = 3.028 (1.100-8.332), p = 0.031]. The predictive power of the adherence model was significantly enhanced with the addition of the PrEP motivation factor.

Conclusions: There was a positive correlation between high PrEP motivation at baseline and an improvement in long-term adherence. Surveillance and intervention of PrEP motivation in MSM can increase their adherence, and then promote PrEP efficacy.