Loss to Follow up and Visit Non-Adherence in an HIV Incidence Cohort in Kisumu, Kenya

Adherence to study visits enhances safety and validity of human research studies. We identified characteristics associated with missed visits in a Kenyan HIV incidence study to inform retention strategies. We enrolled volunteers 18-35 years-of-age, without HIV, who reported 2+ sex partners into a study with visits every 3 months for 24 months. We used zero-inflated Poisson regression to assess sociobehavioral and demographic characteristics associated with missed visits and loss-to-follow-up. Latent class analysis (LCA) identified clusters of characteristics associated with each outcome. Among 619participants without HIV, 278 (44.9%) were female with median age of 24 (interquartile range: 21-28). During follow-up, 134 (21.6%) missed 1+ and 84 (13.6%) 2+ visits. Missed visits were more common among participants with 3+ sexual partners compared to 2 (adjusted risk ratio [RR]: 1.50, 95% confidence interval [CI]: 1.13-1.97) and less common in participants who completed secondary school (aRR: 0.74, 95%CI: 0.56-0.99, compared to some primary school or less). Females were more likely to be lost to follow-up (aRR: 1.85, 95%CI: 1.05-3.26) LCA showed that missed visits were more likely among females aged 24+ years with less than secondary education who reported transactional sex compared to largely younger unmarried males with less than secondary education and 3+ sexual partners (RR: 1.24, 95%CI: 1.01-1.54) and poorly educated, largely older married males (RR: 1.41, 95%CI: 1.05-1.90). Older unmarried females with less education, more sexual partners, and transactional sex may benefit from targeted retention strategies like optimizing accessibility to testing and prevention services and frequent visit reminders.