Loss to Follow-Up and Visit Nonadherence 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 619 participants without HIV, 278 (44.9%) were women with median age of 24 years (interquartile range: 21-28). During follow-up, 134 (21.6%) missed 1+ and 84 (13.6%) missed 2+ visits. Missed visits were more common among participants with 3+ sexual partners than among 2 partners (adjusted risk ratio: 1.50, 95% confidence interval: 1.13 to 1.97) and less common in participants who completed secondary school (aRR: 0.74, 95% CI: 0.56 to 0.99, compared with some primary school or less). Women were more likely to be lost to follow-up (aRR: 1.85, 95% CI: 1.05 to 3.26). LCA showed that missed visits were more likely among women aged 24+ years with less than secondary education who reported transactional sex than among largely younger unmarried men with less than secondary education and 3+ sexual partners (RR: 1.24, 95% CI: 1.01 to 1.54) and poorly educated, largely older married men (RR: 1.41, 95% CI: 1.05 to 1.90).

Older unmarried women with less education, more sexual partners, and transactional sex may benefit from targeted retention strategies such as optimizing accessibility to testing and prevention services and frequent visit reminders.