Retention of sufficient numbers of participants in longitudinal research studies is a serious methodological
concern, as retention influences the validity of the research findings. An assessment of participant
retention or attending all study visits was made quarterly during a 12 month follow-up of an HIV incident
cohort in Kisumu, Kenya. The study objectives were to determine 1) the proportion of participants
attending all study visits and 2) demographic and behavioral factors associated with missing ≥ 1 visit.
The Kisumu Incidence Cohort Study (KICoS) was initiated in January 2007 (N=831). Detailed contact
information was collected from each participant to enhance retention. Bivariate and multivariable
analyses were used to determine factors associated with missing ≥ 1 visit. Overall retention was 90%. Of
those enrolled, 46.4% were females. The adjusted odds of missing ≥ 1 study visit were greater for
participants who were female (AOR=2.85; CI=1.90-4.28) and who had technical training (AOR=2.51;
CI=1.20-5.25) or college/university education (AOR=1.89; CI=1.10-3.24) compared to having no or only
primary education. Retention was high in this HIV prevention cohort study. However, studies could
benefit by tailoring retention strategies for women.