Age, HIV status, and research context determined attrition in a longitudinal cohort in Nigeria

We explored determinants of attrition in a longitudinal cohort study in Nigeria. We enrolled 1,020 women into a prospective study. Of these, 973 were eligible to return for follow-up. We investigated the determinants of attrition among eligible women using a sequential mixed methods design. We used logistic regression models to compare the baseline characteristics of responders and nonresponders. At the end of the parent study, we conducted four focus group discussions and eight key informant interviews with nonresponders. Of the 973 women included in the quantitative analysis, 26% were nonresponders. From quantitative analysis, older women were less likely to drop out than younger women (reference: women ≤30 years; OR 0.46; 95% confidence interval [CI] 0.30–0.70, P