Cumulative lifetime incidence of abortion in Soweto, South Africa: A respondent-driven sampling study (Preprint)

BACKGROUND Estimation of abortion incidence, particularly in settings where the majority of abortions occur outside of health facility settings, is plagued with methodological challenges. Respondant Driven Sampling (RDS) may offer a previously untested alternative to the estimation of abortion incidence. OBJECTIVE In this study, we test the feasibility of using RDS to sample participants and measure cumulative lifetime incidence of non-facility based abortion among women of reproductive age in Soweto, South Africa. METHODS Participants were eligible if they identified as a woman between the ages of 15 – 49 years old, spoke English, Tswana, isiZulu, Sotho, or Xhosa, and lived in Soweto. Working with community partners, we identified 11 seeds who were provided with coupons to refer eligible peers to the study. On arrival to the study site, recruits completed an interviewer-administered questionnaire that solicited information about demographic characteristics, social network composition, health behaviors, sexual history, pregnancy history, and experience with abortion.and received three recruitment coupons. Recruitment was tracked through coupon numbering. We used the RDS-II estimator to estimate population proportions of demographic characteristics and our primary outcome, cumulative lifetime incidence of abortion. RESULTS Between April 4 and December 17, 2018, 849 eligible participants were recruited into the study. The lifetime cumulative incidence of abortion was 12.0% (95% CI 9.7% - 14.3%) (Table 2). A total of 7.4% (95% CI 5.5% - 9.2%) reported a facility-based abortion, and 4.3% (95% CI 2.8% - 5.7%) reported an out-of-facility abortion. CONCLUSIONS The estimated cumulative lifetime incidence of 12.0% in our study likely represents a substantial underestimate of the actual lifetime incidence of abortion among this study population—representing a failure of the RDS method to generate more reliable estimates of abortion incidence within our study. We caution the use of RDS in studies on abortion due to persistent concerns with under-reporting. CLINICALTRIAL n/A