We should really keep in touch: predictors of the ability to maintain contact with contraception clinical trial participants over 12 months

ObjectivesThis study assesses the ability to maintain contact with participants enrolled in an emergency contraception (EC) trial with 12 months of follow-up based on the modes of contact they provided at enrollment.Study DesignData came from a clinical trial offering women the copper intrauterine device or oral levonorgestrel for EC. A modified Poisson regression was used to assess predictors associated with the ability to contact study participants 12 months after enrollment.ResultsData were available for 542 participants; 443 (82%) could be contacted at 12 months. Contact at 12 months was greatest for those whose preferred the method of contact was text messaging, e-mail or any (62/68; 91% contacted) and worst for the 18 who had a landline phone (only 7 contacted; 39%). After controlling for age, having an e-mail address, text messaging, language preference, type of EC chosen and insurance, preferred contact other than phone increased the likelihood of follow-up by 10% [risk ratio (RR) 1.1 95% confidence interval (CI) 1.0–1.2], while having a landline reduced a woman's likelihood of being contacted at 12 months by 50% compared to women with a contract cell (RR 0.5, 95% CI 0.3–1.0).ConclusionThe few women with a landline for contact had poor follow-up at 1 year, while women who preferred e-mail or text had the highest rate of follow-up.ImplicationsUnderstanding how best to reduce loss to follow-up is an essential component of conducting a contraceptive clinical trial. Improved participant retention maximizes internal validity and allows for important clinical outcomes, such as pregnancy, to be assessed.