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Table 5 Effect of multi-faceted strategies

From: Non-randomised evaluations of strategies to increase participant retention in randomised controlled trials: a systematic review

Study ID Study design Comparator Intervention Difference in response rate (primary end point) Difference in response rate (secondary end point)
Ezell 2013 [37] Post-hoc analysis method All partcipants were offered the possibility of receiving incentives ($80) for completion of all program modules and surveys) 4 retention strategies (re-dials of non-working telephone numbers, mailings to the student’s home, obtaining assistance from school administration and communication through Facebook) were used to reconnect with partcipants who were overdue for the 12-month follow-up surveys The increase in overall questionnaire response (i.e. retention) rate was 21.6% at 12-month follow-up No secondary end point reported
Sellers 2015 [38] Before and after study The first 1686 participants received routine strategies (support groups, home visits, transportation to and from study visits, frequent attempts to contact clients to reschedule missed visits) The subsequent 683 participants received enhanced intensive tracing efforts (broadcast a radio announcement in Chichewa, the local language, hiring a community educator to trace missing participants via motorcycle) Intensive tracing efforts increased the overall response rate from 80% to 87.8% at 28 weeks after randomisation No secondary end point reported