Retention strategies in longitudinal cohort studies: a systematic review and meta-analysis

Table 3 Meta-analytic regression results between retention strategy themes and retention rate

	Estimate	CI (Lower - Upper)	P	I²
Model 1: Continuous total number of retention strategy types				99.86%
Barriers	0.17	0.03–0.32	0.02*
Community	−0.03	− 0.18 - 0.11	0.63
Follow-up/reminder	−0.15	−0.29 - -0.01	0.04*
Tracing	0.11	−0.06 - 0.27	0.22
Study duration	−0.04	−0.08 - 0.00	0.06
Number of waves	0.00	−0.02 - 0.03	0.81
Model 2: Binary usage of retention strategy types				99.84%
Barriers	0.35	−0.15 - 0.86	0.16
Community	0.35	−0.14 - 0.83	0.16
Follow-up/reminder	−0.83	−1.40 - -0.27	0.00**
Tracing	0.11	−0.36 - 0.59	0.64
Study duration	−0.03	−0.08 - 0.01	0.10
Number of waves	0.01	−0.02 - 0.03	0.61
Model 3: All individual strategies with p < 0.1				99.85%
Tracing - Locator form documentation	0.59	−0.44 - 1.62	0.26
Follow-up - Reminder Phone call	−0.72	−1.20 - -0.25	0.00**
Community - Thank you and birthday cards	0.44	−0.11 - 0.98	0.12
Barriers - Site and home visits	0.42	−0.05 - 0.88	0.08
Barriers - Consistency in research staff	0.39	−0.42 - 1.20	0.34
Barriers - Alternative method of data collection	0.59	0.14–1.05	0.01**
Study duration	−0.04	− 0.08 - − 0.00	0.05*
Number of waves	-0.00	−0.03 - 0.02	0.89

ISSN: 1471-2288