Strategies and determinants for recovering participants after 12 years: CHICAMOCHA cohort, Bucaramanga, Colombia

Abstract: This article seeks to describe the results of a participant recovery protocol in the CHICAMOCHA cohort after 12 years of follow-up and to identify factors associated with re-contact. In a prospective cohort study with 1,644 participants in Bucaramanga, Colombia (mean age 36 years; standard deviation = 8.5 years; 63% men), we implemented a participant recovery protocol that included 4 sequential strategies: (1) phone contact; (2) sending mail; (3) visiting the household; and (4) Publishing notices in the press local. Following steps 1-2, we attempted to update contact information through government databases in order to once again apply steps 1-2 for individuals who had not been contacted. We calculated crude and weighted rates of contact by participant recovery protocol strategy and overall return. We estimated the association between baseline participant characteristics and their state after participant recovery protocol through multiple logistical regression. We contacted 1,258 (76.4%) participants; 65% (n = 825) through phone contact. Weighted rates of contact were: 41% phone contact, 14.6% mail and 31% visits. Contact through newspaper ads was practically null. Age > 36 years (OR = 1.48); low socioeconomic stratum (OR = 1.42) or being a home owner at baseline (OR = 2.05) were associated with re-contact. Consistent with other descriptions, phone contact is the re-contacting strategy with greatest returns in longitudinal studies. Individuals with characteristics that increase geographical mobility may require shorter follow-up periods and additional contact strategies.