Abstract
Purpose: :
A longitudinal study of visual development in Native American children in which 6-month to 3-year-old children are recruited at WIC clinics was begun in August, 2005. Yearly follow-up was expected to be achieved through subjects’ ongoing participation in the WIC program, but the follow-up rate was less than anticipated. The purpose of the present analysis was to determine whether new retention strategies implemented after the first year of follow-up have significantly improved the follow-up rate.
Methods: :
Infants and toddlers ages 6 months to 3 years were recruited at WIC clinics on the Tohono O’odham Reservation. New retention strategies were implemented during the second follow-up year of the study. They included: (1) widening the follow-up window by opening it at 1.1 rather than 1.25 years for 1-year-olds and opening the window at 2.1 years rather than 2.25 years for 2-year-olds, (2) providing a $10 gas card at follow-up visits, (3) attempting to contact parents of all unseen subjects who are nearing the end of their follow-up window, and (4) frequently updating subject contact information. To determine if new strategies are increasing overall follow-up rate, we compared 1) overall follow-up rate up to 1/28/08 (after which follow-up retention efforts were increased) vs 2) overall follow-up rate up to 12/1/08. Separate analyses were conducted to examine follow-up rate for 1-year-olds and 2-year-olds. Follow-up rates were calculated conservatively assuming open windows are "missed" follow-ups:Follow-up (FU) Rate= (FUs complete) / (FUs complete+open windows+FUs missed)
Results: :
Conservative estimates of overall study follow-up rate increased significantly for both 1- and 2-year-olds (22.7% vs. 38.9% for 1-year-olds (X2(1) = 16.93, p< 0.001), 28.6% vs. 38.3% for 2-year-olds, (X2(1) = 7.12, p<0.009)).
Conclusions: :
The increase in follow-up rate after just 10 months of implementation indicates that the new retention strategies had a significant positive effect on subject follow-up. However, the data also suggest that additional efforts are needed to further increase follow-up rates.
Keywords: visual development: infancy and childhood • clinical (human) or epidemiologic studies: biostatistics/epidemiology methodology • astigmatism