Objective: Text messages significantly improve uptake of infant HIV testing in clinical trial contexts. Women who were excluded from a randomized trial in Kenya were followed to create a comparison between women who were enrolled and did not receive the study SMS intervention and women who were screened but not enrolled.
Design: Parallel-cohort randomized controlled trial analysis.
Methods: We compared time to infant HIV testing between women in three groups: the Trial SMS group, the Trial Control group, and the Comparison Cohort comprised of women who were screened but not enrolled.
Results: Of the 1,115 women screened, 388 (35%) were eligible for trial enrollment, and were randomized to receive either intervention text messages (Trial SMS; N = 195) or continue usual care (Trial Control; N = 193). Among 727 women not enrolled in the study (Comparison Cohort), we obtained infant HIV testing data from clinic records for 510 (70%). The cumulative probability of infant HIV testing was highest in the Trial SMS group (92.0%; 95% CI 87.5-95.3), followed by the Trial Control group (85.1%; 95% CI 79.5-89.8), and lowest among women in the Comparison Cohort (43.4%; 95% CI 39.2-47.8).
Conclusions: Both the Trial SMS group and the Trial Control group were significantly more likely to have their infants tested for HIV compared to the Comparison Cohort, providing evidence of a "clinical trial effect." This analysis suggests that SMS interventions should be implemented as an adjunct to consistent and engaged delivery of basic health services.