Child undernutrition in Cambodia is a persistent public health problem requiring low‐cost and scalable solutions. Rising cellphone use in low‐resource settings represents an opportunity to replace in‐person counselling visits with phone calls; however, questions remain on relative effectiveness. Our objective was to evaluate the impact of two options for delivering a World Vision infant and young child feeding (IYCF) counselling programme: (1) traditional Positive Deviance/Hearth (PDH) programme with in‐person visits or (2) PDH with Interactive Voice Calling (PDH‐IVC) which integrates phone calls to replace 62.5% of face‐to‐face interaction between caregivers and volunteers, compared to the standard of care (SOC). We conducted a longitudinal cluster‐randomised controlled trial in 361 children 6–23 months. We used an adjusted difference‐in‐difference approach using baseline, midline (3 months) and endline (12 months) surveys to evaluate the impact on child growth among the three groups. At baseline, nearly a third of children were underweight, and over half were food insecure. At midline the PDH group and the PDH‐IVC groups had improved weight‐for‐age z‐scores (0.13 DID, p = 0.011; 0.13 DID, p = 0.02, respectively) and weight‐for‐height z‐score (0.16 DID, p = 0.038; 0.24 DID, p = 0.002), relative to SOC. There were no differences in child height‐for‐age z‐scores. At endline, the impact was sustained only in the PDH‐IVC group for weight‐for‐age z‐score (0.14 DID, p = 0.049), and the prevalence of underweight declined by 12.8 percentage points (p = 0.036), relative to SOC. Integration of phone‐based IYCF counselling is a potentially promising solution to reduce the burden of in‐person visits; however, the modest improvements suggest the need to combine it with other strategies to improve child nutrition.
Evaluation of mobile phone‐based Positive Deviance/Hearth child undernutrition program in Cambodia