Comparison of methods to assess adherence to small-quantity lipid-based nutrient supplements (SQ-LNS) and dispersible tablets among young Burkinabe children participating in a community-based intervention trial

Adherence to supplementation provided during an intervention trial can affect interpretation of study outcomes. We compared different approaches for estimating adherence to small-quantity lipid-based nutrient supplements (SQ-LNS) and dispersible tablets in a randomised clinical trial in Burkina Faso. A total of 2435 children (9-18 months) were randomly assigned to receive daily 20 g SQ-LNS with varying contents of zinc and a dispersible tablet containing 0 or 5 mg zinc. Adherence to SQ-LNS and tablets was assessed for all children through weekly caregiver interviews, and disappearance rate was calculated based on empty and unused packages returned during home visits. Additional adherence data were collected in different randomly selected subgroups of children: 12-h home observations were completed for children 11 and 16 months of age (n = 192) to assess consumption of SQ-LNS and dispersible tablets, and plasma zinc concentration was measured at baseline and 18 months (n = 310). Apparent adherence to SQ-LNS and dispersible tablets differed according to the assessment method used. Average daily caregiver-reported adherence to both SQ-LNS and dispersible tablets was 97 +/- 6%. Disappearance rates showed similarly high average weekly adherence (98 +/- 4%). In contrast, only 63% and 54% of children at 11 and 16 months, respectively, received SQ-LNS during the 12-h home observation periods, and fewer (32% and 27%) received a tablet. The lack of change in plasma zinc concentration after 9 months of supplementation suggests low adherence to the zinc tablet. Better methods are needed to assess adherence in community-based supplementation trials.