2.9. Statistical Analyses
fits, MP, stunting, inflammation
INFLAMMATION
Paper case report forms were used to collect data, which were then doubly entered in EpiData with inbuilt range checks before uploading to REDCap (Open-Source Vanderbilt University) to a secure server at UCPH weekly. Data comparison was performed and any discrepancies were verified by both entrants with the aid of the hard-copy case report forms and consultations from respective research assistants before rectification. Statistical analysis was performed using Stata SE14 and descriptive statistics presented as mean ± SD, median [IQR], or % (n).We generated internal MDAT developmental age-adjusted z-scores. This involved using the 2-parameter logistic (2PL) model [Statistical analyses were based on the intention-to-treat (ITT) principle using available case data. We analyzed the 2 × 2 factorial design using linear mixed effects models in all analyses, utilizing the ‘xtmixed’ command in Stata version 14. We first tested for any interactions between the two interventions in the matrix (MP and WP). In case of no interaction effect, we then tested for the main effects on child development. The compound symmetry variance–covariance structure was assumed, and no robust standard errors were applied because the linear mixed model fits showed no marked departures from the model assumptions. Furthermore, we compared the intervention (LNS) irrespective of milk ingredients among 600 children against the 150 un-supplemented group. Prespecified subgroup analyses were performed for all outcomes, testing for any effect modifications by sex, breastfeeding, stunting severity, inflammation (serum α-1 acid glycoprotein, AGP ≥ 1.2 g/L), and stimulative home environment (having any children’s book at home, with >2 sources of play materials of >3 varieties, and with >3 engagements with older family members in interactive activities).All linear mixed models were adjusted for the baseline value of the outcome, age, sex, and season, as fixed effects, as well as site, as a random effect. Restricted maximum likelihood estimation was used, and model assumptions were assessed visually using residual and Q–Q plots. Estimates, and 95% CI, were reported, and a significance level of 0.05 was used.A per protocol analysis was performed, retaining only those children who remained until the study-endline visit, and had at least 80% compliance with LNS supplementation for those in the interventional group. Details on the measure of compliance are reported in the main paper [