Recurrence rate of malaria and associated factors in infants born to mothers who received either IPTp-SP or IPTp-DP in Busia, Uganda; a Secondary Conditional Frailty Model analysis.

Background In sub-Saharan Africa, malaria remains a leading cause of morbidity and mortality in children under five years of age. Infants in high malaria transmission areas experience malaria recurrence which not only increases the risk of severe anaemia and developmental delays but also presents unique challenges for statistical modelling, as episodes are often correlated and influenced by individual-level heterogeneity. Studies have explored different malaria dynamics in infants but gaps remain in contextualizing specific risk factors and how they influence malaria recurrence in this age group using appropriate modelling techniques to account for event dependence and heterogeneity. This study compared malaria recurrence among infants born to mothers who received IPTp-DP or IPTp-SP and explored the associated risk factors. Methods This was a secondary analysis of data from the PROMOTE trial which was a double-blind randomized controlled trial conducted in Busia district, Uganda. Up to 640 infants born to women who received IPTp-DP or IPTp-SP were included. To assess dependence in malaria episodes and heterogeneity in infants, the conditional frailty model was used. Results Compared with IPTp-SP, IPTp-DP reduced the risk of malaria recurrence in infants by 6% (HR = 0.94, 95% CI: 0.82–1.07). Compared with infants whose mothers had no education, infants born to mothers with primary, secondary, and higher education had 21%, 42%, and 48% lower risks of malaria recurrence. Infants whose mothers were 30–45 years had a 28% lower risk of malaria recurrence compared to those of mothers 16–19 years (HR = 0.72, 95% CI: 0.53–0.97). Multigravida mothers (≥ 3 pregnancies) had 36% increased risk of malaria recurrence in their infants compared with primi-gravida mothers (HR = 1.36, 95% CI: 1.02–1.80). Infants living 3–5 km from a health facility had 40% greater risk of malaria recurrence compared with infants in less than 1km (HR = 1.40, 95% CI: 1.11–1.77). Malaria episodes in the infants were found to be correlated. Conclusions Compared with IPTp-SP, IPTp-DP did not significantly reduce malaria recurrence in infants. Socio-demographic factors such as maternal education, maternal age, and distance to health centers were associated with the risk of malaria recurrence in infants. A malaria episode in an infant increases the risk of experiencing another episode.