Association between concurrence of multiple risk factors and under-5 mortality: a pooled analysis of data from Demographic and Health Survey in 61 low-and-middle-income countries

Background: Exposure to multiple risk factors is prevalent in low-and middle-income countries (LMICs), challenging one-directional strategies to address preventable under-5 mortality (U5M). This study aims to assess the associations between concurrence of multiple risk factors and U5M in LMICs. Methods: We extracted data from the Demographic and Health Surveys conducted between 2010 and 2021 across 61 LMICs. Our primary outcome was U5M, defined as deaths from birth to 59 months. Binary logistic regression model was applied to ascertain the association between U5M and a total of 20 critical risk factors. Upon identifying the risk factors demonstrating the strongest associations, we investigated the simultaneous presence of multiple risk factors in each individual and assessed their combined effects on U5M with logistic regression models. Findings: Of the 604,372 under-5 children, 18,166 (3.0%) died at the time of the survey. Unsatisfied family planning needs was the strongest risk factor for U5M (odds ratio [OR]: 2.0, 95% confidence interval [CI]: 1.9–2.1), followed by short birth interval (<18 months; OR: 2.0, 95% CI: 1.9–2.1), small birth size (OR: 2.0, 95% CI: 1.8–2.1), never breastfed or delayed breastfeeding (OR: 2.0, 95% CI: 1.9–2.0), and low maternal education (OR: 1.6, 95% CI: 1.4–1.8). 66.7% (66.6%–66.8%) of the children had 2 or more leading risk factors simultaneously. Simultaneous presence of multiple leading risk factors was significantly associated with elevated risk of U5M and children presenting with all 5 leading risk factors exhibited an exceedingly high risk of U5M (OR: 5.2, 95% CI: 4.3–6.3); a dose–response relationship between the number of risk factors and U5M was also observed–with the increment of numbers of leading risk factors, the U5M showed an increasing trend (p-trend < 0.001). Interpretation: Exposure to multiple risk factors is very common in LMICs and underscores the necessity of developing multisectoral and integrated approaches to accelerate progress in reducing U5M in line with the SDG 3.2. Funding: This research is funded by Research Fund, Vanke School of Public Health, Tsinghua University.