Age and gender trends in insecticide-treated net use in sub-Saharan Africa: a multi-country analysis

Background: The degree to which insecticide-treated net (ITN) supply accounts for age and gender disparities in ITN use among household members is unknown. This study explores the role of household ITN supply in the variation in ITN use among household members in sub-Saharan Africa. Methods: Data was from Malaria Indicator Surveys or Demographic and Health Surveys collected between 2011 and 2016 from 29 countries in sub-Saharan Africa. The main outcome was ITN use the previous night. Other key variables included ITN supply (nets/household members), age and gender of household members. Analytical methods included logistic regressions and meta-regression. Results: Across countries, the median (range) of the percentage of households with enough ITNs was 30.7% (8.5-62.0%). Crude analysis showed a sinusoidal pattern in ITN use across age groups of household members, peaking at 0-4years and again around 30-40years and dipping among people between 5-14 and 50+ years. This sinusoidal pattern was more pronounced in households with not enough ITNs compared to those with enough ITNs. ITN use tended to be higher in females than males in households with not enough ITNs while use was comparable among females and males in households with enough ITNs. After adjusting for wealth quintile, residence and region, among households with not enough ITNs in all countries, the odds of ITN use were consistently higher among children under 5years and non-pregnant women 15-49years. Meta-regressions showed that across all countries, the mean adjusted odds ratio (aOR) of ITN use among children under 5years, pregnant and non-pregnant women aged 15-49years and people 50years and above was significantly higher than among men aged 15-49years. Among these household members, the relationship was attenuated when there were enough ITNs in the household (dropping 0.26-0.59 points) after adjusting for geographical zone, household ITN supply, population ITN access, and ITN use:access ratio. There was no significant difference in mean aOR of ITN use among school-aged children compared to men aged 15-49years, regardless of household ITN supply. Conclusions: This study demonstrated that having enough ITNs in the household increases level of use and decreases existing disparities between age and gender groups. ITN distribution via mass campaigns and continuous distribution channels should be enhanced as needed to ensure that households have enough ITNs for all members, including men and school-aged children.