Multilevel Modelling of Individual, Community and Regional Level Factors Associated with Insecticide-Treated Net Usage among Pregnant Women in Ethiopia

G-formula for observational studies under stratified interference, with application to bed net use on malaria

Assessing population-level effects of vaccines and other infectious disease prevention measures is important to the field of public health. In infectious disease studies, one person's treatment may affect another individual's outcome, that is, there may be interference between units. For example, the use of bed nets to prevent malaria by one individual may have an indirect effect on other individuals living in close proximity. In some settings, individuals may form groups or clusters where interference only occurs within groups, that is, there is partial interference. Inverse probability weighted estimators have previously been developed for observational studies with partial interference. Unfortunately, these estimators are not well suited for studies with large clusters. Therefore, in this paper, the parametric g-formula is extended to allow for partial interference. G-formula estimators are proposed for overall effects, effects when treated, and effects when untreated. The proposed estimators can accommodate large clusters and do not suffer from the g-null paradox that may occur in the absence of interference. The large sample properties of the proposed estimators are derived assuming no unmeasured confounders and that the partial interference takes a particular form (referred to as 'weak stratified interference'). Simulation studies are presented demonstrating the finite-sample performance of the proposed estimators. The Demographic and Health Survey from the Democratic Republic of the Congo is then analyzed using the proposed g-formula estimators to assess the effects of bed net use on malaria.

Utilization of long-lasting insecticide-treated net and its associated factors among pregnant women in Dawo district, Southwest Shoa Zone, Oromia, Ethiopia, 2023

Introduction

The use of long-lasting insecticide-treated net (LLIN) is one of the most effective malaria prevention strategies, particularly among pregnant women. It has mosquito-killing repellent and physical barrier properties. Pregnant women, children under 5 years of age, and patients with HIV/AIDS, as well as non-immune migrants, mobile populations, and travelers, are the most vulnerable groups to malaria. Even when pregnant women are given priority, not all nets owned by households are used by pregnant women. Therefore, the risk of the occurrence of malaria during pregnancy is also high.

Objective

This study aimed to assess the utilization of long-lasting insecticide-treated net and its associated factors among pregnant women in Dawo district, Southwest Shoa Zone, Oromia, Ethiopia, 2023.

Methods

A community-based analytical cross-sectional study was carried out in Dawo district, Southwest Shoa Zone, Oromia, Ethiopia, from 21 to 30 April 2023. A total of 353 pregnant women were chosen through simple random sampling and interviewed face-to-face using a structured and pre-tested questionnaire. Before being exported to the Statistical Package for Social Science (SPSS) version 23, the data were coded and entered into EPIDATA version 4.6. The study examined the prevalence of long-lasting insecticide-treated net use among pregnant women in the Dawo district using descriptive statistics. Analytical statistics, such as bivariable and multivariable logistic regression analyses, were used to determine the relationship between independent and dependent variables. Statistical significance was determined using a P-value of <0.05 and adjusted odd ratios with 95% confidence intervals.

Results

Long-lasting insecticide-treated nets were utilized by 55.5% (95% CI: 50.4-60.7%) of all pregnant participants in the study, which was below the national target. Pregnant women who have antenatal care (ANC) contact for current pregnancy adjusted odds ratio (AOR = 4.66, 95% CI: 1.95, 11.10), community-based health insurance (CBHI) enrollment (AOR = 2.38, 95% confidence intervals, CI: 1.38, 4.11), children under 5 years of age (AOR = 2.68, 95% CI: 1.62, 4.43), understanding that malaria poses a risk to fetuses (AOR = 3.25, 95% CI: 1.26, 8.41), and LLINs access (AOR = 12.47, 95% CI: 3.98, 39.08), were factors that significantly associated with LLIN utilization.

Conclusion

In conclusion, the utilization of LLINs was relatively low. ANC contact for current pregnancy, CBHI enrollment, having children under the age of 5, having a high income, and understanding that malaria poses a risk to fetuses were factors significantly associated with LLIN utilization among pregnant women.

Utilization of insecticide-treated nets and associated factors among childbearing women in Northern Nigeria

BACKGROUND

Studies have explored the correlates of insecticide-treated nets in Nigeria. The few studies that focused on Northern Nigeria mostly examined individual correlates, but largely ignored the community correlates. Also, the persistence of armed insurgencies in the region calls for more research attention. This study examines the utilization and the associated individual and community factors of insecticide-treated nets in Northern Nigeria.

METHODS

The study adopted a cross-sectional design. Data were extracted from the 2021 Nigeria Malaria Indicator Survey (NMIS). A weighted sample size of 6873 women was analysed. The outcome variable was the utilization of insecticide-treated nets. The explanatory variables selected at the individual/household level were maternal age, maternal education, parity, religion, sex of head of household, household wealth, and household size. The variables selected at the community level were the type of place of residence, geo-political zone of residence, the proportion of children under five who slept under a bed net, the proportion of women aged 15-49 who heard malaria media messages, and the community literacy level. Two variables, namely, the number of mosquito bed nets in the household, and the number of rooms used for sleeping were included for statistical control. Three multilevel mixed-effect regression models were fitted.

RESULTS

The majority of childbearing women (71.8%) utilized insecticide-treated nets. Parity and household size were the significant individual/household characteristics associated with the utilization of insecticide-treated nets. The proportion of under-five children in the community who slept under mosquito bed nets, and the geopolitical zone of residence were significant community correlates of the use of insecticide-treated nets. In addition, the number of rooms for sleeping, and the number of mosquito bed nets in the households were significantly associated with the utilization of insecticide-treated nets.

CONCLUSION

Parity, household size, number of sleeping rooms, number of treated bed nets, geo-political zone of residence, and proportion of under-five children sleeping under bed nets are important associated factors of the utilization of insecticide-treated nets in Northern Nigeria. Existing malaria preventive initiatives should be strengthened to target these characteristics.