Presented at the November 2013 ASTHM Conference.

1. Impact of increased district-level insecticide-treated net (ITN) distribution
on all-cause under-five mortality in Malawi, 2004-2010
Lia S. Florey¹; Adam Bennett²; Cameron Taylor¹; Christine Hershey³; Achuyt Bhattarai4; Carrie Nielsen4; S. Rene Salgado³; Doreen Ali5; Misheck Luhanga5; Thomas Eisele²; Yazoume Ye6
¹ICF International, MEASURE DHS; ²Tulane University School of Public Health, Department of Global Health Systems and Development; ³United States Agency for International Development – President’s Malaria Initiative;
4Centers for Disease Control and Prevention – President’s Malaria Initiative; 5National Malaria Control Programme, Malawi; 6ICF International, MEASURE Evaluation
Background
Methods
Interpretation Acknowledgments
The increase in funding for malaria control efforts in the last decade resulted in the scale-up of key interventions. Partners are eager to know if this scale-up resulted in a reduction of malaria burden. Insecticide treated mosquito
nets (ITN) have been shown to be highly effective at reducing malaria morbidity and mortality in children. However, there are limited studies that assess the association between increasing ITN distribution and child mortality over
time at the district level and under programmatic conditions. We used a negative binomial regression model to assess the impact of scale-up of ITNs on all-cause mortality in children less than five years of age (ACCM) in Malawi
from 2004 to 2010 using a district platform analysis. Other predictors of child survival were also examined including measures of socio-economic status, child and maternal health.
• 2010 Demographic and Health Survey (DHS) birth history
data
• 2006 Multiple Indicator Cluster Survey (MICS) and 2010
DHS contextual factors
• District-level ITN distribution data from the Malawi
National Malaria Control Program
• Mid-year district-level population estimates from 1998
and 2008 census data
• District-level mean Plasmodium falciparum prevalence
rate in children 2–10 years of age (PfPR2-10) from MAP
• Mean annual district-level rainfall and anomaly from five-
year average from USGS FEWS NET data portal
Data sources
• Data from women’s birth histories from the 2010 DHS were
used to generate longitudinal records of child deaths
• In order to construct annual estimates covariates that were
collected cross-sectionally only during survey years, data
from both the 2006 MICS and the 2010 DHS were used
• Weighted averages of district-level means for these variables
were constructed for interim years between surveys
• District-level negative binomial regression models were
employed using aggregated estimates of ITN ownership and
other covariates including PfPR2-10 and rainfall anomaly data
at the district-year-level looking for associations with counts
of child deaths per district per year
• ITN coverage was as population-adjusted numbers of ITNs
distributed per district per year using census and program
data.
In Malawi, between 2004 and 2010, ITN distribution was significantly scaled-up and all-cause child mortality
declined significantly. In a negative binomial regression model controlling for year, percent of households with
protected sources of drinking water, percent of children whose mother’s have at least a primary school
education, percent of children who are stunted, and percent of women who were immunized for tetanus during
her most recent pregnancy, higher district ITN program intensity was significantly associated with lower all-cause
under-five mortality (IRR = 0.89; 95% CI = 0.81–0.99). These findings represent a novel use of district-level data
from nationally-representative surveys and suggest that increasing ITN coverage may have significantly
contributed to the decline in all-cause under-five mortality during 2004-2010 in Malawi.
Analysis
The team would like to acknowledge the support of the Ministry of Health and Social Welfare, the National Malaria
Control Programme and the Malawi National Bureau of Statistics. Funding for this research was provided by the United
States Agency for International Development (USAID) through the MEASURE DHS project, implemented by ICF
International in Calverton, Maryland, USA, and MEASURE Evaluation Project supported from the U.S. Agency for
USAID)under the terms of Cooperative Agreement
GPO-A-00-03-00003-00. Views expressed are those of
the authors and do not necessarily reflect the views of
USAID or the United States Government.
Results
859
Figure 1: Ratio of ITNs to population, by district, 2004-2010 Table 1: Multivariable model of under-five mortality, 2004-2010Figure 2: Annual ACCM using DHS and IGME estimates, 1990-2010
This ecological analysis examines the
effect of increasing ITN distribution
over time on numbers of child deaths
by district, controlling for other
variables that affect child survival.
This approach was possible in
Malawi as the national household
surveys used were sampled to be
representative at the district-level.
IRR LCI UCI p-value
Year
2004 ref
2005 0.77 0.67 0.89 <0.001
2006 0.84 0.69 1.03 0.087
2007 0.68 0.57 0.80 <0.001
2008 0.65 0.57 0.74 <0.001
2009 0.80 0.68 0.94 0.006
2010 0.54 0.45 0.65 <0.001
ITN ratio
≤0.25 ITN/person ref
>0.25 ITN/person 0.89 0.81 0.99 0.033
Proportion with improved water
Low ref
High 3.03 1.42 6.47 0.004
Mother’s education greater than primary
Low ref
High 0.56 0.34 0.90 0.017
Proportion with stunting
Low ref
High 2.61 1.04 6.54 0.04
Proportion with tetanus immunization
Low ref
High 2.27 1.27 4.08 0.006
© Diana Mrazikova, courtesy of Photoshare
IRR = Incidence rate ratio; LCI = Lower confidence interval; UCI = Upper confidence interval