Spatial analysis of under-5 mortality and potential risk factors in the Basse Health and Demographic Surveillance System, the Gambia.
OBJECTIVE
To describe the spatial pattern in under-5 mortality rates in the Basse Health and Demographic Surveillance System (BHDSS) and to test for associations between under-5 deaths and biodemographic and socio-economic risk factors.


METHODS
Using data on child survival from 2007 to 2011 in the BHDSS, we mapped under-5 mortality by km(2) . We tested for spatial clustering of high or low death rates using Kulldorff's spatial scan statistic. Associations between child death and a variety of biodemographic and socio-economic factors were assessed with Cox proportional hazards models, and deviance residuals from the best-fitting model were tested for spatial clustering.


RESULTS
The overall death rate among children under 5 was 0.0195 deaths per child-year. We found two spatial clusters of high death rates and one spatial cluster of low death rates; children in the two high clusters died at a rate of 0.0264 and 0.0292 deaths per child-year, while in the low cluster, the rate was 0.0144 deaths per child-year. We also found that children born to Fula mothers experienced, on average, a higher hazard of death, whereas children born in the households in the upper two quintiles of asset ownership experienced, on average, a lower hazard of death. After accounting for the spatial distribution of biodemographic and socio-economic characteristics, we found no residual spatial pattern in child mortality risk.


CONCLUSIONS
This study demonstrates that significant inequality in under-5 death rates can occur within a relatively small area (1100 km(2) ). Risks of under-5 mortality were associated with mother's ethnicity and household wealth. If high mortality clusters persist, then equity concerns may require additional public health efforts in those areas.
Harvard T.H. Chan School of Public Health, Boston, MA, USA.
John
J
Quattrochi
Medical Research Council, Fajara, The Gambia.
Momodou
M
Jasseh
Medical Research Council, Fajara, The Gambia.
Grant
G
Mackenzie
Harvard T.H. Chan School of Public Health, Boston, MA, USA.
Marcia C
MC
Castro
D000293:Adolescent; D000328:Adult; D002423:Cause of Death; D046688:Child Mortality; D002675:Child, Preschool; D003643:Death; D003710:Demography; D005006:Ethnicity; D005191:Family Characteristics; D005260:Female; D005714:Gambia / Q000453:epidemiology; D062305:Geographic Mapping; D054624:Health Status Disparities; D006801:Humans; D007223:Infant; D066088:Infant Death; D007226:Infant Mortality; D007231:Infant, Newborn; D008297:Male; D016016:Proportional Hazards Models; D012307:Risk Factors; D012424:Rural Population; D012923:Social Class; D055815:Young Adult
Cox proportional hazards models; Gambia; Gambie; The Gambia; analyse spatiale; análisis espacial; child mortality; demographic surveillance; facteurs de risque; factores de riesgo; modelos de riesgos proporcionales de Cox; modèles de Cox à risques proportionnels; mortalidad infantil; mortalité infantile; risk factors; spatial analysis; surveillance démographique; vigilancia demográfica