Geographic Inequities in Catastrophic Health Expenditure in Sub-Saharan Africa: Multi-Threshold Evidence from Rural-Urban and Geopolitical Zone Disparities in Kogi State, Nigeria

Abstract

Moses Luke, Abodunrin Gbenga and Adeoye Ojo

Background: Geographic location is a structural determinant of catastrophic health expenditure (CHE) in subSaharan Africa, yet intrastate analyses disaggregating disparities by residential classification and geopolitical zone remain scarce in Nigeria. Kogi State, with three senatorial districts exhibiting distinct facility densities and economic profiles, provides a subnational laboratory for examining how geography shapes CHE risk across Kogi West, Kogi East, and Kogi Central.

Methods: A crosssectional household survey conducted in 2021 across all three senatorial districts of Kogi State included 403 household heads selected through multistage stratified sampling (response rate: 99.3%). CHE was defined using the WHO 40% threshold (OOP payments ≥40% of nonfood expenditure), with 10% and 20% thresholds used for sensitivity analysis. Geographic exposures were residential classification (rural, semiurban, urban) and geopolitical zone. Chi-square tests examined bivariate associations; multivariable logistic regression estimated adjusted odds ratios (aORs) controlling for sociodemographic, insurance, facility, and hospitalization covariates. Exact ClopperPearson 95% confidence intervals were computed for all prevalence estimates.

Results: Rural households accounted for 65.0% of CHE cases (95% CI: 53.5–75.4%), despite comprising 41.2% of the sample, indicating an overrepresentation of 23.8 percentage points. Rural residence was the most consistent predictor (uOR=1.58–1.72), remaining significant after adjustment at the 10% level (aOR=1.66; p<0.01). Kogi East had the highest crude CHE odds (uOR=1.61; p<0.001), consistent with its 1:21 private-to-public PHC ratio.

Conclusions: Rural residence is the main geographic factor influencing CHE in Kogi State. Zonespecific NHIS outreach and incomeadjusted premiums for rural households are recommended to advance Nigeria’s evidence base for SDG 3.8.

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