Statistical Evaluation of National Health Insurance Scheme Enrolment Determinants in South West Nigeria

The National Health Insurance Authority (NHIA) scheme aims to achieve universal health coverage in Nigeria, yet enrolment remains far below targets particularly in the South West informal sector where uptake determinants require statistical identification for targeted policy intervention. This study statistically evaluates the determinants of NHIA enrolment among informal sector workers in Lagos, Oyo, and Ogun States, South West Nigeria. A cross-sectional survey enrolled 360 informal sector workers (120 per state) through market and trade association sampling. Survey data covered NHIA awareness, enrolment status, premium affordability perceptions, benefit knowledge, and sociodemographic characteristics. Logistic regression identified independent enrolment predictors, and chi-square tests examined bivariate associations. NHIA awareness was 63 percent but actual enrolment was only 11.4 percent. Logistic regression identified monthly income above N50,000 (OR 3.6, p < 0.001), awareness of specific NHIA benefits (OR 4.2, p < 0.001), chronic illness history (OR 2.9, p = 0.003), and prior public hospital use (OR 2.1, p = 0.021) as independent positive enrolment predictors. Premium affordability was cited as the primary barrier by 54 percent of non-enrolled respondents. Oyo State showed higher enrolment rates than Lagos or Ogun after socioeconomic adjustment. The study recommends income-graduated NHIA premium structures, enrolment drives through trade associations, and media campaigns emphasising specific scheme benefits to increase informal sector coverage across South West states. Keywords: NHIA, health insurance enrolment, informal sector, logistic regression, South West Nigeria