Patterns and determinants of antimalarial drug use and treatment adherence in Osun State, Southwestern Nigeria: a cross-sectional study.

BACKGROUND

Malaria remains a leading cause of morbidity and mortality in Nigeria. Artemisinin-based combination therapies (ACTs) are first-line treatments, but adherence is suboptimal and resistance is emerging. This study assessed patterns, determinants and barriers related to antimalarial drug use and adherence in Osun State, southwestern Nigeria.

METHODS

A community-based cross-sectional household survey was conducted between October 2024 and September 2025. Using multistage sampling, 1500 residents aged ≥15 years across three senatorial districts were enrolled. Data on sociodemographics, recent antimalarial use, adherence, knowledge and access barriers were collected via structured questionnaires. Descriptive and inferential statistics, including binary logistic regression, were used to identify factors associated with treatment completion.

RESULTS

The mean age of participants was 26.7 (±10.7) years; 77.0% were female. Among 713 recent antimalarial users, 70.5% completed the full course. Persistent chloroquine use was reported by 46.0% of users. Cost (40.5%) was the most cited access barrier. In adjusted analysis, treatment completion was significantly associated with tertiary education (adjusted OR (aOR)=1.85, 95% CI 1.32 to 2.59), urban residence (aOR=1.55, 95% CI 1.10 to 2.18), formal drug sources (aOR=2.20, 95% CI 1.55 to 3.12) and awareness of drug resistance (aOR=1.95, 95% CI 1.42 to 2.68).

CONCLUSIONS

Suboptimal adherence, persistent use of discontinued drugs and high out-of-pocket costs threaten malaria control and may accelerate drug resistance. Public health strategies should enforce prescription policies, institute basic universal health coverage to subsidise ACTs, implement behaviour change communication and address drug unavailability in rural areas to mitigate resistance risks.