Out-of-Pocket Health Expenditure, Cost-Related Barriers and Treatment Non-Adherence among Patients with Non-Communicable Diseases in Low- and Middle-Income Countries: A Systematic Review

Background: Non-communicable diseases (NCDs) impose a growing burden in low- and middle-income countries (LMICs), where health financing relies heavily on out-of-pocket (OOP) payments. Whether OOP costs lead patients to skip or discontinue treatment has not been synthesised across NCDs in LMICs. Methods: Following PRISMA 2020, seven structured web searches (8 November 2026) and citation searching identified primary studies and systematic reviews from LMICs that examined direct out-of-pocket (OOP) expenditure, cost-related barriers or insurance status in relation to treatment non-adherence in adults with NCDs. Exposures were classified by type and analysed separately. One reviewer screened records and appraised risk of bias provisionally. Findings were synthesised narratively (SWiM guidance) because measures were too heterogeneous to pool. Results: Of 31 records, 17 were included: 10 primary studies (Nigeria, Ghana, India, Ethiopia, Kenya) and 7 systematic reviews. Three primary studies found a significant association between higher medical or drug cost, or absence of insurance, and poorer adherence; one was mixed, one found no association, one found higher non-adherence among insured patients, and four reported cost only as a stated reason for non-adherence. Insurance was associated with better adherence in a Nigeria–Ghana cohort (adjusted OR 4.48, 95% CI 1.84–10.92), and low medical cost with good adherence in Ethiopia (adjusted OR 2.06, 95% CI 1.13–3.76). Pooled non-adherence was 43.5% (hypertension, sub-Saharan Africa) and 43.4% (diabetes, LMICs). Conclusions: Evidence from LMICs suggests that higher OOP costs, cost-related barriers and lack of insurance are associated with poorer adherence in hypertension, diabetes and kidney disease, but few studies measured expenditure directly and insurance did not always improve adherence. The evidence is largely cross-sectional, and none was found for cancer, respiratory or mental disorders.