Many definitions, one measurement problem: developing the Self-Medication in Older Adults‑Core framework for self-directed medication use in older adults

Abstract

Background: Self-directed medication use among older adults may contribute to preventable medication-related harm, but prevalence estimates are difficult to compare because studies apply different definitions, product scopes, authorization rules, recall periods and denominators. We developed the Self-Medication in Older Adults‑Core (SMOA-Core) as a testable framework for reconstructing medication-use episodes rather than relying on a single self-medication label. Methods: We conducted a framework-development study informed by a structured, purposive evidence scan last updated on 21 July 2026. We descriptively compared five older-adult prevalence studies from India and Pakistan and four global reviews, then mapped their measurement problems to survey-methods, medication-safety and reporting guidance. We did not pool prevalence or claim systematic-review, consensus or validation methods. Each framework rule was labelled as evidence-informed or an author-proposed convention requiring empirical appraisal. Results: Across the five illustrative studies, reported prevalence ranged from 19.7% to 88.5%, alongside material differences in sampling, product scope, authorization criteria and recall periods. SMOA-Core separates behaviour, authorization, professional involvement, regulatory status, verification and safety into distinct fields. It supplies an episode rule, plain-language behavioural screen, minimum dataset, derivation algorithm and reporting checklist. Safety-priority flags are reported separately; they are not presented as a validated composite risk scale. Conclusion: SMOA-Core is a transparent, testable survey architecture rather than a validated standard. Stakeholder appraisal, cognitive interviews, cross-language work, recall-window calibration, reliability testing and field evaluation remain prespecified future work.