District Hospital Trauma Mental Health Screening Pre-Injury Psychiatric History Documentation and Post-Traumatic Stress Disorder Referral Equity in Ghanaian Clinics: A Fairness-Aware Machine Learning Audit of Triage Decision Rules

Triage decision rules that allocate post-traumatic stress disorder (PTSD) referral after district hospital trauma presentations may encode inequities when pre-injury psychiatric history is documented unevenly across patients. The framework formalises documentation completeness as a mediating variable between patient characteristics and referral allocation, and specifies three fairness metrics—demographic parity difference, equal opportunity difference, and predictive parity—that can be estimated from routinely collected triage data. Using the DHS Program indicator 'Family planning use decisionmaking mainly by wife' (FP_DMKF_W_UWF) across 35 African countries and 95 country-survey observations from 1999 to 2022 (mean 25.946, SD 11.643, range 9.16 in Rwanda to 58.23 in Guinea) as a comparative benchmark for women's decision-making autonomy in the region, the paper illustrates how distributional properties of a social determinant can inform fairness threshold selection. The framework proposes that documentation completeness should be treated as a modifiable system property rather than a fixed patient attribute, and that fairness audits should be conducted at the level of the triage rule rather than the individual clinician. The contribution is a transferable audit methodology that makes the documentation-referral pathway visible and contestable in resource-constrained trauma settings.