Factors associated with in-hospital mortality after stroke at a tertiary hospital in Angola

Abstract

Most Angolan patients with stroke reach hospital beyond the thrombolysis window, and many deaths occur within 72 h of admission. We investigated routinely recorded variables associated with in-hospital mortality at Hospital do Prenda. We conducted a single-centre retrospective cohort study at Hospital do Prenda, a public tertiary hospital in Luanda, from January 2023 to December 2025. The unit of analysis was the hospitalisation episode; four episodes ending in transfer were excluded. Hypertension and type 2 diabetes were extracted from free-text fields using predefined string rules. Univariable analyses used Pearson chi-square, crude odds ratios (OR; 95% CI), and Mann–Whitney tests. Exploratory multivariable logistic regression adjusted for age, sex, year, stroke subtype, recorded comorbidities, and head-CT status. Given the low events-per-variable ratio (~7) and poor calibration in some models, adjusted estimates were considered exploratory associations rather than independent prognostic effects. Among 479 episodes, 75 patients died (15.7%; 95% CI 12.7–19.2). Median age was 58.5 years among decedents versus 52.0 among survivors ( p  = 0.049). Median length of stay was 3 versus 6 days ( p  < 0.0001), reflecting early mortality rather than a prognostic exposure. Mortality increased from 6.7% at age 45–54 years to 28.0% at ≥75 years and remained graded after adjustment (≥75 years: adjusted OR 5.92, 95% CI 2.28–15.38; p  = 0.0003). Mortality among patients <45 years was also elevated (17.2%; adjusted OR 2.97, 95% CI 1.28–6.87), predominantly among haemorrhagic strokes (22.2% versus 10.8% for ischaemic stroke; age-by-subtype interaction p  = 0.0009). Sex, year, stroke subtype, recorded hypertension, and diabetes were not associated with mortality. Absence of head CT showed higher crude mortality (30.0% versus 15.0%; OR 2.42, 95% CI 0.90–6.52). Recorded hypertension prevalence was only 19.8%, indicating substantial under-ascertainment. Older age was the strongest admission-available correlate of in-hospital mortality, while elevated mortality among younger patients was concentrated in haemorrhagic stroke. Under-ascertainment limits interpretation of comorbidities. Absence of stroke-severity, functional-status, ICU, ventilation, and reperfusion data further limits causal or independent prognostic inference.