Long-term Consequences of Further Post-stroke Disability in Patients with Pre-morbid Disability: Potential for Acute Stroke Therapies

Objective: To assess the extent to which increased disability following ischaemic stroke influences 5-year mortality and institutionalization in pre-morbidly disabled patients. Background: Patients with pre-morbid disability – typically defined as a modified Rankin Scale score (mRS) ≥2 or ≥3 – are often excluded from trials of acute ischaemic stroke therapies. Decisions to use such therapies in pre-morbidly disabled patients will partly depend on whether long-term clinical outcomes of patients who accumulate greater disability following their stroke differ markedly from those of patients who retain their pre-morbid disability. Design/Methods: In a population-based, prospective cohort of 3-month survivors of ischaemic stroke (Oxford Vascular Study, OXVASC; 2002–2014), we tracked mortality and institutionalization (admission to nursing or residential care home) through overlapping methods of interview-based assessments of patients/carers and ongoing searches of health records. We used Cox regressions – adjusted for age, sex, and initial NIHSS(National Institutes of Health Stroke Scale) score – to compare outcomes of 1-year and 5-year mortality and/or new post-stroke institutionalization in survivors with pre-morbid mRS of 2–4 (excluding severe pre-stroke disability, mRS 5), based on the degree of change in mRS (ΔmRS) from pre-stroke to 3-months post-stroke. Results: Among 1,425 3-month survivors, 420(29.5%) had pre-morbid mRS 2–4; only 2 received thrombolysis. ΔmRS independently predicted 1-year mortality in pre-morbidly disabled patients (adjusted hazard-ratio[aHR] versus no change for ΔmRS 1: 2.52, 95%CI 1.47–4.30, p=0.001; ΔmRS 2: 3.22,1.66–6.24, p=0.001; ΔmRS 3: 4.27,1.40–13.02, p=0.011). Similar results were seen for 5-year mortality/institutionalization (aHR for ΔmRS 1: 1.72,1.30–2.27, p<0.001; ΔmRS 2: 2.19,1.50–3.19, p<0.001; ΔmRS 3: 3.56,1.69–7.47, p=0.001). Results were similar on examining pre-morbid mRS 2, 3, 4 separately (e.g. 5-year institutionalization aHR for pre-morbid mRS 3 with ΔmRS 1: 2.13,1.25–3.64, p=0.006; ΔmRS 2: 3.55,1.76–7.15, p<0.001). Conclusions: Pre-morbidly disabled patients who accumulate additional post-stroke disability have worse mortality and institutionalization outcomes. This justifies trialling or administering acute stroke therapies in patients with mild-moderate disability to potentially mitigate further post-stroke disability.