Prestroke Rehabilitation Reserve and Mobility and Self-Care Outcomes After Incident Stroke Across Four International Aging Cohorts.

OBJECTIVE: To examine whether lower multidimensional prestroke rehabilitation reserve was associated with adverse mobility/self-care status after incident stroke.

DESIGN: Harmonized longitudinal cohort study.

SETTING: Population-based aging cohorts in China, the United States, England, and continental Europe.

PARTICIPANTS: Adults who were stroke-free at prestroke assessment and reported incident stroke at follow-up (descriptive sample, N=7486; mean age, 70.0 years [SD, 10.2]). The first stroke-report interview typically occurred 2 to 3 years after the prestroke wave.

INTERVENTIONS: Not applicable.

MAIN OUTCOME MEASURES: Adverse mobility/self-care status, defined as at least 2 limitations in walking, transferring, dressing, bathing, toileting, or stair climbing at the first interview reporting stroke.

RESULTS: The adjusted sample included 7429 participants and 2104 events. Each 1-SD lower cohort-standardized prestroke rehabilitation reserve score was associated with 27.7% higher risk (risk ratio [RR], 1.277; 95% CI, 1.230-1.327). Descriptive adjusted risks were 20.6%, 26.0%, and 37.4% for high, intermediate, and low reserve, respectively; the low-vs-high adjusted risk difference was 16.8 percentage points (95% CI, 14.0-19.7). Results were consistent across cohorts and functional-overlap sensitivity analyses. The cohorts lacked harmonized National Institutes of Health Stroke Scale scores, acute treatment, and rehabilitation dose.

CONCLUSIONS: Lower prestroke reserve was associated with a higher subsequent mobility/self-care burden. The score may describe group-level vulnerability but is not an individual prediction or treatment-allocation tool. Future studies should test whether prevention or prehabilitation strategies targeting modifiable reserve domains can reduce poststroke disability.