Effectiveness of rehabilitation dose heterogeneity for improving functional outcomes of patients with acute stroke: a nationwide observational study.

To examine heterogeneity in the impact of increased early rehabilitation intensity and to identify which ischemic stroke patients benefit most. We analysed 39,140 propensity score-matched ischemic stroke patients using Diagnosis Procedure Combination database. Patients who received ≥ 60 min of daily rehabilitation within the 14 hospital days were compared with those who received less, in terms of achieving a modified Rankin Scale (mRS) score of 0, 1, or 2 at 60 days. We employed a causal forest model to estimate individualized treatment effectiveness and assessed for heterogeneity in rehabilitation impact across subgroups. Patients in the highest-benefit quartile showed substantial functional improvement (mean Conditional Average Treatment Effect: +17.1%; 95% CI, 15.3-19.0%), characterized by severe baseline activities of daily living (ADL) impairment, age, fewer comorbidities, higher socioeconomic status, better consciousness, and higher rates of reperfusion therapy. Conversely, patients in the lowest-benefit quartile, typically older with moderate ADL impairment, high comorbidities, low socioeconomic status, and limited reperfusion therapy, showed minimal or negative benefit (-16.5%; 95% CI, -18.1% to -14.9%). Rehabilitation dosing impact varied substantially regarding functional ability, with patients having severe strokes, age, fewer comorbidities, and better baseline consciousness deriving the greatest benefit from increased rehabilitation dosing.