Stroke Recovery Redefined: Why Returning to Baseline May Matter More Than a ‘Favorable’ Score

For more than half a century, doctors and clinical trialists have judged stroke recovery with a blunt but convenient instrument: the modified Rankin Scale, or mRS. Scores from zero to two are labeled favorable, scores from three to six unfavorable, and treatments are deemed successful if they push patients across that threshold. A new study from University Hospital RWTH Aachen, published in Frontiers in Neurology, argues that this rigid dichotomy systematically erases the recovery of a substantial slice of the stroke population, and proposes a deceptively simple corrective: counting patients as treatment successes if they return to their own pre-stroke level of function, whatever that level was.

The modified Rankin Scale, first described in the 1950s, grades functional independence on an ordinal scale from zero, meaning no symptoms at all, to six, meaning death. Because clinical trials needed a single binary endpoint to power their sample-size calculations, the scale was cleaved into two categories: zero to two, roughly corresponding to independent living, and three to six, spanning moderate disability through death. The approach has genuine practical value, but it collapses a vast spectrum of human function into two bins. For patients who were already disabled before their stroke, the upper bin is mathematically unreachable, no matter how well their treatment goes. Premorbid disability cutoffs have, by some estimates, excluded more than a third of stroke patients over age 65 from most major trials.

The Aachen team, led by Julia-Laura Schulz and João Pinho, mined a prospective single-center stroke registry covering admissions from January 2010 to December 2022. Of 3,724 ischemic stroke patients, 2,070 had complete documentation of their pre-stroke, admission, discharge and 90-day mRS scores and formed the final cohort. Their median age was 75.7 years, 47.4 percent were women, and the comorbidity burden was heavy: 80.5 percent had arterial hypertension, 38.8 percent atrial fibrillation and 26.5 percent diabetes. Critically, 243 patients, 11.7 percent of the cohort, carried a pre-stroke mRS of three to five, meaning they were already disabled before the index event. For these patients, the study argues, the conventional endpoint was decided before the stroke ever occurred.

The headline numbers confirm the problem. Among the 1,827 patients with a favorable pre-stroke score of zero to two, only 47.6 percent achieved a favorable outcome at discharge and 47.5 percent at 90 days. Among the pre-stroke disabled group, by definition, not a single patient achieved a favorable outcome, regardless of treatment. Yet when the investigators instead asked whether patients had returned to their exact pre-stroke mRS score, a point-wise, directional measure of recovery to one’s own baseline, the picture changed. At discharge, 16.2 percent of the favorable group and 19.3 percent of the unfavorable group had returned to baseline, a difference that was not statistically significant. At 90 days the figures were 21.8 versus 11.9 percent, and simply adding baseline-returners to the favorable pool lifted overall favorable outcome rates from 42.0 to 44.3 percent at discharge and from 41.9 to 43.3 percent at 90 days, both statistically significant shifts.

The most technically interesting result emerges from the multivariable logistic regression models, which adjusted for pre-stroke mRS group, age, sex, admission stroke severity measured by the NIHSS, treatment modality and vascular territory. An unfavorable pre-stroke mRS showed no association with returning to baseline at 90 days in the full cohort, with an odds ratio of 1.02. But it was strongly associated with death by 90 days, with an odds ratio of 4.40, and among survivors alone it was actually associated with a higher probability of returning to baseline, with an odds ratio of 2.34. As the authors put it in substance, premorbid disability acts primarily as a risk factor for death rather than as an obstacle to functional recovery in those who survive.

This survivorship effect is the analytical heart of the paper. Among patients alive at the 90-day mark, 50.0 percent of the unfavorable pre-stroke group had returned to baseline at discharge, compared with only 20.8 percent of the favorable group, and by 90 days the two groups had converged to 37.2 versus 28.4 percent. The apparent decline in recovery among disabled patients over time, from 19.3 percent at discharge to 11.9 percent at 90 days, was driven almost entirely by mortality rather than by functional deterioration, since death removes patients from the denominator before their recovery can be observed. The authors are careful to note a statistical subtlety: because the absolute functional gain required to reach one’s own baseline shrinks as baseline disability rises, return to baseline is a relative endpoint and should complement, not replace, absolute measures of independence.

The metric also passes a crucial validation test: it responds to treatment. In a model restricted to the 1,154 endovascularly treated patients and additionally adjusted for reperfusion grade, successful recanalization, defined as TICI 2b, 2c or 3, was independently associated with returning to baseline at 90 days, with an odds ratio of 3.46. The point estimate remained directionally similar among survivors alone. The authors frame treatment coefficients as associations with the treatment actually received rather than causal effects, a necessary caveat given that treatment allocation followed clinical judgment in a non-randomized cohort. Still, the finding that the new endpoint tracks procedural success in the same direction as established endpoints strengthens the case that it is measuring something clinically real.

The findings align with external evidence. The MR CLEAN Registry reported a 27 percent return-to-baseline rate among pre-stroke dependent patients undergoing thrombectomy, and a pooled meta-analysis of thrombectomy in patients with pre-existing disability found a roughly 30 percent rate. The Aachen cohort’s crude 11.9 percent is lower because it is unselected for treatment, includes patients who received no reperfusion therapy at all, and demands exact equality with the pre-stroke score; among survivors alone, the 37.2 percent rate is closely comparable. The study also situates itself against the HERMES collaboration’s ordinal shift analysis, which softened the dichotomy but still ignored each patient’s pre-stroke functional status and therefore cannot register return to baseline.

The authors are candid about limitations. The design is retrospective and single-center, 90-day scores were often collected by telephone with attendant recall and reporting biases, and missing mRS values excluded 1,654 patients, a source of possible selection bias. Stroke etiology and infarct size were not modeled, leaving residual confounding possible. The mRS itself weights motor deficits far more heavily than cognitive ones, so a patient can score well yet harbor serious cognitive impairment, and because the scale is ordinal rather than interval, a one-point change does not mean the same thing at every level of the scale. Return to baseline mitigates but does not eliminate this problem: recovering from mRS four to a pre-stroke score of three is not functionally equivalent to recovering from five to four, yet both count identically.

Nevertheless, the practical implication is clear and, the authors argue, essentially free to implement. Adding return to baseline alongside the conventional dichotomy reclassifies success for the roughly one in eight patients whose conventional endpoint was unattainable from the outset, and could guide more tailored care strategies, particularly for elderly patients with higher pre-stroke disability. An unfavorable score of three to five, the study concludes, does not necessarily signal treatment failure; in the right patient it can represent a better outcome than a favorable score in someone else. In an aging world where multimorbid patients make up a growing share of stroke admissions, outcome measures that judge patients against their own former lives, rather than an abstract ideal of independence, may finally let modern stroke therapies show what they can do for everyone they treat.

Subject of Research: Redefining favorable outcomes in ischemic stroke using return to pre-stroke modified Rankin Scale score

Article Title: Rethinking favorable outcomes: “return to baseline” as an additional outcome in ischemic stroke

Article References: Schulz, J.-L., Reich, A., Weyland, C. S., Ridwan, H., Hasan, D., May, R., Wiesmann, M., Nikoubashman, O., & Pinho, J. (2026). Rethinking favorable outcomes: “return to baseline” as an additional outcome in ischemic stroke. Frontiers in Neurology, 17, Article 1866829. https://doi.org/10.3389/fneur.2026.1866829

Image Credits: AI Generated

DOI: 10.3389/fneur.2026.1866829

Keywords: ischemic stroke, modified Rankin Scale, stroke outcomes, return to baseline, pre-stroke disability, endovascular treatment, thrombolysis, functional recovery, clinical trials, stroke registry, mortality, neurorehabilitation