Title: What the proportional recovery rule is (and is not): Methodological and statistical considerations
Authors: Jeff Goldsmith - Columbia University (United States) [presenting]
Abstract: In 2008, it was proposed that the magnitude of recovery from non-severe impairment over the first 3-6 months after stroke, as measured with the Fugl-Meyer Assessment (FMA), is approximately 0.7*initial impairment (proportional recovery). In contrast to patients with non-severe hemiparesis, about 30\% of patients with severe initial paresis do not show such recovery (non-recoverers). Based on these findings it was suggested that the proportional recovery rule (PRR) was a manifestation of a spontaneous mechanism that is present in all patients with mild-to-moderate paresis but only in some with severe paresis. Since the introduction of the proportional recovery (PR) rule, it has subsequently been applied to other motor outcomes and to non-motor deficits. This more general investigation of the PR rule has led to inconsistencies in its formulation and application, making it difficult to draw conclusions across studies and precipitating some cogent criticism. We conduct a detailed comparison of the different studies reporting proportional recovery and, where appropriate, critique statistical methodology. On balance, we conclude that existing data in aggregate are largely consistent with the PRR as a population-level mechanism for FMA-UE recovery; recent reports of its demise are exaggerated, as these excessively focus on less conclusive subject-level predictions.