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A prospective, multi-institutional, population based study identified 1274 non-surgical stroke admissions to all hospitals in a major Australian city during 1984. The demographic and diagnostic profile and the nature of functional recovery of all 258 first stroke survivors who were referred for inpatient rehabilitation are presented. The median duration of rehabilitation stay was 49 days. The mean functional independence score, as measured on a modified Barthel Index at admission was 44, compared with 78 on discharge, a mean improvement of 34. Stair climbing had the lowest mean value on admission (12), while bowel control had the lowest residual deficit on discharge (95). The stroke study group was representative of the unimpaired aged population in all respects except ethnicity, where differences are attributed to age. The variables identified as significant are; side and severity of paralysis, age and sex, marital status and ethnicity. Stroke rehabilitation outcome was not influenced by etiology, site of lesion, arterial distribution, occupation or education.

I examine statistical considerations in the analysis of functional outcome following stroke and discuss the mathematical relation between improvement in function and discharge functional score. I demonstrate mathematically that the predictor variables of improvement and discharge functional score are the same and that the regression coefficients for improvement and discharge functional score will be equal, except for the admission functional score, for which a mathematically defined relation exists. I argue that the relation between admission functional score and discharge functional score must be positive and strong and that the relation between admission functional score and improvement must be negative for the stroke population. I believe that an ignorance of statistical concepts, especially confounding, and of the differences between raw correlations, partial correlations, and predictors have led to much confusion in functional outcome research.