Factors influencing rate of Barthel Index change in hospital following stroke

Randomized controlled trials of specific interventions in stroke rehabilitation are few. In using this study design to compare different rehabilitation interventions or different intensity of those interventions, measuring disability status at a fixed time point is one outcome option. In order for this approach to be valid, factors that might independently affect the speed of disability change have to be matched at baseline. We sought to investigate the impact of different factors on rate of disability change following stroke.

A prospective hospital-based study of consecutive patients admitted to each of three general hospitals in Wellington, New Zealand with acute stroke. Patients were assessed using the Barthel Index (BI, scored 0-20) within a few days of stroke and fortnightly until hospital discharge. Strokes were classified using the Oxfordshire Community Stroke Project classification.

Barthel Index rate of change (BRC) computed from the difference between the first and last hospital BI scores divided by the time in weeks between these assessments.

Of 104 subjects with two or more disability assessments in hospital, BRC was a mean 1.26 units per week (95% confidence interval (CI) 0.97, 1.56). The only factors significantly associated with BRC on univariate analysis were stroke type, pre-stroke Modified Rankin Scale (MRS) and pre-stroke London Handicap Score. In a general linear model analysis of covariance, stroke type (p = 0.015) and pre-stroke MRS (p < 0.001) remained significant. The mean BRC for lacunar infarcts (1.76 units per week, 95% CI 1.22, 2.30) was over three times that of total anterior circulation infarcts (0.48 units per week, 95% CI 0.20, 0.76).

Future randomized controlled trials of rehabilitation interventions for stroke in hospitalized patients need to allow for pre-stroke level of dependence and stroke type in the study design, either excluding particular patients or ensuring even randomization of these key variables if speed of disability change is to be a valid outcome variable.