Normalization of Functional Independence Measure variation improves assessment of stroke rehabilitation outcome

Assessment of rehabilitation outcome is based on measuring the change in Functional Independence Measure (FIMTM) score between the start and end of rehabilitation. However, the raw FIMTM score gain is subject to a ceiling effect. Proposed solutions to this problem have incongruities that limit their use.

The aim of this study was to determine the factors that influence functional outcome in stroke rehabilitation, exploring the possibility of developing an outcome index free of the ceiling effect and of the incongruities revealed by the proposed solutions.

Retrospective study of the electronic clinical records of patients admitted to a rehabilitation unit over a period of 5 years.

Rehabilitation unit.

A total of 224 patients admitted for first post-stroke rehabilitation of either ischaemic or hemorrhagic etiology.

Rehabilitation outcome was evaluated based on changes in both raw and "normalized" FIMTM motor and cognitive scores observed between hospital admission and discharge. Normalized differences are in the range 0-1 and may be considered an estimate of the actually attained fraction of the maximum expected recovery, while the modified algebraic formula (+1 to both numerator and denominator) is intended to correct the incongruities observed in available solutions. Seventeen prognostic factors were selected as possible effect modifiers of the outcome. A multivariable model-building strategy, based on fractional polynomials, was adopted to select the significant factors, and the stability of the results.

The procedure adopted to normalize both FIMTM outcomes resolves the ceiling effect and corrects the incongruities noted with available solutions. The level of disability at admission is confirmed as the strongest prognostic factor associated with both cognitive and motor outcomes. The onset-admission interval negatively influence motor recovery, bat not cognitive one.

There is strong evidence to support the proposal that it is advantageous to measure functional recovery by means of the normalized change in FIMTM score. Following a rehabilitation programme, functional recovery should be evaluated separately for motor and cognitive domains. Rehabilitation program should begin as soon as possible.

Improved assessment of rehabilitation outcome leads to increased achievement of a favourable treatment outcome.