The interval scaling properties of the London Handicap Scale: an example from the adaptation of the scale for use in Turkey.

OBJECTIVES

To adapt the London Handicap Scale into the Turkish language, and to investigate the scaling properties of this version in a sample of people who have experienced a stroke.

DESIGN

After the translation process, the internal construct validity was tested by Rasch analysis and the reliability by internal consistency and intraclass correlation coefficient. The interval scaling properties were assessed by contrasting the raw and weighted London Handicap Scale scores with the Rasch latent estimates.

SETTING

An outpatient rehabilitation unit of a university hospital.

SUBJECTS

One hundred and eighty-eight community-dwelling post-stroke patients (mean age 63 (SD 12) years, 54% male) were assessed by the Turkish version of the London Handicap Scale.

RESULTS

After adjustment for local dependency, the data showed good fit to Rasch model expectations with a mean item fit -0.240 (SD 1.868), person fit -0.403 (SD 0.893) and chi-square interaction 8.55 (df 10, P = 0.575). The reliability was good with a Cronbach's α and intraclass correlation coefficient of 0.845. Analysis of the scaling properties showed that either the raw London Handicap Scale score or its weighted score were non-linear with respect to the Rasch latent estimate.

CONCLUSIONS

The London Handicap Scale is a valid and reliable scale for use in stroke in Turkey. Its unweighted raw scores and weighted scores are equivalent and ordinal, but a linear transformation is possible through Rasch analysis.