Application of Rasch analysis in health care is increasing and is applied for variable reasons in mobility instruments

Abstract

Objective: To identify the frequency of Rasch analysis use in health instrument development or refinement and the characteristics of Rasch application in mobility scales.

Study design and setting: The entire databases of Medline, CINAHL, PEDro, EMBASE, Cochrane Central Register of Controlled Trials, and Cochrane Database of Systematic Reviews were searched until January 2009. Articles that reported the development or refinement of health instruments using Rasch analysis were included. Of the 234 articles that met inclusion, 10 were categorized as "mobility" instruments. Data were extracted relating to each instrument and the use of Rasch analysis in the development or refinement of the instruments.

Results: The number of articles reporting the use of Rasch analysis of health instruments is increasing, from 1 article in 1987 to 48 articles in 2007. Of the 10 mobility instruments examined, the primary reason Rasch was used varied. Reasons included assessing instrument unidimensionality, differential item functioning, rating categories, item hierarchy, and redundant items.

Conclusion: The application of Rasch analysis in health instrument development has markedly increased in recent years. However, few mobility instruments have been developed or refined using Rasch analysis. The reasons that the Rasch model was used varied across mobility instruments.