Commentary on “past and present issues in Rasch analysis: the fim revisited”.

A recent paper by Lundgren-Nilsson & Tennant (1) and accompanying commentary (2) reviewed the development of Rasch analysis in rehabilitation. The authors of the two papers acknowledge the advances that have been made in terms of analysis. However, they did not highlight an important issue with regards to the use of Rasch measures once developed. We believe this is a fundamental issue that needs to be addressed to ensure the potential of Rasch is fulfilled. There has been a recognised increase in Rasch analysis in rehabilitation (3, 4), with Lundgren-Nilsson & Tennant (1) reporting over 50 papers applying Rasch to the Functional Independence Measure. Given the importance of measurement in clinical trials and clinical practice, it would seem logical that a technique that enabled 'better' measures and improved interpretation (5) would have been welcomed by both the research and clinical communities. Rasch analysis has the advantage of interval level measurement which has potential to allow parametric analysis in clinical trials, improve synthesis in systematic reviews and map individual and service outcomes over time in a more robust manner. However, the extent to which Rasch developed and refined measures have been used in research or practice has not been investigated. It has been supposed that Rasch analysis is rarely applied to practical implementation of outcome measures (3). We undertook a review to explore how often Rasch developed scales have been used in research. RevIeW oN uSe oF RASCH deveLoped MeASuReS The review methodology as detailed by Tesio et al. (3) was repeated, searching for Rasch as free text. published articles that specified they applied Rasch developed or refined measures to a study were included. The entire electronic databases Medline, eMBASe, Cinahl, pedro, Cochrane Central Register of Controlled Trials, and Cochrane database of Systematic Reviews, psychINFo and Web of Science searched from the earliest publication to June 2011. Initially the number of studies using Rasch analysis were documented to compare with Tesio et al. (3) to document the increase in Rasch analysis over the last 4 years. The title and/or abstract of articles identified from the initial Medline search were then examined to identify those papers which had applied a Rasch developed or derived scale to clinical trials, case studies or clinical practice. From the initial search of the electronic databases, it was clear that the use of Rasch analysis has continued to increase across all of the databases (Table I). From …