Development of a functional disability measurement tool to assess early arthritis: the Recent-Onset Arthritis...

To develop a self-administered questionnaire, the ROAD (Recent-Onset Arthritis Disability), to probe physical disability in Italian patients with early arthritis (EA) of less than one year's duration.

The development of the ROAD follows a series of major steps: (1) identification of a specific patient population, (2) item pool development, (3) item reduction, (4) internal consistency, (5) pre-testing of the prototype instrument, and (6) a validation study which results in determination, reliability, validity and responsiveness. In this study we have verified the first five steps. Pre-defined areas of disability were culled from eight existing Italian version arthritis-specific questionnaires, and three generic global health measurement tools. Semi-structured interviews helped to derive a 76-item pool from an initial group of 122 items. This questionnaire was administered to 78 EA patients.

For scale generation, a combination of frequency importance product (FIP = frequency x mean relevance score) and factor analysis was applied. The top 20 items based on the FIP were then subjected to further analysis. Each question was correlated with every other question. This allowed us to eliminate 8 questions that were therefore highly correlated and were measuring the same concept. The final instrument has 12 items, representing a combination of symptoms that are common, frequently recurring and of general importance to EA patients. Factor analysis provides a 3-factor health status model explaining 70.1% of the variance. The upper extremity function (5 items) is loaded on the first factor, which explains 45.4% of the total measured variance. The lower extremity function (4 items) formed the second factor (14.2% of the total variance). The third factor was determined by activities of daily living/work (3 items) and explain 10.5% of the total variance. The score of the different subscales can be presented graphically as a ROAD profile.

Using a traditional development strategy, we have constructed a self-administered instrument for measuring physical functioning in patients with EA. The next stage includes reliability, validity and responsiveness testing of the 12-item questionnaire.