Objective: The purpose of this study was to develop a brief measure of severity for rheumatoid arthritis (RA) that would not be seriously confounded by psychological functioning. The Rheumatoid Arthritis Severity Scale (RASS), designed for use by physicians on their own patients, consists of three visual analogue scales: Disease Activity, Functional Impairment and Physical Damage.
Methods: Ninety-four RA outpatients completed the Health Assessment Questionnaire (HAQ) Disability, Pain Severity, Health State subscales and the Symptom Checklist-90-Revised (SCL-90-R) Anxiety, Depression and Somatization subscales. Rheumatologists completed the RASS on their own patients.
Results: Results suggest that the RASS is internally consistent (alpha=0.85) and valid. RASS Disease Activity, Functional Impairment, Physical Damage correlated with HAQ Disability (r=0.40, 0.68, 0.61; P<0.01), Pain (r=0.37, 0.34, 0.34; P<0.01) and Health State (r=-0.27, -0.36, -0.27; P<0.01). RASS Physical Damage uniquely predicted longer illness duration (years with RA). In contrast to the HAQ, RASS subscales shared less variance with anxiety, somatization and depression scores.
Conclusions: Preliminary data suggest that the RASS may be a quick, reliable, valid physician-completed RA severity scale that compares favourably with the longer, patient-completed HAQ.