Objective: To gain insight into the overlap between additional information supplied by recently developed health status instruments for rheumatoid arthritis (RA) and traditional clinical and laboratory tests.
Methods: A cross sectional study of 282 outpatients with RA was made. From each patient, variables of clinical and laboratory measurements were obtained and the modified health assessment questionnaire (MHAQ) and a Dutch quality of life questionnaire, the IRGL, were completed. These variables were analysed for their interrelationship.
Results: Clinical and laboratory variables correlated significantly with the scales of the physical dimension and the disease impact scale of the IRGL. Their significant correlations with the IRGL psychological scales were weak. There were no significant correlations between any of the traditional variables and the IRGL social scales. Factor analysis yielded five factors: functionality, pain, depressive mood, social support, and laboratory. The laboratory factor is a measure of the disease process. The other four factors provide a health model.
Conclusion: The results suggest that the IRGL questionnaire that was studied covers a complete health model that incorporates aspects of health that are not measured by clinical and laboratory tests. A simple questionnaire for the psychological and social dimension of health status, however, would probably be more cost effective and easier to use in clinical practice.