Approach to evaluation of impairment in rheumatoid arthritis--a study by multiple regression analysis

We investigated the weight of various factors involved in the activity of rheumatoid arthritis (RA) and joint deformity in an attempt to establish a more objective method of evaluation of the impairment in RA using these factors as parameters. The subjects were 100 patients with RA. Multiple regression analysis was undertaken using Lansbury parameters and Stage as predictor variables and the classification of functional capacity (Class) as a criterion variable. The results of analysis showed that the weight was greatest, 32% for the time of appearance of fatigue, followed by 29% for the Stage, 16% for joint index, 10% for grasping power, 7% for ESR, 5% for morning stiffness and 0% for the dose of aspirin used. On the basis of these results, an original method of evaluation of impairment in RA was proposed. There was a close correlation (R = 0.82) between the Class and the total score obtained by this method.