Prediction of pain behavior and functional status of rheumatoid arthritis patients using medical status and psychological variables.

This study examined the extent to which the psychological variables of depression, anxiety, and helplessness predicted the pain behavior and functional status of 64 rheumatoid arthritis (RA) patients beyond what could be predicted on the basis of demographic and medical status variables. Pain behavior was evaluated using a standardized observation method, and functional status was assessed using a modified Health Assessment Questionnaire (MHAQ) and rheumatologists' ratings. Regression analyses revealed that a modified rheumatoid activity index and/or disease duration were significant predictors of levels of guarding, rigidity, and total pain behavior. The psychological variables examined did not predict independently RA pain behavior. The rheumatoid activity index explained a significant proportion of the variance in functional status ratings and MHAQ daily function scores. Age, disease duration and depression also were independent predictors of functional status ratings. Thus, depression had a significant relationship with physician ratings of functional status but not with patient self-reports of disability. Psychological factors not examined in this study that might influence RA pain behavior and self-reports of functional status are discussed.