Despite significant improvements in the medical management, treatment, and prognosis of RA, it is common for patients to experience deficits in physical and mental health functioning. This research adopted an integrated, biopsychosocial framework [16
] to evaluate the relative contribution of disease activity and psychosocial factors to physical and mental health functioning outcomes in a sample of RA patients living in greater metropolitan Los Angeles. Hierarchical multiple regression isolated the sequential contribution of variables to physical functioning, mental health functioning, and disability, according to this framework. A major objective of these analyses was to determine the impact of psychosocial factors on physical and mental health and disability after controlling for medication use and disease activity. Analyses provided important, new information on the contribution of psychosocial factors and the overall relevance of this framework to functional outcomes in RA.
In general, psychosocial factors and self-reported disease activity proved very influential in explaining variability in all three outcomes. While self-reported RADAR scores were significantly correlated with physical functioning, mental health functioning, and disability scores, physician-assessed DAS28 scores were not correlated with any outcome, a finding that is consistent with previous research showing that physician-based assessments of RA disease activity may not be associated with functional outcomes or psychological variables [10
]. Together, these findings underscore the importance of using patient-reported outcomes such as HRQOL and evaluating the clinical status of patients based on their subjective appraisal of their illness experience.
It is noteworthy that the contribution of psychosocial variables in this research varied across HRQOL domains and disability. Higher active coping was associated with better physical functioning, while passive coping and helplessness were correlated, although not significantly, with poorer physical functioning. Active coping has been shown to correlate modestly with less pain and psychological distress in RA patients [15
] and more strongly with better psychosocial functioning in elderly populations with health problems [28
]. Active coping refers to the ability of patients to function in spite of their pain and to actively manage their medical condition, and may be central to achieving enhanced quality of life and mechanisms of positive psychological adaptation. Active coping has proven to be a stronger determinant of positive adaptation than passive coping and helplessness, which have been shown to predict negative physical and psychological outcomes in arthritis [29
], whiplash [30
], and fibromyalgia [31
Psychological factors were particularly important in explaining mental health functioning. High personal mastery and low perceived stress accounted for a major proportion of the variance in mental health functioning, although these factors did not predict physical functioning. Other research [11
] has shown depression to be a major determinant of SF-36 mental health scores in RA patients. Personal mastery, unlike arthritis internality, is a global measure of perceived control that reflects a general disposition of competence that may serve as a mechanism through which better mental health functioning is achieved. Perceived stress, on the other hand, is a general indicator of burden that may be the result of numerous life stressors, including those connected with having a chronic disease. Acting influentially but in opposite directions, these factors were far more important in explaining mental health functioning than self-reported disease activity.
The findings on disability illustrated the contribution of helplessness. Helplessness independently accounted for variability in disability, over and above the effects of disease activity. Similar results have been reported elsewhere [18
] and indicate that perceptions of helplessness are key to understanding deficits in functioning, but not quality of life. Specific functional problems in RA reflect idiosyncratic beliefs about the uncontrollability of pain and other aspects of the disease course but, as this research has shown, are independent of both general beliefs of mastery or specific expectancies of control over RA. That different psychological processes may be involved in quality of life and disability is not surprising in view of the disparate nature of these outcomes, including their level of specificity or generality, and their differential sensitivity to the disease process.
This study has demonstrated the applicability of a comprehensive framework for understanding HRQOL and disability in RA. A significant limitation of the study, however, was its cross-sectional design, which precluded interpretations of directionality among model variables. Future research evaluating this model longitudinally would shed light on whether psychosocial factors predict functional outcomes over time while controlling for prior levels of disease activity. Longitudinal research could also address the potential mediating roles of variables such as coping and perceived stress to these outcomes. Another limitation of the study was that participants were volunteers recruited from the community. Volunteers tend to be more mobile and possess fewer of the medical comorbidities associated with more advanced RA. A larger sample of patients with varying stages of disease progression would enable tests of the generalizability of the model, including the importance of the specific variables that were identified in this research as critical to understanding functional outcomes
In spite of these limitations, the data suggest that the evaluation of patients with RA in clinical settings should address psychosocial functioning using PROs and psychological measurements. The identification of psychosocial factors that interfere with HRQOL and lead to disability would set the stage for behavioral interventions that could facilitate management and contribute to more positive functional adaptations [32