Confirmatory factor analysis of the Pittsburgh Sleep Quality Index in rheumatoid arthritis patients.

The purpose of this research was to evaluate the factor structure of the Pittsburgh Sleep Quality Index (PSQI) in rheumatoid arthritis (RA). The sample included 107 patients with RA, 88 females and seven males, with an average age of 56.09 years, recruited from the greater Southern California area. Confirmatory factor analysis evaluated single, two- and three-factor models. The single factor solution yielded a poor fit to the data. While the three-factor solution had the best fit, the two-factor solution, comprised of sleep efficiency and perceived sleep quality factors, was optimal because it had very good fit, and acceptable reliability for its individual factors. Clinical indices were consistently correlated with the sleep quality factor, but not with the sleep efficiency factor.

A multidimensional model of fatigue in patients with rheumatoid arthritis.

OBJECTIVE: To evaluate a multidimensional model testing disease activity, mood disturbance, and poor sleep quality as determinants of fatigue in patients with rheumatoid arthritis (RA). METHOD: The data of 106 participants were drawn from baseline of a randomized comparative efficacy trial of psychosocial interventions for RA. Sets of reliable and valid measures were used to represent model constructs. Structural equation modeling was used to test the direct effects of disease activity, mood disturbance, and poor sleep quality on fatigue, as well as the indirect effects of disease activity as mediated by mood disturbance and poor sleep quality. RESULTS: The final model fit the data well, and the specified predictors explained 62% of the variance in fatigue. Higher levels of disease activity, mood disturbance, and poor sleep quality had direct effects on fatigue. Disease activity was indirectly related to fatigue through its effects on mood disturbance, which in turn was related to poor sleep quality. Mood disturbance also indirectly influenced fatigue through poor sleep quality. CONCLUSION: Our findings confirmed the importance of a multidimensional framework in evaluating the contribution of disease activity, mood disturbance, and sleep quality to fatigue in RA using a structural equation approach. Mood disturbance and poor sleep quality played major roles in explaining fatigue along with patient-reported disease activity.

An evaluation of a biopsychosocial framework for health-related quality of life and disability in rheumatoid arthritis.

OBJECTIVE: To examine the relationships between physical, psychological, and social factors and health-related quality of life (HRQOL) and disability in rheumatoid arthritis (RA). METHODS: A sample of 106 patients with rheumatoid arthritis (RA) completed measures of self-reported disease activity and psychosocial functioning, including coping, personal mastery, social network, perceived stress, illness beliefs, the SF-36 and Health Assessment Questionnaire Disability Index (HAQ-DI). In addition, physician-based assessment of disease activity using the Disease Activity Scale (DAS-28) was obtained. Hierarchical multiple regression analyses were used to evaluate the relationships between psychosocial factors and scores on the SF-36 and HAQ-DI. RESULTS: Lower self-reported disease activity was associated with higher SF-36 physical functioning scores, while the contribution of active coping, passive coping, and helplessness was significant only as a block. Lower self-reported disease activity, higher personal mastery, and lower perceived stress contributed to higher SF-36 mental health functioning, and higher self-reported disease activity and lower helplessness were associated with greater disability, as indexed by the HAQ-DI. The DAS-28, an objective of measure of disease activity, was unrelated to any of these outcomes. CONCLUSIONS: The findings highlight the importance of targeting psychological factors to enhance HRQOL and disability in the clinical management of RA patients.