Steps Towards an Intervention: Exploring Correlates and Measurement of Fatigue in Osteoarthritis

Abstract

Background: Fatigue affects up to 90% of adults with osteoarthritis and contributes to disability and reduced quality of life. Treatment options are non-specific and limited to self-management. These limitations are due to least two gaps in current research: the lack of a standardized, reliable, and valid fatigue measure, and the lack of mechanistic insight. Purpose: To begin to address these limitations, the purposes of this three-manuscript dissertation were: 1) to examine standardized, valid, and reliable measures of osteoarthritis fatigue and 2) to explore correlates of fatigue to provide mechanistic insight. Methods: The first manuscript is a narrative literature review of osteoarthritis fatigue correlates. The second and third manuscripts analyze data from cross-sectional, retrospective studies. Analyzing pilot study data in SPSS and WINSTEPS, the second manuscript examines psychometrics of the standardized PROMIS Fatigue Short Forms 8a and 7a in osteoarthritis. The third manuscript uses data from the 2007-2010 National Health and Nutrition Examination Survey (NHANES) to examine fatigue correlates. Using SPSS complex samples analysis, adjusted logistic regression models were generated to predict odds of osteoarthritis fatigue as a function of a biological correlate (i.e., systemic inflammation: c-reactive protein [CRP] and white blood cell count [WBCC]). Results: Correlates of osteoarthritis fatigue include age, gender, medications, comorbidities, anxiety, depression, joint pain, physical activity, physical exercise, physical function, sleep quality, and systemic inflammation. The 8a and 7a were reliable (α =.86-.93) in adults with osteoarthritis. Differences existed in 8a, but not 7a, total scores, between adults with (N=20) and without osteoarthritis (t29=-2.8, p<.001; N=11). From the NHANES data, with every 1 mg/dL increase in CRP, adults with osteoarthritis had 3.19 times higher odds of fatigue (95% CI 1.11-9.19, p=.03) when controlling for age, pain, depression, sleep quantity, sleep disturbances, and body mass index. Conclusion: These findings have begun to fill the gaps that hindered development and testing of targeted interventions. Future research is necessary to gain more understanding of the use of the 7a and 8a in osteoarthritis and to delineate the relationship between other correlates, including additional systemic inflammatory markers, and fatigue in osteoarthritis. This will propel development and testing of targeted interventions.