The temporal relation between pain and fatigue in individuals receiving treatment for chronic musculoskeletal pain.

BACKGROUND: Numerous investigations have revealed significant relations between pain and fatigue in individuals with persistent pain conditions. However, the direction of influence between pain and fatigue remains unclear. Shortcomings of design and analytic approaches used in previous research limit the nature of conclusions that can be drawn about possible causal or directional relations between pain and fatigue. The present study investigated the temporal relation between changes in pain and changes in fatigue in individuals with musculoskeletal pain enrolled in a 10-week behavioral activation intervention. On the basis of previous findings, it was hypothesized that analyses would support a bi-directional relation between pain and fatigue. METHODS: The study sample consisted of 104 individuals with chronic musculoskeletal pain participating in a 10-week standardized rehabilitation intervention. Measures of pain intensity and fatigue were completed pre-, mid-, and post-treatment. The three-wave data panel permitted examination of the direction of influence between pain and fatigue through the course of the intervention. A random-intercept cross-lagged panel model (RI-CLPM) was used to examine the temporal relation between pain and fatigue. RESULTS: Consistent with previous research, cross-sectional analyses of pre-treatment data revealed significant correlations between measures of pain and fatigue. Significant reductions in pain and fatigue were observed through the course of treatment (d = 0.33 and d = 0.66, p < .001, respectively). RI-CLPM revealed that pain severity predicted later fatigue (pre to mid-treatment standardized path coefficient (ß) = 0.55, p = 0.02; mid to post-treatment ß = 0.36, p = 0.001); however, fatigue did not predict later pain severity. CONCLUSIONS: Discussion addresses the processes that might underlie the temporal relation between pain and fatigue. Clinical implications of the findings are also discussed.

The Sequential Relation Between Changes in Catastrophizing and Changes in Posttraumatic Stress Disorder Symptom Severity.

Catastrophizing has been discussed as a cognitive precursor to the emergence of posttraumatic stress disorder (PTSD) symptoms following the experience of stressful events. Implicit in cognitive models of PTSD is that treatment-related reductions in catastrophizing should yield reductions in PTSD symptoms. The tenability of this prediction has yet to be tested. The present study investigated the sequential relation between changes in a specific form of catastrophizing-symptom catastrophizing-and changes in PTSD symptom severity in a sample of 73 work-disabled individuals enrolled in a 10-week behavioral activation intervention. Measures of symptom catastrophizing and PTSD symptom severity were completed at pre-, mid-, and posttreatment assessment points. Cross-sectional analyses of pretreatment data revealed that symptom catastrophizing accounted for significant variance in PTSD symptom severity, ß = .40, p < .001, sr = .28 (medium effect size), even when controlling for known correlates of symptom catastrophizing, such as pain and depression. Significant reductions in symptom catastrophizing and PTSD symptoms were observed during treatment, with large effect sizes, ds = 1.42 and 0.94, respectively, ps < .001. Cross-lagged analyses revealed that early change in symptom catastrophizing predicted later change in PTSD symptoms; early changes in PTSD symptom severity did not predict later change in symptom catastrophizing. These findings are consistent with the conceptual models that posit a causal relation between catastrophizing and PTSD symptom severity. The clinical implications of the findings are discussed.

Reductions in Fatigue Predict Occupational Re-engagement in Individuals with Work-Related Musculoskeletal Disorders.

Background Symptoms of fatigue have been shown to be associated with heightened levels of disability in patients suffering from a wide range of debilitating health and mental health conditions. The role of fatigue as a determinant of work disability in individuals with work-related musculoskeletal disorders (WRMD) has received little attention. The present study examined the role of fatigue as a determinant of work-disability in individuals with WRMDs. Methods Participants included 117 individuals with WRMDs who completed measures of pain severity, fatigue, depression and disability before and after participating in a behavioral activation rehabilitation intervention. Results Cross-sectional analyses on pre-treatment measures revealed that fatigue contributed significant variance to the prediction of self-reported disability, beyond the variance accounted for by pain severity and depression. Prospective analyses revealed that reductions in fatigue through the course of treatment predicted occupational re-engagement following termination of the intervention. Conclusions The results of the present study suggest fatigue contributes to occupational disability, independent of the effects of pain and depression. The findings also suggest that meaningful reductions in fatigue might be achieved through psychosocial interventions that promote gradual re-integration into discontinued activities, increase participants' exposure to success and achievement experiences, and reduce the severity of depressive symptoms. Behavioural activation interventions such as the one used in the present study might contribute to more positive occupational outcomes in work-disabled individuals who report high levels of fatigue.