The findings of this study support the use of a biopsychosocial model for understanding chronic pain and its impact in persons with MMD1 and FSHD. The hypothesis that attributions, coping responses, and psychosocial factors are all independent, significant contributions to chronic pain in this population is supported. The data also indicate that measures of psychological functioning and pain interference are associated with psychosocial variables in this patient population. Moreover, with the exception of positive associations between most of the coping responses (whether considered adaptive or maladaptive) and pain interference, the current study shows positive associations between patient functioning and psychosocial factors thought to be maladaptive (eg, guarding and resting coping responses, disability and harm beliefs), as well as negative associations between patient functioning and factors thought to be adaptive (e.g., perceived support and control beliefs). In particular, and in both the multivariate and univariate analyses, we found that greater pain-related catastrophizing (symptom magnification, rumination, and helplessness) was significantly related with both poorer psychological functioning and increased pain interference. This finding is consistent with many prior studies in persons with different pain conditions and disabilities, and across different age groups. Specifically, pain-related catastrophizing has been associated with poorer outcomes in children,46
and elderly patients with pain48
as well as persons with chronic pain secondary to a number of disabilities such as multiple sclerosis,49
spinal cord injury,17,18,23,53
and phantom limb pain.22,36
To our knowledge, this is the first time that pain-related catastrophizing has been studied in patients with MMD1 and FSHD and pain. Given the correlational nature of the current study, it is not possible to draw conclusions regarding the causal nature of this relationship. Catastrophizing cognitions may influence and lead to greater dysfunction, dysfunction may influence and lead to greater catastrophizing, dysfunction and catastrophizing may influence each other, or both may reflect or be caused by a third variable (eg, a generally negative or pessimistic attitude). However, there is some evidence that decreases in catastrophizing are associated with improved outcomes for persons receiving multidisciplinary treatment for chronic pain.27
Moreover, an intervention that specifically targets catastrophizing has been shown to decrease reports of pain intensity in persons with disabilities.54
Further studies are needed to determine the generalizability of our findings to other samples of persons with MMD1 or FSHD, and to confirm that changes in catastrophizing actually contribute to improved functioning, as opposed to merely reflect improved functioning, in persons with disabilities and chronic pain.
Our results showed that higher levels of perceived social support were associated with less pain interference and better psychological functioning, even after controlling for pain intensity and demographic variables. Again, it is not possible to determine the causal direction of the relationships found using correlational data. However, these findings are generally consistent with other research of persons with disabilities and chronic pain17,22,36,49
as well as with studies of persons with pain and other various health problems.16,53,55,56
The consistent associations found in this body of research raises the possibility that social support, or at least one’s perceived access to support, may act as a buffer for maintaining physical health, and psychological functioning, in persons with disabilities and pain. Longitudinal and experimental research is needed to test and confirm this causal hypothesis.
The multivariate analyses revealed that the pain belief factor scores made statistically significant and unique contributions to the prediction of the criterion measures. Interestingly, while the Emotion and Solicitude beliefs factor was associated most closely to psychological functioning, the Disability and Harms Beliefs factor was related most closely to pain interference. Univariate analysis revealed that certain pain beliefs were significantly related to both psychological functioning and pain interference (ie, Disability, Harm, Solicitude, Control). These results are consistent with previous studies finding similar associations between pain beliefs related to disability and pain interference.17,49,52,57
Moreover, the findings showed significant contributions of coping to the prediction of the criterion measures. However, only the Passive Coping factor showed statistically significant relationships with pain interference in the multivariate analyses. The univariate analyses, 7 of the 9 CPCI coping scales showed significant associations with pain interference (all associations were positive), with the strongest negative associations occurring among those coping responses considered to be maladaptive (eg, guarding, resting, and asking for assistance). These findings are consistent with research in other disability groups where pain coping has been found to be associated with pain and functioning. For example, guarding and resting have been found to be associated with increased pain interference and pain intensity in patients with phantom limb pain,36
The positive univariate associations found between 4 coping responses generally thought to be adaptive and pain interference helps to further illustrate the difficulty of identifying causal associations from correlational data. Such results could be obtained if these coping responses are, in fact, maladaptive in our sample. For example, it is possible that the coping strategies thought to be adaptive (eg, coping self-statements, seeking social support, and pacing) may be helpful at the outset of a disability or injury, but once maximum gains have been achieved, some of these strategies may become less effective or even hinder progress toward more independent functioning. However, it is possible that positive associations found between coping responses thought to be adaptive and pain interference occurred because people find them useful, and so they tend to be used more when patients suffer from higher levels of pain or pain interference; in the same way that one might expect a positive association between pain intensity and the use of effective analgesic medications. Thus, the current findings indicate that (1) pain coping responses predict and may be important to adjustment to pain in persons with MMD1 and FSHD and (2) research is needed to further explore the relationship of these variables with pain interference in this population, in particular, to help elucidate the presence and extent of any causal associations. Such research would help guide clinicians in the development of effective interventions for persons with MMD1 and FSHD suffering from chronic pain. Future studies should also implement longitudinal designs to better understand these relationships and experimental designs that can help to elucidate causal relationships between all these factors.54
Several methodological limitations of the current study should be acknowledged. A primary limitation, already discussed, is that the data are cross-sectional. Because of this, we cannot draw causal conclusions from the study; longitudinal and experimental research is needed to better understand the nature of the relationships between the variables, and to determine whether changes in specific psychosocial variables are associated with changes in pain-related criterion measures. Also, the use of component scores versus individual subscales of the SOPA and CPCI in the multivariate analyses represents a limitation. Although use of this strategy was necessary to ensure an adequate N to k ratio in the multivariate analyses, this approach limits the interpretability of the multivariate findings and increases the risk of type II error.17,27,58
A third limitation is that the sample was drawn primarily from persons with MMD1 and FSHD who were registered with a NIH-funded National Registry. This limits the generalizability of the findings. We are unable to determine whether and to what extent our findings generalize to other persons with MMD1 or FSHD not participating in the registry. Moreover, we do not know to what extent the participants who agreed to participate in this study are similar to or different from other patients who are listed in the NIH registry but did not choose to participate in the study. In addition, a large majority of the participants in this study were Caucasians. Thus, future studies should seek to replicate these findings in broader and more representative samples of persons with MMD1 and FSHD. Finally, the current findings may be affected by responder bias (eg, social desirability effects or memory failure), as the data are self-report. Moreover, using only self-report data increases the possibility that some of the significant associations observed could be due in part to shared method variance. Future studies should also include objective measures, and/or measures from other sources (eg, spouses/partners, health care providers) when possible.
Despite the limitations of the current study, the findings have important research and clinical implications; specifically regarding how chronic pain in individuals with these neuromuscular disorders should be understood and treated. Currently, chronic pain management in these populations is guided primarily by biomedical approaches, with research-limited success.59–63
Our study provides novel, empirical support for broadening the treatment approach to include biopsychosocial variables as potential treatment targets. Our data also point to a need for further research to determine if biopsychosocial interventions are as effective in these populations as they have been for other groups of individuals, both disabled and able-bodied, with chronic pain.