Relationships between pain-related and cognitive variables and disability in women with fibromyalgia and occupational overuse syndrome : a thesis presented in partial fulfilment of the requirements for the degree of Master of Arts in Psychology at Massey University
There is an expanding body of evidence indicating that cognitive factors contribute to the prediction of disability resulting from chronic pain. Indeed, some research amongst chronic low back pain sufferers has demonstrated that pain-related fear is actually more disabling than pain itself (Crombez, Vlaeyen, Heuts, & Lysens, 1999). The present study utilised a sample comprising individuals with fibromyalgia syndrome (FMS) and occupational overuse syndrome (OOS), and an asymptomatic comparison group. There were three broad aims: The first aim was to evaluate between group differences in pain-related and cognitive variables; and the second, was to assess the relevance of the fear component of the model proposed by Vlaeyen, Kole-Snijders, Boeren, and van Eek (1995) for this sample. The third aim, related to the second, was to explore the relationship between pain and disability, considering the effects of fear of movement, catastrophising, and vigilance for pain. Symptomatic individuals (n = 68) completed measures of pain, fear of movement, vigilance for pain, disability, catastrophising, and cognitive errors. The comparison group (n = 24) completed only the last two measures. Medical assessment, including tender point examination, was also carried out on all participants. There were no differences between individuals with OOS and FMS in relation to current pain, catastrophising, vigilance, or fear of movement. However, significant differences were revealed between participants with FMS and the comparison group in terms of somatic cognitive errors, but not general cognitive errors. Multiple regression using data from symptomatic participants demonstrated that although pain had the largest impact on disability, fear of movement and vigilance also contributed uniquely to this outcome. However, further analysis revealed that catastrophising moderated the relationship between pain and disability. Catastrophising did not impact on disability reporting amongst women experiencing high levels of pain, but amongst women with low levels of pain high catastrophising was associated with more disability reporting than low catastrophising. Furthermore, the association between pain and catastrophising rendered the contribution of fear of movement to disability non significant. Theoretical and methodological implications of these results are discussed.