Catastrophizing as a prognostic factor for pain and physical function in the multidisciplinary rehabilitation of fibromyalgia and low back pain.

Background: Quantitative data on longitudinal associations between catastrophizing and pain or physical function are patchy. The study aimed to quantify the prognostic value of catastrophizing for pain and function in fibromyalgia and low back pain before and after rehabilitation.

Methods: The associations of state and change on the Multidimensional Pain Inventory (MPI) Pain severity scale, the Short Form 36 (SF-36) Physical functioning scale and the Six-Minute Walking Distance (6MWD) with the Coping Strategies Questionnaire (CSQ) Catastrophizing scale were quantified by multiple regression modelling to adjust for confounders.

Results: Sex- and age-matched cohorts (n = 71 each) were compared. Pain and catastrophizing were worse in fibromyalgia than in low back pain, whereas the function levels were comparable. Baseline catastrophizing predicted pain change by adjusted correlations of 0.552 (fibromyalgia) and 0.450 (low back pain), self-rated function by 0.403 and 0.308, and the 6MWD by 0.270 and - 0.072. The change in catastrophizing was associated to the change in pain by 0.440 (fibromyalgia) and 0.614 (low back pain), self-rated function by 0.122 and 0.465, and the 6MWD by 0186 and 0.162.

Conclusions: Catastrophizing (pain-related worrying) was a potential prognostic factor, especially for pain and somewhat less for self-rated physical function but it was only weakly predictive for the walking distance in both conditions, independently of potential confounders, such as sex, age, baseline severity and others. Reduction of maladaptive coping should be integrated into the management of chronic pain.

Significance: Our study showed surprisingly high associations between state and change in catastrophizing to pain relief and functional improvement in chronic pain patients. This is supported by clinical experience and research data, even if the construct and measurement of catastrophizing is under debate. Our findings and those of literature point to more pessimistic self-rating of pain and catastrophizing in fibromyalgia when compared to other conditions. This might obscure positive effects on pain and function achieved by adaptive coping in fibromyalgia.