Recurrent low-back pain : Exercise intervention and predictive factors

Abstract: Low-back pain continues to be one of the main problems for which subjects seek treatment in primary care. While the natural history of low-back pain is often considered to be good, many sufferers get further episodes that affect well-being as well as quality of life. Aim: The main aim of the work presented in this thesis was to evaluate the efficacy of a graded exercise intervention in a sample of subjects with recurrent low-back pain still at work, and to investigate factors predicting future outcome of disability and pain. Methods: One-hundred-and-eighteen subjects with recurrent low-back pain participated. In addition, Study I included 57 healthy age- and gender-matched controls. Pre-intervention, post-intervention, 6-month, 12-month (Studies II, III, IV) and 36-month (Study III) follow-ups evaluated pain, disability, physical health, fear-avoidance beliefs and self-efficacy beliefs. Self-rated questionnaires were used. Level of aerobic fitness was compared between the group with low-back pain and healthy controls (Study I), and a graded exercise intervention emphasizing stabilizing exercises was evaluated in comparison with either manual treatment (Study II) or daily walks (Study III). Predictive factors for a future outcome of disability and pain were investigated using multivariate regression analysis (Study IV). Results: There was no difference in aerobic fitness level between subjects with low-back pain and healthy controls. In the group with LBP, regression analysis showed an association between a lower level of aerobic fitness and higher age, gender and lower levels of selfefficacy (Study I). In Study II, comparing a graded exercise intervention with manual treatment, a significant difference in favour of the exercise group regarding disability after the treatment was maintained in the long term. No significant difference emerged between the groups regarding pain. (Study II). In Study III, between-group testing showed significant differences in favour of the exercise group for perceived disability at 12-months, maintained at the 36-month follow-up. In addition, between-group results for pain showed greater reduction for the exercise group post-intervention than for the daily-walks group. Regarding secondary outcome, the results showed a significant group difference in favour of the exercise group in short- and long term regarding physical health and in self rated selfefficacy at 12- and 36-month follow-ups. Regarding fear-avoidance, no such differences emerged (Study III). Lower levels of self-efficacy, higher levels of perceived disability painlevel and pain frequency emerged as predictors of an unfavourable clinical outcome, and these predictors remained significant in the post-intervention models. (Study IV). Conclusion: In conclusion, a graded exercise intervention emphasizing stabilizing exercises alleviated disability levels and improved physical health and rated self-efficacy more than manual treatment or daily walks did, in subjects with recurrent low-back pain and currently at work. The graded exercises also reduced recurrent need for treatment in the long term, indicating that the exercises had a preventive effect. Levels of aerobic fitness were comparable between the subjects with low-back pain and the healthy controls. However, lower levels of aerobic fitness were associated with higher age, gender and low self-efficacy in the sample of subjects with low-back pain. Importantly, higher levels of perceived pain, pain frequency and disability and a lower level of self-efficacy emerged as predictors of an unfavourable outcome of disability and pain in the long term, indicating that such early screening information might be useful for further management of patients with LBP.