Illness Perceptions Explain the Variance in Functional Disability, but Not Habitual Physical Activity, in Patients With Chronic Low Back Pain: A Cross-Sectional Study

IntroductionAlthough the importance of psychosocial factors has been highlighted in many studies in patients with chronic low back pain (CLBP), there is a lack of research examining the role of illness perceptions in explaining functional disability and physical activity in patients with CLBP. AimThe aim of the study was to explore the value of illness perceptions in explaining functional disability and physical activity in patients with CLBP. MethodsEighty-four participants with CLBP (of >3months' duration) completed a battery of questionnaires investigating psychosocial factors (Pain Catastrophizing Scale [PCS], Illness Perceptions Questionnaire Revised [IPQ-R], and 36-Item Short Form mental health scale [SF-36_MH]) and perceived pain intensity (visual analog scale [VAS]), as well as the Oswestry Disability Index (ODI) and Baecke questionnaire. The latter 2 were entered separately as dependent variables in a regression analysis. ResultsThe combined variables (VAS, PCS, SF-36_MH, IPQ-R) accounted for 62% of the variance in functional disability (ODI). Adding the results of the IPQ-R to the scores of the other 3 variables (VAS, PCS, SF-36_MH) significantly increased the explained variance of ODI scores in CLBP patients, yielding 18% additional information (P<0.01). Only 5% of the variance in the Baecke questionnaire was explained by combining the 4 variables. None of the single variables alone made a significant contribution to R-2. ConclusionsIllness perceptions are an important factor for explaining functional disability, but not for explaining habitual physical activity in CLBP patients.