Illness perceptions as an independent predictor of chronic low back pain and pain-related disability: a prospective cohort study

OBJECTIVES: To investigate whether illness perceptions, measured with the Brief Illness Perception Questionnaire, are an independent predictor of chronic low back pain and pain-related disability at 12 weeks. DESIGN: A prospective, observational cohort study. SETTING: 26 outpatient primary care physiotherapy practices throughout the Netherlands. PARTICIPANTS: Acute nonspecific low back pain patients between the age of 18 and 60 years, with or without radiating pain, and a pain-free episode of at least three months before onset. INTERVENTIONS: Standard physiotherapy care according to Dutch clinical practice guidelines. OUTCOME MEASURE: Chronic low back pain defined as pain ≥3/10 on the Numeric Pain Rating Scale and as pain-related disability ≥19/70 on the Pain Disability Index measured after 12 weeks. RESULTS: Two hundred and four people with acute nonspecific low back pain completed both assessments. In the multivariable analyses, adjusted for pain intensity, disability, duration, radiating pain, depressed mood, associations of illness perceptions were OR 1.04 (95% CI: 1.01 to 1.08) for pain and 1.04 (95% CI: 0.99 to 1.09) for pain-related disability. CONCLUSIONS: Illness perceptions independently predicted chronic low back pain but not pain-related disability at 12 weeks. The added predictive value of illness perceptions was relatively low