Factors associated with pain-related functional interference in people with chronic low back pain enrolled in a physical exercise programme: the role of pain, sleep, and quality of life.

Objective: To identify the factors associated with the pain-related functional interference level in people with chronic low back pain.

Design: Cross-sectional.

Subjects/patients: Chronic low back pain patients.

Psychometric Properties of the Pictorial Pain Interference Questionnaire for Assessing Functional Interference in Chronic Low Back Pain.

Objective: To analyze the psychometric properties of the Pictorial Pain Interference Questionnaire (PPIQ) for evaluating functional interference in the population with chronic low back pain (CLBP).

Design: Cross-sectional study.

Setting: Rehabilitation Unit in a hospital.