To assess: a) The prevalence of Modic changes and other findings on lumbar magnetic resonance imaging (MRI), among Spanish adult chronic LBP patients, b) Patient characteristics and radiological findings associated with Modic changes.

Ten radiologists from six hospitals across six cities in Spain, consecutively recruited 487 adult patients (263 women and 224 men) in whom lumbar MRI had been prescribed for low back pain lasting ≥ 3 months. Patients' characteristics and imaging findings were assessed through previously validated instruments. A multivariate logistic regression model was developed to assess the features associated with Modic changes.

Outcome measures were: Gender, age, body mass index (BMI), life time smoking exposure, degree of physical activity, and image features (disk degeneration, type and extension of Modic changes, disk contour, annular tears, spinal stenosis and spondylolisthesis).

Inclusion Criteria:

• Patients between 35 and 50 years of age having a diagnosis of chronic low back pain (of 3 or more months' duration, and including sciatica and lumbar cytalgia), who get a prescription for an MRI.

Exclusion Criteria:

• Racial characteristics suggesting a non-Spanish origin; central nervous system pathology (with or without treatment);
• Diagnosis or suspicion of systemic disease (inflammatory disease such as rheumatoid arthritis, or infections).

Patients seen for chronic low back pain at the hospitals of the Spanish National Health Service.