Type 1 Modic changes was a significant risk factor for 1-year outcome in sick-listed low back pain patients: a nested cohort study using magnetic resonance imaging of the lumbar spine.

Abstract

It is not clear whether Modic changes (MC) is associated with low back pain (LBP) outcome. To study associations between baseline degenerative manifestations and outcome in sick-listed LBP patients. Prospective nested cohort study based on a randomized controlled trial. Out of 325 sick-listed LBP patients, 141 were consecutively examined by magnetic resonance imaging (MRI) and included and 140 completed the study. Degenerative manifestations of the lumbar spine were quantified; associations were studied in relation to the three primary outcomes: change of back+leg pain, change of function as measured by Roland-Morris questionnaire, and 1-year unsuccessful return to work (U-RTW). By using a previously validated MRI protocol, a specialist in radiology, who had no access to clinical data, described the images. Associations were studied by linear and logistic regression with adjustment for previously identified prognostic factors for 1-year pain and function and for U-RTW. Clinically, 43% of the patients had radiculopathy. Degenerative changes were prevalent with altered disc contours in 84%, high-intensity zones in 70%, and nerve root touch or impingement in 63% of the patients. MC was identified in 60% of the patients, 18% with Type 1 changes and 42% with Type 2 changes, Type 1 including both Type 1 and Type 1 in combination with Type 2. Patients with Type 1 changes reported more back pain and did not improve in pain or disability. They increased to include 30% of the patients with U-RTW at 1 year. Patients with Type 2 changes did not differ significantly from patients without MC but differed significantly from patients with Type 1 changes in all three outcomes. Other degenerative manifestations were not significantly associated with any of the three outcomes. The only degenerative manifestation negatively associated with outcome was Type 1 MC that affected 18% of the cohort at baseline and implied an increased risk for no improvement in pain and function and for U-RTW, even after adjustment for other prognostic factors.