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

Background context: It is not clear whether Modic changes (MC) is associated with low back pain (LBP) outcome.

Purpose: To study associations between baseline degenerative manifestations and outcome in sick-listed LBP patients.

Study design: Prospective nested cohort study based on a randomized controlled trial.

Patient sample: Out of 325 sick-listed LBP patients, 141 were consecutively examined by magnetic resonance imaging (MRI) and included and 140 completed the study.

Outcome measures: 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).

Methods: 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.

Results: 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.

Conclusions: 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.

Keywords: Disc herniation; Low back pain; Modic changes; Prognosis; Return to work; Sick listing.