Predictors of clinical success with stabilization exercise are associated with lower levels of lumbar multifidus intramuscular adipose tissue in patients with low back pain.

Purpose: Investigate the construct validity of prognostic factors purported to predict clinical success with stabilization exercise for low back pain by exploring their associations with lumbar multifidus composition. Methods: Patients with low back pain were recruited from a hospital imaging department. The presence of fivepredictors (age <40 years, positive prone instability test, aberrant trunk flexion movements, straight leg raise range of motion >91 degrees, spinal hypermobility) were identified by standardized physical examination. Predictors were grouped by total positive findings and status on a clinical prediction rule. The proportion of lower lumbar multifidus intramuscular adipose tissue was measured with 3.0 T magnetic resonance imaging. Univariate and multivariate associations were examined with linear regression and reported with standardized beta coefficients (beta) and 95% confidence intervals. Results: Data from 62 patients (11 female) with mean (SD) age of 45.2 (11.8) years were included. Total number of predictors (beta[95% CI] = -0.37[-0.61,-0.12]; R-2 = 0.12), positive prediction rule status (beta[95% CI] = -0.57[-0.79,-0.35]; R-2 = 0.30), and age <40 years were associated with lower intramuscular adipose tissue (beta[95% CI] = -0.55[-0.77,-0.33]; R-2 = 0.27). No other individual factors were associated with lumbar multifidus intramuscular adipose tissue. Conclusions: These findings support the construct validity of the grouped prognostic criteria. Future research should examine the clinical utility of these criteria.