Baseline MRI characteristics in asymptomatic subjects as predictors for future first-time LBP episode

Abstract

INTRODUCTION: Previously, it has been noted that there is no predictive value of MRI findings of degenerative changes of the lumbar spine in asymptomatic individuals in the development of first time episodes of low back pain (LBP). In a population-based cohort, this study addressed if radiographic findings on MRI in asymptomatic individuals are predictive in the development of first-time episodes of LBP and pain severity. MATERIALS AND METHODS: A prospective, radiographic and clinical study was performed in 248 asymptomatic individuals of Southern Chinese origin with no previous history of LBP. All subjects underwent sagittal MRI assessment of the lumbar spine. Assessment of disk degeneration was based on the Schneiderman et al radiographic criteria to determine the presence, extent, and severity of disk degeneration. A summated degenerative disk disease (DDD) score of the lumbar spine was obtained, representing the global severity of disk degeneration. The presence of disk bulge/extrusion, Schmorl's nodes (SN), and Modic changes were also noted. At 2 years minimum follow-up, clinical assessment was performed and subject demographics were noted to identify the development of LBP and functional outcome status (e.g., Oswestry disability index). RESULTS: There were 93 males and 155 females with a mean age at MRI of 42.9 years ( ± SD = 7.6, range: 21.1 to 54.6 years). Overall presence of disk degeneration, disk space narrowing, and disk bulge/extrusion was noted in 60.5, 19.0, and 34.3% of individuals, respectively. The mean DDD score was 2.2 ( ± SD = 2.9; range: 0 to 12). SN and Modic changes were noted in 10.5 and 1.2%, respectively. Clinical follow-up was performed at a mean of 4.3 years ( ± SD = 1.9, range: 2.2 to 10.0 years). The incidence rate of first-time LBP episodes on clinical follow-up was 34.7%. The mean age of first-time LBP episode was 44.8 years ( ± SD = 8.5; range: 22 to 57 years). Regression modeling noted that the presence of disk bulge/extrusion (OR: 2.37; 95% CI, 1.30–4.32) and increasing DDD score (>7 score OR: 6.90; 95% CI, 1.86–25.52), in particular if segments involved the mid lumbar region, demonstrated significant predictive utility for developing first-time LBP episode. DDD score and disk bulge/extrusion were found predictive to the severity of LBP, greater functional disability, and increased frequency of future LBP episodes (p < 0.05). CONCLUSION: This large-scale prospective study substantiates that spinal changes are found in asymptomatic subjects on MRI; however, the “global severity” of disk degeneration on initial MRI may be predictive in the development of first-time LBP episodes.