Risk factors for progression of lumbar spine disc degeneration: the Chingford Study

Abstract

Objective: Few data exist concerning the natural history of lumbar spine disc degeneration and associated risk factors. We therefore undertook this study to examine the radiographic progression of lumbar spine disc degeneration over the course of 9 years in a population-based inception cohort of women from the Chingford Study.

Methods: Seven hundred ninety-six paired lumbar spine radiographs were read by a single reader for anterior osteophytes (AO) and disc space narrowing (DSN) using the Lane atlas at each lumbar disc space (L1-5). Disc degeneration was defined using thresholds of AO and DSN grade 1+ in one or more vertebrae (L1-5) within a subject. Progression was defined as an increase in grade in an affected year-1 vertebra. Potential risk factors were assessed using odds ratios and 95% confidence intervals adjusted for age, body mass index (BMI), and other potential confounders in logistic regression models using the STATA statistical package.

Results: The mean +/- SD age at baseline was 53.8 +/- 6.0 years, and mean +/- SD BMI was 25.4 +/- 4.1 kg/m(2). Progression rates for AO and DSN were 4% per annum and 3% per annum, respectively. Progression of DSN was predicted by age, back pain, and radiographic hip and knee osteoarthritis (OA). Progression of AO was predicted by age and radiographic hip OA, with borderline significance for BMI >30 kg/m(2). No significant effects were seen for smoking, physical activity, hormone replacement therapy use, multiparity, or hand OA.

Conclusion: This is the first population-based longitudinal study to assess progression of the individual radiographic features of AO and DSN in lumbar spine disc degeneration. We demonstrated progression rates of 3-4% per annum, with important risk factors for progression, including age, back pain, and radiographic OA at the hip and knee.