To determine the incidence and worsening of lumbar spine structure and low back pain (LBP) and whether they are predicted by demographic characteristics or clinical characteristics or appendicular joint osteoarthritis (OA).
Paired baseline (2003-2004) and follow-up (2006-2010) lumbar spine radiographs from the Johnston County Osteoarthritis Project were graded for osteophytes (OST), disc space narrowing (DSN), spondylolisthesis, and presence of facet joint OA (FOA). Spine OA was defined as at least mild OST and mild DSN at the same level for any level of the lumbar spine. LBP, comorbidities, and back injury were self-reported. Weibull models were used to estimate hazard ratios and 95% confidence intervals (CI) of spine phenotypes accounting for potential predictors including demographics, clinical characteristics, comorbidities, obesity, and appendicular OA.
Obesity was a consistent and strong predictor of incidence of DSN (HR=1.80, 95%CI 1.09-2.98), spine OA (HR=1.56, 95%CI 1.01-2.41), FOA (HR=4.99, 95%CI 1.46-17.10), spondylolisthesis (HR=1.87, 95%CI 1.02-3.43), and LBP (HR=1.75, 95%CI 1.19-2.56), and worsening of DSN (HR=1.51, 95%CI 1.09-2.09) and LBP (HR=1.51, 95%CI 1.12-2.06). Knee OA was a predictor of incident FOA (HR=4.18, 95%CI 1.44-12.2). Spine OA (HR=1.80, 95%CI 1.24-2.63) and OST (HR=1.85, 95%CI 1.02-3.36) were predictors of incidence of LBP. Hip OA (HR=1.39, 95%CI 1.04-1.85) and OST (HR=1.58, 95%CI 1.00-2.49) were predictors of LBP worsening.
Among the multiple predictors of spine phenotypes, obesity was a common predictor for both incidence and worsening of lumbar spine degeneration and LBP.