Lumbar disc degeneration is longitudinally associated with low back pain presence in older adults

Abstract

Purpose: Low back pain (LBP) is the most prevalent musculoskeletal complaint throughout the world and causes activity limitation and work absenteeism. The large majority of people with LBP are given the label ‘non-specific’, meaning that a specific patho-anatomical cause for the pain cannot be established. As a phenotype of spinal osteoarthritis, lumbar disc degeneration (LDD) was found to be associated with LBP and can be one of the pain contributing factors. Nevertheless, the predictive value of LDD for long-term LBP outcomes has not been investigated. This study assessed the longitudinal association between LDD and long-term outcomes in older adults presenting with LBP in primary care. Methods: The BACE cohort study was used, including 675 patients aged >55 years visiting a general practitioner with a new episode of non-specific LBP. Osteophytes and disc space narrowing were considered LDD features, and they were investigated as categorical and dichotomous determinants. The 4-grade Lane Atlas classification was used (i.e. grade 0= none, grade 1= mild, grade 2= moderate, grade 3= severe); osteophytes of grade 2 or higher at two or more levels for L1-2 to L5-S1 were defined as LDD presence, likewise disc space narrowing grade 1 or higher at two or more levels from L1-2 to L5-S1. Outcomes at 1-year follow-up were: LBP presence (yes/no), and LBP severity [measured on an 11-point numeric rating scale (NRS)] defined as a NRS score ≥ 4/10. The association between LDD at baseline and 1-year follow-up outcomes was assessed with logistic regression models. Models were adjusted for age, gender and BMI. Results: Five-hundred and forty-three patients (85% of the cohort) with baseline and 1-year follow-up data were included in this study. Mean age was 67 years (SD 8), 59% was female and 62% reported severe LBP at baseline. One-hundred eighty-six patients (34%) met the LDD definition for osteophytes and 389 (72%) the LDD definition of disc space narrowing. The LDD definition of osteophytes was significantly associated with LBP presence, but not the 4-grade classification of osteophytes (Table 1). The LDD definition of disc space narrowing was not associated, but patients with grade 1 to 3 narrowing displayed higher odds (compared to grade 0) of having LBP at follow-up (Table 1). LDD definitions for osteophytes (OR=1.4, 95% CI 0.9-2.1) and narrowing (OR=1.5, 95% CI 0.9-2.4) were not associated with LBP severity. Patients with grade 3 disc space narrowing exhibited higher odds (compared to grade 0 patients) of having severe LBP (OR=2.9, 95% CI 1.0-8.3); patients with other LDD grade classification did not show an association with pain severity. Conclusions: This study found an association between some of the features of LDD at baseline and the presence of LBP at 1-year follow-up (Table 1). On the other hand, LDD features were not associated with LBP severity, with the sole exception of grade 3 disc space narrowing (as compared to grade 0). This study warrants further investigation of LDD features as potential prognostic factors in future longitudinal studies.