A set of factors, including more vertebral fractures, higher body mass index (BMI), and erosion of the vertebral endplate and facet, may be associated with dysfunctional low back pain in patients with rheumatoid arthritis, according to a study results published in the European Spine Journal.
For this cross-sectional study, a total of 1276 outpatients with rheumatoid arthritis from 2 hospitals (average age of onset, 51.1; average disease duration, 13.4 years) were enrolled. Participants were asked to complete the Roland-Morris Disability Questionnaire to classify their low back pain as functional or dysfunctional, and were assessed for clinical variables that included disease activity, bone mineral density, and spinopelvic alignment parameters.
A total of 419 study participants (32.8%) were classified as having dysfunctional low back pain. These patients tended to be older and shorter (P <.001 for both), have higher BMI (P <.001), higher C-reactive protein level (P =.017), and longer disease duration (P <.001), and to be older at onset of rheumatoid arthritis (P =.001) compared with individuals with functional back pain. The following factors were found to be associated with dysfunctional low back pain in a multivariate analysis: vertebral fractures (odds ratio [OR], 2.13; P =.001), disease activity score in 28 joints-C-reactive protein (OR, 1.59; P =.001), endplate and/or facet erosion (OR, 1.41; P =.043), BMI (OR, 1.12; P <.001), duration of rheumatoid arthritis (OR, 1.04; P <.001), pelvic tilt (OR, 1.02; P =.019), age of onset (OR, 1.02; P =.02), sagittal vertical axis (OR; 1.01; P =.043), and methotrexate use (OR, 0.61; P =.007).
Study limitations include the lack of accounting for psychological factors.
“The dysfunctional low back pain in rheumatoid arthritis patients was considered to be influenced by multiple factors. Strict control of the body weight and disease activity in rheumatoid arthritis patients with methotrexate and avoiding spinopelvic malalignment by preventing vertebral fractures are important,” noted the study authors.
Miura K, Morita O, Hirano T, et al. Prevalence of and factors associated with dysfunctional low back pain in patients with rheumatoid arthritis [published online March 8, 2019]. Eur Spine J. doi: 10.1007/s00586-019-05938-x