Background Low back pain (LBP) is one of the most common problems leading to health disabilities; the 1-month prevalence of LBP in general population has been reported to be 30%. Female gender, obesity, smoking, physical activity, disc degeneration, radiologic changes, or sagittal spinal alignment are risk factors for LBP in the general population. Several reports demonstrated that LBP in patients with rheumatoid arthritis (RA) was more common than in those without RA1,2. Radiologic examination of patients with RA often reveals lumbar lesions induced by RA, including lumbar scoliosis, spondylolisthesis, or vertebral fracture. However, no report has discussed the risk factors for LBP in patients with RA including radiographic findings and other characteristics.
Objectives The purpose of this cross-sectional study was to investigate the prevalence and correlated risk factors for LBP among patients with RA.
Methods This study included 201 RA patients without prior spinal surgery. LBP was evaluated by visual analogue scales (VAS) in the previous 4 weeks. Disease activity was evaluated by disease activity score of 28 joints and erythrocyte sedimentation rate (DAS28-ESR). Patient’s global pain was evaluated as that within one week using VAS (VAS-pain) Plain standing X-ray and MRI of lumbar spine were obtained to evaluate lumbar lesions, lumbosacral sagittal alignment, and lumbar degeneration. Correlated factors for LBP of VAS ≥50 mm were investigated with age, sex, BMI, smoking, alcohol use, severity of RA, and X-ray and MRI findings using multiple logistic regression analysis.
Results The mean VAS for LBP was 27.8 ± 26.8 mm; 48 patients (23.9%) had scores ≥50 mm. Univariate analysis indicated that age, moderate and high disease activity on DAS28-ESR, functional impairment, vertebral fracture, decrease of lumbar lordosis, and vertical sacrum significantly increased the odds ratio (OR) for LBP. Multivariate analysis indicated that correlated factors for LBP were female gender (OR 4.00; 95% confidence interval [CI] 1.07-14.9), smoking habit (OR 3.03; 95% CI 1.05-8.78), and moderate and high disease activity on DAS28-ESR (OR 3.19, 6.97; 95% CI 1.04-9.79, 1.45-33.5). Patients with LBP had significantly higher tender joint count 28 (TJC28) and VAS for general health among subscores of the DAS28-ESR than those without LBP (6.6 ± 7.4 vs 3.0 ± 4.5 p <0.001, 43.8 ± 23.0 vs 24.8 ± 20.1 p <0.001), although there was no difference in swollen joint count or ESR. VAS of LBP also positively correlated with VAS-pain (r=0.313 p <0.001).
Conclusions Radiologic findings were not correlated with LBP but disease activity was. LBP among RA patients was related to tender joint count or subjective complaints of RA. Appropriate control of RA might be important in terms of control of LBP, although it is possible that these findings occurred because assessments were highly sensitive to pain, which would have increased the VAS of LBP, TJC-28, or general pain-VAS.
Helliwell PS, Zebouni LN, Porter G, et al. A clinical and radiological study of back pain in rheumatoid arthritis. Br J Rheumatol 1993;32:216-21.
Kothe R, Kohlmann T, Klink T, et al. Impact of low back pain on functional limitations, depressed mood and quality of life in patients with rheumatoid arthritis. Pain 2007;127:103-8.
Disclosure of Interest K. Yamada: None Declared, T. Koike Grant/research support from: Takeda Pharmaceutical, Mitsubishi Tanabe Pharma Corporation, Chugai Pharmaceutical, Eisai, Abbott Japan, Teijin Pharma, Banyu Pharmaceutical, Ono Pharmaceutical, A. Suzuki: None Declared, S. Takahashi: None Declared, H. Yasuda: None Declared, K. Inui: None Declared, M. Tada: None Declared, Y. Sugioka: None Declared, T. Okano: None Declared, H. Nakamura: None Declared