Propensity-matched Comparison between Chronic non-specific Low Back Pain and Axial Spondyloarthritis: Impact on patient-perceived Quality of Life.

Abstract

Prospective study. To compare the burden between chronic non-specific low back pain (LBP) and axial spondyloarthropathy (SpA). Chronic non-specific LBP and SpA are two debilitating yet different chronic musculoskeletal disorders. To compare their burden, propensity score matching is used to control for potential confounders and match the study subjects. Two prospectively collected cohorts of LBP (n=269) and SpA (n=218) patients were studied. Outcomes included current LBP, 36-item short form (SF-36) questionnaire, Oswestry Disability Index (ODI), EuroQol 5-dimension 5-level (EQ-5D-5L) questionnaire and EuroQol visual analogue scale (EQ-VAS). With the inherent differences between the two types of patients, propensity score matching was performed for comparing the two groups. Baseline covariates of age, gender, education level, occupation, smoking and drinking history were selected for the estimation of propensity scores for each subject with the logistic regression model. Significant independent variables for the outcome of current back pain were included in the multivariate logistic regressions. A total of 127 matched pairs were identified, with 254 patients. In the matched cohort, more patients with chronic LBP had current back pain (95.3%) as compared to SpA (71.7%). Patients with SpA were younger (P<0.001), with more males (P<0.001) and better educated (P=0.001). There were less current back pain and higher non-steroidal anti-inflammatory drug use (P<0.001). Most SpA patients have lower ODI than LBP patients and with low disease activity. Patients with LBP had worse outcome scores as compared to SpA patients given the same VAS. LBP patients had 8.6 times odds (95%CI: 3.341-20.671; P<0.001) of experiencing current back pain compared to SpA patients. The disease activity of SpA patients is well-controlled. However, patients with chronic LBP have worse pain severity, disability and HRQOL. This has implications on resource utilization and necessity of advancing LBP understanding and management. Type I prognostic study.