Magnetic resonance in the study of low back pain. An analysis of the missed opportunity for the diagnosis of axial spondyloarthritis

Objective: To describe the characteristics of a population with low back pain studied by MR and to analyze the patients that had to be derived for SpA study. Materials and methods: Retrospective observational study, included patients who were asked for MRI for the study of low back pain. 'Potential population for SpA research' was defined for patients younger than 45 years with chronic low back pain. Statistical analysis: descriptive analysis, Chi2 test (categorical) and Student's or Mann Whitney test (continuous). Multivariate logistic regression analysis where it was considered dependent variable ^Potential population for SpA research^. Results: Of 1530 MRI performed, 569 patients had follow-up. 56% were men with a mean age of 47.1 years (SD 16.7). Fifty percent of the lumbalgias were chronic. The potential population for SpA research was 23%. We compared the potential population for SpA research with the other patient. The differential characteristics of the potential group for SpA research with respect to those that did not meet the criteria were: greater indication of NSAIDs (76% vs 54% p: 0.0006), physical therapy (35% vs 50% p: 0.01) and less pathology degenerative (6% vs 16% p: 0.01). In the multivariate analysis, we found an independent association with a higher NSAID prescription and a lower diagnosis of degenerative disease. Conclusion: The prevalence of potential population for SpA research was 23%. The target population to search for SpA was associated with greater use of NSAIDs and less diagnosis of degenerative pathology. (authors)