Appropriateness of lumbar spine magnetic resonance imaging in Spain.

To determine the minimum percentage of lumbar spine magnetic resonance imaging (LSMRI) which are inappropriately prescribed in routine practice.LSMRI performed prospectively on 602 patients in 12 Radiology Services across 6 regions in Spain, were classified as "appropriate", "uncertain" or "inappropriate" based on the indication criteria established by the National Institute for Clinical Excellence, the American College of Physicians and Radiology, and current evidence-based clinical guidelines. Studies on patients reporting at least one "red flag" were classified as "appropriate". A logistic regression model was developed to identify factors associated with a higher likelihood of inappropriate LSMRI, including gender, reporting of referred pain, health care setting (private/public), and specialty of prescribing physician. Before performing the LSMRI, the radiologists also assessed the appropriateness of the prescription.Eighty-eight percent of LSMRI were appropriate, 1.3% uncertain and 10.6% inappropriate. The agreement of radiologists' assessment with this classification was substantial (k=0.62). The odds that LSMRI prescriptions were inappropriate were higher for patients without referred pain [OR (CI 95%): 13.75 (6.72; 28.16)], seen in private practice [2.25 (1.20; 4.22)], by orthopedic surgeons, neurosurgeons or primary care physicians [2.50 (1.15; 5.56)].Efficiency of LSMRI could be improved in routine practice, without worsening clinical outcomes.