Risk Factors for Serious Underlying Pathology in Adult Emergency Department Nontraumatic Low Back Pain Patients

Background: Nontraumatic low back pain (LBP) is a common emergency department (ED) complaint and can be caused by serious pathologies that require immediate intervention or that lead to death.

Objective: The primary goal of this study is to identify risk factors associated with serious pathology in adult nontraumatic ED LBP patients.

Methods: We conducted a health records review and included patients aged ≥ 16 years with nontraumatic LBP presenting to an academic ED from November 2009 to January 2010. We excluded those with previously confirmed nephrolithiasis and typical renal colic presentation. We collected 56 predictor variables and outcomes within 30 days. Outcomes were determined by tracking computerized patient records and performance of univariate analysis and recursive partitioning.

Results: There were 329 patients included, with a mean age of 49.3 years; 50.8% were women. A total of 22 (6.7%) patients suffered outcomes, including one death, five compression fractures, four malignancies, four disc prolapses requiring surgery, two retroperitoneal bleeds, two osteomyelitis, and one each of epidural abscess, cauda equina, and leaking abdominal aortic aneurysm graft. Risk factors identified for outcomes were: anticoagulant use (odds ratio [OR] 15.6; 95% confidence interval [CI] 4.2-58.5), decreased sensation on physical examination (OR 6.9; CI 2.2-21.2), pain that is worse at night (OR 4.3; CI 0.9-20.1), and pain that persists despite appropriate treatment (OR 2.2; CI 0.8-5.6). These four predictors identified serious pathology with 91% sensitivity (95% CI 70-98%) and 55% specificity (95% CI 54-56%).

Conclusion: We successfully identified risk factors associated with serious pathology among ED LBP patients. Future prospective studies are required to derive a robust clinical decision rule.