Diagnostic testing and treatment of low back pain in United States emergency departments: a national perspective

Abstract

Study design: This study is an analysis of the National Hospital Ambulatory Medical Care Survey (NHAMCS), a large sample representative of all emergency department (ED) visits throughout the United States.

Objective: To use NHAMCS to describe the frequency of ED visits for the treatment of low back pain, and the diagnostic and therapeutic strategies employed by emergency clinicians.

Summary of background data: Low back pain is common in the general population. While it accounts for 2.5% of all outpatient office visits, the role of the ED has yet to be described.

Methods: We included cases if they had both a reason for visit related to back pain and a primary ED discharge ICD9 code consistent with low back pain. The outcomes included frequency of ED use, and frequency of various diagnostic and therapeutic strategies. Individual patient visits are weighted so that data can be extrapolated to all ED visits throughout the United States.

Results: Low back pain related disorders caused 2.63 million (95% CI: 2.32, 2.93 million) annual ED visits in the US. Of all patients with low back pain, 30.5% (28.1, 32.9) had a plain radiograph; 9.6% (95% CI: 7.2, 12.6) had a CT or MRI in 2006 compared with 3.2% (95% CI: 2.0, 5.1) in 2002 (P for trend <0.01). Age and type of insurance were associated with advanced imaging, though geographic region was not. Of medications either administered in the ED or prescribed at discharge, the most frequently used classes were opioids (61.0%, 95% CI: 58.4, 63.5), followed by nonsteroidal anti-inflammatory drugs (49.9%, 95% CI: 47.2, 52.7) and muscle relaxants (43.1%, 95% CI: 40.4, 45.8).

Conclusion: Low back pain related disorders are a frequent cause of ED visit. Diagnostic imaging is performed in one-third of all patients. There was a strong secular trend in use of advanced imaging; patients were nearly 3 times as likely to receive a CT or MRI in 2006 as they were 4 years earlier. Although opioids were administered or prescribed to two-thirds of patients, use of therapeutic agents was generally in keeping with guideline recommendations.