Patterns of Ordering Diagnostic Tests for Patients with Acute Low Back Pain

15 November 1996 | Volume 125 Issue 10 | Pages 807-814

Background: Low back pain is a common reason for visiting a physician. Authors of guidelines and insurance payers are currently scrutinizing use of radiography and computed tomography (CT) or magnetic resonance imaging (MRI).

Objective: To study the determinants of the use of lumbar spine radiography and either CT or MRI in patients with acute low back pain.

Design: Prospective cohort study.

Setting: Community-based practices in North Carolina in six strata: urban primary care physicians, rural primary care physicians, urban chiropractors, rural chiropractors, orthopedic surgeons, and practitioners at a group-model health maintenance organization.

Patients: 1580 patients with acute low back pain.

Measurements: Telephone interviews done after the index office visit and at 2, 4, 8, 12, and 24 weeks or until complete recovery; survey of practitioners; and chart abstraction.

Results: During the acute back pain episode, 46% of patients had radiography and 9% had CT or MRI. Patient variables related to use of radiography included pain that began more than 2 weeks before the index visit and no previous episodes of low back pain. Practitioner variables associated with use of radiography were being a chiropractor or orthopedic surgeon and having a solo practice. Use of CT or MRI was associated with white race, neurologic deficit at baseline, sciatica, poor functional status at baseline, and small group-practice size. Practitioners' responses to clinical vignettes were associated with aggregate practitioner behavior: In the vignettes and in real life, practitioners were more likely to order CT for patients with sciatica. However, a practitioner's response to a vignette did not predict that practitioner's use of CT or MRI for similar patients in his or her own practice.

Conclusion: Radiography is commonly used as a diagnostic test for patients with acute back pain. Clinical factors and provider specialty are major correlates of the use of imaging studies.

*For members of the North Carolina Back Pain Project, see the Appendix.

Author and Article Information

The North Carolina Back Pain Project*
From the University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.
Grant Support: By grant HSO 6664 from the Agency for Health Care Policy and Research.
Requests for Reprints: Timothy S. Carey, MD, Sheps Center for Health Services Research, University of North Carolina at Chapel Hill, CB 7590, Chapel Hill, NC 27599.
Current Author Addresses: Drs. Carey and Garrett: Sheps Center for Health Services Research, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599.