Finding cancer in primary care outpatients with low back pain: a comparison of diagnostic strategies

J Gen Intern Med. 2001 Jan;16(1):14-23. doi: 10.1111/j.1525-1497.2001.00249.x.


Objective: To compare strategies for diagnosing cancer in primary care patients with low back pain. Strategies differed in their use of clinical findings, erythrocyte sedimentation rate (ESR), and plain x-rays prior to imaging and biopsy.

Design: Decision analysis and cost effectiveness analysis with sensitivity analyses. Strategies were compared in terms of sensitivity, specificity, and diagnostic cost effectiveness ratios.

Setting: Hypothetical

Measurements: Estimates of disease prevalence and test characteristics were taken from the literature. Costs were represented by the Medicare reimbursement for the tests and procedures employed.

Main results: In the baseline analysis, using magnetic resonance imaging (MRI) as the imaging procedure prior to a single biopsy, strategies ranged in sensitivity from 0.40 to 0.73, with corresponding diagnostic costs of $14 to $241 per patient and average cost effectiveness ratios of $5,283 to $49,814 per case of cancer found. Incremental cost effectiveness ratios varied from $8,397 to $624,781; 5 strategies were dominant in the baseline analysis. Use of a higher ESR cutoff point (50 mm/hr) improved specificity and cost effectiveness for certain strategies. Imaging with MRI, or bone scan followed in series by MRI, resulted in a fewer unnecessary biopsies than imaging with bone scan alone. Cancer prevalence was an important determinant of cost effectiveness.

Conclusions: We recommend a strategy of imaging patients who have a clinical finding (history of cancer, age > or = 50 years, weight loss, or failure to improve with conservative therapy) in combination with either an elevated ESR (> 50 mm/hr) or a positive x-ray, or using the same approach but imaging directly those patients with a history of cancer.

Publication types

  • Comparative Study
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Aged
  • Biopsy / economics
  • Humans
  • Low Back Pain / complications
  • Low Back Pain / diagnosis*
  • Magnetic Resonance Imaging
  • Middle Aged
  • Outpatients
  • Spinal Neoplasms / complications*
  • Spinal Neoplasms / diagnosis*
  • Spinal Neoplasms / economics