Finding Cancer in Primary Care Outpatients with Low Back Pain

A Comparison of Diagnostic Strategies

Authors

  • Jerry D. Joines MD, PhD,

    Corresponding author
    1. From the Internal Medicine Training Program, Moses H. Cone Memorial Hospital, Greensboro, NC.(JDJ); and the
    2. Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC (JDJ, TSC);
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  • Robert A. McNutt MD,

    1. Department of Medicine, Cook County Hospital, Chicago, Il. (RAM);
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  • Timothy S. Carey MD, MPH,

    1. Cecil G. Sheps Center for Health Services Research (TSC),
    2. Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC (JDJ, TSC);
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  • Richard A. Deyo MD, MPH,

    1. Department of Medicine, Department of Health Services, and Center for Cost and Outcomes Research, University of Washington, Seattle, WASH. (RAD); and
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  • Roya Rouhani MS

    1. Center for Distance Learning and Telehealth, University of Texas Health Science Center, San Antonio, TEX. (RR)
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Address correspondence and reprint requests to: Dr. Joines: Internal Medicine Training Program Moses H. Cone Memorial Hospital, 1200 North Elm St., Greensboro, NC 27401-1020.

Abstract

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 ≥=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.

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