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Costs by Prevalence

Martin S. Robinette, PhD; Christopher D. Bauch, PhD; Wayne O. Olsen, PhD; Michael J. Cevette, PhD

Arch Otolaryngol Head Neck Surg. 2000;126:963-966.

Objective  To compare hypothetical costs for identification of acoustic tumors when using magnetic resonance imaging with gadolinium Gd 64 (MRI-⁶⁴Gd) as a sole diagnostic test and when using auditory brainstem response (ABR) testing followed by MRI-⁶⁴Gd (ABR + MRI-⁶⁴Gd) for those with positive ABR findings.

Patients and Methods  Retrospective review of the medical records of 75 patients having surgically confirmed acoustic neuromas to categorize them into 3 subgroups relative to their risk of having a cerebellopontine angle tumor based on history, symptoms, and routine pure-tone and speech audiometric findings. Hypothetical costs associated with identification of patients with acoustic neuroma in each subgroup were calculated for MRI-⁶⁴Gd alone and ABR + MRI-⁶⁴Gd. Auditory brainstem response sensitivity and specificity data for the 75 patients with acoustic neuroma and 75 patients without a tumor matched for hearing loss were applied to the hypothetical subgroups. Tumor size was considered also.

Setting  Tertiary care center.

Main Outcome Measure  Comparison of costs for MRI-⁶⁴Gd and ABR + MRI-⁶⁴Gd.

Results  Fouteen patients with acoustic neuroma were assigned to the high-risk category (30% probability); 45 were in the intermediate-risk category (5% probability); and 16 were in the low-risk category (1% probability). Auditory brainstem response testing correctly identified 100% of the large tumors (>2.0 cm), 93% of the medium-sized tumors (1.1-2.0 cm), and 82% of the small tumors (<1.0 cm). The hypothetical costs for identifying 14 patients with acoustic neuroma among 47 patients in the high-risk category using MRI-⁶⁴Gd would be $70,500; ABR + MRI-⁶⁴Gd costs for the 13 patients identified by ABR would be $39,600. Hypothetically 900 patients would be tested to identify the 45 acoustic neuromas in the intermediate-risk category. Magnetic resonance imaging with ⁶⁴Gd screening would reach $1.35 million for this sample. Auditory brainstem response testing and MRI-⁶⁴Gd would be $486,000, but 4 acoustic neuromas would be missed. For the low-risk subgroup MRI-6⁴Gd screening of 1600 patients to identify 16 acoustic neuromas would total $2.4 million; ABR + MRI-⁶⁴Gd to identify 15 of them would be $787,500. In this sample of 75 acoustic neuromas, large tumors were more prevalent in the low-risk subgroup than in the high- or intermediate-risk subgroups.

Conclusions  Decisions regarding assessment of patients at risk for acoustic neuromas must be made on a case-by-case basis. Use of ABR + MRI-⁶⁴Gd allows considerable savings when patients are in the intermediate- or low-risk subgroups. New MRI and ABR testing techniques offer promise for reducing costs.

From the Department of Otolaryngology Head & Neck Surgery/Audiology, Mayo Clinic Scottsdale, Scottsdale, Ariz (Drs Robinette and Cevette); and the Section of Audiology, Department of Otorhinolaryngology Mayo Clinic Rochester, Rochester, Minn (Drs Bauch and Olsen). The authors have no commerical, proprietary, or financial interest in the products and companies described in this article.