Unnecessary, Expensive Tests Used to Diagnose Neuropathy

Fran Lowry

February 24, 2012

February 24, 2012 — The high cost of diagnosing peripheral neuropathy could be greatly reduced if doctors ordered the right tests, researchers suggest.

A survey of the tests used to diagnose neuropathy showed that almost one quarter of patients undergo high-cost, low-yield magnetic resonance imaging (MRI), while few patients get the inexpensive, high-yield glucose tolerance tests advocated by current guidelines, lead author, Brian Callaghan, MD, from the University of Michigan Medical School, Ann Arbor, told Medscape Medical News.

"We order some expensive tests that probably are not needed, and we don't order some of the cheap tests that probably are," Dr. Callaghan said. "The glucose tolerance test, a cheap blood test looking for diabetes and pre-diabetes, is almost never done, and the MRIs are often done but rarely needed."

Their findings are published in the January 23 issue of the Archives of Internal Medicine.

Variation in Practice

Dr. Callaghan said it became clear to him during his training that neurologists varied a great deal in the way they evaluate a patient for peripheral neuropathy.

This observation prompted the current study. In it, he and his team used the 1996-2007 Health and Retirement Study-Medicare claims database to identify individuals with a diagnosis of peripheral neuropathy. They focused on 15 relevant tests and examined the number of patterns of tests 6 months before and after the initial diagnosis.

Of the 12,673 patients in the database, 1031 (8.1%) were diagnosed with peripheral neuropathy during the 10-year study period. The patients' mean age was 77.6 years, 54.0% were female, 41.5% met the Chronic Condition Data Warehouse definition of diabetes, and 16.3% had diabetic complications.

Each patient had a median of 4 diagnostic tests, with an interquartile range of 2 to 5 tests.

The study found that MRI of the brain or spine was the test most commonly done, in 23.2% of the patients. A glucose tolerance test was done in only 1.0% of patients.

The study also found that in the period before neuropathy was diagnosed, the mean Medicare expenditures were $8067. During the diagnostic period, the mean expenditures significantly increased, to $14,362 (P < .001).

When the researchers excluded patients with diabetes in determining the mean Medicare expenditures, the increase was still observed (mean, $12,190 vs $6633; P < .001).

Other tests that were done included a fasting glucose level in 23.4% of patients, a hemoglobin A1c in 43.2%, vitamin B12 levels in 32.6%, and serum protein electrophoresis (SPEP) in 13.3%.

The fasting glucose level, B12 level, and SPEP, which are tests supported by the American Academy of Neurology (AAN) practice guidelines, were ordered less frequently than expected, Dr. Callaghan said.

"I agree with the AAN guidelines that say we should be getting a glucose tolerance test, a B12, a serum protein electrophoresis, and that we should limit the rest of the tests that we order," he concludes.

Wake-up Call

Writing in an invited commentary, A. Gordon Smith, MD, from the University of Utah School of Medicine, Salt Lake City, called the study "important" and said it provides "strong evidence that the history and examination are both indispensable and cost-effective…."

Dr. Smith notes that the study "should serve as a wake-up call to providers, educators and policymakers."

"We must take more time to listen to our patients, use our clinical 'senses,' and follow evidence-based guidelines for diagnostic testing," he concludes.

Dr. Callaghan has disclosed no relevant financial relationships. Dr. Smith reports that he received grants from the National Institutes of Health and the American Diabetes Association.

Arch Intern Med. 2012;172:127-132, 132-133. Abstract Editorial

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