Costly, ineffective tests used more often than more effective, but inexpensive tests to diagnose peripheral neuropathy
Research Activities, July 2012, No. 383
Peripheral neuropathy is a common disorder, generally caused by diabetes, which can cause distal extremity numbness, tingling, and pain. A new study found that the evaluation of neuropathy in routine practice represents an important opportunity to improve the efficiency and effectiveness of care. The population of the study was 1,031 Medicare-age patients evaluated for peripheral neuropathy from the 1997-2007 Health and Retirement Study's Medicare claims-linked database.
The researchers found frequent use of high-cost, low-yield magnetic resonance imaging (MRI) and infrequent use of low-cost, high-yield glucose-tolerance tests that indicate diabetes. In this study, 23 percent of the patients underwent at least one MRI during the diagnostic period for neuropathy, even though this procedure is primarily useful for identifying problems in the central nervous system, not peripheral nerves. The glucose-tolerance test was performed in only 1 percent of patients.
The researchers also found that patterns of diagnostic test use in neuropathy were highly variable. Focusing on 15 relevant diagnostic tests, more than 400 different combinations of testing were found. No single pattern of test ordering occurred in more than 4.8 percent of the patients, and no particular test was common to all of the most frequently used patterns.
A 2009 systematic review and guideline statement by the American Academy of Neurology found evidence for the effective use of only four tests: fasting glucose levels, vitamin B12 levels, serum protein electrophoresis (SPEP), and 2-hour oral glucose-tolerance tests. These tests detect neuropathy related to diabetes or treatable vitamin B12 deficiency. Both abnormal glucose-tolerance test and SPEP findings are known to be substantially more common among patients with neuropathy than among control groups. In this study, fewer than half of patients with neuropathy received 1 or more of these 4 tests, and only 17.3% received 2 or more. Patients with neuropathy had mean Medicare expenditures nearly twice that of control patients during the diagnostic period. This study was supported in part by the Agency for Healthcare Research and Quality (HS17690).
More details are in "Tests and expenditures in the initial evaluation of peripheral neuropathy," by Brian Callahan, M.D., Ryan McCammon, A.B., Kevin Kerber, M.D., and others in the January 23, 2012, Archives of Internal Medicine 172(2), pp. 127-132, 2012.