Standard, Efficient, Cost-Effective Guidelines Needed for Diagnosis of Peripheral Neuropathy
Less expensive, more effective tests such as glucose tolerance tests are less likely to be used to diagnose peripheral neuropathy than high cost, less effective Magnetic Resonance Imaging (MRI) tests, according to a study published in the January 23, 2012 issue of the Archives of Internal Medicine.
Peripheral neuropathy results from damage to the nerves that carry information to the brain. Symptoms include numbness in the arms, legs, hands and feet, and often tingling and burning. The condition can be caused by traumatic injury, infection, metabolic problems, or exposure to toxins.
The most common cause of neuropathy is diabetes. As many as half of those who suffer from diabetes develop some form of neuropathy, because high levels of blood sugar over a long period of time can damage the nerves. Peripheral neuropathy is found in 15 percent of individuals over the age of 40 and in 8 percent over the age of 55, with the numbers steadily increasing as the rates of diabetes increase.
Thomas Brannagan, MD, Director of Neuropathy at New York Presbyterian Hospital/Columbia University Medical Center in New York says that diabetes is the most common cause of neuropathy and testing for this as well as other causes of neuropathy such as b12 deficiency and a monoclonal protein are important. He says these tests are recommended by the American Academy of Neurology practice parameter, but this study notes that emgs to confirm neuropathy and glucose blood tests are frequently not done. “More research is needed,” he says, “to find an efficient strategy for diagnosis, but it’s also important that a patient be diagnosed before significant nerve damage occurs.”
Led by Brian Callaghan, MD and Assistant Professor of Neurology at the University of Michigan Medical School, the study was conducted by several researchers at the University of Michigan. They analyzed the cost of the diagnosis of peripheral neuropathy using the 1996-2007 Health and Retirement Study. Of the 12,633 patients in the database, 1,031 or 8.1 percent had a confirmed diagnosis of neuropathy and met the criteria for the study. The focus of the study was on 15 relevant tests and it examined the patterns of testing carried out six months before and six months after initial diagnosis.
The findings of this analysis show that of the 1,031 patient records studied, 23.2 percent were given an MRI of the brain or spine, an expensive procedure that cannot identify diabetes. One percent underwent an inexpensive and much more reliable blood glucose tolerance test. It was also found that the test ordering patterns of physicians varied widely, primarily because there is no standard approach to diagnosing peripheral neuropathy and few diagnostic tests are supported by evidence-based research.
Callaghan says the biggest problem is that neither doctors nor patients consider costs. “Because costs are often not an issue,” he says, “lots of tests are ordered, although we should be thinking of which tests have the best value.” He remarks that one of the ways physicians show that they care about their patients is by ordering tests. “It validates patient complaints,” he says, “but we – both physicians and patients – have to begin to think about costs.” The momentum, he says, is beginning to swing toward thinking about costs in healthcare.
Because of the lack of best practices, physicians often order large numbers of very costly tests that have little clinical benefit. “Far and away, the most important thing is a good history,” says lead study author Brian Callaghan in a press release. “The vast majority of causes,” he stated, “are determined based on talking with the patient, and if you don’t figure it out based on talking to the patient, the chance that testing is going to help with the diagnosis is small.” Callaghan says that most of the 40-50 tests that can be given to try to diagnose neuropathy have low yield and many have little influence on the treatment given.
Perry Shieh, MD, PhD, Director of the Neuromuscular program at UCLA School of Medicine agrees that glucose tolerance tests to diagnose diabetes and pre-diabetes are the most sensitive to diagnosing symptoms of neuropathy and pick up at least one third of the cases. “Sometimes,” he says, “it’s easier for doctors to order more tests because the time allowed for an office visit has become so limited.”
Callaghan says that testing often does not lead to determining an underlying cause, but it is a rule rather than an exception that physicians order a battery of tests for diagnosis, highlighting the importance of standardizing a more efficient approach to diagnosing neuropathy. He calls for and is working on additional research to determine such an approach.
Russ A. Bodner, MD, neurologist at Carolinas Health System in North Carolina is surprised that the study researchers found so many patterns of testing without consistency. “The most revealing test is glucose-tolerance,” he says “and this study shows that it’s tested only one percent of the time.” He says that unless some patterns of standard testing are pursued, many patients will be misdiagnosed. “I hope this study will stimulate discussion and change,” he says.
Since this study, says Callaghan, physicians have been surveyed about the tests they order. Medical claims have also been studied to see what was really ordered and not what was said was ordered. In Texas, well-documented medical records are being studied to determine how often testing changes what’s done for patients. “Regardless of what they say,” says Callaghan, “a high number of tests are being ordered.”
The study clearly demonstrates the importance of standardizing a more efficient approach to diagnosing neuropathy. “The limitation of this particular study,” says Callaghan, “is the lack of detailed clinical information, which we are working on analyzing in follow-up studies.”