The prevalence of neuropathy among those with diabetes has been estimated to be as high as 50%. Painful diabetic neuropathy (PDN), which tends to affect the feet and legs, has been estimated to affect roughly 16% to 20% of the more than 25 million people in the United States who are living with diabetes. The condition often goes unreported and even more are untreated, with an estimated 40% of patients not receiving care for PDN.
A Need for Guidance for Diabetic Neuropathy
“Painful diabetic neuropathy is a big problem for all healthcare providers who treat patients with diabetes,” says John D. England, MD, FAAN. “There are increasingly more drugs being developed and brought to market that can be used for treating diabetic neuropathy. For a busy practitioner, it’s often difficult to keep up with all of the new evidence and to decide what a rational, tiered approach should be to treatment.” Part of the issue is the volume of literature on the topic. In 2007, when members of the American Academy of Neurology (AAN) felt there was a need to update guidelines for the treatment of PDN, the process started with more than 2,200 papers. Of them, 463 were deemed relevant and 79 were highly pertinent to the guidelines. Since then, many more studies have emerged.
Physicians should refer to the AAN guidelines to learn which drugs have the best scientific evidence supporting their use to treat PDN.
In the May 17, 2011 issue of Neurology, the AAN published its first evidence-based guidelines on use of a range of pharmacologic and non-pharmacologic treatments for diabetic neuropathy. “There is no ‘cookbook’ approach to treatment for PDN,” explains Dr. England, who co-chaired the AAN panel that developed the guidelines. “We can, however, use the scientific evidence in the literature and make sure that it conforms to our clinical judgment and patient preferences. What one patient may respond to may be very different from that of another. The evidence provides some guidance on how we should treat this complication of diabetes.” Dr. England adds that it is important to explain to patients that it is not common for patients to achieve complete pain relief even though medications are available to help relieve some of their pain.
Key Recommendations for Diabetic Neuropathy
Physicians need to be particularly careful with pain measurements because pain is a subjective complaint, says Dr. England. “Pain is measured with standardized scales, but what level of pain relief is actually experienced by patients is a subjective response. That is why well-studied research populations are needed. We want to exclude any potential confounding factors. Over the past couple decades, the AAN has developed a robust system for classifying evidence from the therapeutic trials that study this patient population.”
Using this system, Dr. England and colleagues rated the level of evidence for several therapeutic modalities that can be used to treat patients with PDN. “It should be noted that many of these patients have severe enough pain that they require multiple modalities to help them,” noted Dr. England. He adds that most of the agents listed in Table 1 reduce pain by 30% to 50%, on average. Therefore, mixing and matching agents and other therapies is often required to help patients feel as comfortable as possible. “In addition, several agents are still being used to treat this population when there is either insufficient evidence to support or even evidence against their use,” says Dr. England. “Physicians should refer to the AAN guidelines to learn which drugs have the best scientific evidence supporting their use to treat PDN.”
A Need for Change on PDN Treatment
Dr. England says special attention should be paid to the medications indicated for PDN that have level B recommendations. “Unfortunately, the paucity of data makes it challenging for physicians to truly know which therapeutic interventions are better and the ideal candidates for each option,” he says. “We need comparative effectiveness trials to determine which drugs in the treatment of PDN are superior.”
Among other changes Dr. England would like to see made in research is the selection of a single pain rating scale (Table 2). “Using such a scale in all trials would enable investigators to compare trials against each other with greater accuracy. Also, aside from a few recent studies, most analyses only measure pain relief. They should also measure quality of life and function. Patients could have some pain relief but still experience deteriorated quality of life and function, depending on adverse events from medications. We have come a long way in improving the management of diabetic neuropathy, but we still have a long way to go. The only way that we’re going to get better is to fund more research.”
Readings & Resources (click to view)
Bril V, England J, Franklin GM, et al. Evidence-based guideline: treatment of painful diabetic neuropathy : Report of the American Academy of Neurology, the American Association of Neuromuscular and Electrodiagnostic Medicine, and the American Academy of Physical Medicine and Rehabilitation. Neurology. 2011 Apr 11 [Epud ahead of print]. Available at: http://www.neurology.org/content/early/2011/04/08/WNL.0b013e3182166ebe.
Boulton AJ, Vinik AI, Arezzo JC, et al. Diabetic neuropathies: a statement by the American Diabetes Association. Diabetes Care. 2005;28:956-962.
Gordois A, Scuffham P, Shearer A, et al. The health care costs of diabetic peripheral neuropathy in the US. Diabetes Care. 2003;26:1790-1795.
Daousi C, MacFarlane IA, Woodward A, et al. Chronic painful peripheral neuropathy in an urban community: a controlled comparison of people with and without diabetes. Diabet Med. 2004;21:976-982.
Farrar JT, Pritchett YL, Robinson M, et al. The clinical importance of changes in the 0 to 10 numeric rating scale for worst, least, and average pain intensity: analyses of data from clinical trials of duloxetine in pain disorders. J Pain. 2010;11:109-118.