Diabetic Neuropathy

Posted on Apr 19, 2011 in Clinical Updates | 5 comments

AAN Issues New Guidelines for the Treatment of Painful Diabetic Neuropathy

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Painful diabetic neuropathy (PDN) is among the most common neurological problems—affecting an estimated 16% of the 25 million Americans living with diabetes. Primary care has an increasing role in the diagnosis and treatment of PDN, as early accurate diagnosis and intervention can greatly improve the prognosis. Many patients with PDN experience only mild symptoms, but for some the pain can be excruciating, sleep can be affected, and long-term depression can follow. 

Up to 40% of patients with PDN may be untreated, in part because there is so much anecdotal evidence regarding treatment[1] and because PDN typically does not respond to conventional analgesics.[2] To help provide guidance for clinicians who treat patients with diabetes, the American Academy of Neurology (AAN) has issued a new guideline for the treatment of painful diabetic neuropathy.[3] Based on an evaluation of the best available evidence, the guideline cites pregabalin as having the strongest evidence for efficacy among both pharmacologic and nonpharmacologic modalities (Level A). Overall, the authors reviewed 79 scientific studies that described interventions, reported completion rates, and defined the outcome measures; reviews and case reports were excluded from consideration. 

The recommendation for the use of pregabalin is based on four randomized trials. In the three studies of the highest quality, pregabalin reduced pain by 11% to 13% on an 11-point Likert scale relative to placebo. The fourth study found that a relatively large dose (600 mg/day) reduced pain scores by as much as 50% relative to placebo. The authors of the guideline indicated that the drug’s effect against diabetic nerve pain was relatively modest but “should be offered for the [condition's] treatment.” 

The guideline was developed in collaboration with the American Association of Neuromuscular and Electrodiagnostic Medicine and the American Academy of Physical Medicine and Rehabilitation. 

Medications that received a “B” recommendation (probably effective, based on moderate-quality randomized trials or matched cohort studies), included the following: 

• Gabapentin
• Sodium valproate
• Amitriptyline
• Venlafaxine
• Duloxetine
• Opioids including dextromethorphan, tramadol, morphine sulfate, and oxycodone
• Topical capsaicin

The guideline also gave a “probably effective” rating to transcutaneous electric nerve stimulation. 

In addition, the authors identified a number of treatments that scientific studies have demonstrated to be mostly ineffective, including certain anticonvulsants, pentoxifylline, pulsed electromagnetic field therapy, low-intensity lasers, or reiki therapy. 

The writing team recognizes that PDN is a chronic disease and that there are no data on the efficacy of the chronic use of any treatment, as most trials have durations of 2 to 20 weeks. They also note that the evidence is limited, the degree of effectiveness can be minor, the side effects can be intolerable, the impact on improving physical function is limited, and the cost is high, particularly for novel agents. 

There are several limitations to the research. For instance, measures of pain and quality of life vary significantly between studies, the authors noted, and data on long-term efficacy and safety were generally lacking. Also, although some studies gave number-needed-to-treat estimates, none provided numbers needed to harm. And although most studies included in the analysis failed to address cost-effectiveness, the AAN does not generally take cost into account as it develops new treatment guidelines. To address some of these limitations, the authors call for standardized rating scales for pain, quality of life, and physical function and that these should be reported for all future studies of treatments for diabetic nerve pain. 

The AAN has also announced that it is developing a set of care-quality measures for physicians treating neuropathic pain, which it plans to release in 2012. 

The guideline is accompanied by a disclaimer from the AAN emphasizing that final decisions on treatment are up to individual patients and their physicians “based on all of the circumstances involved,” and that the document should not be interpreted as a formal practice recommendation. 

In addition to pharmacotherapy, ongoing care of the feet is an important component of managing DPN. The American Podiatric Medical Association[4] recommends that patients— 

• Inspect their feet daily  for cuts, bruises, sores, or changes to the toenails, such as thickening or discoloration.
• Exercise. Walking can keep weight down and improve circulation. Be sure to wear appropriate athletic shoes when exercising.
• Have new shoes properly measured and fitted.
• Don’t go barefoot, even at home. The risk of cuts and infection is too great for those with diabetes.
• Never try to remove calluses, corns, or warts on their own. Over-the-counter products can burn the skin and cause irreparable damage to the foot for people with diabetes.
• Avoid extremes of hot or cold, as PDN can be accompanied by a loss of temperature sensation. Remind patients to test the water temperature with an elbow before stepping in a bath. If the feet are cold at night, wear socks and avoid the use of heating pads or hot water bottles.

Jill Shuman, MS, ELS
Published on April 19, 2011

References

1. Unger J, Cole BE. Recognition and management of diabetic neuropathy. Prim Care. 2007;34(4):791-808.
2. Kirby M. Painful diabetic neuropathy—current understanding and management for the primary care team. Br J Diabetes Vasc Dis. 2003;3(2):138-144.
3. 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 [published online ahead of print April 11, 2011]. Neurology.doi:10.1212/WNL.0b013e3182166ebe.
4. Diabetes: startling statistics. American Podiatric Medical Association Website. http://www.apma.org/MainMenu/Foot-Health/Foot-Health-Brochures-category/Learn-About-Your-Feet/Diabetes.aspx. Accessed April 13, 2011.