American Academy of Pain Medicine (AAPM) 27th Annual Meeting

March 24-27, 2011 National Harbor, MD

Clinicians Discuss Osteoarthritis Management

National Harbor, MD—Osteoarthritis (OA) affects approximately 27 million Americans, and is the most common form of arthritis and the leading source of physical disability in the United States. Although there is no known cure for OA, several pharmacological and nonpharmacological treatments are available to manage this disease and its symptoms. During a satellite symposium titled “Osteoarthritis: From Biomarkers to New Strategies for Pain Management” at the recent AAPM meeting, researchers discussed these treatment options and several guidelines that clinicians can use to better manage OA in their patients. The session began with Virginia Byers Kraus, MD, PhD, professor of medicine, Division of Rheumatology, Duke University’s Medical Center, Durham, NC, outlining the 4 stages of OA: molecular, preradiographic, radiographic, and joint replacement. While pain can occur in any stage, Kraus noted that differentiating between stages through the use of biomarkers may help clinicians determine the best strategies for easing pain in OA patients. For example, biomarkers may identify preradiographic OA or pain sensitivity and differentiate joint pain with or without structural degeneration. In addition, there are biomarkers of drug metabolism that could predict efficacy and biomarkers that could predict short- and long-term pain outcomes. Because OA pain correlates with biomarkers that are indicative of structural degeneration and joint inflammation, she suggested that biomarkers could help researchers understand the sources of joint pain; however, to gain a better understanding of the biology and etiology of joint pain, Kraus said researchers must assess intermediate phenotypes associated with causal pathways. After this discussion, Marc C. Hochberg, MD, MPH, professor of medicine and epidemiology and public health, University of Maryland School of Medicine, Baltimore, reviewed the management of knee OA, which he noted focuses on reducing pain, maintaining or improving joint mobility, limiting functional impairment, and improving health-related quality of life.

Hochberg noted that several organizations provide guidelines and recommendations to treat knee OA, including the Osteoarthritis Research Society International, the National Institute for Health and Clinical Excellence, the European League Against Rheumatism, and the American College of Rheumatology.Pharmacological treatments for OA include acetaminophen (ACT), oral nonsteroidal anti-inflammatory drugs (NSAIDs), topical analgesics, intra-articular therapy, and duloxetine. Hochberg said ACT is normally recommended for first-line treatment of OA because of its safety profile and superiority in efficacy compared with placebo; however, studies have shown that ACT is associated with increased risk of hypertension, cardiovascular events, perforations, ulcers and bleeding, and a decline in glomerular filtration rate. According to Hochberg, an updated meta-analysis from 2010 also indicated that ACT had minimal effect on pain and no significant effect on function or stiffness. Furthermore, because of liver toxicity concerns with ACT, a US Food and Drug Administration Advisory Committee suggested lowering the maximum individual dose from 1000 mg to 650 mg, ensuring patients could only get a 1000 mg dose through a prescription. Hochberg said that because daily doses of ACT below 4000 mg are not effective, rheumatologists should consider not using ACT in OA patients. Hochberg proceeded to discuss nonselective NSAIDs and COX-2 selective inhibitors, which studies have shown to be superior in efficacy to ACT. He also noted that duloxetine was found to be effective in controlling pain and improving physical function in two, 13-week, placebo-controlled randomized trials; thus, it could be used alone or as adjunctive therapy for patients taking ACT or oral or topical NSAIDs.

Finally, F. Michael Gloth III, MD, FACP, AGSF, associate professor of medicine, Johns Hopkins University School of Medicine, and adjunct associate professor, University of Maryland School of Medicine, Baltimore, discussed the potential role of opioids in managing OA, reviewing guidelines from the American Geriatrics Society (AGS) for opioid therapy in older patients with persistent pain. The AGS guidelines indicate that when using fixed-dose opioid combination agents in an analgesic regimen, patients should not exceed a maximum safe dose of ACT or NSAIDs. In addition, the AGS recommends that physicians consistently reassess patients who take opioid analgesics to track therapeutic goals, adverse effects, and safe and responsible medication use. Gloth stressed that physicians should be cognizant of the risks associated with opioids. Although relatively few patients abuse opioids, genetic and environmental factors can place some patients at higher risk of abuse, including a personal or family history of substance abuse, younger age, presence of a mental disease, or history of preadolescent sexual abuse.

The Opioid Risk Tool can be used to assess for these risks, but if an older adult does not have a history of substance abuse, they are at relatively low risk of becoming addicted, Gloth noted. When opioid abuse is suspected, several assessments can used to make a determination, including the Screener and Opioid Assessment for Patients with Pain, which contains 24 items that indicate potential opioid abuse, and the Current Opioid Misuse Measure, which is a 17-question self-assessment survey for patients who are already taking opioids.