Underestimated Pain in Osteoarthritis and Central Sensitization Affects Pharmacist Counseling

Underestimated Pain in Osteoarthritis and Central Sensitization Affects Pharmacist Counseling

osteoarthritis and central sensitizationSometimes commonly accepted knowledge about healthcare isn’t all that accurate, especially when you compare doctor and patient perceptions. Osteoarthritis is the perfect example. After surveying patients and physicians, researchers discovered that clinicians significantly underestimated the degree of pain caused by the disease, as compared to the pain levels reported by patients—and it wasn’t merely a case of poor communication. It turns out that, due to central sensitization, osteoarthritis patients actually do experience more pain.

These types of discordant opinions are a big problem, as they can result in therapy that isn’t effective and patients who become noncompliant. But pharmacists can help patients get clinically appropriate treatment through proactive counseling and collaboration with physicians.

Differing Perceptions of Osteoarthritis

Since osteoarthritis (OA) is caused by wear-and-tear, compared to the autoimmune basis and systemic effects of rheumatoid arthritis (RA), it’s easy to see why RA might be considered the more painful and severe condition. But when you actually ask patients, the picture changes. In June 2016, a presentation at the European League Against Rheumatism Annual Congress (EULAR) showed that rheumatologists are more likely to underestimate the impact of OA than RA.

The study presented at EULAR surveyed 243 patients with OA, 216 patients with RA, and their physicians. They were asked to rate their disease severity and complete a health assessment that included a symptom checklist plus scores for pain, fatigue, and physical function. Perceptions of disease severity between physicians and patients differed for both OA and RA, but only 18 percent of RA patients displayed a split from their doctors, while physicians underestimated disease severity in 34 percent of OA patients.1 More significantly, over half of OA patients agreed in their pain assessments—and pain level was the strongest predictor of discordance with physician opinion.

Before you shrug and say that these measures are subjective, remember two critical points: first, they are still important to patients. Issues like pain and level of functioning affect future outcomes, noted lead author Isabel Castrejon, MD, PhD, assistant professor in the division of Rheumatology at Rush University Medical Center in Chicago. Second, the clinical measures that doctors rely upon, like imaging studies, don’t accurately reflect pain levels due to the role of central sensitization.

Osteoarthritis Pain and Sensitization of the Central Nervous System

The confounding thing about OA is that the pain it causes seldom matches actual joint damage. About 30 to 50 percent of patients with moderate-to-severe radiographic changes are asymptomatic, while 10 to 20 percent of patients with moderate-to-severe pain have normal findings on radiography.2 These disparities are attributed to the fact that pain in OA comes not only from damage to joint structures—it also comes from changes in central pain processing, which is called central sensitization.

Central sensitization occurs when ongoing pain causes cellular changes that put the nervous system into a state of hyper-reactivity. While central sensitization develops differently in each patient, depending on factors like their response to stress and their pain threshold, the end result is chronic and heightened sensitivity to pain beyond what their physical presentation suggests. Patients with OA experience sensitivity to pressure and widespread, referred, and radiating pain. Researchers don’t have all the answers, but PET scans show that OA triggers areas of the brain responsible for fear, and that mild discomfort from mechanical knee stimulation activates brain regions associated with acute pain.

Treatment Guidelines for Osteoarthritis

Osteoarthritis treatment revolves around two goals: relieve pain and improve functional status. The regimen is multimodal, but it’s important to remember that the keystone of treatment revolves around non-pharmacologic methods such as:

  • Application of heat and cold
  • Weight loss
  • Exercise
  • Physical therapy
  • Occupational therapy

A variety of pharmaceuticals are conditionally recommended by the American College of Rheumatology and the American Academy of Orthopaedic Surgeons, including:3

  • Topical capsaicin – conditionally – against its use for knee osteoarthritis
  • Glucosamine and chondroitin sulfate – conditionally – against its use in knee osteoarthritis
  • Topical NSAIDs
  • Oral NSAIDs
  • Acetaminophen
  • Tramadol
  • Intra-articular corticosteroid injections

The Agency for Healthcare Research and Quality (AHRQ) summed it up by saying there’s just not enough evidence to show that any particular analgesic is more effective than another, so the benefits and risks for each patient must be considered. However, AHRQ noted that topical diclofenac had similar efficacy as oral NSAIDs. A more recent meta-analysis published in the Lancet in May 2016 concluded that there was sound evidence for oral diclofenac but no role for single-agent paracetamol in the treatment of knee and hip osteoarthritis.4 When assessing the patient’s risk and medication choices, pharmacists should also consider the patient’s age, other medications they’re taking, and any comorbid conditions.

Quality Care Indicators and Pharmacist Intervention

Good things happen when pharmacists replace a standard educational pamphlet with a full-fledged osteoarthritis intervention program. What kind of good things? In one study, measures of pain, function, and daily activity significantly improved when the intervention included:5

  • Knee OA screening questionnaire
  • Patient education
  • Pain medication management
  • Physiotherapy-guided exercise
  • Communication with the primary care physician

If that sounds like more than you can manage, remember that you can bill for some services through the physician’s practice or Medicare when you’re part of a health care team that conforms to your state’s requirements. Under this scenario, you’ll also need to develop a way to record all your activities and to track your patient’s adherence to medications, as well as changes in pain and functioning. And even if this isn’t the right time for you to collaborate with a team, you can still implement some aspects, such as a simple screening questionnaire, during your normal medication management consultations.

Patient Education is a Key Element of Treatment

Beyond your pharmaceutical expertise, one of the biggest contributions you can make is to talk with patients. Chances are they’re not familiar with the process of central sensitization and how it impacts medication choices. Open communication between patients, pharmacists, and doctors is the key to improving the quality of life for those struggling with osteoarthritis.

Pharmaceutica North America provides prescription NSAIDs, bulk active pharmaceutical ingredients that can be used for topical delivery, and OTC supplements such as glucosamine and chondroitin sulfate. Contact us today to talk about how we can support all of your pharmaceutical needs.

Show 5 footnotes

  1. “Osteoarthritis Disability is Often Underestimated by Rheumatologists,” June 2016, http://www.practicalpainmanagement.com/pain/myofascial/osteoarthritis/osteoarthritis-disability-often-underestimated-rheumatologists
  2. “Osteoarthritis and Central Pain,” August 2016, http://www.practicalpainmanagement.com/pain/myofascial/osteoarthritis/osteoarthritis-central-pain
  3. “Osteoarthritis,” July 2016, http://emedicine.medscape.com/article/330487-overview
  4. “Effectiveness of Non-Steroidal Anti-Inflammatory Drugs for the Treatment of Pain in Knee and Hip Osteoarthritis: A Network Meta-Analysis, May 2016, http://www.ncbi.nlm.nih.gov/pubmed/26997557
  5. “Pharmacist-Initiated Intervention Trial in Osteoarthritis: A Multidisciplinary Intervention for Knee Osteoarthritis,” December 2012, http://www.ncbi.nlm.nih.gov/pubmed/22930542

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