CHRONIC PAIN

It is estimated that 19% of American adults have chronic pain^1,2 (approximately 50 million Americans).

Chronic pain often consists of two components: persistent pain, which is pain that is continuous throughout the day, and breakthrough pain (BTP), which involves transitory flares of moderate-to-severe pain in a person whose persistent pain is otherwise controlled. Chronic pain can also be intermittent in which there is no constant component.

Patients with moderate-to-severe chronic pain have extremely low health-related quality of life (HRQL) compared with patients who have other disease states. In addition, these patients utilize a disproportionate share of healthcare resources because of uncontrolled pain.³ In common pain conditions, the majority of the lost productivity time may occur in the form of reduced performance while at work, rather than work absence.⁴

Depending on the patient population examined, 51–89% of cancer pain patients taking chronic opioid therapy for controlled, persistent pain experience BTP.^5,6,7 The epidemiology of BTP in chronic noncancer pain is generally similar to that in chronic cancer pain. A recent survey of 228 outpatients with chronic noncancer pain and controlled, persistent pain found that the prevalence of BTP was 74%.⁸

Generally, the clinical presentation dictates the type of opioid to be used. Persistent pain is often treated with long-acting opioids (LAOs) because of their longer duration of action. If any BTP occurs, this is often treated with short-acting opioids (SAOs) including transmucosal immediate-release fentanyl (TIRF) products, also known as rapid-onset opioids, or ROOs, because of their shorter time to onset.

According to the guidelines of the World Health Organization,⁹ the choice of analgesic should be based on the intensity of pain reported by the patient, rather than its specific etiology. The starting point for mild pain is acetaminophen and nonsteroidal anti-inflammatory drugs (NSAIDs). For moderate pain, weak opioids and combination products, such as oxycodone/hydrocodone-acetaminophen and tramadol, are recommended. For severe pain, strong opioids, such as morphine, hydromorphone, fentanyl, and oxycodone, are recommended.  


References
1. Shi Q, Langer G, Cohen J, Cleeland CS. People in pain: How do they seek relief? J Pain 2007;8:624–36.
2. Langer G. Poll: Americans searching for pain relief. New poll shows nearly four in 10 American adults suffer from pain on a regular basis. Available at: http://www.abcnews.go.com/Health/PainManagement/ story?id=732395. Accessed May 25, 2010.
3. Becker N, Thomsen AB, Olsen AK, et al. Pain epidemiology and health related quality of life in chronic non-malignant pain patients referred to a Danish multidisciplinary pain center. Pain 1997;73:393–400.
4. Stewart WF, Ricci JA, Chee E, et al. Lost productive time and cost due to common pain conditions in the US workforce. JAMA 2003;290:2443–54.
5. Portenoy RK, Hagen NA. Breakthrough pain: definition, prevalence and characteristics. Pain 1990;41:273–81.
6. Portenoy RK, Payne D, Jacobsen P. Breakthrough pain: characteristics and impact in patients with cancer pain. Pain 1999;81:129–34.
7. Zeppetalla G, O’Doherty CA, Collins S. Prevalance and characteristics of breakthrough pain in cancer patients admitted to a hospice. J Pain Symptom Manage 2000;20:87–92.
8. Portenoy R, Bennett DS, Rauck R, et al. Prevalence and characteristics of breakthrough pain in opioid-treated patients with chronic noncancer pain. J Pain 2006;7:583–91.
9. World Health Organization. Cancer pain relief and palliative care: report of a WHO Expert Committee. Geneva, Switzerland: World Health Organization; 1990.