Evaluating and Managing Chronic Pain

Everyone at one time or another has suffered some form of pain from an injury or illness. In most cases, people experience acute pain, which, with effective pain management coupled with the healing process, eventually goes away. Chronic pain is another form of pain, which also occurs as the result of some type of injury or illness but persists even after the apparent healing has occurred. It can last for weeks, months, or years and may not respond to any form of treatment. As a result, an individual's quality of life may be impaired, and the pain may lead to future long-term physical, psychological, and social problems. The pain can occur in any region of the body and can vary from mild to severe. Chronic pain often results in sleep disorders or depressive states in some patients. Although most causes of chronic pain are known, the causes of some pain are never identified, and pain can occur without longterm illness or injury.

Chronic pain is considered to be the leading cause of disability among individuals in the United States.¹ It is very prevalent in approximately 90% of cancer patients and is often considered to be undertreated. According to the American Chronic Pain Association, 86 million individuals in the United States are afflicted with some form of chronic pain.²

Causes

As stated above, the most prevalent causes of chronic pain are long-term illness (Table 1) and injuries. Other possible factors include damage to the central or peripheral nervous system and vascular conditions.

Classification

Chronic pain can be categorized into 3 classes³:

• Pathophysiologic?pain due to functional changes related to or the result of an illness or injury
• Neuropathic?pain resulting from damage to the nervous system (spinal cord, brain, or peripheral nerves)
• Nociceptive?pain associated with continual tissue damage due to circumstances such as surgery, osteoarthritis, or sports injuries

Symptoms

Chronic pain may be experienced in the following forms:

• Mild-to-severe episodes of pain that does not subside
• Severe episodes of discomfort, aching, burning, stiffness, or soreness
• Persistent episodes of tingling or radiating pain

Diagnosis

Diagnosis usually is made through review of the patient's medical history, a neurologic examination, and a series of diagnostic tests, which may include the following:

• Hematologic analysis
• Imaging tests (eg, magnetic resonance imaging, x-ray, computerized axial tomography scan, bone scan)
• Functional assessment (eg, evaluation of an individual's ability to perform day-to-day activities)

Treatment and Management

Pain management for an individual suffering from chronic pain often can be challenging. The goal of pain management is to relieve or decrease the intensity of the pain, enabling the person to function. Several treatment plans may be attempted before adequate pain relief is achieved (Table 2). Patients should be advised to seek aid from their health care provider if their pain persists for more than a month.

The initial treatment depends on the severity and type of the person's pain. Treatment varies from individual to individual. The use of pharmacologic agents is the most common form of treatment. Most individuals suffering with chronic pain initially resort to nonprescription analgesics. In conjunction with regularly used analgesics (eg, nonopioids, opioids, and opioid agonist/ antagonists), adjunctive therapies may be incorporated into a pain-management plan.

Nonopioids

Nonopioids commonly are used in the initial stages of chronic pain. These agents are a rational choice when the etiology of the chronic pain is associated with an inflammatory response. These agents must be monitored carefully on a consistent basis. Renal and hepatic functions should be routinely monitored, as well as signs of gastrointestinal irritation and the potential for developing ulcers. Pharmacists should inform patients that some of these agents should not be used for more than 10 days unless otherwise directed by their physicians. These nonopioids are as follows:

• Nonsteroidal anti-inflammatory drugs
• Acetaminophen
• Aspirin
• Cyclooxygenase-2 inhibitors (celecoxib, rofecoxib, valdecoxib)

Opioids

The use of opioids, although effective in most cases of chronic pain, is still somewhat controversial among health care providers. These agents should be reserved for uncontrolled pain and should be used with caution, because they may interfere with cognitive skills and the potential exists for tolerance and addictive effects. Patients should be instructed to adhere to regular follow-ups to monitor progress. Common adverse effects include somnolence, confusion, dry mouth, constipation, and nausea. Patient-controlled analgesia is re-served for severe chronic pain that has been uncontrolled with oral medications. Opioids include:

• Codeine
• Hydrocodone
• Propoxyphene
• Hydromorphone
• Methadone
• Morphine
• Fentanyl
• Meperidine
• Levorphanol
• Oxycodone

Opioid Agonist/Antagonists

These drugs include the following:

• Pentazocine
• Nalbuphin
• Butorphanol

Adjunctive analgesic therapy often is utilized (Table 3). For other treatment options, see Table 4.

Conclusion

The treatment of chronic pain with only analgesics can be successful, but the adverse effects associated with long-term use of these drugs are important factors to consider. Patients need to be made aware that repeated administration of pain medications could result in tolerance and psychological as well as physical dependence. Therefore, the incorporation of other forms of therapy?such as physical, rehabilitation, and nutritional therapies?also should be evaluated. Multidisciplinary treatment plans involving education, medication, physical therapy, and behavioral therapy have demonstrated effectiveness in most pain-management cases.

Help from pharmacists can be indispensable for individuals afflicted with chronic pain. Pharmacists can serve as educational resources and can refer patients to specialists who may aid in identifying treatment plans that may in some way enhance their quality of life. Although chronic pain cannot always be cured, it can be managed in some cases. Effective pain management often requires both pharmacologic and nonpharmacologic interventions.

Ms. Terrie is a clinical pharmacy writer based in Slidell, La.

For a list of references, send a stamped, self-addressed envelope to: References Department, Attn. A. Stahl, Pharmacy Times, 241 Forsgate Drive, Jamesburg, NJ 08831; or send an e-mail request to: astahl@mwc.com.