Consequences of Persistent Pain

US Pharm. 2008;33(5):28-30.

There are numerous consequences of persistent pain in older adults (TABLE 1 ). The clinical manifestations of persistent pain cross physiologic, psychologic, and social domains.¹ Understanding these potential consequences provides insight into the challenging task of formulating an appropriate pharmaceutical care plan for individuals with this condition. The greatest challenge usually involves the treatment of the oldest, sickest, and most frail seniors with multiple comorbidities and few to no social supports. ¹ Furthermore, some conditions may be worsened by the presence of pain, including gait disturbances, slow rehabilitation, and adverse effects from polypharmacy (e.g., nonsteroidal anti-inflammatory drug [NSAID]-induced acute renal failure).^1,2 Through the integration of information regarding persistent pain with pharmacokinetic and pharmacodynamic principles associated with drug utilization in the elderly, pharmacists involved in pain management can become skillful in recommending medication regimens tailored to each individual patient.

Persistent Pain
The most common reason patients seek out medical care is pain.³ Persistent pain, common among older Americans (TABLE 2), may be defined as a painful experience that continues for a prolonged period of time and may or may not be associated with a recognizable disease process, according to The American Geriatrics Society Panel on Persistent Pain in Older Persons.¹ The term chronic pain has been replaced with the preferred term persistent pain in an attempt to remove negative connotations (e.g. chronic psychiatric problems, malingering, drug-seeking behavior) and foster a more positive attitude by those involved in the management of pain and alleviation of suffering in the elderly (e.g., patients, caregivers, and professionals).¹ Patients with persistent pain can experience a pain exacerbation, referred to as breakthrough pain, as well as acute pain secondary to a new illness or condition.^4,5

Consequences of Persistent Pain
Unlike acute pain that is often associated with hyperactivity of the sympathetic nervous system (e.g., elevated blood pressure and respiratory rate, tachycardia, diaphoresis, dilated pupils), persistent pain frequently leads to gradually developing vegetative signs (e.g., listlessness, decreased appetite, loss of taste for food, weight loss, decreased libido, constipation, and sleep disturbance).³ Impaired ambulation may also be observed. In the elderly, psychosocial factors both affect pain and are affected by pain. ¹ Patients with persistent pain may withdraw socially; psychologic and social impairment may be severe, resulting in virtual lack of function.³ Older adults with good coping strategies have been shown to have considerably lower pain and psychologic disability.¹ Depression may occur in patients with persistent pain and is commonly associated with pain in the elderly; a significant correlation has been shown between pain and depression among nursing home residents.^1,3 Untreated pain may manifest as anxiety, refusal of care (i.e., physical assistance or handling of the patient may exacerbate pain), and agitated behaviors.^6,7 Patients may become preoccupied with physical health, further contributing to the increased health care utilization and costs resulting as a consequence of persistent pain.

Pain Assessment
The patient's report is the most accurate and reliable evidence of the existence of pain and its intensity; in most older people, a verbally administered 0-10 scale is recommended to measure pain intensity.¹ This concept has driven the phrase fifth vital sign, which refers to pain and the need for its ongoing assessment. Ongoing assessment of pain intensity is required to deliver quality of care since factors that exacerbate pain and promote pain relief vary from patient to patient.⁷ Assessment may be especially challenging in older patients with dementia, sensory impairments, and disability.¹ Reference 8 contains an example of a pain thermometer and faces scale that has been studied in the elderly; a table of commonly identifiable pain-associated behaviors is also available.⁸ It is important to note that an assessment should include evaluation of acute pain that may indicate a new comorbidity distinguishable from an exacerbation of persistent pain.¹ Information obtained from caregivers and family members should be included in the pain assessment.¹

Minimum Data Set in Nursing Homes
Consultant pharmacists who refer to the Minimum Data Set (MDS) 2.0 in the medical records of nursing home and physical rehabilitation residents should be aware of draft version MDS 3.0 containing changes involving pain assessment items. These include: 1) treatment items added; 2) resident interview replaces staff observations for residents who can report pain symptoms; 3) section expanded to capture effect on function; 4) staff assessment of pain changed to an observational checklist of pain behaviors and only completed for residents who cannot self-report; and 5) a 10-point scale, providing a broader spectrum of intensity and more broadly used in nursing homes and other settings, has replaced the three-point scale. For a thorough review of the draft changes, see Reference 9.

Management of Persistent Pain
Control of persistent pain involves analgesic medication dosed on a regular, round-the-clock basis to avoid anxiety associated with the anticipation of pain. Relieving breakthrough pain, escalating pain, or an exacerbation of a preexisting morbidity that may contribute to the underlying pain requires a rescue, as-needed analgesic medication order in addition to the scheduled analgesic. Close monitoring of the frequency of use of rescue analgesics is required for ongoing pain assessment; this enables the clinician to recalculate an appropriate and adequate round-the-clock dosage regimen for the relief of persistent pain. Cognitively intact patients may participate in their treatment by using patient-controlled analgesia prescribed by their physician.¹⁰

Adjuvant analgesic drugs, including anticonvulsants (e.g., carbamazepine, valproate, gabapentin) and antidepressants (e.g., tricyclics [TCAs]), venlafaxine, bupropion), are often utilized.³ These agents are used for a variety of indications (both FDA-approved and off label); however, they most notably target neuropathic pain. Gabapentin is the most widely prescribed for this use.³ In the elderly: 1) TCAs (i.e., especially amitriptyline, imipramine, and doxepin) can be problematic with regard to anticholinergic and cardiac adverse effects; 2) gabapentin has been shown to have decreased clearance as age increases--most likely due to age-related decreases in renal function--and dose reductions may be necessary; and 3) NSAIDs have the potential to produce gastrointestinal bleeding, renal failure, high blood pressure, and heart failure.¹¹ Topical medications such as capsaicin (e.g., cream, lotion), compounded creams (e.g., local anesthetics and NSAIDs), and a lidocaine 5% patch have low risk of side effects and should be considered for various types of pain.³ Pharmacists, through identifying, resolving, and preventing adverse effects of medications (e.g., constipation, excessive sedation, which may lead to respiratory depression), are an integral part of the overall pain managementÜapproach.¹²

It has been suggested that in order to achieve comprehensive pain management, it is important to relieve and prevent both the physical and emotional symptoms.^3,7,13,14 If depression is comorbid with persistent pain, it should be treated with antidepressants.³ Psychologic and behavioral treatments are usually helpful.³ Behavioral treatments are capable of improving patient function, even without reducing pain.³ Pain control through cognitive techniques (e.g., biofeedback, hypnosis, relaxation training, distraction techniques [guided imagery]) may be useful. ³

Physical therapy or occupational therapy may be beneficial in many patients; some require an orthosis.³ Myofacial trigger points can be relieved by spray-and-stretch techniques.³ Other treatments, depending on the condition, include joint and spinal injections, trigger point injection, nerve blocks, spinal cord stimulation, and neuraxial infusion.³

Future Trend in Persistent Pain Management
The treatment of persistent pain in the future appears to be evolving. Instead of the current modalities providing symptomatic relief (e.g., morphine), newer agents will aim at the disease process.¹⁵ Pain-sensing neurons of the peripheral nervous system express several sodium channel subtypes, and pharmacologic agents that target the Na 1.8 selective small molecule sodium channel (subtype selective sodium channel blockers) are currently in development.¹⁵

Conclusion
Clinical manifestations of persistent pain are usually multifactorial. Pharmacists should develop an understanding of the nature of persistent pain with regard to its consequences and ultimate potential to cause physical impairment, psychologic disability, and social withdrawal. By integrating this knowledge with appropriate pharmaceutical recommendations and ongoing pain assessment, individualized medication regimens for persistent pain may be achieved.

REFERENCES
1. The management of persistent pain in older persons. American Geriatrics Society (AGS) Panel on Persistent Pain in Older Adults. 2002. www.americangeriatrics.org/products/positionpapers/JGS5071.pdf. Accessed April 9, 2008.
2. Zagaria ME. Drug-induced acute renal failure: nonsteroidal anti-inflammatory drugs. US Pharm. 2003;28(5):19-23. www.uspharmacist.com/oldformat.asp?url=publish/content/8_1069.htm. Accessed April 9, 2008.
3. Beers MH, Porter RS, eds. The Merck Manual of Diagnosis and Therapy. 18th ed. Whitehouse Station, NJ: Merck & Co.; 2006:1769-1779.
4. Burton AW. Outpatient management of breakthrough pain. Medscape Neurology & Neurosurgery. 2005;7:1-6. www.medscape.com/viewarticle/506124. Accessed April 10, 2008.
5. Portenoy RK, Hagen NA. Breakthrough pain: definition, prevalence and characteristics. Pain. 1990;41:273-281.
6. Martin CM. Understanding palliative care. The Consultant Pharmacist. 2006;21:698-713.
7. Zagaria ME. Geriatric palliative care: when the focus shifts from care to comfort. US Pharm. 2007;32(5):28-34.
8. Zagaria ME. Pain assessment in older adults: the cornerstone of controlling pain. US Pharm. 2006;31(5):30-36. www.uspharmacist.com/oldformat.asp?url=publish/content/8_1735.htm. Accessed April 9, 2008.
9. The MDS 3.0. Special Open Door Forum. January 24, 2008. www.cms.hhs.gov/OpenDoorForums/Downloads/MDS30Word012408.pdf. Accessed April 11, 2008.
10. Lorenz K, Lynn J. Care of the dying patient. In: Hazzard WR, Blass JP, Halter JB, et al. Principles of Geriatric Medicine and Gerontology. 5th ed. New York: McGraw-Hill, Inc.; 2003:323-334.
11. Semla TP, Beizer JL, Higbee MD. Geriatric Dosage Handbook. 12th ed. Hudson, OH: Lexi-Comp, Inc.; 2007.
12. ASHP 2006: Highlights of the 2006 American Society of Health-System Pharmacists Midyear Clinical Meeting. Methadone, Pain Management, and Palliative Care. www.medscape.com/viewarticle/550895. Accessed April 10, 2008.
13. Cohen AB, Koenig HG. Spirituality in palliative care. Geriatric Times. 2002;Nov/Dec:25.
14. Steinhauser KE, Clipp EC, Tulsky JA. Evolution in measuring the quality of dying. J Palliat Med. 2002;5:407-414.
15. An Overview of the Decade of Pain Lecture From AAPM 2008: An Expert Interview With Joshua P. Prager, MD, MS. Medscape Neurology & Neurosurgery. 2008; www.medscape.com/ viewarticle/570384. Accessed April 10, 2008.

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