Pain Management and Terminal Illness
It is challenging to face a potentially terminal illness: hoping for the best, while planning for the worst. The importance of pain management at the end of life is a professional, moral, and ethical obligation. Although pain may not be the most prevalent symptom at the end of life, it is the most feared. Pain steals both the quality and satisfaction of remaining life, contributes to anxiety, depression, despair, loss of self-efficacy, and interferes with medical decision-making. For many families, the last memory of their loved one may either be that of a “peaceful” and comfortable transition or that of a painful and agonizing end.
Prevalence of End-of life Pain
Pain at end of life is most often equated with the medical consequences of significant illness such as cancer, late HIV disease, degenerative diseases, but it occurs not simply because of the underlying diagnosis, but rather as a consequence of the underlying pathology. Most people equate pain at the end of life with cancer. Surveys of adult cancer patients with advanced disease—often performed in a hospice or palliative care setting—indicate that the prevalence of pain ranges from 50% to 90%.1 It is said that 40-50% of those with pain from cancer report it to be severe while 25-30% describe it to be very severe.2
With cardiovascular disease, as many as 75% of those with heart failure may experience pain in the last six months of life.3 Many of these patients with advanced cardiovascular disease also have painful co-morbidities (e.g. osteoarthritis, neuro-pathy from diabetes).
About 50% of those with AIDS experience pain either related to the virus or the treatment. Pain at the end of life for those with AIDS has been seen in up to 93% of a patient population observed in an inpatient setting.4
Patients with neurological diseases such as multiple sclerosis, Parkinson’s disease, and central pain related to cerebral vascular disease or spinal cord injury often experience pain.5-7 The extent of pain experienced by those with dementia is unclear due to the difficulty of assessing their pain late in the disease. However, at the end of life, functional decline, weight loss, development of skin breakdown, and contractures are known sources of pain.
Care Setting at the End of Life
The care setting, availability of resources, and the level of expertise of the care provider influences pain management at the end of life. Although surveys suggest that most people prefer to die at home, only 25% die there—with 50% dying in hospital settings and 25% dying in nursing homes or other long-term care facilities.8 About 50% of nursing home patients at end of life have daily pain, with about 85% of them experiencing moderate intensity pain.9 With the advent of the hospice Medicare benefit, people have the opportunity to receive pain management services at the end of life. However, only 36% utilize their benefit with a median length of stay of about three weeks.10
Pain Assessment in Advanced Disease
Ideally, pain should be assessed utilizing a thorough pain assessment—including location, duration, onset, characteristics, severity, alleviating/relieving factors, and associated symptoms. Identifying the underlying pain mechanisms (nociceptive versus neuropathic) should direct appropriate treatment. As the end of life nears, and cognition decreases, it becomes important to utilize behavioral pain tools; e.g., Pain Assessment in Advanced Dementia (PAINAID),11 Behavioral Pain Scale (BPS),12 Critical Care Pain Observation Tool (CPOT).13
There has been a reluctance to use surrogates (individuals who make medical decisions when patients cannot do so) to report patients’ pain because of their emotional attachment to these patients and their potential for overestimating pain. In a large study of seriously ill hospitalized patients, surrogates correctly identified the existence of pain 73% of the time, but estimated its severity with only 53% accuracy.14 Although surrogates may be less accurate about estimating pain’s severity, they are able to assist with pain’s assessment when patients cannot give self-reports.
If unable to adequately assess pain due to cognitive impairment, clinicians should ask themselves “Would I be in pain in this situation?” If the answer is “Yes,” or if the condition is known to predictably cause pain, it is best to assume that pain is present and treat accordingly.
Pharmacotherapy for Pain in Advanced Disease and at the End of Life
Pharmacotherapy remains the mainstay of treatment for pain at the end of life. The first step in treating cancer pain according to the World Health Organization guidelines is to use nonsteroidal anti-inflammatory drugs (NSAIDs). However, NSAIDs are not always used at the end of life because of their many side effects and need for oral route of administration. One parenteral NSAID, ketorolac, may be used for pain relief at the end of life. While it is only indicated for a maximum of 5 days of acute administration, there have been discussions at end of life meetings regarding longer periods of “off label” administration.
Adjuvant analgesics are routinely used in pain management for many types of pain. However, commonly used agents—antidepressants and anticonvulsants—are generally not available as intravenous preparations and thus potentially limits their use at the end of life. In advanced disease, the use of these adjuvants may be beneficial for neuropathic pain, pain related to bony metastases, and pain related to bowel obstruction.
Opioids are the principal class of analgesics used at the end of life because of their potency, concomitant mild sedative and anxiolytic properties, and ability to be administered by multiple routes. Some say that only lack of imagination on the part of healthcare practitioners prevents them finding routes of administration for patients needing opioid medications. Opioid therapy fortunately provides adequate pain relief for greater than three quarters of patients with cancer pain.2 Opioids—specifically excluding meperidine—that are typically utilized in end-of-life settings include:
Caution: Meperidine use must be avoided due to accumulation of its metabolite normeperidine, which is not reversed by naloxone and produces neurotoxicity (e.g., seizures, hallucinations, and delirium).20 There is no recommended long term use of meperidine.
Morphine has been the most widely used medication for cancer pain and is considered a mainstay in end of life care. It is the standard by which other opioids are compared. Morphine does have active metabolites of concern, including morphine-3-glucuronide (M-3-G) and morphine-6-gluconoride (M-6-G). Accumulation of M-6-G in those with renal insufficiency enhances morphine’s analgesic potency, and may cause worsening nausea, sedation, and respiratory depression. Accumulation of M-3-G may lead to CNS irritability, myoclonus, and delirium.15-17 Morphine use should be avoided for patients with known renal insufficiency or failure.