Using opioids to treat pain in older adults

Managing pain in older adult patients is a unique challenge. Compared to a younger population they have altered physiology—reduced hepatic metabolism, age-related renal impairment, and lower muscle-to-fat mass ratio. They often have one or several chronic comorbidities and may be on multiple disease-specific medications, raising the spectre of interactions and side effects.[1] Further, seniors may believe that pain is a normal part of aging and may be reluctant to admit to having pain or to ask for help treating it. They may worry that pain is a harbinger of something sinister in their body and, therefore, prefer not to undertake investigations aimed at uncovering the causes.

Yet, pain is common in older adults. More than 40% of community-dwelling and up to 80% of institutionalized elders report pain.[2] Their pain is frequently due to degenerative musculoskeletal conditions or neuropathies. The demented elderly are equally burdened by pain, although they may not be able to articulate their suffering. Acute, chronic, and multiple pains of various etiologies are, sadly, a pervasive part of our aging patients’ experience. This common symptom is often underrecognized and undertreated.[3]

Nonpharmacological strategies, the ones we recommend to younger patients—exercise, yoga, meditation, and cognitive behavioral therapy—should be considered for frail seniors but may be impractical or ineffective.[4] Prescribing non-opioid analgesics to frail older adults may have risks. There is a lower recommended limit for acetaminophen (3000 mg per day) due to risk of hepatic toxicity,[3] and a systematic review concludes that it offers little benefit in osteoarthritic and back pain.[5]

NSAIDs and COX-2 inhibitors must be used with extreme caution, if at all, due to the risk of GI bleeding and worsening of heart failure, kidney dysfunction, or both. Treating neuropathic pain with tricyclic antidepressants isn’t recommended for older adults due to high incidence of adverse effects, and limited evidence exists for SSRIs. SNRIs (duloxetine) and anticonvulsants (gabapentin, pregabalin) do show promise in neuropathic pain, though the latter may be limited by side effects.[4] Cannabis may also play a role, though there is scant evidence and seniors may find tolerability to be an issue.

With a rather limited pharmaceutical armamentarium, opioids must be considered an option for managing pain in elders. Morphine and other synthetic opioid analgesics have long been effective, relatively safe, and well-tolerated.[4] Yet prescribing opioids is complex and challenging. Canadian and US guidelines offer commonsense approaches to mitigating risks when opioids are included in a pain treatment plan. Understandably, increasing rates of diversion, addiction, and overdose are huge concerns. Clinicians may feel themselves under scrutiny and, therefore, be more reluctant to offer opioids. This can lead to a cycle of undertreatment and desperation in patients with legitimate pain syndromes and for whom opioid treatment could be appropriate.

The College of Physicians and Surgeons of BC, in its publication Safe Prescribing of Drugs with Potential for Misuse/Diversion, states that patients with cancer pain and those nearing end of life, in nursing homes, or for whom a palliative approach is being taken are not subject to the standards written for other chronic oncancer pain patients.[6] For all older adults experiencing pain, since there are limited alternatives, prescribers should certainly consider opioids. Thorough pain assessment and appropriate dosing, monitoring, and prescribing practices underscore the successful use of opioids. Seniors should be started on opioid doses that are half or less of what would be prescribed for a younger adult (start low). Titrating the dose needs to be done in consideration of altered pharmacokinetics in older patients (go slow). Lastly, nondrug modalities should be offered and non-opioid adjuvants should be used in combination with opioids to take advantage of complementary effects while minimizing the toxicity of higher doses.[4] 
—Jay Slater, MD
Geriatrics and Palliative Care Committee

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This article is the opinion of the author and has not been peer reviewed by the BCMJ Editorial Board.

References

1.    Kaye AD, Baluch A, Scott JT. Pain management in the elderly population: A review. Ochsner 2010;10:179-187.
2.    Helme RD, Gibson SJ. The epidemiology of pain in elderly people. Clin Geriatr Med 2001;17:417-431.
3.    Tracy B, Morrison RS. Pain management in older adults. Clin Ther 2013;35:1659-1668.
4.    Makris UE, Abrams RC, Gurland B, Reid MC. Management of persistent pain in the older patient: A clinical review. JAMA 2014;312:825-836.
5.    Machado G, Maher CG, Ferreira PH, et al. Efficacy and safety of paracetamol for spinal pain and osteoarthritis: Systematic review and meta-analysis of randomised placebo controlled trials. BMJ 2015;350:h1225.
6.    College of Physicians and Surgeons of BC. Safe prescribing of drugs with potential for misuse/diversion. 2016. Accessed 15 December 2016. www.cpsbc.ca/files/pdf/PSG-Safe-Prescribing.pdf.