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Assistant Professor of Pharmacy Practice
College of Pharmacy and Health Sciences
Chronic nonmalignant pain (CNMP), or chronic noncancer pain, is generally defined as pain related to non-life-threatening causes that persists for more than six months and has variable response to available therapies. It is typically associated with impairment in functioning and wellbeing, thereby creating a significant negative impact on a patient’s quality of life. Underlying pathology, if identifiable, can be nociceptive, neuropathic or of mixed origin (see Table 1). Goals of therapy for CNMP include reducing pain to a level that is acceptable for the patient, improving quality of life and minimising toxicities associated with the use of analgesic regimens. The management of CNMP is multimodal and involves the expertise of clinicians from various disciplines. Nonpharmacological intervention, such as physical, behavioural and/or psychological therapy, are recommended to be initiated along with an analgesic regimen that is directed at the identified or suspected cause. Pharmacists’ knowledge of pain pharmacotherapy warrants their involvement in the care of patients with CNMP. Nonetheless, even with provider collaboration, CNMP remains undertreated.
Initially, when pain is not appropriately assessed and treated, changes occur within the central nervous system that allow for the pain pathway to cycle continuously, a phenomenon known as neuroplasticity. The pain response is perpetuated, and in such circumstances patients can progress to develop a psychosocial disorder known as chronic pain syndrome. This syndrome can cause the patient to centre his/her lifestyle around seeking immediate pain relief that can at times have negative consequences. Several organisations, including the World Health Organization (WHO), have recognised the need for enhancing the standard of care of patients afflicted with pain. These standards require that healthcare organisations address a patient’s right to appropriate pain assessment and management. Most health systems have adopted the assessment of pain as the “fifth vital sign”, requiring the presence and severity of pain to be assessed at each patient visit.
Several barriers to the appropriate assessment and management of CNMP have been identified, and of particular importance are those related to healthcare professionals. Ethnic, including racial, and gender biases can provoke some clinicians to display negative attitudes and behaviours towards patients who report CNMP. Some providers with prescribing authority may not consider the use of controlled substances such as opioid analgesics because of fear of regulatory scrutiny, while certain pharmacists reported that the use of such medications is only acceptable in patients with chronic cancer pain.(1,2) Misconceptions about pain and inadequate knowledge of pain pathophysiology and pharmacotherapy may stem from the limited time spent in medical, nursing and pharmacy schools on pain management education. Pharmacists can work towards removing these barriers by participating in continuing education programmes that focus on pain and its management.
Assessment of CNMP
It is important for clinicians to utilise quick yet efficient tools for the proper assessment of pain at each healthcare visit. Several assessment tools are available for use, with the verbal numeric rating scale being the most widely adopted in clinical practice. Multidimensional scales such as the Brief Pain Inventory provide the clinician with more detailed characteristics of the current pain syndrome while also addressing its effect on the patient’s quality of life.
Once a pain diagnosis has been made and treatment has been initiated, these assessment tools should be used continuously to identify changes in pain severity. Whenever analgesics are utilised, it is prudent that clinicians monitor for medication efficacy and toxicity.(3) Opioid analgesics, such as morphine, require more vigilant monitoring because of their ability to cause numerous adverse effects. In addition, patients treated chronically with an opioid analgesic require a continual assessment of behaviours related to drug tolerance, physical dependence and addiction.
Treatment of CNMP
Because pain is a subjective experience, there are several patient-specific factors that should be considered when choosing therapy, particularly in regard to analgesics. Pain can originate from different locations within the body and can involve various systems, which can further complicate pain. Pain severity must also be addressed, with different analgesics available for use in mild, moderate or severe CNMP. The patient should be asked about therapies that have been tried either as self treatment or as prescribed by other clinicians. Reviewing past medical records and using the patient as a historian may assist in eliminating therapies that have been attempted but failed. Other patient characteristics that are crucial when selecting therapy include age, current prescription and nonprescription drugs and co-morbidities.
The treatment of chronic pain is considered to be multimodal, and patients should be managed by a multidisciplinary team. In addition to nonpharmacological therapies, analgesics are routinely initiated because they are easily accessible and less invasive, making them a desirable therapeutic option for both the patient and the clinician.(3) However, identifying an analgesic that will provide effective pain relief without significant adverse effects can be a daunting task. Nonopioid analgesics such as paracetamol or nonsteroidal anti-inflammatory drugs are effective therapeutic options for pain of nociceptive origin but typically only control pain that is of mild to moderate severity. Opioid analgesics such as morphine have demonstrated efficacy for the treatment of moderate-to-severe nociceptive and neuropathic CNMP, but fear of adverse effects such as addiction or respiratory depression has stimulated debate about the use of such medications in this population. Currently, there are no practice guidelines for the general management of CNMP. However, the standard of care for patients with chronic cancer pain has been extrapolated to the care of patients with CNMP. The use of the WHO pain relief ladder has assisted in decision-making, particularly when choosing analgesic therapy.(4)
Pharmacists as pain specialists
Recently, Dole et al(5) reported that patients with CNMP were managed effectively by a pharmacist with prescribing authority and refill authorisation in a pain management clinic, resulting in significant positive clinical outcomes. This model highlights the ever-changing role of the pharmacist and emphasises the importance of pharmacist involvement in the care of such patients.
International Association for the Study of Pain
American Chronic Pain Association
US National Pain
Education Council (NPEC)