Pain (Professional) (cont.)
IN THIS ARTICLE
Failure to assess pain is a critical factor leading to undertreatment. Assessment involves both the clinician and the patient. Assessment should occur at the following times:
Identifying the etiology of pain is important to its management. Clinicians treating patients with cancer should recognize the common cancer pain syndromes (see lists below). Prompt diagnosis and treatment of these syndromes can reduce morbidity associated with unrelieved pain. Distinct cultural components may need to be incorporated into a multidimensional assessment of pain.[1,2,3,4] A comprehensive review of cancer pain with a focus on neuropathic pain describes pathophysiologies as well as available and investigational pharmacotherapies.
Common Pain Syndromes: Pain Associated with Tumor
Common Pain Syndromes: Pain Secondary to Treatment
The goal of the initial assessment of pain is to characterize the pathophysiology of the pain and to determine the intensity of the pain and its impact on the patient's ability to function. For example, one study evaluated the association between psychological distress and pain in 120 patients with advanced cancer. Pain intensity and pain that interfered with walking ability, normal work, and relations with other people, as measured by the Brief Pain Inventory (Greek version), were found to be significant predictors of anxiety, as measured by the Hospital Anxiety and Depression Scale on multivariate analysis. Using the same tools, the authors also found pain that interfered with enjoyment of life was a predictor of depression.[Level of evidence: II] Factors that may influence analgesic response and result in persistent pain include changing nociception due to disease progression, intractable side effects, tolerance, neuropathic pain, and opioid metabolites.[Level of evidence: IV] The following are essential to the initial assessment:
The experience of cancer pain is complex and includes physical, psychosocial, and spiritual dimensions. There is no universally accepted pain classification measure that assists with predicting the complexity of pain management, particularly for cancer pain patients, who may be more difficult to treat. Clinicians and researchers lack a common language to discuss and compare outcomes of cancer pain assessment and management. Oncologists use the tumor, nodes, metastases (TNM) system as a universal language to describe a variety of cancers. The need for a similar classification system for cancer pain resulted in the development of the Edmonton Staging System.[9,10] This system has been further refined in two reports that have gathered construct validity evidence using an international panel of content experts  and a multicenter study to determine interrater reliability and predictive value. The development of an internationally recognized classification system for cancer pain could play a significant role in improving the assessment of cancer pain, allow a more meaningful assessment of clinical prognosis and treatment, and better enable researchers to compare results with regard to cancer pain management.[Level of evidence: II]
The mainstay of pain assessment is the patient self-report; however, family caregivers are often used as proxies for patient reports, especially in situations in which communication barriers exist, such as cognitive impairment or language difficulties. Family members who act as proxies typically, as a group, report higher levels of pain than patient self-reports, but there is individual variation.[Level of evidence: II] Differences in clinician assessment of pain intensity are also significant. A retrospective review of 41 patient charts using pain ratings of palliative care consultants as the gold standard found high agreement with assessments performed by bedside nurses (registered nurses [RNs] and clinical nurse assistants [CNAs]) when pain was not present or was mild but poor agreement for moderate or severe pain (sensitivity: RNs, 45%; CNAs, 30%).[Level of evidence: III]
Pain assessment tools may be unidimensional or multidimensional. Multiple assessment tools exist. Among the more commonly used bedside tools are numeric rating scales, verbal rating scales, visual analog scales, and picture scales.[16,17][Level of evidence: IV] Pain intensity at initial assessment has been demonstrated to be a significant predictor of subsequent pain management complexity (i.e., the need for more pharmacological and multidimensional approaches) and length of time to achieve stable pain control.[Level of evidence: II] To enhance pain management across all settings, clinicians should teach families to use pain assessment tools in their homes. The clinician should help the patient to describe:
Changes in Pattern
Intensity or Severity
Aggravating and Relieving Factors
Cognitive Response to Pain
Goals for Pain Control
A thorough physical examination is required to determine the pathophysiology of pain. Specific features of the neurologic examination such as altered sensation (hypoesthesia, hyperesthesia, hyperpathia, allodynia) in a painful area are suggestive of neuropathic pain. Physical findings of tumor growth and metastasis are also important to identify.
Information obtained from the synthesis of history, physical examination, and diagnostic evaluations is used to generate a pain diagnosis with respect to etiology (cancer, its treatment, or other) and pathophysiology (somatic, visceral, and/or neuropathic). This diagnosis, in conjunction with contributing psychosocial and spiritual factors, is used to generate a comprehensive pain treatment plan.
Assessment of the Outcomes of Pain Management
Pain-related outcomes: Clinicians should document and be aware of outcomes of pain therapy. It is helpful to think of pain-related outcomes as primarily measured in two ways: decreased pain intensity and improvement in psychosocial functioning. Using rating scales of pain intensity at its worst and on average and using pain interference scales can help clinicians monitor outcomes. Measurement of the percentage of pain relief is also useful, though measuring patient satisfaction is less useful because of the low expectations patients sometimes hold for pain control.[24,25]
Drug-taking outcomes: Clinicians prescribing chronic opioids should also monitor and document patients' drug-taking behaviors. Outcomes related to addiction in cancer patients are rare but nonetheless should be periodically assessed; these assessments can be reassuring to patients. Tolerance and dependence are not addiction related. Documentation of patients' compliance with regard to changes in dosing and duration of prescriptions is essential in all pain practice.
The clinical assessment of drug-taking behaviors in medically ill patients with pain is complex. Aberrant drug-taking behavior from cancer pain management is related to premorbid history of drug addiction and the likelihood of other pain treatment. A pilot questionnaire was used to characterize drug-related behaviors and attitudes in cancer and AIDS patients. Despite limitations, this study highlights wide potential variation among different palliative care populations in patterns of past and present aberrant drug-taking behaviors and the need for a clinically useful screening approach. The implications for psychosocial and pharmacological management of symptoms such as pain, as well as any aberrant behavior, remain unclear.[26,27,28]
Previous drug abuse is likely to lead to specific needs for appropriate dosing during cancer pain therapy. A prospective open-label study compared morphine dosage and effectiveness in AIDS patients with and without previous substance abuse. Results demonstrated that both groups benefited, but patients with a history of drug use required and tolerated substantially higher morphine doses to achieve stable pain control.[Level of evidence: II] This study should increase confidence in providing appropriate pain management to patients who have a history of drug use.[Level of evidence: IV]
eMedicineHealth Public Information from the National Cancer Institute
This information is produced and provided by the National Cancer Institute (NCI). The information in this topic may have changed since it was written. For the most current information, contact the National Cancer Institute via the Internet web site at http://cancer.gov or call 1-800-4-CANCER
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