- Email: [email protected]
Hidden Pain or Hidden Evidence?
658
also known to be implicated in the development of movement disorders. Oxycodone is metabolized in the liver by N- and O-demethylation to form noroxycodone and oxymorphone. The O-demethylation is catalyzed by CYP2D6. One postulated effect of incomplete metabolism of oxycodone would be drug accumulation and subsequent opioid toxicity (Napp Pharmaceuticals, personal communication, September 8, 2005). It is more difficult to implicate domperidone in this case, as theoretically it is a dopamine antagonist with limited penetration across the blood brain barrier. In contrast to metoclopramide, it rarely causes central nervous system adverse effects and for this reason is the antiemetic of choice for patients with Parkinson’s disease. The MHRA reports a few cases of movement disorders related to domperidone, but the information given does not allow the clinician to determine which patient group is more likely to be affected.5 It is clear from the literature that a significant proportion of our patients are deficient in CYP2D6 and, therefore, poor metabolizers of drugs commonly prescribed in palliative care. Knowing that these patients are poor metabolizers may be helpful in determining why a patient has severe or unexpected adverse effects with certain drugs. This would not necessarily change our management, which in similar situations would be to review drugs, reduce dose, and rotate opioids as clinically indicated. It would mean, however, that one could predict more accurately the side effects of drugs known to be metabolized by this isoenzyme and that these drugs could either be avoided or be used more cautiously in clinical practice. Steven M. Simpson, M Pharm (Hons), Clin Dip, MRPharmS West Lancashire, Southport and Formby Primary Care Trusts United Kingdom Andrea Whitfield, MB ChB, MRCGP West Lancashire, Southport and Formby Palliative Care Services, Umbrella House Southport, United Kingdom doi:10.1016/j.jpainsymman.2007.01.002
References 1. Stockley IH. Stockley’s drug interactions, 6th ed. London: Pharmaceutical Press, 2002.
Letters
Vol. 33 No. 6 June 2007
2. Cupp MJ, Tracy TS. Cytochrome P450: new nomenclature and clinical implications. Am Fam Physician 1998;57(1):107e116. 3. Vandel P, Haffen E, Vandel S, et al. Drug extrapyramidal side effects. CYP2D6 genotypes and phenotypes. Eur J Clin Pharmacol 1999;55:659e665. 4. Cohen LJ, DeVane CL. Clinical implications of antidepressant pharmacokinetics and pharmacogenetics. Ann Pharmacother 1996;3:1471e1480. 5. Medicines Healthcare Regulatory Authority. Drug analysis prints: data on suspected adverse drug reactions. [online]. Available from http://www.mhra. gov.uk/home/. Accessed December 12, 2005.
Hidden Pain or Hidden Evidence? To the Editor: We read with interest Hølen et al.’s1 review of pain tools for use in palliative medicine, which concludes that none of the identified assessment tools covers all important dimensions of pain assessment adequately. There is a need to develop pain tools that are flexible, which can be used in different patient populations and situations. Surprisingly, perhaps, the review chose not to identify tools that are designed for use with those unable to communicate. And yet, this is an important group of palliative patients that includes those with advanced dementia, severe intellectual difficulties, end-stage amytrophic lateral sclerosis, severe mental health problems, children with progressive neurodegenerative disorders, and some patients with brain tumors. Several studies have demonstrated that pain is underrecognized and undertreated in those with advanced dementia;2,3 there is a need, therefore, to develop appropriate assessment tools. If communication and cognition are impaired, then the ability to complete self-report measures diminishes.4 Numerous behavioral assessment tools have been developed for people with these problems. Two recent reviews of behavioral assessment tools have been published,5,6 both of which highlighted deficiencies in the current scales in terms of reliability, validity, and clinical utility. The review by Herr et al.6 concludes that no nonverbal pain assessment tool could be recommended for broad adoption in clinical practice.
Vol. 33 No. 6 June 2007
In our view, the problems of using pain tools in such patients fall into four main areas:6 1) The experience of pain: Pain is a personal experience. How an individual behaves in response to a painful stimulus is unique; hence, a prescriptive behavioral pain tool may ignore important markers of distress. Work in people with severe intellectual disability has shown that they demonstrate a set pattern of distress cues that is unique to each individual.7 2) Pain cues: There is an absence of clear evidence that pain generates signs or behaviors exclusive to pain.8 A concern, therefore, is that pain tools used in people with severe communication difficulties may pick up other forms of distress such as fear, anger, embarrassment, or, indeed, signs of mental disorder. 3) Validity: As there is no gold standard for assessing pain in those unable to communicate, it is very difficult to establish validity. The claim that pain tools for people with dementia are valid may depend on pain being very common, so that a ‘‘pain’’ tool would correctly identify pain in many distress situations by chance. In addition, since certain analgesics can be sedating, the behaviors incorrectly labeled as pain may resolve because of side effects rather than treatment of the underlying cause. 4) Risk of poor analgesia: Any claim that morphine should be the first line for treating distress in someone with communication difficulty would be strongly, and rightly, criticized. And yet if a tool claiming to be a pain tool demonstrated a problem, the response would be an analgesic prescription. There is a risk, therefore, that if other causes of distress are incorrectly labeled as pain, this may lead to the inappropriate prescribing of analgesics. An alternative to attempting to identify pain alone is to identify distress and to be aware that pain is only one of its potential causes.7 With these issues in mind, a pilot study is being undertaken in a population of patients with advanced dementiadusing PAINAD9 (a behavioral pain assessment tool) and DisDAT7 (a distress assessment tool designed for those with learning difficulties that uses the patient’s
Letters
659
own distress cues to identify distress)dto assess pain and comment on the validity of the two assessment tools. Initial results suggest that prescriptive behavioral pain assessment tools will identify pain, but will also identify distress from other causes. Hence, simply identifying pain in those unable to communicate is enormously complex. Any attempt to develop a single pain assessment tool that could be used as an international standard in different palliative populations would run the risk of ignoring the needs of those unable to communicate.
Alice Isabel Jordan, MBBS, MRCP North Tyneside General Hospital North Shields, Tyne and Wear United Kingdom Claud Regnard, MB ChB, FRCP St. Oswald’s Hospice Newcastle City Hospitals NHS Trust and Northgate and Prudhoe NHS Trust Newcastle-upon-Tyne United Kingdom Julian C. Hughes, MA, MB ChB, MRCPsych, PhD North Tyneside General Hospital and the Institute for Ageing and Health, Newcastle University Newcastle-upon-Tyne United Kingdom doi:10.1016/j.jpainsymman.2007.02.026
References 1. Hølen JC, Hjermstad MJ, Loge JH, et al. Pain assessment tools: is the content appropriate for use in palliative care? J Pain Symptom Manage 2006;32(6): 567e580. 2. Ferrell BA, Ferrell BR, Osterweil D. Pain in the nursing home. J Am Geriatr Soc 1990;38: 409e414. 3. Feldt KS, Ryden MB, Miles S. Treatment of pain in cognitively impaired compared with cognitively intact older patients with hip fracture. J Am Geriatr Soc 1998;46:1079e1085. 4. Ferrell BA, Ferrell BR, Rivera L. Pain in cognitively impaired nursing home patients. J Pain Symptom Manage 1995;10:591e598. 5. Zwakhalen SMG, Hamer JPH, Abu-Saad HH, Berger MPF. Pain in elderly people with severe dementia: a systemic review of behavioural pain assessment tools. BMC Geriatrics 2006;6:3.
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6. Herr K, Bjoro K, Decker S. Tools for assessment of pain in nonverbal older adults with dementia: a state-of-the-science review. J Pain Symptom Manage 2006;31:170e192. 7. Regnard C, Reynolds J, Watson B, et al. Understanding distress in people with severe communication difficulties: developing and assessing the Disability Distress Assessment Tool (DisDAT). [published online] Sept 2006. Available from http:// dx.doi.org/10.1111/j.1365-2788.2006.00875.x. Accessed March 2001. 8. Regnard C, Mathews D, Gibson L, Clarke C. Difficulties in identifying distress and its causes in people with severe communication problems. Int J Palliat Nurs 2003;9:173e176. 9. Warden V, Hurley A, Volicer L. Development and psychometric evaluation of the Pain Assessment in Advanced Dementia (PAINAD) Scale. J Am Med Dir Assoc 2003;4:9e15.
Author’s Response
Letters
Vol. 33 No. 6 June 2007
literature on pain assessment in general, and in part because we aimed at making recommendations for which pain dimensions self-report tools should include. Assessment of pain by self-report differs from behavioral pain assessment. In behavioral assessments, pain is usually addressed as a unidimensional phenomenon (paineno pain, or degree of pain), while multidimensional approaches are recommended in self-report assessments.2 In our view, tools for self-report and for behavioral assessments are best reviewed in separate studies. Jacob Chr. Hølen, Cand Polit (Psychology) The Pain and Palliation Research Group Department of Cancer Research and Molecular Medicine The Norwegian University of Technology and Science Trondheim Norway doi:10.1016/j.jpainsymman.2007.04.001
To the Editor: We want to thank Jordan et al. for the constructive comments on our paper1 and for emphasizing the importance of valid pain assessment in those unable to communicate pain through self-report tools. The primary intention of our paper was to examine the content of the existing pain assessment tools for self-report, as stated in the paragraph on literature searches. The reason for applying this limitation was, in part, due to the vast
References 1. Holen JC, Hjermstad MJ, Loge JH, et al. Pain assessment tools: is the content appropriate for use in palliative care? J Pain Symptom Manage 2006;32(6): 567e580. 2. Caraceni A, Cherny N, Fainsinger R, et al. Pain measurement tools and methods in clinical research in palliative care: recommendations of an Expert Working Group of the European Association of Palliative Care. J Pain Symptom Manage 2002;23(3): 239e255.
also known to be implicated in the development of movement disorders. Oxycodone is metabolized in the liver by N- and O-demethylation to form noroxycodone and oxymorphone. The O-demethylation is catalyzed by CYP2D6. One postulated effect of incomplete metabolism of oxycodone would be drug accumulation and subsequent opioid toxicity (Napp Pharmaceuticals, personal communication, September 8, 2005). It is more difficult to implicate domperidone in this case, as theoretically it is a dopamine antagonist with limited penetration across the blood brain barrier. In contrast to metoclopramide, it rarely causes central nervous system adverse effects and for this reason is the antiemetic of choice for patients with Parkinson’s disease. The MHRA reports a few cases of movement disorders related to domperidone, but the information given does not allow the clinician to determine which patient group is more likely to be affected.5 It is clear from the literature that a significant proportion of our patients are deficient in CYP2D6 and, therefore, poor metabolizers of drugs commonly prescribed in palliative care. Knowing that these patients are poor metabolizers may be helpful in determining why a patient has severe or unexpected adverse effects with certain drugs. This would not necessarily change our management, which in similar situations would be to review drugs, reduce dose, and rotate opioids as clinically indicated. It would mean, however, that one could predict more accurately the side effects of drugs known to be metabolized by this isoenzyme and that these drugs could either be avoided or be used more cautiously in clinical practice. Steven M. Simpson, M Pharm (Hons), Clin Dip, MRPharmS West Lancashire, Southport and Formby Primary Care Trusts United Kingdom Andrea Whitfield, MB ChB, MRCGP West Lancashire, Southport and Formby Palliative Care Services, Umbrella House Southport, United Kingdom doi:10.1016/j.jpainsymman.2007.01.002
References 1. Stockley IH. Stockley’s drug interactions, 6th ed. London: Pharmaceutical Press, 2002.
Letters
Vol. 33 No. 6 June 2007
2. Cupp MJ, Tracy TS. Cytochrome P450: new nomenclature and clinical implications. Am Fam Physician 1998;57(1):107e116. 3. Vandel P, Haffen E, Vandel S, et al. Drug extrapyramidal side effects. CYP2D6 genotypes and phenotypes. Eur J Clin Pharmacol 1999;55:659e665. 4. Cohen LJ, DeVane CL. Clinical implications of antidepressant pharmacokinetics and pharmacogenetics. Ann Pharmacother 1996;3:1471e1480. 5. Medicines Healthcare Regulatory Authority. Drug analysis prints: data on suspected adverse drug reactions. [online]. Available from http://www.mhra. gov.uk/home/. Accessed December 12, 2005.
Hidden Pain or Hidden Evidence? To the Editor: We read with interest Hølen et al.’s1 review of pain tools for use in palliative medicine, which concludes that none of the identified assessment tools covers all important dimensions of pain assessment adequately. There is a need to develop pain tools that are flexible, which can be used in different patient populations and situations. Surprisingly, perhaps, the review chose not to identify tools that are designed for use with those unable to communicate. And yet, this is an important group of palliative patients that includes those with advanced dementia, severe intellectual difficulties, end-stage amytrophic lateral sclerosis, severe mental health problems, children with progressive neurodegenerative disorders, and some patients with brain tumors. Several studies have demonstrated that pain is underrecognized and undertreated in those with advanced dementia;2,3 there is a need, therefore, to develop appropriate assessment tools. If communication and cognition are impaired, then the ability to complete self-report measures diminishes.4 Numerous behavioral assessment tools have been developed for people with these problems. Two recent reviews of behavioral assessment tools have been published,5,6 both of which highlighted deficiencies in the current scales in terms of reliability, validity, and clinical utility. The review by Herr et al.6 concludes that no nonverbal pain assessment tool could be recommended for broad adoption in clinical practice.
Vol. 33 No. 6 June 2007
In our view, the problems of using pain tools in such patients fall into four main areas:6 1) The experience of pain: Pain is a personal experience. How an individual behaves in response to a painful stimulus is unique; hence, a prescriptive behavioral pain tool may ignore important markers of distress. Work in people with severe intellectual disability has shown that they demonstrate a set pattern of distress cues that is unique to each individual.7 2) Pain cues: There is an absence of clear evidence that pain generates signs or behaviors exclusive to pain.8 A concern, therefore, is that pain tools used in people with severe communication difficulties may pick up other forms of distress such as fear, anger, embarrassment, or, indeed, signs of mental disorder. 3) Validity: As there is no gold standard for assessing pain in those unable to communicate, it is very difficult to establish validity. The claim that pain tools for people with dementia are valid may depend on pain being very common, so that a ‘‘pain’’ tool would correctly identify pain in many distress situations by chance. In addition, since certain analgesics can be sedating, the behaviors incorrectly labeled as pain may resolve because of side effects rather than treatment of the underlying cause. 4) Risk of poor analgesia: Any claim that morphine should be the first line for treating distress in someone with communication difficulty would be strongly, and rightly, criticized. And yet if a tool claiming to be a pain tool demonstrated a problem, the response would be an analgesic prescription. There is a risk, therefore, that if other causes of distress are incorrectly labeled as pain, this may lead to the inappropriate prescribing of analgesics. An alternative to attempting to identify pain alone is to identify distress and to be aware that pain is only one of its potential causes.7 With these issues in mind, a pilot study is being undertaken in a population of patients with advanced dementiadusing PAINAD9 (a behavioral pain assessment tool) and DisDAT7 (a distress assessment tool designed for those with learning difficulties that uses the patient’s
Letters
659
own distress cues to identify distress)dto assess pain and comment on the validity of the two assessment tools. Initial results suggest that prescriptive behavioral pain assessment tools will identify pain, but will also identify distress from other causes. Hence, simply identifying pain in those unable to communicate is enormously complex. Any attempt to develop a single pain assessment tool that could be used as an international standard in different palliative populations would run the risk of ignoring the needs of those unable to communicate.
Alice Isabel Jordan, MBBS, MRCP North Tyneside General Hospital North Shields, Tyne and Wear United Kingdom Claud Regnard, MB ChB, FRCP St. Oswald’s Hospice Newcastle City Hospitals NHS Trust and Northgate and Prudhoe NHS Trust Newcastle-upon-Tyne United Kingdom Julian C. Hughes, MA, MB ChB, MRCPsych, PhD North Tyneside General Hospital and the Institute for Ageing and Health, Newcastle University Newcastle-upon-Tyne United Kingdom doi:10.1016/j.jpainsymman.2007.02.026
References 1. Hølen JC, Hjermstad MJ, Loge JH, et al. Pain assessment tools: is the content appropriate for use in palliative care? J Pain Symptom Manage 2006;32(6): 567e580. 2. Ferrell BA, Ferrell BR, Osterweil D. Pain in the nursing home. J Am Geriatr Soc 1990;38: 409e414. 3. Feldt KS, Ryden MB, Miles S. Treatment of pain in cognitively impaired compared with cognitively intact older patients with hip fracture. J Am Geriatr Soc 1998;46:1079e1085. 4. Ferrell BA, Ferrell BR, Rivera L. Pain in cognitively impaired nursing home patients. J Pain Symptom Manage 1995;10:591e598. 5. Zwakhalen SMG, Hamer JPH, Abu-Saad HH, Berger MPF. Pain in elderly people with severe dementia: a systemic review of behavioural pain assessment tools. BMC Geriatrics 2006;6:3.
660
6. Herr K, Bjoro K, Decker S. Tools for assessment of pain in nonverbal older adults with dementia: a state-of-the-science review. J Pain Symptom Manage 2006;31:170e192. 7. Regnard C, Reynolds J, Watson B, et al. Understanding distress in people with severe communication difficulties: developing and assessing the Disability Distress Assessment Tool (DisDAT). [published online] Sept 2006. Available from http:// dx.doi.org/10.1111/j.1365-2788.2006.00875.x. Accessed March 2001. 8. Regnard C, Mathews D, Gibson L, Clarke C. Difficulties in identifying distress and its causes in people with severe communication problems. Int J Palliat Nurs 2003;9:173e176. 9. Warden V, Hurley A, Volicer L. Development and psychometric evaluation of the Pain Assessment in Advanced Dementia (PAINAD) Scale. J Am Med Dir Assoc 2003;4:9e15.
Author’s Response
Letters
Vol. 33 No. 6 June 2007
literature on pain assessment in general, and in part because we aimed at making recommendations for which pain dimensions self-report tools should include. Assessment of pain by self-report differs from behavioral pain assessment. In behavioral assessments, pain is usually addressed as a unidimensional phenomenon (paineno pain, or degree of pain), while multidimensional approaches are recommended in self-report assessments.2 In our view, tools for self-report and for behavioral assessments are best reviewed in separate studies. Jacob Chr. Hølen, Cand Polit (Psychology) The Pain and Palliation Research Group Department of Cancer Research and Molecular Medicine The Norwegian University of Technology and Science Trondheim Norway doi:10.1016/j.jpainsymman.2007.04.001
To the Editor: We want to thank Jordan et al. for the constructive comments on our paper1 and for emphasizing the importance of valid pain assessment in those unable to communicate pain through self-report tools. The primary intention of our paper was to examine the content of the existing pain assessment tools for self-report, as stated in the paragraph on literature searches. The reason for applying this limitation was, in part, due to the vast
References 1. Holen JC, Hjermstad MJ, Loge JH, et al. Pain assessment tools: is the content appropriate for use in palliative care? J Pain Symptom Manage 2006;32(6): 567e580. 2. Caraceni A, Cherny N, Fainsinger R, et al. Pain measurement tools and methods in clinical research in palliative care: recommendations of an Expert Working Group of the European Association of Palliative Care. J Pain Symptom Manage 2002;23(3): 239e255.