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Chronic widespread pain and interference with functioning
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PAIN 152 (2011) 2449–2450
www.elsevier.com/locate/pain
Commentary
Chronic widespread pain and interference with functioning To what degree functional ability is impaired in patients with a chronic painful condition is an important question, but assessment of impairment is not straightforward. Because it is difficult to measure objectively, functional ability has usually been measured subjectively, using questionnaires. In this issue of Pain, Amris and colleagues have risen to the challenge of using objective tools. They present an observation-based assessment of functional ability in 257 women with chronic widespread pain (CWP), 199 of whom fulfilled criteria for fibromyalgia [1]. They used the Assessment of Motor and Process Skills (AMPS), an evaluation of the ability to perform activities of daily living (ADL), specified as motor and process skill ability. AMPS has already been employed in psychiatric, neurological and geriatric patients, as well as in a small study (n = 50) of patients with CWP [10]. With their new, larger study Amris and colleagues have shown that AMPS is a promising addition to the tools available to assess patients with chronic pain. Amris et al. found that the interference with ADL experienced by women with CWP was substantial. Analyses were performed based on average data and on more clinically relevant cut-off levels for effortless and independent ADL task performance: 97% of participants achieved scores below the ADL motor cut-off and 42% below the ADL process cut-off. Only 1 in 20 had both ADL motor and ADL process ability scores comparable with age norms. In fact, the degree of interference with functional ability seen in women with CWP was comparable to that seen in patients with other severe conditions, including stroke, rheumatoid arthritis, depression, and heart failure. Amris and colleagues illustrate this point by providing an overview of the literature. Determining the magnitude of functional ability impairment in patients with a chronic painful condition is difficult not only with regard to measuring functional ability but also because the problem is wider in scope than the question how pain interferes with functional ability. Complicating factors are chronicity of the disease and between-patient heterogeneity. Chronicity of the disease means that adaptation has to be considered, though this is clearly more relevant for some aspects of functioning than others. The study presented by Amris et al. is valuable because the authors investigated activities of daily living familiar and relevant to individual patients. Study participants chose at least two of 85 standardised ADL tasks that were relevant to their daily life; an occupational therapist observed and rated motor and process skills. This approach takes account of one aspect of between-patient variability, but significant inter-individual heterogeneity also exists regarding symptomatology and response to treatment. Patients with CWP or fibromyalgia can experience a range of symptoms in addition to pain, to varying degrees and with varying impact on their lives. The study by Amris et al. illustrates this point. The authors observed a wide range in AMPS motor and process skill scores
within the study population. In fact, individual variability with regard to disease manifestation and treatment response is increasingly being described and recognised as important in the pain field [4,5]. What precisely underlies this variability is unclear. Conditions such as CWP or fibromyalgia are likely not homogeneous with regard to their pathophysiology but rather may represent a mixture of disease entities. This heterogeneity, of course, may explain why any particular treatment for fibromyalgia only works well in a minority of patients [2,7,9]. Of course, the molecular basis of the disease(s) is not at all clear. Nevertheless, realising that there is substantial between-patient heterogeneity can be very helpful in current clinical practice and for planning future research. The issue of how functional ability is impaired in patients with a chronic painful condition can be analysed in terms of the various factors that interfere with functioning. Interference with functioning, whether it relates to basic tasks such as ADL or a more complex domain of life such as work, does not occur directly as a result of a particular diagnosis. Rather, interference with functioning occurs because of symptoms. These may be symptoms of the disease, symptoms associated with its treatment (side effects of medications), or ‘background’ symptoms [3] that may or may not be associated with a particular diagnosis. The study highlights the need for more detailed investigations into functional ability in patients with chronic pain in general, and with methods. The study compared patient-reported functional ability (based on a number of questionnaires) and observationbased AMPS; the weak-to-moderate correlation between the two indicates that assessments based on questionnaires and observation probably measure different aspects of functioning. We have shown that substantial pain reduction parallels improvements in other outcomes, including functional ability (as assessed from questionnaire data). Patients with fibromyalgia who experience pain reduction with treatment also benefit in other areas – physical and social functioning, fatigue, sleep, depression, anxiety, missed workdays, and interference with work; those without meaningful pain reduction do not share these benefits [6,8]. Observation-based assessments of functional ability would be a valuable addition to questionnaire-based assessments in future pain trials, but the findings should be reported in the context of the level of pain relief. Interference with functioning is wider than interference with ADL. The patients with CWP studied by Amris and colleagues also experienced significant interference with work and reported on average more than one workday lost per week, which is comparable to patients with fibromyalgia in clinical trials [6]. In a world where cost-effectiveness of therapy trumps efficacy alone, and where cost-effectiveness is determined by quality of life and work improvements, measurement and understanding of the interaction between pain and functional ability needs to be centre-stage.
0304-3959/$36.00 Ó 2011 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved. doi:10.1016/j.pain.2011.06.013
2450
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Commentary / PAIN 152 (2011) 2449–2450
Conflict of interest statement The authors declare that they have no conflicts of interest. References [1] Amris K, Wæhrens EE, Jespersen A, Bliddal H, Danneskiold-Samsøe B. Observation-based assessment of functional ability in patients with chronic widespread pain: A cross sectional study. Pain 2011;152:2470–6. [2] Bennett RM, Kamin M, Karim R, Rosenthal N. Tramadol and acetaminophen combination tablets in the treatment of fibromyalgia pain: a double-blind, randomized, placebo-controlled study. Am J Med 2003;114:537–45. [3] McAteer A, Elliott AM, Hannaford PC. Ascertaining the size of the symptom iceberg in a UK-wide community-based survey. Br J Gen Pract 2011;61: e1–e11. [4] Moore RA, Edwards JE, McQuay HJ. Acute pain: individual patient metaanalysis shows the impact of different ways of analysing and presenting results. Pain 2005;116:322–31. [5] Moore RA, Straube S, Derry S, McQuay H. Does this work for you? Individuals, averages, and evidence based medicine. BMJ 2008;337:a2585. [6] Moore RA, Straube S, Paine J, Phillips CJ, Derry S, McQuay HJ. Fibromyalgia: moderate and substantial pain intensity reduction predicts improvement in other outcomes and substantial quality of life gain. Pain 2010;149:360–4. [7] Straube S, Derry S, Moore RA, McQuay HJ. Pregabalin in fibromyalgia: metaanalysis of efficacy and safety from company clinical trial reports. Rheumatology (Oxford) 2010;49:706–15.
[8] Straube S, Moore RA, Paine J, Derry S, Phillips CJ, Hallier E, McQuay HJ. Interference with work in fibromyalgia – effect of treatment with pregabalin and relation to pain response. BMC Musculoskelet Disord 2011;12:125. [9] Sultan A, Gaskell H, Derry S, Moore RA. Duloxetine for painful diabetic neuropathy and fibromyalgia pain: systematic review of randomised trials. BMC Neurol 2008;8:29. [10] Waehrens EE, Amris K, Fisher AG. Performance-based assessment of activities of daily living (ADL) ability among women with chronic widespread pain. Pain 2010;150:535–41.
Sebastian Straube Department of Occupational, Social and Environmental Medicine, University Medical Center Göttingen, Waldweg 37 B, D-37073 Göttingen, Germany Tel.: +49 551 398044; fax: +49 551 396184. E-mail address: [email protected] Sheena Derry R. Andrew Moore Pain Research, Nuffield Division of Anaesthetics, Nuffield Department of Clinical Neurosciences, University of Oxford, Churchill Hospital, Oxford, UK
PAIN 152 (2011) 2449–2450
www.elsevier.com/locate/pain
Commentary
Chronic widespread pain and interference with functioning To what degree functional ability is impaired in patients with a chronic painful condition is an important question, but assessment of impairment is not straightforward. Because it is difficult to measure objectively, functional ability has usually been measured subjectively, using questionnaires. In this issue of Pain, Amris and colleagues have risen to the challenge of using objective tools. They present an observation-based assessment of functional ability in 257 women with chronic widespread pain (CWP), 199 of whom fulfilled criteria for fibromyalgia [1]. They used the Assessment of Motor and Process Skills (AMPS), an evaluation of the ability to perform activities of daily living (ADL), specified as motor and process skill ability. AMPS has already been employed in psychiatric, neurological and geriatric patients, as well as in a small study (n = 50) of patients with CWP [10]. With their new, larger study Amris and colleagues have shown that AMPS is a promising addition to the tools available to assess patients with chronic pain. Amris et al. found that the interference with ADL experienced by women with CWP was substantial. Analyses were performed based on average data and on more clinically relevant cut-off levels for effortless and independent ADL task performance: 97% of participants achieved scores below the ADL motor cut-off and 42% below the ADL process cut-off. Only 1 in 20 had both ADL motor and ADL process ability scores comparable with age norms. In fact, the degree of interference with functional ability seen in women with CWP was comparable to that seen in patients with other severe conditions, including stroke, rheumatoid arthritis, depression, and heart failure. Amris and colleagues illustrate this point by providing an overview of the literature. Determining the magnitude of functional ability impairment in patients with a chronic painful condition is difficult not only with regard to measuring functional ability but also because the problem is wider in scope than the question how pain interferes with functional ability. Complicating factors are chronicity of the disease and between-patient heterogeneity. Chronicity of the disease means that adaptation has to be considered, though this is clearly more relevant for some aspects of functioning than others. The study presented by Amris et al. is valuable because the authors investigated activities of daily living familiar and relevant to individual patients. Study participants chose at least two of 85 standardised ADL tasks that were relevant to their daily life; an occupational therapist observed and rated motor and process skills. This approach takes account of one aspect of between-patient variability, but significant inter-individual heterogeneity also exists regarding symptomatology and response to treatment. Patients with CWP or fibromyalgia can experience a range of symptoms in addition to pain, to varying degrees and with varying impact on their lives. The study by Amris et al. illustrates this point. The authors observed a wide range in AMPS motor and process skill scores
within the study population. In fact, individual variability with regard to disease manifestation and treatment response is increasingly being described and recognised as important in the pain field [4,5]. What precisely underlies this variability is unclear. Conditions such as CWP or fibromyalgia are likely not homogeneous with regard to their pathophysiology but rather may represent a mixture of disease entities. This heterogeneity, of course, may explain why any particular treatment for fibromyalgia only works well in a minority of patients [2,7,9]. Of course, the molecular basis of the disease(s) is not at all clear. Nevertheless, realising that there is substantial between-patient heterogeneity can be very helpful in current clinical practice and for planning future research. The issue of how functional ability is impaired in patients with a chronic painful condition can be analysed in terms of the various factors that interfere with functioning. Interference with functioning, whether it relates to basic tasks such as ADL or a more complex domain of life such as work, does not occur directly as a result of a particular diagnosis. Rather, interference with functioning occurs because of symptoms. These may be symptoms of the disease, symptoms associated with its treatment (side effects of medications), or ‘background’ symptoms [3] that may or may not be associated with a particular diagnosis. The study highlights the need for more detailed investigations into functional ability in patients with chronic pain in general, and with methods. The study compared patient-reported functional ability (based on a number of questionnaires) and observationbased AMPS; the weak-to-moderate correlation between the two indicates that assessments based on questionnaires and observation probably measure different aspects of functioning. We have shown that substantial pain reduction parallels improvements in other outcomes, including functional ability (as assessed from questionnaire data). Patients with fibromyalgia who experience pain reduction with treatment also benefit in other areas – physical and social functioning, fatigue, sleep, depression, anxiety, missed workdays, and interference with work; those without meaningful pain reduction do not share these benefits [6,8]. Observation-based assessments of functional ability would be a valuable addition to questionnaire-based assessments in future pain trials, but the findings should be reported in the context of the level of pain relief. Interference with functioning is wider than interference with ADL. The patients with CWP studied by Amris and colleagues also experienced significant interference with work and reported on average more than one workday lost per week, which is comparable to patients with fibromyalgia in clinical trials [6]. In a world where cost-effectiveness of therapy trumps efficacy alone, and where cost-effectiveness is determined by quality of life and work improvements, measurement and understanding of the interaction between pain and functional ability needs to be centre-stage.
0304-3959/$36.00 Ó 2011 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved. doi:10.1016/j.pain.2011.06.013
2450
Ò
Commentary / PAIN 152 (2011) 2449–2450
Conflict of interest statement The authors declare that they have no conflicts of interest. References [1] Amris K, Wæhrens EE, Jespersen A, Bliddal H, Danneskiold-Samsøe B. Observation-based assessment of functional ability in patients with chronic widespread pain: A cross sectional study. Pain 2011;152:2470–6. [2] Bennett RM, Kamin M, Karim R, Rosenthal N. Tramadol and acetaminophen combination tablets in the treatment of fibromyalgia pain: a double-blind, randomized, placebo-controlled study. Am J Med 2003;114:537–45. [3] McAteer A, Elliott AM, Hannaford PC. Ascertaining the size of the symptom iceberg in a UK-wide community-based survey. Br J Gen Pract 2011;61: e1–e11. [4] Moore RA, Edwards JE, McQuay HJ. Acute pain: individual patient metaanalysis shows the impact of different ways of analysing and presenting results. Pain 2005;116:322–31. [5] Moore RA, Straube S, Derry S, McQuay H. Does this work for you? Individuals, averages, and evidence based medicine. BMJ 2008;337:a2585. [6] Moore RA, Straube S, Paine J, Phillips CJ, Derry S, McQuay HJ. Fibromyalgia: moderate and substantial pain intensity reduction predicts improvement in other outcomes and substantial quality of life gain. Pain 2010;149:360–4. [7] Straube S, Derry S, Moore RA, McQuay HJ. Pregabalin in fibromyalgia: metaanalysis of efficacy and safety from company clinical trial reports. Rheumatology (Oxford) 2010;49:706–15.
[8] Straube S, Moore RA, Paine J, Derry S, Phillips CJ, Hallier E, McQuay HJ. Interference with work in fibromyalgia – effect of treatment with pregabalin and relation to pain response. BMC Musculoskelet Disord 2011;12:125. [9] Sultan A, Gaskell H, Derry S, Moore RA. Duloxetine for painful diabetic neuropathy and fibromyalgia pain: systematic review of randomised trials. BMC Neurol 2008;8:29. [10] Waehrens EE, Amris K, Fisher AG. Performance-based assessment of activities of daily living (ADL) ability among women with chronic widespread pain. Pain 2010;150:535–41.
Sebastian Straube Department of Occupational, Social and Environmental Medicine, University Medical Center Göttingen, Waldweg 37 B, D-37073 Göttingen, Germany Tel.: +49 551 398044; fax: +49 551 396184. E-mail address: [email protected] Sheena Derry R. Andrew Moore Pain Research, Nuffield Division of Anaesthetics, Nuffield Department of Clinical Neurosciences, University of Oxford, Churchill Hospital, Oxford, UK