Pain assessment in humans -- a reply to Hall

Dor no doente com câncer: características e controle

Este estudo objetivou compor o perfil da dor e do seu controle, além de verificar a influência de fatores terapêuticos na expressão do sintoma álgico em 57 doentes com doença neoplásica avançada, seqüencialmente atendidos no ambulatório de oncologia de um hospital geral. A dor foi moderada na maioria dos doentes e intensa em cerca de 1/5 dos casos, com duração média de 10 meses. Em 40,9 % das escolhas, observou-se preferência por 12 descritores do questionário de dor McGill. Descritores afetivos foram, significantemente, os mais escolhidos (p < 0,05). O alívio obtido foi insatisfatório, na maioria dos casos. O índice de controle da dor foi negativo em 49,1% dos doentes, isto é, em cerca de metade dos casos foram empregados analgésicos com potência inferior à exigida pela intensidade da dor. Não se observou correlação entre a intensidade da dor e a compatibilidade ou não dos esquemas analgésicos propostos ao padrão da OMS Constatou se que os doentes que fizeram uso dos analgésicos de modo regular, experienciaram dor de menor intensidade do que aqueles que só os utilizaram quando a dor se acentuava (p <0,05). Observou-se que a irregularidade na utilização dos fármacos associou-se a dores mais intensas.

Beyond Pain Scales: A Critical Phenomenology of the Expression of Pain

In this paper, we discuss the qualitative dimension of painful experiences by exploring the role of imagination and metaphorical association in the conceptualization and expression of pain. We employ an engaged critical-phenomenological approach to offer original analysis influenced by the perspectives of people in pain. The paper is organized into three parts. Part 1 reviews literature on the expression of pain, its communication, and its reception-attending in particular to the emphasis on verbalizing pain in healthcare contexts. We here discuss benefits and limitations of standard methods aimed at facilitating the meaningful expression of pain (such as "pain scales") from the perspectives of patients and practitioners, respectively. We suggest that these methods might be importantly complemented by facilitating creative expression of painful lived experiences with respect to personal lifeworlds. Part 2 deals with the role of imagination and metaphorical association in making sense of pain. We explore how imagination is a cognitive and affective mode of experiencing the world which plays a crucial role in determining how pain is experienced, as well as helping to make sense of pain figuratively in relation to the lifeworld. In Part 3, we draw from principles of engaged phenomenology to foreground case studies in which projects have been able facilitate the intersubjective expression of pain. These examples demonstrate the value of attending to the contours of painful lifeworlds in their specificity, affording both agency and accessibility in their communication, while remaining mindful of the complex power relations which govern perceived legitimacy and testimony relating to the transformation of pain. The overall paper aims to contribute to literature on qualitative pain research on both theoretical and practical levels. By exploring the expression of pain through phenomenology, we aim to enrich current debate on the qualitative experience of pain. We also seek to critically highlight the socio-political dimensions which frame painful experiences, their expression, their lived significance, and their treatment.

A Prospective Multicenter Clinical Performance Evaluation of the C-CGM System

BACKGROUND

Continuous glucose monitors (CGMs) have had a significant impact on the management of diabetes mellitus. We present the results of a multinational evaluation of the Cascade CGM ("C-CGM") over 14 days of in-clinic and home use.

METHOD

Each of the 57 enrolled type 1 diabetes mellitus and type 2 diabetes mellitus subjects wore 2 C-CGMs on the abdomen for 14 days. One part of the evaluation was the performance versus reference glucose values generated for 12 -hour in-clinic sessions on days 1, 4, 7, 10, and 14. Glucose blood samples were drawn every 15 minutes and analyzed with the Yellow Spring Instruments (YSI) 2300 glucose analyzer. The performance assessment on in-clinic days was based on paired YSI/CGM data points and on home-use days was based on paired fingerstick BGM (blood glucose monitoring)/CGM data points.

RESULTS

A total of 17 823 CGM/YSI data points during in-clinic use was analyzed. The mean absolute relative difference for glucose values between 100 and 400 mg/dL (MARD) and mean absolute difference for values between 40 and 100 mg/dL (MAD) were 11.5% and 15.1 mg/dL, respectively. The system accuracy during home use was 12.7% and 15 mg/dL for MARD and MAD, respectively. There were no serious adverse events or infectious complications reported. A modified algorithm "Hybrid Algorithm" was used in a prospective analysis of the in-clinic data, resulting in a MARD of 9.9% and MAD of 14.5 mg/dL.

CONCLUSIONS

The performance of the C-CGM device over 14 days meets the safety and efficacy standards of CGM systems for managing blood glucose levels in people with diabetes. This was further confirmed when the C-CGM system was given approval for CE Mark in October 2019.

Evaluation of low back pain: comparative study between psychophysical methods

OBJECTIVE

The aims of this study were to validate the measurement of low back pain by different psychophysical methods and to compare different methods of pain measurement.

METHODS

This double-blind, randomized experimental study was realized in Brazil. The sample was 60 patients with low back pain, divided into two groups: group I (methylprednisolone 80 mg + 8 mL of 0.9% saline solution) and group II (methylprednisolone 80 mg + 5 mL of levobupivacaine without epinephrine + 3 mL of 0.9% saline solution), both using 10-mL syringes. The methods were the serial exploration and psychophysical (magnitude estimation, category estimation, and cross-modality matching).

RESULTS

Pain evaluation was carried out before the block and 30 minutes, 6, 12, and 24 hours after it. After 30 minutes of epidural block, the levobupivacaine group presented more significant reaction of reduction pain than the saline group. The magnitude and line-length scales were evaluated every period of time, showing no significant differences, except in 12 and 24 hours after the first block. The exponential function to every evaluation ranged from 0.87 to 1.00.

CONCLUSION

This research tries to bring to health care an original method for measuring low back pain. It is noteworthy that in the future, more research is needed to apply this method in clinical and scientific fields.

Frequency and use of pain assessment tools implemented in randomized controlled trials in the adult burns population: a systematic review

INTRODUCTION

Pain continues to be an ongoing issue of concern in adult burn patients. Inadequate pain assessment hinders meaningful research, and prevents the optimal management of burn pain. The objective of this study was to examine the content of existing research in burn pain with the frequency and context of pain assessment tool use in randomized clinical trials in order to further inform their use for future researchers and clinicians.

METHODS

Electronic searches of MEDLINE, CINAHL, EMBASE and The Cochrane Library databases from 1966 onwards were used to identify English articles related to clinical trials utilising pain assessment in adult burns patients.

RESULTS

The systematic literature search identified 25 randomized clinical trials utilising pain assessment tools. Unidimensional pain assessment tools were most frequently used pain assessment tools, with multidimensional tools used less often, despite the multifaceted and complex nature of burn pain.

CONCLUSION

The review highlights the lack of consistency of pain assessment tool use in randomized clinical trials with respect to managing burn pain. We recommend a broader but consistent use of multidimensional pain assessment tools for researchers undertaking clinical trials in this field. The review supports the need for an international expert consensus to identify the necessary critical outcomes and domains for clinicians and researchers undertaking further research into burn pain.

Avaliação psicofísica da percepção de dor

Dor é uma experiência pessoal e subjetiva influenciada por fatores culturais, situacionais, atentivos e outras variáveis psicológicas. Abordagens para a mensuração de dor incluem variados instrumentos, tais como, escalas verbais, numéricas, observacionais, questionários, autorregistros e respostas fisiológicas. Nesta revisão, descrevemos e analisamos como as sofisticadas técnicas psicofísicas podem ser designadas para mensurar separadamente as dimensões sensoriais e afetivas da percepção de dor. Destacamos que estas técnicas produzem mensurações válidas e fidedignas da percepção de dor, com propriedades de escalonamento de razão e, também, podem ser usadas, facilmente, em ambientes clínicos.

Validation of the ratio scale of the differents types of pain

The main aim was to validate the ratio scale derived from the non-metric continuum of the intensity of the different types of pain using cross-modality matching. Magnitude estimation method and cross-modality matching were used with perceived line lengths. The study was formed by 30 outpatients from various specialty clinics, 30 physicians and 90 nurses. The results were: Cancer Pain, Myocardium Infarct Pain, Renal Colic, Burn Injury Pain, and Childbirth Labor Pain were regarded as the pains of greater intensity; the rank order of pain intensity for the different types of pain, comparing the different psychophysical methods used resulted in levels of significant agreement. The conclusion was that the relation between the magnitude estimates and cross modality matching estimates of the line-lengths is a power function, and the scale for the different types of pain is valid, stable and consistent.

Pain measurement in humans

Sound measurement, an essential component of any scientific discipline, remains a particular problem in pain research. The measurement of pain intensity, for example, is a difficult and often a subjective undertaking. This is of little surprise to clinicians and researchers, because it is well recognised that pain intensity, like other sensations and perceptions, is a private experience that displays considerable variability both across patients and within a patient across time. Nonetheless, pain measurement and discerning factors that may affect its measurement are important for diagnosis and to determine the effectiveness of treatment interventions. This article reviews the basic concepts, roles, instruments used, and factors affecting pain measurement. A variety of the most commonly used pain measurement instruments are evaluated for their advantages and disadvantages. The article aims to assist clinicians and researchers to select the pain measurement instruments that best serve their purposes.

The measurement of pain, 1945-2000

Three strands of activity can be identified in the history of pain measurement. The first, psychophysics, dates back to the nineteenth century and measures the effect of analgesia by quantifying the noxious stimulation required to elicit pain, as well as the maximum stimulation tolerated. The second uses standardized questionnaires for patients, developed to categorize pain according to its emotional impact, distribution, character, and other dimensions. The third asks patients to report on pain intensity using rating scales, and is used in clinical trials where analgesics are evaluated and results can be combined to influence clinical guidelines and protocols. Although all three strands have found a place in modern clinical practice or drug development, it is the reporting of pain by patients undergoing treatment using simple scales of intensity which has emerged as the crucial method by which analgesic therapies can now be evaluated and compared.

The pain visual analog scale: is it linear or nonlinear?

The visual analog scale (VAS) is a tool widely used to measure pain, yet controversy surrounds whether the VAS score is ratio or ordinal data. We studied 52 postoperative patients and measured their pain intensity using the VAS. We then asked them to consider different amounts of pain (conceptually twice as much and then half as much) and asked them to repeat their VAS rating after each consideration (VAS2 and VAS3, respectively). Patients with unrelieved pain had their pain treated with IV fentanyl and were then asked to rate their pain intensity when they considered they had half as much pain. We compared the baseline VAS (VAS1) with VAS2 and VAS3. The mean (95% confidence interval) for VAS2:1 was 2.12 (1.81-2.43) and VAS3:1 was 0.45 (0.38-0.52). We conclude that the VAS is linear for mild-to-moderate pain, and the VAS score can be treated as ratio data.

IMPLICATIONS

A change in the visual analog scale score represents a relative change in the magnitude of pain sensation. Use of the VAS in comparative analgesic trials can now meaningfully quantify differences in potency and efficacy.

Measurement of pain

Pain is a personal, subjective experience influenced by cultural learning, the meaning of the situation, attention, and other psychologic variables. Approaches to the measurement of pain include verbal and numeric self-rating scales, behavioral observation scales, and physiologic responses. The complex nature of the experience of pain suggests that measurements from these domains may not always show high concordance. Because pain is subjective, patients' self-reports provide the most valid measure of the experience. The VAS and the MPQ are probably the most frequently used self-rating instruments for the measurement of pain in clinical and research settings. The MPQ is designed to assess the multidimensional nature of pain experience and has been demonstrated to be a reliable, valid, and consistent measurement tool. A short-form MPQ is available for use in specific research settings when the time to obtain information from patients is limited and when more information than simply the intensity of pain is desired. The DDS was developed using sophisticated psychophysical techniques and was designed to measure separately the sensory and unpleasantness dimensions of pain. It has been shown to be a valid and reliable measurement of pain with ratio-scaling properties and has recently been used in a clinical setting. Behavioral approaches to the measurement of pain also provide valuable data. Further development and refinement of pain measurement techniques will lead to increasingly accurate tools with greater predictive powers.

[Evaluation of postoperative pain]

Pain is a subjective feeling; its assessment is therefore difficult, and no "gold standard" method exists for humans. Major improvements have, however, been made in the last decade by widespread acceptation of the concept of pain evaluation and widespread use on surgical wards. Evaluation by the patient himself is the rule (unless communication is impaired), as assessment of pain by nurses or doctors systematically leads to underestimation (which also occurs with observational scales). Theoretically, pain should be evaluated in its multiple dimensions such as intensity, location, emotional consequences and semiologic correlates. Scales which have been developed to evaluate these dimensions are, however, too complex for widespread and repetitive use in surgical patients. The Mac Gill Pain Questionnaire is therefore only used in the surgical setting for research purposes. Moreover, its scientific accuracy, although often accepted, is poor and in our opinion cannot be accepted as a reference method. Only methods assessing pain intensity can be used in the clinical setting because of their simplicity. The verbal rating scale (VRS), the numerical rating scale (NRS) and the visual analogue scale (VAS) are preferred by an increasing number of groups. Although scientific validation is difficult, VAS seems the most accurate and reproducible scale. Post-operative pain should be assessed several times a day in every patient, at rest and in dynamic conditions (cough, movement) and should focus on present pain rather than on pain in the previous hours. Assessment of pain is essential before quality-assurance programmes can be implemented.

A call for standardizing the clinical rating of pain intensity using a 0 to 10 rating scale

Pain is difficult to measure, regardless of etiology. Furthermore, the measurement of pain is complicated by variation in the use of visual analogue scales as well as other pain assessment measures. This brief article reviews situations contributing to confusion regarding pain intensity measures and argues for consistency in its measurements with adults not experiencing cognitive disorders in the clinical setting.

A visual analogue thermometer for measuring pain intensity

A new instrument for measuring pain intensity--the visual analogue thermometer (VAT)--was developed to overcome limitations and disadvantages of the conventional visual analogue scale (VAS). Two studies were performed to assess the validity and utility of the VAT as compared to conventional pain instruments whose psychometric qualities are scientifically recognized. The first study was carried out with a group of 65 chronic pain patients who provided pain intensity ratings using the VAT, a standard VAS, and the McGill Pain Questionnaire. A second set of measures was obtained from a group of 243 adult healthy volunteers who quantified the intensity of a set of descriptive pain terms with the VAT, a numerical scale (NUM), and a VAS. The results of both studies support the concurrent validity of the VAT as a pain measure. When assessing changes in pain levels, the VAT was able to distinguish between different pain intensities, confirming the construct validity of the instrument. No major difference emerged in the relative sensitivity of the VAT compared to the standard VAS, both scales yielding comparable pain estimates. In contrast, the NUM scale tended to produce higher pain ratings. Regardless of the pain scale used, the results showed unequal differences between descriptive pain terms that are commonly considered equidistant on an ordinal scale. No major problem was noticed in subjects' understanding or using either the VAT, VAS, or NUM scales. When questioned about pain scale preference, a substantial number of participants preferred the VAT to the standard VAS as a means of rating pain intensity. In view of the results obtained in the present studies, it is concluded that the VAT is a valid accurate, and clinically useful tool for measuring pain. Its design makes it suitable and effective for clinical use and as an outcome measure in clinical trials.

The Descriptor Differential Scale of Pain Intensity: an evaluation of item and scale properties

Improved methods for pain measurement have both theoretical and clinical importance. This study evaluated the Descriptor Differential Scale (DDS) of Pain Intensity, a recent methodology designed for assessing pain reports in clinical samples. Experiment 1 evaluated the sensitivity of the measure to small changes in electrocutaneous stimulation relative to a traditional visual analogue scale (VAS) of pain intensity. Additionally, direct psychophysical scaling methods were employed to determine ratio-scale values for the DDS sensory items in relation to the electrocutaneous stimuli. This ratio scale was cross-validated by comparison with previously published ratio-scaled data from cross-modality matching pain intensity judgement studies. Experiment 2 evaluated the performance of the measure in both experimental and clinical pain samples, as well as the similarity of item-response patterns in each of these samples. Results indicate that the DDS of Pain Intensity is sensitive to small changes in electrocutaneous stimulation, has consistent ratio-scale properties across two different psychophysical methods, and demonstrates similar item-response patterns across divergent experimental and clinical samples. The results support the validity of the sensory DDS as a measure of pain intensity.

A comparison of pain measurement characteristics of mechanical visual analogue and simple numerical rating scales

Numerical rating scales and mechanical visual analogue scales (M-VAS) were compared for their capacity to provide ratio scale measures of experimental pain. Separate estimates of experimental pain sensation intensity and pain unpleasantness were obtained by each method, as were estimates of clinical pain. Orofacial pain patients made numerical scale and VAS ratings in response to noxious thermal stimuli (45-51 degrees C) applied for 5 sec to the forearm by a contact thermode. The derived stimulus-response function was well fit as a power function only in the case of sensory M-VAS. The power function derived from sensory M-VAS ratings predicted temperatures chosen as twice as intense as standard temperatures of 47 degrees C and 48 degrees C, thereby providing evidence for ratio scale characteristics of M-VAS. The stimulus-response function derived from sensory numerical ratings differed from that obtained with M-VAS and did not provide accurate predictions of temperatures perceived as twice intense at 47 degrees C or 48 degrees C. Both M-VAS and numerical rating scales produced reliably different stimulus response functions for pain sensation intensity as compared to pain unpleasantness and both provided consistent measures of experimental and clinical pain intensity. Finally, both mechanical and pencil-and-paper VAS produced very similar stimulus-response functions. The ratio scale properties of M-VAS combined with its ease of administration and scoring in clinical settings offer the possibility of a simple yet powerful pain measurement technology in both research and health care settings.

Pain and fatigue in patients with rheumatic disorders

The purpose of the study was to investigate whether fibromyalgia patients (n = 50) differed from patients with rheumatoid arthritis (n = 22) and ankylosing sponylitis (n = 31) with respect to pain experience, pain coping and fatigue. A high general pain intensity level was recorded by the McGill Pain Questionnaire (p < 0.01) and the visual analogue scale (p < 0.01) in the fibromyalgia group compared to the other groups. The pain was of continuous duration in the fibromyalgia patients while the rheumatoid arthritis and ankylosing spondylitis patients experienced intermittent pain. A high correlation between sensory and affective pain rating indexes was determined in all patient groups (p < 0.01). No statistically significant difference between the groups in pain coping was recorded. A high frequency of reported gastrointestinal problems (p < 0.01) and high intensity of fatigue (p < 0.01) were seen in the fibromyalgia group compared to the other groups. In the fibromyalgia group there was no correlation between the sleep problems and fatigue intensity. Thus, the fibromyalgia patients differed from the other groups in reporting frequently shoulder and upper arm pain, continuous pain, higher levels of fatigue and pain intensities as well as high frequency of gastrointestinal problems.

Childbirth in Kuwait: the experiences of three groups of Arab mothers

The aims of the present study were to characterize the childbirth experiences of three groups of Arab mothers delivering in Kuwait and to evaluate the use of visual analog scales (VAS) for assessing their pain (N = 301). Kuwaiti, Palestinian, and Bedouin women who were expected to have an uncomplicated vaginal delivery were studied. 73% of the women described their maximum labor pain as "unbearably painful," and more than one-half reported that they were "very frightened" or "terrified." The deliveries of Bedouin mothers were remarkable for the absence of pain behaviors; yet their VAS reports indicated that they experienced no less pain. Painful menstruation and fear of childbirth emerged as risk factors for a painful labor. Among the issues discussed are the validity of the VAS data, the difficulties of managing Bedouin mothers' pain, and the importance of excluding physical factors before cultural differences in pain perception are assumed.

[Measurement of pain.]

The aim of this study was to evaluate a new modified visual analog scale, called the dolorimeter, together with a verbal rating scale (VRS) and a linear visual scale (VAS), in the measurement of acute postoperative pain. The scales were evaluated with reference to their sensitivity, reliability and validity, and correlation. During the study 200 patients 11-70 years of age (125 men, 75 women) were interviewed after orthopedic surgery to ascertain the intensity of the pain. We had the patients judge the intensity of pain before and 1 h after giving analgesics by using the dolorimeter, VRS, and VAS. At the end of the examination, we asked the patients whether the pain had decreased or not which method they preferred, and why they preferred this method. The results of this interrogation proved that the sensitivity of the VRS is low; its parameters overlap greatly on the analog, scale, and it is therefore too rough to be a sufficient measurement of pain. On the other hand, the high sensitivity of the two analog scales which patients can use to determine their individual pain intensity proved to be much more sensitive. All three methods correlated statistically; the highest correlation coefficients were found between the analog scales VAS and the dolorimeter. Because the dolorimeter is clearly preferred to the other methods, especially by elderly patients, we came to the conclusion that the dolorimeter is less abstract than the VAS and more practical to handle.

Reliability and validity of verbal descriptor scales of painfulness

Previous studies have provided information about the reliability and validity of verbal descriptor scales of sensory intensity and unpleasantness and have shown that these two dimensions can be differentially affected by pharmacological manipulations. Since the relation between these dimensions and the general term 'pain' is not known, two experiments developed a verbal descriptor scale of painfulness and compared the sensitivity of this scale to pharmacological manipulations used previously with scales of sensory intensity and unpleasantness. In exp. I, 20 subjects used cross-modality matching to both handgrip force and tone duration to quantify the amount of pain implied by verbal descriptor phrases such as 'slightly painful,' 'somewhat painful' and 'very painful.' Ratio scales of relative magnitude for each individual were highly correlated within subjects (mean r = 0.92) and between a scale from each individual and a combined scale from others in the group (mean r = 0.93). These correlations indicate agreement between individual scales; an individual's scale values were predicted equally well by that individual or by a group of similar persons. In exp. II, 4 groups of 10 subjects rated the magnitude of painful tooth pulp sensations by choosing pain descriptors from randomized lists. Seven electrical stimuli spaced between individually determined pain threshold and tolerance values were delivered in random sequence 6 times before and after double-blind intravenous infusions of placebo, 0.11 mg/kg diazepam, 0.66 microgram/kg fentanyl or a combination of the diazepam and fentanyl doses. Mean responses were reduced significantly after all active drugs but not after placebo. These results suggest that the term pain does not represent a simple combination of sensory intensity and/or unpleasantness and shows that the sensitivity to an inert placebo, an active placebo, and an analgesic can vary with the type of pain assessment procedure.

Pain measurement: an overview

The practice and theoretical basis of pain measurement is reviewed and critically examined in the areas of animal research, human subjects laboratory investigation and clinical study. The advantages and limitations of both physiological and behavioral methods are discussed in each area, and subjective report procedures are evaluated in human laboratory and clinical areas. The need for procedures that bridge these areas is emphasized and specific issues are identified. Progress in the technology of pain measurement over recent decades is reviewed and directions for future work are suggested.

The validation of visual analogue scales as ratio scale measures for chronic and experimental pain

Visual analogue scales (VAS) of sensory intensity and affective magnitude were validated as ratio scale measures for both chronic and experimental pain. Chronic pain patients and healthy volunteers made VAS sensory and affective responses to 6 noxious thermal stimuli (43, 45, 47, 48, 49 and 51 degrees C) applied for 5 sec to the forearm by a contact thermode. Sensory VAS and affective VAS responses to these temperatures yielded power functions with exponents 2.1 and 3.8, respectively; these functions were similar for pain patients and for volunteers. The power functions were predictive of estimated ratios of sensation or affect produced by pairs of standard temperatures (e.g. 47 and 49 degrees C), thereby providing direct evidence for ratio scaling properties of VAS. Vas sensory intensity responses to experimental pain, VAS sensory intensity responses to different levels of chronic pain, and direct temperature (experimental pain) matches to 3 levels of chronic pain were all internally consistent, thereby demonstrating the valid use of VAS for the measurement of and comparison between chronic pain and experimental heat pain.

Pain measurement and experience

Issues and developments in clinical pain assessment will be considered. The focus will be on measuring pain, rather than degree of relief. Three main response channels may be distinguished: subjective, behavioral and physiological, although the latter will not be elaborated upon here. The measurement of subjective report of pain, although an anathema to behaviorists, continues to be one of the most widely used measures. Recent developments in assessing verbal report, of the form of questionnaires and ratings derived from psychophysical scaling methods, will be reviewed. Although behavioral indices at first sight lend themselves to well-established methods of measurement, issues in establishing rather than assuming the reliability and validity of such measures will be considered. Parallel monitoring across response channels, as well as attending to questions concerning the psychometric adequacy of measures employed, will both further our understanding of pain mechanisms and provide sound indications as to treatment efficacy.