The influence of a manipulation of threat on experimentally-induced secondary hyperalgesia

Pain is thought to be influenced by the threat value of the particular context in which it occurs. However, the mechanisms by which a threat achieves this influence on pain are unclear. Here, we explore how threat influences experimentally-induced secondary hyperalgesia, which is thought to be a manifestation of central sensitization. We developed an experimental study to investigate the effect of a manipulation of threat on experimentally-induced secondary hyperalgesia in 26 healthy human adults (16 identifying as female; 10 as male). We induced secondary hyperalgesia at both forearms using high-frequency electrical stimulation. Prior to the induction, we used a previously successful method to manipulate threat of tissue damage at one forearm (threat site). The effect of the threat manipulation was determined by comparing participant-rated anxiety, perceived threat, and pain during the experimental induction of secondary hyperalgesia, between the threat and control sites. We hypothesized that the threat site would show greater secondary hyperalgesia (primary outcome) and greater surface area (secondary outcome) of induced secondary hyperalgesia than the control site. Despite a thorough piloting procedure to test the threat manipulation, our data showed no main effect of site on pain, anxiety, or threat ratings during high-frequency electrical stimulation. In the light of no difference in threat between sites, the primary and secondary hypotheses cannot be tested. We discuss reasons why we were unable to replicate the efficacy of this established threat manipulation in our sample, including: (1) competition between threats, (2) generalization of learned threat value, (3) safety cues, (4) trust, and requirements for participant safety, (5) sampling bias, (6) sample-specific habituation to threat, and (7) implausibility of (sham) skin examination and report. Better strategies to manipulate threat are required for further research on the mechanisms by which threat influences pain.

Freeze-like responses to pain in humans and its modulation by social context

Background

Maladaptive defensive responses such as excessive avoidance behavior have received increasing attention as a main mechanism for the development and maintenance of chronic pain complaints. However, another defensive response which is commonly studied in animals as a proxy for fear is freezing behavior. No research to date has investigated human freezing behavior in the context of pain. In addition, there is an increasing realization that social context can affect pain-relevant processes such as pain experience and pain behavior but less is known about the effects of social context on defensive responses to pain. Hence, this study investigated freezing behavior and facial pain expression in the context of pain, and their modulation by social context.

Methods

Healthy, pain-free participants (N = 39) stood on a stabilometric force platform in a threatening or safe social context, which was manipulated using angry or happy facial stimuli. In some trials, an auditory cue (conditioned stimulus; CS) predicted the occurrence of painful electrocutaneous stimulus (unconditioned stimulus; pain-US). We assessed body sway (an index of freezing), heart rate, facial pain expression, self-reported pain intensity, unpleasantness, and pain-US expectancy during the CS and the context alone (no CS).

Results

The results were mixed. Neither the anticipation of pain, nor social context affected body sway. Heart rate and painful facial expression were reduced in the threatening social context at high anxiety levels. A threatening social context also elicited higher pain-US expectancy ratings. In sum, a threatening social context increases the expectation of pain, but reduces the facial expression of pain and lowers heart rate in highly anxious individuals.

The effect of differential spatiotopic information on the acquisition and generalization of fear of movement-related pain

Fear of movement-related pain significantly contributes to musculoskeletal chronic pain disability. Previous research has shown that fear of movement-related pain can be classically conditioned. That is, in a differential fear conditioning paradigm, after (repeatedly) pairing a neutral joystick movement (conditioned stimulus; CS+) with a painful stimulus (unconditioned stimulus; pain-US), that movement in itself starts to elicit self-reported fear and elevated psychophysiological arousal compared to a control joystick movement (CS−) that was never paired with pain. Further, it has been demonstrated that novel movements that are more similar to the original CS+ elicit more fear than novel movements that are more similar to the CS−, an adaptive process referred to as stimulus generalization. By default, movement/action takes place in reference to the three-dimensional space: a movement thus not only involves proprioceptive information, but it also contains spatiotopic information. Therefore, the aim of this study was to investigate to what extent spatiotopic information (i.e., endpoint location of movement) contributes to the acquisition and generalization of such fear of movement-related pain besides proprioception (i.e., movement direction). In a between-subjects design, the location group performed joystick movements from the middle position to left and right; the movement group moved the joystick from left and right to the middle. One movement (CS+) was paired with pain, another not (CS−). Feature overlap between CSs typically reduces differential learning. The endpoint of both CSs in the movement group is an overlapping feature whereas in the location group the endpoint of both CSs is distinct; therefore we hypothesized that there would be less differential fear learning in the movement group compared to the location group. We also tested generalization to movements with similar proprioceptive features but different endpoint location. Following the principle of stimulus generalization, we expected that novel movements in the same direction as the CS+ but with a different endpoint would elicit more fear than novel movement in the same direction of the CS− but with a different endpoint. Main outcome variables were self-reported fear and pain-US expectancy and eyeblink startle responses (electromyographic). Corroborating the feature overlap hypothesis, the location group showed greater differential fear acquisition. Fear generalization emerged for both groups in the verbal ratings, suggesting that fear indeed accrued to proprioceptive CS features; these effects, however, were not replicated in the startle measures.

Anxiety Sensitivity and Fear of Pain in Children

Associations among scores on scales of anxiety sensitivity and trait anxiety and a fear of pain questionnaire were examined for 118 children. Analysis showed that anxiety sensitivity was positively and substantially related to fear of pain in the children. Furthermore, the data suggested anxiety sensitivity to be a better predictor of fear of pain than trait anxiety.

Role of fear of movement in cancer survivors participating in a rehabilitation program: a longitudinal cohort study

OBJECTIVE

To study the relationship between fear of movement and perceived global health status and the role of rehabilitation with graded activity in cancer survivors.

DESIGN

Longitudinal cohort study.

SETTING

Rehabilitation centers.

PARTICIPANTS

Cancer survivors (N=1236).

INTERVENTION

Twelve-week graded activity rehabilitation program.

MAIN OUTCOME MEASURES

Fear of movement (Modified Tampa Scale for Kinesiophobia-Fatigue), fatigue (Functional Assessment of Cancer Therapy-Fatigue), and perceived global health status (European Organisation Research and Treatment of Cancer Quality of Life Questionnaire C30) were measured at baseline and after rehabilitation. We performed multiple linear regression analyses to examine the association between fear of movement and perceived global health status at baseline. Differences between baseline and postintervention scores were assessed with a paired t test and effect sizes (ESs). Hierarchical multiple regression analyses were used to investigate whether changes in fear of movement were associated with perceived global health status.

RESULTS

Fear of movement was associated with perceived global health status prior to rehabilitation (P=.001). Only participants with high scores on baseline fear of movement showed a considerable decrease in fear of movement after rehabilitation (ES=-.69; 95% confidence interval [CI], -.80 to -.57); the reduction was largest for fears because of a somatic focus (ES=-.57; 95% CI, -.68 to -.45). Changes in fear of movement because of a somatic focus were related to perceived global health status postintervention (P=.001).

CONCLUSIONS

Fear of movement is associated with the perceived global health status of cancer survivors. Fear of movement decreases after rehabilitation with graded activity in high scorers on baseline fear of movement.

Pain-Related Factors Contributing to Muscle Inhibition in Patients With Chronic Low Back Pain

OBJECTIVE

To evaluate muscle strength, as a component of physical deconditioning, and central activation ratio, representing the performance level during testing, in patients with chronic low back pain as compared to healthy controls, and to evaluate the contribution of cognitive-behavioral and pain-related factors to the central activation ration of patients with chronic low back pain.

METHODS

Twenty-five patients with chronic low back pain and 25 age and gender-matched controls participated. Muscle strength, that is, peak torque of the quadriceps muscle, was measured on a Cybex dynamometer. During peak torque, the quadriceps muscle was percutaneously stimulated using superimposed electrical stimulation, generating an additional twitch torque in case of submaximal performance. The central activation ratio was calculated as peak torque/(peak torque + additional twitch torque). To evaluate cognitive-behavioral and pain-related factors influencing the central activation ratio, measures of fear of injury, pain catastrophizing, psychologic distress, and pain intensity were used. Differences between groups were tested using either T tests or Mann-Whitney U tests. Associations were tested by partial correlation coefficients controlling for gender.

RESULTS

The male:female ratio was 15:10. Mean age and chronic low back pain duration were 42.7 (+/-9.5) and 9.9 (+/-8.3) years, respectively. Mean muscle torque (per kg lean body mass) in patients (1.95 Nm/kg +/-0.8) was less than in controls (3.16 Nm/kg +/-0.7) (P < 0.01). Median central activation ratio was lower in patients (P < 0.05). Patients experiencing increased psychologic distress and patients with a higher current pain level showed a lower central activation ratio (P < 0.05).

CONCLUSIONS

When interpreting decreased muscle strength in terms of physical deconditioning in patients with chronic low back pain, submaximal performance has to be taken into account. The results suggest that patients with chronic low back pain who report increased psychologic distress and a higher level of current pain tend to show increased inhibition of muscle activity, leading to submaximal performance.

Psychometric Evaluation of the Pain Anxiety Symptoms Scale (PASS) in Chronic Pain Patients

This study examined psychometric properties of the Pain Anxiety Symptoms Scale (PASS), a measure of pain-related fear. A recently developed shortened version of the PASS, the PASS-20, was also investigated. Previously reported factor structures of the PASS were tested by means of confirmatory factor analysis. Results indicated that all models fitted adequately but that a five-factor solution fitted slightly better compared to the other models tested. The four-factor solution of the PASS-20 was tested by means of confirmatory factor analysis and results indicated adequate fit. Moreover, the four-factor solution of the PASS-20 was invariant among fibromyalgia and low-back pain patients. Convergent validity of the original PASS and the PASS-20 was good and internal consistency reliability adequate to excellent. The suitability of the original PASS and the PASS-20 are discussed and directions for future research are provided.

Fear of injury and physical deconditioning in patients with chronic low back pain

OBJECTIVES

To test the assumption that fear of injury leads to disability and physical deconditioning in patients with chronic low back pain (CLBP) and to evaluate the relation between disability and physical deconditioning.

DESIGN

Survey in a cross-sectional design.

SETTING

A rehabilitation center in the Netherlands.

PARTICIPANTS

Forty patients with nonspecific CLBP.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Fear of injury was measured with the Tampa Scale of Kinesiophobia. Physical fitness was expressed in aerobic fitness measured as predicted maximum oxygen consumption derived in a submaximal exercise test according the protocol of Siconolfi. Disability was measured with the Roland Disability Questionnaire. The association between fear of injury and physical fitness or disability was examined with correlational and multiple linear regression analyses.

RESULTS

Fear of injury correlated significantly with disability (r=.44), but did not correlate significantly with aerobic fitness. There was no statistically significant association between disability and aerobic fitness. Multiple regression analysis revealed that aerobic fitness was predicted by gender only.

CONCLUSIONS

Fear of injury appears to be more strongly associated with perceived disability than with aerobic fitness. The assumption that fear of injury leads to physical deconditioning was not confirmed in this sample of patients with CLBP.

Disuse and deconditioning in chronic low back pain: concepts and hypotheses on contributing mechanisms

For years enhancement of a patient's level of physical fitness has been an important goal in rehabilitation treatment in chronic low back pain (CLBP), based on the hypothesis that physical deconditioning contributes to the chronicity of low back pain. However, whether this hypothesis in CLBP holds is not clear. In this paper, possible mechanisms that contribute to the development of physical deconditioning in CLBP, such as avoidance behaviour and suppressive behaviour, are discussed. The presence of both deconditioning-related physiological changes, such as muscle atrophy, changes in metabolism, osteoporosis and obesity as well as deconditioning related functional changes, such as a decrease in cardiovascular capacity, a decrease in muscle strength and impaired motor control in patients with CLBP are discussed. Results of studies on the level of physical activities in daily life (PAL) and the level of physical fitness in patients with CLBP compared to healthy controls were reviewed. In studies on PAL results that were either lower or comparable to healthy subjects were found. The presence of disuse (i.e., a decrease in the level of physical activities in daily life) in patients with CLBP was not confirmed. The inconclusive findings in the papers reviewed may partly be explained by different measurement methods used in research on PAL in chronic pain. The level of physical fitness of CLBP patients also appeared to be lower or comparable to the fitness level of healthy persons. A discriminating factor between fit and unfit patients with back pain may be the fact that fit persons more frequently are still employed, and as such may be involved more in physical activity. Lastly some suggestions are made for further research in the field of disuse and deconditioning in CLBP.

Pain catastrophizing predicts pain intensity, disability, and psychological distress independent of the level of physical impairment

OBJECTIVE

The aim of the current study was to examine the relation between catastrophizing and pain intensity, pain-related disability, and psychological distress in a group of patients with chronic pain, controlling for the level of physical impairment. Furthermore, it was examined whether these relations are the same for three subgroups of chronic pain patients: those with chronic low back pain, those with chronic musculoskeletal pain other than low back pain, and those with miscellaneous chronic pain complaints, low back pain and musculoskeletal pain excluded.

DESIGN

Correlational, cross-sectional.

PATIENTS AND SETTING

Participants in this study were 211 consecutive referrals presenting to a university hospital pain management and research center, all of whom had a chronic pain problem.

RESULTS

Overall, chronic pain patients who catastrophize reported more pain intensity, felt more disabled by their pain problem, and experienced more psychological distress. Regression analyses revealed that catastrophizing was a potent predictor of pain intensity, disability, and psychological distress, even when controlled for physical impairment. No fundamental differences between the three subgroups were found in this respect. Finally, it was demonstrated that there was no relation between physical impairment and catastrophizing.

CONCLUSIONS

It was concluded that for different subgroups of chronic pain patients, catastrophizing plays a crucial role in the chronic pain experience, significantly contributing to the variance of pain intensity, pain-related disability, and psychological distress. These relations are not confounded by the level of physical impairment. Some clinical implications of the results are discussed. Finally, the authors concluded that these results support the validity of a cognitive-behavioral conceptualization of chronic pain-related disability.

Physical activity in daily life in patients with chronic low back pain

OBJECTIVES

To evaluate disuse (ie, a decreased daily physical activity level) in patients with chronic low back pain (LBP) and to evaluate the construct validity of accelerometry for measuring physical activity in daily life.

DESIGN

Case-control study in a cross-sectional design; comparison of accelerometry to the criterion standard (doubly labeled water technique).

SETTING

Normal daily living (unrestricted by the measurement devices).

PATIENTS

Thirteen patients with chronic nonspecific LBP and 13 age- and gender-matched healthy controls.

MAIN OUTCOME MEASURES

Physical activity in daily life, expressed as whole-body acceleration measured with a triaxial accelerometer (Tracmor), and as the ratio between average daily metabolic rate (ADMR), measured by the doubly labeled water technique, and resting metabolic rate (RMR), measured by the ventilated hood. Both techniques were used simultaneously for 14 days.

RESULTS

Mean physical activity level in patients and controls did not differ significantly. The correlation between the Tracmor and ADMR and RMR was .72 (p < .01).

CONCLUSIONS

Decreased physical activity levels in this sample of chronic LBP patients was not confirmed. The Tracmor is a valid instrument for measuring daily activity in LBP patients.

The effects of failure feedback and pain-related fear on pain report, pain tolerance, and pain avoidance in chronic low back pain patients

The aim of this study was to investigate the influence of non-pain-related failure experiences and pain-related fear on pain report, pain tolerance and pain avoidance in chronic low back pain (CLBP) patients. Moreover, the mediating and moderating role of negative affectivity (trait-NA) in the relationship between failure experiences and pain was examined. Seventy-six patients were divided into high and low pain-related fear groups and within each group they were randomly assigned to the failure or success feedback condition. In the first part of the study patients completed a 'social empathy test' and experimenter 1 subsequently delivered false failure or success feedback. A second experimenter, who was blind for the condition, subsequently administered two lifting tasks in order to obtain measures of pain report, tolerance and avoidance. Failure feedback did have an effect on pain avoidance but unexpectedly, and not as hypothesized, pain avoidance was reduced instead of enhanced. With regard to pain report and pain tolerance similar patterns were found, but these were not statistically significant. The effect of failure feedback on pain avoidance was moderated by trait-NA. Only in the subgroup of patients who scored low on trait-NA did failure feedback decrease pain avoidance. State-NA did not mediate the effects of feedback. In line with previous findings, pain-related fear resulted in lower pain tolerance. Moreover, this study was the first to show that pain-related fear predicted higher pain report in CLBP patients. Pain-related fear did not predict pain avoidance when pre-lifting pain and gender were controlled for. Finally, pre-lifting pain turned out to be the strongest predictor with regard to all pain measures. The role of pain-related fear and unexpected findings with regard to feedback are discussed as well as some clinical implications.

Does failure hurt? The effects of failure feedback on pain report, pain tolerance and pain avoidance

In this study an experiment was conducted to examine whether failure experiences have an effect on pain report, pain tolerance and pain avoidance. Furthermore, it was investigated if negative affectivity (NA) affected the impact of failure feedback on pain report, either as a mediator, in the case of negative state affect, or as a moderator when NA as a personality trait was considered. Fifty-four healthy female volunteers were included and randomly assigned to one of three conditions: (1) failure feedback; (2) success feedback; (3) neutral control task. After the manipulation, subjects were given a cold pressor task in order to obtain pain measures. Regarding the effects of failure feedback on pain report, it was found that, in comparison with success feedback, failure feedback led to increased pain report. With regard to pain tolerance, pain was tolerated for longer when preceded by success feedback than when preceded by failure feedback. Differences between failure and control conditions did not reach significance. With regard to pain avoidance, no differences between the conditions were found. The hypothesized mediating role of negative state affect was not found. Though in the hypothesized direction, no significant effect was found for NA-trait moderating the influence of failure on pain. The discussion focuses on a number of research questions that remain to be answered, and the clinical relevance of the effects of failure and success experiences on pain report and pain tolerance.

Graded exposure in vivo in the treatment of pain-related fear: a replicated single-case experimental design in four patients with chronic low back pain

The aim of this investigation was to examine the effectiveness of a graded exposure in vivo treatment with behavioural experiments as compared to usual graded activity in reducing pain-related fears, catastrophising and pain disability in chronic low back pain patients reporting substantial fear of movement/(re)injury. Included in the study were four consecutive CLBP patients who were referred for outpatient behavioural rehabilitation, and who reported substantial fear of movement/(re)injury (Tampa Scale for Kinesiophobia score>40). A replicated single-case cross-over design was used. After a no-treatment baseline measurement period, the patients were randomly assigned to one of two interventions. In intervention A, patients received the exposure first, followed by graded activity. In intervention B, the sequence of treatment modules was reversed. Sixty-three daily measures of pain-related cognitions and fears were recorded with visual analogue scales. Before and after the treatment, the following measures were taken: pain-related fear, pain catastrophising, pain control and pain disability. Using time series analysis on the daily measures of pain-related cognitions and fears, we found that improvements only occurred during the graded exposure in vivo, and not during the graded activity, irrespective of the treatment order. Analysis of the pre-post treatment differences also revealed that decreases in pain-related fear concurred with decreases in pain catastrophising and pain disability, and in half of the cases an increase in pain control. This study shows that the external validity of exposure in vivo also extends to the subgroup of chronic low back pain patients who report substantial fear of movement/(re)injury.

Readiness to adopt the self-management approach to cope with chronic pain in fibromyalgic patients

The effectiveness of cognitive-behavior therapy aimed at helping patients with the acquisition of self-management skills to cope with pain, is thought to depend partly on the patients' willingness to adopt a self-management approach. Some patients may not believe that self-management will be helpful while others have decided to adopt it and others already apply the self-management skills in their daily lives. The present study explored the concept of 'Readiness to change' in a population of Dutch fibromyalgic patients. A self-report questionnaire was completed by 321 patients. Factor analysis revealed three scales, each assessing the characteristic of one stage of readiness to change, the Precontemplation, Contemplation and Action scale. Firstly, the reliabilities of these scales were 0.61, 0.86 and 0.61, respectively, and only the latter two scales correlated significantly (r=0.14). Secondly, the scales were validated using subscales from the Multidimensional Pain Inventory, beliefs on the credibility of the self-management approach and subscales from the Illness Perception Questionnaire. These subscales explained 5, 22 and 8% of the variance of the scores on the Precontemplation, Contemplation and the Action scales, respectively. Thirdly, on the basis of the three scale scores, over 80% of the fibromialgia patients could be classified into one of five potentially psychological relevant subgroups: Precontemplation, Contemplation, Preparation, Action and Relapse. The data suggest that improvements in operationalizations of the Precontemplation and Action dimensions of readiness to change are needed and that the theoretical foundation of readiness to change needs further development.

Behavioral treatment for chronic low back pain: a systematic review within the framework of the Cochrane Back Review Group

STUDY DESIGN

A systematic review of randomized controlled trials.

SUMMARY OF BACKGROUND DATA

The treatment of chronic low back pain is not primarily focused on removing an underlying organic disease but at the reduction of disability through the modification of environmental contingencies and cognitive processes. Behavioral interventions are commonly used in the treatment of chronic (disabling) low back pain.

OBJECTIVES

To determine whether behavioral therapy is more effective than reference treatments for chronic nonspecific low back pain and which type of behavioral treatment is most effective.

METHODS

The authors searched the Medline and PsychLit databases and the Cochrane Controlled Trials Register up to April 1999, and Embase up to September 1999. Also screened were references of identified randomized trials and relevant systematic reviews. Methodologic quality assessment and data extraction were performed independently by two reviewers. The magnitude of effect was assessed by computing a pooled effect size for each domain (i.e., behavioral outcomes, overall improvement, back pain-specific and generic functional status, return to work, and pain intensity) using the random effects model.

RESULTS

Only six (25%) studies were high quality. There is strong evidence (level 1) that behavioral treatment has a moderate positive effect on pain intensity (pooled effect size 0.62; 95% confidence interval [CI] 0.25, 0.98), and small positive effects on generic functional status (pooled effect size 0.35; 95% CI: -0.04, 0.74) and behavioral outcomes (pooled effect size 0.40; 95% CI: 0.10, 0.70) of patients with chronic low back pain when compared with waiting-list controls or no treatment. There is moderate evidence (level 2) that a addition of behavioral component to a usual treatment program for chronic low backpain has no positive short-term effect on generic functional status (pooled effect size 0.31; 95% CI: -0.01, 0.64), pain intensity (pooled effect size 0.03; 95% CI:-0.30, 0.36), and behavioral outcomes (pooled effect size 0.19; 95% CI: -0.08, 0.45).

CONCLUSIONS

Behavioral treatment seems to be an effective treatment for patients with chronic low back pain,but it is still unknown what type of patients benefit most from what type of behavioral treatment.

Behavioral treatment for chronic low back pain: a systematic review within the framework of the Cochrane Back Review Group

STUDY DESIGN

A systematic review of randomized controlled trials.

SUMMARY OF BACKGROUND DATA

The treatment of chronic low back pain is not primarily focused on removing an underlying organic disease but at the reduction of disability through the modification of environmental contingencies and cognitive processes. Behavioral interventions are commonly used in the treatment of chronic (disabling) low back pain.

OBJECTIVES

To determine whether behavioral therapy is more effective than reference treatments for chronic nonspecific low back pain and which type of behavioral treatment is most effective.

METHODS

The authors searched the Medline and PsychLit databases and the Cochrane Controlled Trials Register up to April 1999, and Embase up to September 1999. Also screened were references of identified randomized trials and relevant systematic reviews. Methodologic quality assessment and data extraction were performed independently by two reviewers. The magnitude of effect was assessed by computing a pooled effect size for each domain (i.e., behavioral outcomes, overall improvement, back pain-specific and generic functional status, return to work, and pain intensity) using the random effects model.

RESULTS

Only six (25%) studies were high quality. There is strong evidence (level 1) that behavioral treatment has a moderate positive effect on pain intensity (pooled effect size 0.62; 95% confidence interval [CI] 0. 25, 0.98), and small positive effects on generic functional status (pooled effect size 0.35; 95% CI: 0.04, 0.74) and behavioral outcomes (pooled effect size 0.40; 95% CI: 0.10, 0.70) of patients with chronic low back pain when compared with waiting-list controls or no treatment. There is moderate evidence (level 2) that a addition of behavioral component to a usual treatment program for chronic low backpain has no positive short-term effect on generic functional status (pooled effect size 0.31; 95% CI: 0.01, 0.64), pain intensity (pooled effect size 0.03; 95% CI: 0.30,0.36), and behavioral outcomes (pooled effect size 0.19; 95% CI: 0.08, 0.45).

CONCLUSIONS

Behavioral treatment seems to be an effective treatment for patients with chronic low back pain,but it is still unknown what type of patients benefit most from what type of behavioral treatment.

The cost diary: a method to measure direct and indirect costs in cost-effectiveness research

From a societal perspective long-term clinical trials or follow-up studies should preferably not only include an evaluation of the health effect for the patient, but also an economic evaluation. In order to yield comprehensive medical and nonmedical resource use data, we at least partly depend on respondents' recall for collecting these costing data. A patient cost diary was developed in order to estimate total resource use, expenses, and lost production due to illness and treatment. We applied the cost diary in two randomized clinical trials evaluating the cost-effectiveness of behavioral rehabilitation in 205 fibromyalgia and chronic low back pain patients. The use of the diary was evaluated, studying the feasibility, the influence of the period of data collection on the results, and some aspects of validity. Eighty-five percent of the patients completed at least one diary and in total 68% of the diaries were returned. Although the results for the three alternative periods of data collection (keeping the diary 1 week every month, 2 weeks every 2 months, or a full year) were not significantly different, they were only moderately correlated. Finally, self-reported specialist care contacts were generally in agreement with data from an insurance company. However, for physiotherapy contacts there were differences between the self-reported and insurance data. This study shows how the cost diary might be used successfully in cost-effectiveness studies.

Behavioral-graded activity compared with usual care after first-time disk surgery: considerations of the design of a randomized clinical trial

OBJECTIVE

To present the design of a trial on the effectiveness of a behavioral-graded activity model.

DESIGN

Randomized clinical trial.

PATIENTS

Patients undergoing first-time lumbar disk surgery who still have low-back pain at the 6-week neurosurgical consultation.

INTERVENTIONS

A patient-tailored behavioral-graded activity program that is based on operant therapy. The key elements of this program are baseline measurements, goal-setting, and time-contingency. This program is compared with usual care in physiotherapy, which is pain-contingent.

OUTCOME MEASURES

Primary measures are the patient's global impression of the effect and their functional status. Secondary measures are kinesiophobia, catastrophizing, pain, main complaint, range of motion, and relapses. The direct and indirect costs will also be assessed. The effect measures are rated before randomization and 3, 6, and 12 months later.

DISCUSSION

Several trials have been conducted on the effectiveness of behavioral treatments. Subjects were always patients with chronic low-back pain. In this trial, we apply such a treatment in patients after first-time disk surgery in a primary care setting.

Chronic low-back pain: what does cognitive coping skills training add to operant behavioral treatment? Results of a randomized clinical trial

This study examined the supplemental value of a cognitive coping skills training when added to an operant-behavioral treatment for chronic low-back pain patients. The complete treatment package (OPCO) was compared with an operant program + group discussion (OPDI) and a waiting-list control (WLC). After the WL period, the WLC patients received a less protocolized operant program usually provided in Dutch rehabilitation centers (OPUS). Regression analyses showed that, compared with WLC, both OPCO and OPDI led to less negative affect, higher activity tolerance, less pain behavior, and higher pain coping and pain control. At posttreatment, OPCO led to better pain coping and pain control than OPDI. Calculation of improvement rates revealed that OPCO and OPDI had significantly more improved patients than OPUS on all the dependent variables. The discussion includes findings regarding treatment credibility, compliance, and contamination bias.

Behavioural treatment for chronic low back pain

BACKGROUND

The treatment of chronic low back pain is not primarily focused on removing an underlying organic pathology, but at the reduction of disability through the modification of environmental contingencies and cognitive processes. Behavioural interventions are commonly used in the treatment of chronic (disabling) low back pain.

OBJECTIVES

The objective of this systematic review was to determine if behavioural therapy is more effective than reference treatments for chronic non-specific low back pain, and which type of behavioural treatment is most effective.

SEARCH STRATEGY

We searched the Medline, PsycLit databases, and the Cochrane Controlled Trials Register up to April 1999, Embase up to September 1999. We also screened references of identified randomised trials and relevant systematic reviews.

SELECTION CRITERIA

Only randomised trials on any type of behavioural treatment for non-specific chronic low back pain were included.

DATA COLLECTION AND ANALYSIS

Methodological quality assessment and data extraction was done by two reviewers independently. The magnitude of effect was assessed by computing a pooled effect size for each domain (i.e., behavioural outcomes, overall improvement, back pain specific and generic functional status, return to work, and pain intensity) using the random effects model.

MAIN RESULTS

Only 6 studies (25%) were high quality. There is strong evidence (level 1) that behavioural treatment has a moderate positive effect on pain intensity (pooled effect size 0.62; 95% CI 0.25, 0.98), and small positive effects on generic functional status (pooled effect size 0.35; 95% CI -0.04, 0.74) and behavioural outcomes (pooled effect size 0.40; 95% CI 0.10, 0.70) of chronic low back pain patients when compared to waiting list controls or no treatment. There is moderate evidence (level 2) that an additional behavioural component to a usual treatment program for chronic low back pain has no positive short-term effect on generic functional status (pooled effect size 0.31; 95% CI - 0.01, 0.64), pain intensity (pooled effect size 0.03; 95% CI - 0.30, 0. 36) and behavioural outcomes (pooled effect size 0.19; 95% CI - 0.08, 0.45).

REVIEWER'S CONCLUSIONS

Behavioural treatment seems to be an effective treatment for chronic low back pain patients, but it is still unknown what type of patients benefit most from what type of behavioural treatment.

Chronic low-back pain: what does cognitive coping skills training add to operant behavioral treatment? Results of a randomized clinical trial

This study examined the supplemental value of a cognitive coping skills training when added to an operant-behavioral treatment for chronic low-back pain patients. The complete treatment package (OPCO) was compared with an operant program + group discussion (OPDI) and a waiting-list control (WLC). After the WL period, the WLC patients received a less protocolized operant program usually provided in Dutch rehabilitation centers (OPUS). Regression analyses showed that, compared with WLC, both OPCO and OPDI led to less negative affect, higher activity tolerance, less pain behavior, and higher pain coping and pain control. At posttreatment, OPCO led to better pain coping and pain control than OPDI. Calculation of improvement rates revealed that OPCO and OPDI had significantly more improved patients than OPUS on all the dependent variables. The discussion includes findings regarding treatment credibility, compliance, and contamination bias.

Fear of movement/(re)injury, avoidance and pain disability in chronic low back pain patients

Chronic pain syndromes such as chronic low back pain are responsible for enormous costs for health care and society. For these conditions a pure biomedical approach often proves insufficient. Numerous studies have shown that there is little direct relationship between pain and disability and suggest that the biopsychosocial approach offers the foundations for a better insight in how pain can become a persistent problem. The main assumption is that pain and pain disability are not only influenced by organic pathology, if found, but also by psychological and social factors. In this contribution, a behavioural analysis of chronic musculoskeletal pain will be discussed, with special attention to the role of pain-related fear in the development and maintenance of chronic pain disability, and the behavioural rehabilitation perspective of chronic pain management.

Effect of butorphanol tartrate on shock-related discomfort during internal atrial defibrillation

BACKGROUND

In patients with atrial fibrillation, intracardiac atrial defibrillation causes discomfort. An easily applicable, short-acting analgesic and anxiolytic drug would increase acceptability of this new treatment mode.

METHODS AND RESULTS

In a double-blind, placebo-controlled manner, the effect of intranasal butorphanol, an opioid, was evaluated in 47 patients with the use of a step-up internal atrial defibrillation protocol (stage I). On request, additional butorphanol was administered and the step-up protocol continued (stage II). Thereafter, if necessary, patients were intravenously sedated (stage III). After each shock, the McGill Pain Questionnaire was used to obtain a sensory (S), affective (A), evaluative (E), and total (T) pain rating index (PRI) and a visual analogue scale analyzing pain (VAS-P) and fear (VAS-F). For every patient, the slope of each pain or fear parameter against the shock number was calculated and individual slopes were averaged for the placebo and butorphanol group. All patients were cardioverted at a mean threshold of 4.4+/-3.3 J. Comparing both patient groups for stage II, the mean slopes for PRI-T (P=0.0099), PRI-S (P=0.019), and PRI-E (P=0.015) became significantly lower in the butorphanol group than in the placebo group. Comparing patients who received the same shock intensity ending stage I and going to stage II, in those patients randomized to placebo the mean VAS-P (P=0.023), PRI-T (P=0. 029), PRI-S (P=0.030), and PRI-E (P=0.023) became significantly lower after butorphanol administration.

CONCLUSIONS

During a step-up internal atrial defibrillation protocol, intranasal butorphanol decreased or stabilized the value of several pain variables and did not affect fear. Of the 3 qualitative components of pain, only the affective component was not influenced by butorphanol. The PRI evaluated pain more accurately than the VAS.

Pain-related fear is more disabling than pain itself: evidence on the role of pain-related fear in chronic back pain disability

There is growing evidence for the idea that in back pain patients, pain-related fear (fear of pain/physical activity/(re)injury) may be more disabling than pain itself. A number of questionnaires have been developed to quantify pain-related fears, including the Fear-Avoidance Beliefs Questionnaire (FABQ), the Tampa Scale for Kinesiophobia (TSK), and the Pain Anxiety Symptoms Scale (PASS). A total of 104 patients, presenting to a rehabilitation center or a comprehensive pain clinic with chronic low back pain were studied in three independent studies aimed at (1) replicating that pain-related fear is more disabling than pain itself (2) investigating the association between pain-related fear and poor behavioral performance and (3) investigating whether pain-related fear measures are better predictors of disability and behavioral performance than measures of general negative affect or general negative pain beliefs (e.g. pain catastrophizing). All three studies showed similar results. Highest correlations were found among the pain-related fear measures and measures of self-reported disability and behavioral performance. Even when controlling for sociodemographics, multiple regression analyses revealed that the subscales of the FABQ and the TSK were superior in predicting self-reported disability and poor behavioral performance. The PASS appeared more strongly associated with pain catastrophizing and negative affect, and was less predictive of pain disability and behavioral performance. Implications for chronic back pain assessment, prevention and treatment are discussed.

Patient utilities in chronic musculoskeletal pain: how useful is the standard gamble method?

The main goal of current pain management approaches is to increase the patients' quality of life by improving pain coping skills and by reducing the levels of disability in daily life, often despite persistent pain. Direct measurement of quality of life is of crucial importance in economic evaluation research, in which not only is the estimation of financial costs and benefits included, but so is the evaluation of costs and benefits in terms of changes in health states. The purpose of this study is to compare the psychometric qualities of two instruments for assessing patients' utilities, the rating scale (RS) and the standard gamble (SG). Such instruments are designed for their application in economic evaluation research, but have seldomly been used in chronic pain trials. Both methods provide a single measure between 0 and 1. The relationship between these utility measures and descriptive and domain-specific quality of life measures was examined in 133 fibromyalgia patients and 148 patients with chronic non-specific low back pain. Mean utility score at baseline was 0.43 with the RS and 0.78 for the SG. The correlation between both methods was found to be poor (r = 0.21). Both measures appeared to be fairly stable in a 2-week test-retest period (intra class correlation coefficient (ICC) = 0.74 and 0.77). Scores on the description of patient's own health on six domains, global assessment of change and domain specific measures correlated moderately with the RS scores and low with the SG. Multiple regression analyses demonstrated that 32% of the variance in RS values and only 13% of the variance in SG utilities could be explained by domain-specific measures. These results suggest an acceptable construct validity for the RS but insufficient construct validity for the SG. Valuations of ones own health appear only partially to be related to the assessment of the pain-specific measures and measures of distress. It can be concluded that the RS and domain-specific measures assess partly different, but nevertheless complementary aspects of health-related quality of life. It is therefore recommended to include in economic evaluation studies both domain-specific measures and valuation measures. Finally, in chronic musculoskeletal pain patients, RS scores were found to be more responsive in detecting significant changes in preferences than SG scores. For use in patients with chronic musculoskeletal pain, the RS is preferred to the SG for establishing accurate decisions about the impact of new interventions on their health outcomes.

Health economic assessment of behavioural rehabilitation in chronic low back pain: a randomised clinical trial

The aim of this cost-effectiveness study was to compare a combined operant programme plus cognitive/relaxation programme with an operant programme plus attention-control and to compare both programmes with a waiting-list control group and with operant rehabilitation provided, as usual, by the same rehabilitation centre. One hundred and forty eight patients with chronic low back pain were randomly assigned to the different conditions. The economic endpoints were the costs of the programme and other health care utilisation, costs for the patient, and indirect costs associated with production losses due to low back pain. The effects were measured in terms of global assessment of change and utilities, using rating scale and standard gamble methods. The 3-year study determined that adding a cognitive component to an operant treatment did not lead to significant differences in costs and improvement in quality of life when compared with the operant treatment alone. Compared with the common individual rehabilitation therapy it can be concluded that the same effects can be reached at the same or lower costs with a shorter, more intense standardised group programme. The operant treatment alone is more effective than providing no treatment in the waiting-list control group.

Cognitive-educational treatment of fibromyalgia: a randomized clinical trial. I. Clinical effects

OBJECTIVE

This randomized controlled clinical trial evaluates the effectiveness of outpatient group cognitive/educational treatment for patients with the fibromyalgia (FM) syndrome. We hypothesized that the combination of group education with cognitive treatment aimed at developing pain coping skills would be more effective than group education alone.

METHODS

131 patients with FM were randomly assigned to 3 conditions: an experimental condition, which was the combined cognitive/educational intervention (ECO); an attention control condition consisting of group education plus group discussion (EDI); and a waiting list control (WLC). For the treatment conditions ECO and EDI, assessments were made 2 weeks before treatment, at start of treatment, at post-treatment, and at 6 and 12 mo followup. WLC patients received only 3 assessments.

RESULTS

There were no pretreatment differences between the groups, or between dropouts and patients who remained in the study. At post-treatment, and compared with the WLC, the ECO patients improved in knowledge about FM (p = 0.007) and pain coping (p < 0.001). EDI patients improved on pain coping (p = 0.005) and pain control (p = 0.002). EDI patients reported significantly less fear than ECO patients (p = 0.005). There were no other differential effects between ECO and EDI at post-treatment or 6 mo or 12 mo followup. Based on the reliability of change index for clinical significance, the relative short term success rates are 6.4 and 18.4% for ECO and EDI, respectively.

CONCLUSION

The surplus value of a highly structured, 12 session group cognitive treatment added to group education cannot be supported by our study. In EDI, fear reduction might have enhanced pain coping and pain control, while poor compliance, the difficulty of homework assignments, and lack of individual support may have limited the effectiveness of ECO.

Cognitive-educational treatment of fibromyalgia: a randomized clinical trial. II. Economic evaluation

OBJECTIVE

In this 3 year randomized clinical trial the cost effectiveness of a 6 week educational/cognitive intervention (ECO) is compared with an educational discussion intervention (EDI) and a waiting list condition (WLC).

METHODS

A total of 131 patients with fibromyalgia were randomly allocated to the ECO, EDI, or WLC intervention. The ECO and EDI groups were followed for 12 months, whereas the WLC group was followed for 6 weeks. Direct health care and nonhealth care costs, and the indirect costs associated with lost production due to illness, were calculated. The effects were measured in terms of utilities, using rating scale and standard gamble methods.

RESULTS

Treatment costs were estimated to be US $980 per patient for both ECO and EDI. The total direct health care costs of ECO treatment were US $1623 higher than those for EDI. This difference was significant. Indirect costs for the 2 groups were not significantly different. At 6 weeks there was a significant difference in rating scale utilities between the 3 groups, caused by a significantly greater improvement in the EDI group compared to the WLC group. However, no significant differences in either rating scale or standard gamble utilities were found between the ECO and EDI groups immediately after treatment, or at the 6 or 12 month followups.

CONCLUSION

The economic evaluation showed that the addition of a cognitive component to the educational intervention led to significantly higher health care costs and no additional improvement in quality of life compared to the educational intervention alone. This conclusion is robust through a range of plausible values used in a sensitivity analysis.

The role of fear of movement/(re)injury in pain disability

It is now well established that in chronic low back pain, there is no direct relationship between impairments, pain, and disability. From a cognitive-behavioral perspective, pain disability is not only influenced by the organic pathology, but also by cognitive-perceptual, psychophysiological, and motoric-environmental factors. This paper focuses on the role of specific beliefs that are associated with avoidance of activities. These beliefs are related to fear of movement and physical activity, which is (wrongfully) assumed to cause (re)injury. Two studies are presented, of which the first examines the factor structure of the Tampa Scale for Kinesiophobia (TSK), a recently developed questionnaire that is aimed at quantifying fear of movement/(re)injury. In the second study, the value of fear of movement/(re)injury in predicting disability levels is analyzed, when the biomedical status of the patient and current pain intensity levels are controlled for. In addition, the determinants of fear of movement/(re)injury are examined. The discussion focuses on the clinical relevance of the fear-avoidance model in relation to risk assessment, assessment of functional capacity, and secondary prevention.

Behavioural rehabilitation of chronic low back pain: comparison of an operant treatment, an operant-cognitive treatment and an operant-respondent treatment

Seventy-one chronic low back pain patients were assigned to one of three behavioural rehabilitation treatments or a waiting-list condition. The first intervention consisted of an operant treatment, aimed at increasing health behaviours and activity levels and at reducing pain and illness behaviours. In the second intervention, a cognitive treatment, aimed at the reinterpretation of catastrophizing pain cognitions and at enhancing self-control, was combined with an operant treatment. The third intervention consisted of the combination of the operant approach and a respondent treatment. During the respondent treatment, patients were taught to decrease muscle tension levels, using the 'applied relaxation' technique supported by EMG-biofeedback and graded exposure to tension-eliciting situations. A repeated measurements design included observer rating of pain behaviours, observer ratings of mood, self-reported depression, residual health behaviours, pain cognitions and experienced pain intensity. Follow-up assessment occurred at six months and one year after termination of treatment. Results suggest that, for the sample as a whole, improvements are found on measures of pain behaviours, health behaviours, pain cognitions and affective distress and that these improvements are maintained at six months and one year follow-up. During the treatment the three treatment groups improved significantly more than the waiting-list control group on most of the measures. Further, the results of this study provide evidence that the operant-cognitive and operant-respondent conditions are more efficacious in decreasing pain behaviours and in increasing health behaviours and efficacy expectations than operant treatment alone. This differential effect among the conditions is maintained at follow-up. Patients who received the OC and OR treatments catastrophize less than OP patients, and OC patients showed better scores on outcome-efficacy than OR patients. In general, the results suggest that behavioural rehabilitation programmes for chronic low back pain are effective and that the effects of an operant treatment are magnified when self-control techniques are added.

What do chronic pain patients think of their pain? Towards a pain cognition questionnaire

The three-systems model of chronic pain emphasizes the partially independent relationship among physiological, gross motor and verbal-cognitive responses of chronic pain patients. This study describes the development of an assessment instrument representing a measure for the verbal-cognitive response system of chronic pain. Fifty items, each of which is assigned to one of five factors (pain impact, catastrophizing, outcome efficacy, acquiescence and reliance on health care) constitute the new Pain Cognition List (PCL). The PCL was developed using a Dutch back pain population and proves to be stable across sex and back pain diagnosis. By means of three experiments the PCL is shown to be reliable and sufficiently valid. The PCL might be a promising tool for identifying pain patients whose pain problem is mainly controlled by cognitive factors.

A behavioral treatment for sitting and standing intolerance in a patient with chronic low back pain

This study reports on the effectiveness of an individualized shaping treatment program for sitting and standing intolerance in a patient with chronic low back pain following a laminectomy for removal of an intradural tumor. Functional assessment of sitting and standing tolerance, observation of pain behaviors, and a self-report measure regarding the pain experience were carried out during baseline, treatment, posttreatment, and at a 6-month follow-up. By the end of the 6-week inpatient treatment, the patient was able to stand still for 25 min and to sit for 15 min. The overall pain behavior diminished significantly. These findings underscore the importance of relatively simple and cost-effective individualized behavioral programs for chronic pain patients.