The Potential of Treatment Matching for Subgroups of Patients With Chronic Pain

A randomised clinical trial of subgrouping and targeted treatment for low back pain compared with best current care. The STarT Back Trial Study Protocol

Background

Back pain is a major health problem and many sufferers develop persistent symptoms. Detecting relevant subgroups of patients with non-specific low back pain has been highlighted as a priority area for research, as this could enable better secondary prevention through the targeting of prognostic indicators for persistent, disabling symptoms. We plan to conduct a randomised controlled trial to establish whether subgrouping using a novel tool, combined with targeted treatment, is better than best current care at reducing long-term disability from low back pain.

Methods/Design

We will recruit 800 participants aged 18 years and over with non-specific low back pain from 8–10 GP practices within two Primary Care Trusts in Staffordshire, England. Our primary outcome measures are low back pain disability and catastrophising. Secondary outcomes include back pain intensity, global change, leg pain, fear avoidance, anxiety, depression, illness perceptions, patient satisfaction, overall health status and cost-effectiveness. Data will be collected before randomisation, and 4 and 12 months later. Participants are randomised to receive either newly developed interventions, delivered by trained physiotherapists and targeted according to subgroups defined by tool scores, or best current care.

Discussion

This paper presents detail on the rationale, design, methods and operational aspects of the trial.

Trial registration

Current Controlled Trials ISRCTN37113406.

Psychological approaches in the treatment of chronic pain patients--when pills, scalpels, and needles are not enough

BACKGROUND

Chronic pain is a prevalent and costly problem that eludes adequate treatment. Persistent pain affects all domains of people's lives and in the absence of cure, success will greatly depend on adaptation to symptoms and self-management.

METHOD

We reviewed the psychological models that have been used to conceptualize chronic pain-psychodynamic, behavioural (respondent and operant), and cognitive-behavioural. Treatments based on these models, including insight, external reinforcement, motivational interviewing, relaxation, meditation, biofeedback, guided imagery, and hypnosis are described.

RESULTS

The cognitive-behavioural perspective has the greatest amount of research supports the effectiveness of this approach with chronic pain patients. Importantly, we differentiate the cognitive-behavioural perspective from cognitive and behavioural techniques and suggest that the perspective on the role of patients' beliefs, attitudes, and expectations in the maintenance and exacerbation of symptoms are more important than the specific techniques. The techniques are all geared to fostering self-control and self-management that will encourage a patient to replace their feelings of passivity, dependence, and hopelessness with activity, independence, and resourcefulness.

CONCLUSIONS

Psychosocial and behavioural factors play a significant role in the experience, maintenance, and exacerbation of pain. Self-management is an important complement to biomedical approaches. Cognitive-behavioural therapy alone or within the context of an interdisciplinary pain rehabilitation program has the greatest empirical evidence for success. As none of the most commonly prescribed treatment regimens are sufficient to eliminate pain, a more realistic approach will likely combine pharmacological, physical, and psychological components tailored to each patient's needs.

Chronic non-specific low back pain - sub-groups or a single mechanism?

BACKGROUND

Low back pain is a substantial health problem and has subsequently attracted a considerable amount of research. Clinical trials evaluating the efficacy of a variety of interventions for chronic non-specific low back pain indicate limited effectiveness for most commonly applied interventions and approaches.

DISCUSSION

Many clinicians challenge the results of clinical trials as they feel that this lack of effectiveness is at odds with their clinical experience of managing patients with back pain. A common explanation for this discrepancy is the perceived heterogeneity of patients with chronic non-specific low back pain. It is felt that the effects of treatment may be diluted by the application of a single intervention to a complex, heterogeneous group with diverse treatment needs. This argument presupposes that current treatment is effective when applied to the correct patient. An alternative perspective is that the clinical trials are correct and current treatments have limited efficacy. Preoccupation with sub-grouping may stifle engagement with this view and it is important that the sub-grouping paradigm is closely examined. This paper argues that there are numerous problems with the sub-grouping approach and that it may not be an important reason for the disappointing results of clinical trials. We propose instead that current treatment may be ineffective because it has been misdirected. Recent evidence that demonstrates changes within the brain in chronic low back pain sufferers raises the possibility that persistent back pain may be a problem of cortical reorganisation and degeneration. This perspective offers interesting insights into the chronic low back pain experience and suggests alternative models of intervention.

SUMMARY

The disappointing results of clinical research are commonly explained by the failure of researchers to adequately attend to sub-grouping of the chronic non-specific low back pain population. Alternatively, current approaches may be ineffective and clinicians and researchers may need to radically rethink the nature of the problem and how it should best be managed.

What do the numbers mean? Normative data in chronic pain measures

Although self-reported measures play a central role in the assessment of pain and its treatment, it has long been recognized that interpretation of these measures is severely limited by the absence of normative data. Despite that, relatively few of the measures used in pain clinics or research studies have normative data for reference. Using a pain centre sample (n=6124), this paper describes the development of a normative dataset on a number of commonly used pain-related measures. The measures cover many of the key dimensions in pain assessment, including pain severity/quality, disability (physical functioning), and mood (emotional functioning). Measures of different cognitive and coping constructs are also included. Mean scores are reported for each measure according to age group, gender, pain site, as well as percentiles for different scores for patients with chronic low back pain. The potential uses for datasets of this type include the assessment and evaluation of individual cases, as well as the interpretation of published clinical trials. It is also argued that future systematic reviews of pain treatments should include consideration of such patient characteristics as pain levels, disability and mood in the studies reviewed rather than pain site and chronicity alone.

Multidimensional Pain Inventory derived classifications of chronic pain: Evidence for maladaptive pain-related coping within the dysfunctional group

This study examines maladaptive pain-related fear-avoidance and endurance coping in subgroups of patients with chronic back pain. Hypotheses were derived from the avoidance-endurance model of pain [Hasenbring M. Attentional control of pain and the process of chronification. In: Sandkühler J, Bromm B, Gebhart GF, editors. Progress in pain research, vol. 129. New York: Elsevier; 2000. p. 525-34.], which assumes that endurance coping (cognitive, behavioral tendency to endure severe pain to finish current activities irrespective of pain increases) leads to overuse of muscles, joints, and discs with an increase of pain as long-term consequence. Participants were 120 patients referred for treatment of chronic pain to General Practices. They were classified as 'dysfunctional-DYS' (15.8%), 'interpersonally distressed-ID' (10.8%), and 'adaptive copers-AC' (61.7%) based on the Multidimensional Pain Inventory [Kerns RD, Turk DC, Rudy TE. The West Haven-Yale Multidimensional Pain Inventory (WHYMPI). Pain 1985;23:345-56.] and compared on measures of pain-related fear-avoidance coping (anxiety/depression; help-/hopelessness; catastrophizing; avoidance of social/physical activity) and endurance coping (positive mood; thought suppression; endurance behavior) using the Kiel Pain Inventory [Hasenbring M. The Kiel Pain Inventory-Manual. Three questionnaire scales for assessment of pain-related cognitions, emotions and copying strategies. Bern:Huber; 1994.]. Multivariate analysis of variance indicated that groups differed significantly for pain-related fear-avoidance and endurance coping, even after control for pain intensity and depression. Univariate effects revealed that patients classified as DYS reported more anxiety/depression, help-/hopelessness, and catastrophizing than did those classified as AC. Furthermore, the DYS group showed more thought suppression compared to AC; however, subgroups did not differ significantly with regard to avoidance of social and physical activity, and endurance behavior. Further, DYS as well as ID group showed more non-verbal pain behavior compared to AC, which refers to the special role of operant conditioning. Implications are considered for further investigation of endurance coping to provide a more comprehensive assessment and treatment for subgroups of chronic pain patients.

Brain perfusion abnormality in patients with chronic pain

We performed single photon emission computed tomography (SPECT) of the brain in 15 patients with chronic pain (males, 7; females, 8; average age 49.1 +/- 17.9 years) and identified the locus of cerebral blood flow reduction by a new analytical method (easy Z-score Imaging System: eZIS) to clarify the functional neuroanatomical basis of chronic pain. Of the 15 patients, 6 had backache, 2 neck pain, 2 gonalgia, and 5 pain at other sites, with an average Visual analog scale of pain (VAS) value of 6.1 +/- 1.9. In comparison with a information on a data base on physically unimpaired persons, the dorsolateral prefrontal area (both sides, right dominant), medial prefrontal area (both sides), dorsal aspect of the anterior cingulate gyrus nociceptive cortex (both sides) and the lateral part of the orbitofrontal cortex (right side) were found to have blood flow reduction in the group of patients with chronic pain. As for chronic pain and its correlation with clinical features such as a depressive state, anticipation anxiety, PTSD, and conversion hysteria, the mechanism in the brain that was suggested by this study should be followed-up by functional neuroimaging studies.

Does systematic graded exposure in vivo enhance outcomes in multidisciplinary chronic pain management groups?

OBJECTIVES

Graded exposure in vivo (GEXP) treatment has been successfully used to reduce levels of pain-related fear and disability in some chronic pain patients, but its effectiveness has not been evaluated in general clinical settings using group-design studies. The purpose of this study was to determine if the systematic incorporation of GEXP into a multidisciplinary chronic pain management group (PMG) treatment program would result in better treatment outcomes than usual PMG treatment.

METHODS

One hundred forty-three chronic pain patients who were assessed as suitable for an outpatient multidisciplinary chronic PMG program were randomly allocated to 3 experimental conditions; usual PMG, PMG incorporating systematic graded exposure, and wait-list control.

RESULTS

The clinical outcomes of the 2 treatment conditions were not significantly different, suggesting that the systematic incorporation of GEXP into a multidisciplinary PMG program did not result in better treatment outcomes than usual PMG treatment. Both group treatment programs were associated with significant treatment effects when compared with the wait-list control on measures of pain intensity, fear of movement/(re)injury, pain self-efficacy, activity level, and depression. No treatment effects were found on self-report measures of pain disability or anxiety.

DISCUSSION

The addition of systematic graded exposure into a multidisciplinary chronic pain management program did not result in better clinical outcomes than the usual group treatment program. The validity of GEXP to the broader population of chronic pain patients warrants further investigation.

Evidence-based clinical practice guidelines for interdisciplinary rehabilitation of chronic nonmalignant pain syndrome patients

This is an update to evidence-based practice guidelines for chronic nonmalignant pain syndrome patients first published in 1995 and revised in 1999. The current guidelines recommend interdisciplinary-focused rehabilitation, which is goal-directed and time-limited. Emphasis is placed on educating patients in active self-management techniques that stress maximizing function. Integrated treatment involving medical, psychological/behavioral, physical/occupational therapy, and disability/vocational interventions are recommended on an outpatient basis whenever clinically possible. Patient selection criteria are delineated. Updated references providing evidence-based support for the recommendations are provided, including the use of opioids and sedative-hypnotic medications, injection and block procedures, acupuncture, implantable spinal infusion and stimulation devices, and other invasive spinal surgery procedures such as intradiscal electrothermal therapy. Guideline integration and early detection and intervention with chronic pain syndrome patients are encouraged.

Cognitive-behavioural therapies and exercise programmes for patients with fibromyalgia: state of the art and future directions

This review provides an overview of the effects of non-pharmacological treatments for patients with fibromyalgia (FM), including cognitive-behavioural therapy, exercise training programmes, or a combination of the two. After summarising and discussing preliminary evidence of the rationale of non-pharmacological treatment in patients with FM, we reviewed randomised, controlled trials for possible predictors of the success of treatment such as patient and treatment characteristics. In spite of support for their suitability in FM, the effects of non-pharmacological interventions are limited and positive outcomes largely disappear in the long term. However, within the various populations with FM, treatment outcomes showed considerable individual variations. In particular, specific subgroups of patients characterised by relatively high levels of psychological distress seem to benefit most from non-pharmacological interventions. Preliminary evidence of retrospective treatment analyses suggests that the efficacy may be enhanced by offering tailored treatment approaches at an early stage to patients who are at risk of developing chronic physical and psychological impairments.

Patient clusters in acute, work-related back pain based on patterns of disability risk factors

OBJECTIVE

To identify subgroups of patients with work-related back pain based on disability risk factors.

METHODS

Patients with work-related back pain (N = 528) completed a 16-item questionnaire of potential disability risk factors before their initial medical evaluation. Outcomes of pain, functional limitation, and work disability were assessed 1 and 3 months later.

RESULTS

A K-Means cluster analysis of 5 disability risk factors (pain, depressed mood, fear avoidant beliefs, work inflexibility, and poor expectations for recovery) resulted in 4 sub-groups: low risk (n = 182); emotional distress (n = 103); severe pain/fear avoidant (n = 102); and concerns about job accommodation (n = 141). Pain and disability outcomes at follow-up were superior in the low-risk group and poorest in the severe pain/fear avoidant group.

CONCLUSIONS

Patients with acute back pain can be discriminated into subgroups depending on whether disability is related to pain beliefs, emotional distress, or workplace concerns.

Does sleep quality predict pain-related disability in chronic pain patients? The mediating roles of depression and pain severity

Disrupted sleep has long been associated with physical functioning and disability in chronic pain populations and recent research shows that patterns of sleep and rest can predict physical disability, independent of depression and pain levels in this group. However, it is unknown whether sleep quality may independently predict disability in this way. The aim of the present study was to examine the self-reported relationship between sleep and disability in 155 chronic pain patients attending a pain management service. The sample had an average age of 52.9 years and 69% were female with mean pain duration of 10.5 years. Disrupted sleep and rest patterns and poor sleep quality were positively correlated with depression and pain-related disability. Hierarchical regression analyses showed that sleep quality did not predict pain-related disability when depression and pain severity were taken into consideration. Separate mediation analyses of depression and pain severity revealed that both variables were important partial mediators of the relationship between sleep quality and disability. Depression was found to be a stronger mediator than pain severity. These findings highlight the important role of sleep in chronic pain suffering. However, due to the cross sectional nature of this study, the mediation pathways proposed require testing by further research adopting a prospective design. Ideally, future research should evaluate whether targeted interventions to improve sleep can reduce pain severity, depression and ultimately, pain-related disability.

Patterns of responses on health-related quality of life questionnaires among patients with HIV/AIDS

BACKGROUND

Health-related quality of life (HRQoL) has become an important facet of HIV/AIDS research. Typically, the unit of analysis is either the total instrument score or subscale score. Developing a typology of responses across various HRQoL measures, however, may advance understating of patients' perspectives.

METHODS

In a multicenter study, we categorized 443 patients' responses on utility measures (time-tradeoff, standard gamble, and rating scale) and the HIV/AIDS-Targeted Quality of Life (HAT-QoL) scale by using latent profile analysis to empirically derive classes of respondents. We then used linear regressions to identify whether class membership is associated with clinical measures (viral load, CD4, time since diagnosis, highly active antiretroviral therapy [HAART]) and psychosocial function (depressed mood, alcohol use, religious coping).

RESULTS

Six classes were identified. Responses across the HAT-QoL subscales tended to fall into 3 groupings--high functioning (Class 1), moderate functioning (Classes 2 and 3), and low functioning (Classes 4 to 6); utility measures further distinguished individuals among classes. Regression analyses comparing those in Class 1 with those in the other 5 found significantly more symptoms of depression, negative religious coping strategies, and lower CD4 counts among subjects in Class 1. Those in Class 5 had been diagnosed with HIV longer, and members of Class 6 reported significantly less alcohol consumption, had higher viral loads, and were more likely to receive HAART.

CONCLUSION

Patients with HIV respond differentially to various types of HRQoL measures. Health status and utility measures are thus complementary approaches to measuring HRQoL in patients with HIV.

Methodological issues in the recruitment of cancer pain patients and their caregivers

Published pain management guidelines recommend that caregivers of cancer pain patients be provided pain management education, but little is known about the utility of providing such information. This study examined recruitment and retention of cancer pain patients and caregivers for a randomized clinical trial that provided psychoeducation and stress management training to caregivers. Of 397 patient/caregiver dyads screened, only 22 (5.5%) were study eligible, consented to participate, and completed the study. A variety of problems hampered successful participation, including a high proportion of non-cancer-related pain syndromes among patients, a high proportion of patients without caregivers, and participants' perception of study burden. Results suggest that researchers should recruit from a broad patient base and limit study burden on participants.

The relationship between activity and pain in patients 6 months after lumbar disc surgery: do pain-related coping modes act as moderator variables?

BACKGROUND

In LBP patients, the relationship between pain and physical activity remains unclear. Whereas a negative relationship between pain and self-reported physical activity was found, this relation disappeared in the case of overt behavioral data (e.g., accelerometer). Cognitive-behavioral models of the development of chronic pain suggest subgroups with signs of physical underuse and overuse.

AIMS

To examine if patients with pain-related adaptive, endurance and fear-avoidance coping differ in pain, self-reported physical function and overt physical activity 6 months after disc surgery.

METHODS

24 patients completed questionnaires (Von Korff chronic pain grade (CPG), Kiel pain inventory (KPI), Funktionsfragebogen Hannover-Rücken FFbH-R) and underwent an 8-h accelerometer assessment in their daily life (physical activity level (PAL), number of constant postures (CP)). The KPI differed between adaptive coping (AC) (N=9), fear avoidance coping (FAC) (N=1) and endurance coping (EC) (N=14).

RESULTS

In the whole group, pain intensity was negative related to self-reported physical activity whereas PAL and CP displayed no correlation with pain. EC patients showed significantly higher pain scores and lower self-reported physical functioning compared to AC but the same level of PAL and furthermore, a significantly higher number of CPs in daily life. The visual inspection of the FAC patient revealed also high pain, low physical functioning and low overt physical activity.

CONCLUSIONS

The assessment of pain-related coping modes yielded an important differentiation between subgroups of LBP patients 6 months after surgery. Endurance copers displayed signs of overuse in their daily behavior in spite of pain than adaptive copers. The one fear avoidance coper tends to do less physical activity in the sense of underuse.

A randomized clinical trial and subgroup analysis to compare flexion-distraction with active exercise for chronic low back pain

Many clinical trials on chiropractic management of low back pain have neglected to include specific forms of care. This study compared two well-defined treatment protocols. The objective was to compare the outcome of flexion-distraction (FD) procedures performed by chiropractors with an active trunk exercise protocol (ATEP) performed by physical therapists. A randomized clinical trial study design was used. Subjects, 18 years of age and older, with a primary complaint of low back pain (>3 months) were recruited. A 100 mm visual analogue scale (VAS) for perceived pain, the Roland Morris (RM) Questionnaire for low back function, and the SF-36 for overall health status served as primary outcome measures. Subjects were randomly allocated to receive either FD or ATEP. The FD intervention consisted of the application of flexion and traction applied to specific regions in the low back, with the aid of a specially designed manipulation table. The ATEP intervention included stabilizing and flexibility exercises, the use of modalities, and cardiovascular training. A total of 235 subjects met the inclusion/exclusion criteria and signed the informed consent. Of these, 123 were randomly allocated to FD and 112 to the ATEP. Study patients perceived significantly less pain and better function after intervention, regardless of which group they were allocated to (P<0.01). Subjects randomly allocated to the flexion-distraction group had significantly greater relief from pain than those allocated to the exercise program (P=0.01). Subgroup analysis indicated that subjects categorized as chronic, with moderate to severe symptoms, improved most with the flexion-distraction protocol. Subjects categorized with recurrent pain and moderate to severe symptoms improved most with the exercise program. Patients with radiculopathy did significantly better with FD. There were no significant differences between groups on the Roland Morris and SF-36 outcome measures. Overall, flexion-distraction provided more pain relief than active exercise; however, these results varied based on stratification of patients with and without radiculopathy and with and without recurrent symptoms. The subgroup analysis provides a possible explanation for contrasting results among randomized clinical trials of chronic low back pain treatments and these results also provide guidance for future work in the treatment of chronic low back pain.

Possible selves in chronic pain: self-pain enmeshment, adjustment and acceptance

The aim of this study was to test whether enmeshment of self and pain predicted adjustment (depression and acceptance) in a chronic pain population. 89 chronic pain patients completed standardized self-report measures of depression and acceptance and generated characteristics describing their current actual self, hoped-for self and feared-for self, and made judgments about the degree to which their future possible selves (hoped-for and feared-for) were dependent on the absence or presence of pain, i.e. enmeshed with pain. Hierarchical multiple regression analyses showed that after accounting for the influence of demographics (age, gender), pain characteristics and the degree of role interference attributable to pain, the proportion of hoped-for self characteristics that could be achieved even with the presence of pain predicted the magnitude of depression and acceptance scores. The findings are discussed with reference to the enmeshment hypothesis and theories of self-discrepancy, self-regulation and hopelessness.

Cognitive-Behavioral Treatments for Chronic Pain

Since the introduction of behavioral medicine in the early 70s, cognitive-behavioral treatment interventions for chronic pain have expanded considerably. It is now well established that these interventions are effective in reducing the enormous suffering that patients with chronic pain have to bear. In addition, these interventions have potential economic benefits in that they appear to be cost-effective as well. Despite these achievements, there is still room for improvement. First, there is a substantial proportion of patients who do not appear to benefit from treatment interventions available. Second, although the effect sizes of most cognitive-behavioral treatments for chronic pain are comparable to those in psychopathology, they are quite modest. Third, there is little evidence for differential outcomes for different treatment methods. Fourth, there still is relatively little known about the specific biobehavioral mechanisms that lead to chronic pain and pain disability. One direction is to better match treatment programs to patients' characteristics. This can be done according to an "Aptitude X Treatment Interaction" framework, or from the perspective of the Moderator-Mediator distinction. In this introduction to the special series on what works for whom in cognitive-behavioral treatments for chronic pain, we review existing knowledge concerning both moderating and mediating variables in cognitive-behavioral treatments for chronic pain. We further argue in favor of theory-driven research as the only way to define specific a priori hypotheses about which patient-treatment interactions to expect. We also argue that replicated single-participant studies, with appropriate statistics, are likely to enhance new developments in this clinical research area.