Methods for studying naturally occurring human pain and their analogues

Methods for investigating human pain have been developed over the last 100years. Typically, researchers focus on people with clinical pain, or on healthy participants undergoing laboratory-controlled pain-induction techniques focussed mostly on exogenously generated skin nociception. Less commonly investigated are acute pain experiences that emerge naturally. Six common painful complaints were identified: headache, muscular pain, visceral pain, menstrual pain, dental pain, and pain associated with upper respiratory tract infection. Methods used to recruit participants with the natural occurrence of each pain complaint were identified, and features of their use reviewed. Also reviewed were experimental analogues designed to mimic these pains, with the exception of menstrual pain. Headache and menstrual pain appear to be most effectively researched in their naturally occurring form, whereas muscle and dental pain may be more easily induced. Upper respiratory tract infection and abdominal pain provide further challenges for researchers. Summary guidance is offered, and directions for methods development outlined.

Psychological therapies for the management of chronic and recurrent pain in children and adolescents

BACKGROUND

Chronic pain affects many children, who report severe pain, distressed mood, and disability. Psychological therapies are emerging as effective interventions to treat children with chronic or recurrent pain. This update adds recently published randomised controlled trials (RCTs) to the review published in 2009.

OBJECTIVES

To assess the effectiveness of psychological therapies, principally cognitive behavioural therapy and behavioural therapy, for reducing pain, disability, and improving mood in children and adolescents with recurrent, episodic, or persistent pain. We also assessed the risk of bias and methodological quality of the included studies.

SEARCH METHODS

Searches were undertaken of MEDLINE, EMBASE, and PsycLIT. We searched for RCTs in references of all identified studies, meta-analyses and reviews. Date of most recent search: March 2012.

SELECTION CRITERIA

RCTs with at least 10 participants in each arm post-treatment comparing psychological therapies with active treatment were eligible for inclusion (waiting list or standard medical care) for children or adolescents with episodic, recurrent or persistent pain.

DATA COLLECTION AND ANALYSIS

All included studies were analysed and the quality of the studies recorded. All treatments were combined into one class: psychological treatments; headache and non-headache outcomes were separately analysed on three outcomes: pain, disability, and mood. Data were extracted at two time points; post-treatment (immediately or the earliest data available following end of treatment) and at follow-up (at least three months after the post-treatment assessment point, but not more than 12 months).

MAIN RESULTS

Eight studies were added in this update of the review, giving a total of 37 studies. The total number of participants completing treatments was 1938. Twenty-one studies addressed treatments for headache (including migraine); seven for abdominal pain; four included mixed pain conditions including headache pain, two for fibromyalgia, two for pain associated with sickle cell disease, and one for juvenile idiopathic arthritis. Analyses revealed five significant effects. Pain was found to improve for headache and non-headache groups at post-treatment, and for the headache group at follow-up. Mood significantly improved for the headache group at follow-up, although, this should be interpreted with caution as there were only two small studies entered into the analysis. Finally, disability significantly improved in the non-headache group at post-treatment. There were no other significant effects.

AUTHORS' CONCLUSIONS

Psychological treatments are effective in reducing pain intensity for children and adolescents (<18 years) with headache and benefits from therapy appear to be maintained. Psychological treatments also improve pain and disability for children with non-headache pain. There is limited evidence available to estimate the effects of psychological therapies on mood for children and adolescents with headache and non-headache pain. There is also limited evidence to estimate the effects on disability in children with headache. These conclusions replicate and add to those of the previous review which found psychological therapies were effective in reducing pain intensity for children with headache and non-headache pain conditions, and these effects were maintained at follow-up.

Ketamine as an adjuvant to opioids for cancer pain

BACKGROUND

This is an update of the original review published in Issue 1, 2003. Ketamine is a commonly used anaesthetic agent, and in subanaesthetic doses is also given as an adjuvant to opioids for the treatment of cancer pain, particularly when opioids alone prove to be ineffective. Ketamine is known to have psychotomimetic (including hallucinogenic), urological and hepatic adverse effects.

OBJECTIVES

To determine the effectiveness and adverse effects of ketamine as an adjuvant to opioids in the treatment of cancer pain.

SEARCH METHODS

Studies were originally identified from MEDLINE (1966 to 2002), EMBASE (1980 to 2002), CancerLit (1966 to 2002), The Cochrane Library (Issue 1, 2001); by handsearching reference lists from review articles, trials, and chapters from standard textbooks on pain and palliative care. The manufacturer of ketamine (Pfizer Parke-Davis) provided search results from their in-house database, PARDLARS.An improved and updated search of the following was performed in May 2012: CENTRAL, MEDLINE & OVID MEDLINE R, EMBASE.

SELECTION CRITERIA

Randomized controlled trials (RCTs) of adult patients with cancer and pain being treated with an opioid, and receiving either ketamine (any dose and any route of administration) or placebo or an active control. Studies having a group size of at least 10 participants who completed the trial.

DATA COLLECTION AND ANALYSIS

Two independent review authors identified four RCTs for possible inclusion in the review, and 32 case studies/case series reports. Quality and validity assessment was performed by three independent review authors, and two RCTs were excluded because of inappropriate study design. Patient-reported pain intensity and pain relief was assessed using visual analogue scales (VAS), verbal rating scales or other validated scales, and adverse effects data were collated. For the update three RCTs were identified for possible inclusion in the review.

MAIN RESULTS

Three new studies were identified by the updated search. All three were excluded from the review. Two studies were eligible for inclusion in the original review and both concluded that ketamine improves the effectiveness of morphine in the treatment of cancer pain. However, pooling of the data was not appropriate because of the small total number of participants (30), and the presence of clinical heterogeneity. Some patients experienced hallucinations on both ketamine plus morphine and morphine alone and were treated successfully with diazepam. No other serious adverse effects were reported.

AUTHORS' CONCLUSIONS

Since the last version of this review three new studies were identified but excluded from the review. Current evidence is insufficient to assess the benefits and harms of ketamine as an adjuvant to opioids for the relief of cancer pain. More RCTs are needed.

Psychological therapies for the management of chronic pain (excluding headache) in adults

BACKGROUND

Psychological treatments are designed to treat pain, distress and disability, and are in common practice. This review updates and extends the 2009 version of this systematic review.

OBJECTIVES

To evaluate the effectiveness of psychological therapies for chronic pain (excluding headache) in adults, compared with treatment as usual, waiting list control, or placebo control, for pain, disability, mood and catastrophic thinking.

SEARCH METHODS

We identified randomised controlled trials (RCTs) of psychological therapy by searching CENTRAL, MEDLINE, EMBASE and Psychlit from the beginning of each abstracting service until September 2011. We identified additional studies from the reference lists of retrieved papers and from discussion with investigators.

SELECTION CRITERIA

Full publications of RCTs of psychological treatments compared with an active treatment, waiting list or treatment as usual. We excluded studies if the pain was primarily headache, or was associated with a malignant disease. We also excluded studies if the number of patients in any treatment arm was less than 20.

DATA COLLECTION AND ANALYSIS

Forty-two studies met our criteria and 35 (4788 participants) provided data. Two authors rated all studies. We coded risk of bias as well as both the quality of the treatments and the methods using a scale designed for the purpose. We compared two main classes of treatment (cognitive behavioural therapy(CBT) and behaviour therapy) with two control conditions (treatment as usual; active control) at two assessment points (immediately following treatment and six months or more following treatment), giving eight comparisons. For each comparison, we assessed treatment effectiveness on four outcomes: pain, disability, mood and catastrophic thinking, giving a total of 32 possible analyses, of which there were data for 25.

MAIN RESULTS

Overall there is an absence of evidence for behaviour therapy, except a small improvement in mood immediately following treatment when compared with an active control. CBT has small positive effects on disability and catastrophising, but not on pain or mood, when compared with active controls. CBT has small to moderate effects on pain, disability, mood and catastrophising immediately post-treatment when compared with treatment as usual/waiting list, but all except a small effect on mood had disappeared at follow-up. At present there are insufficient data on the quality or content of treatment to investigate their influence on outcome. The quality of the trial design has improved over time but the quality of treatments has not.

AUTHORS' CONCLUSIONS

Benefits of CBT emerged almost entirely from comparisons with treatment as usual/waiting list, not with active controls. CBT but not behaviour therapy has weak effects in improving pain, but only immediately post-treatment and when compared with treatment as usual/waiting list. CBT but not behaviour therapy has small effects on disability associated with chronic pain, with some maintenance at six months. CBT is effective in altering mood and catastrophising outcomes, when compared with treatment as usual/waiting list, with some evidence that this is maintained at six months. Behaviour therapy has no effects on mood, but showed an effect on catastrophising immediately post-treatment. CBT is a useful approach to the management of chronic pain. There is no need for more general RCTs reporting group means: rather, different types of studies and analyses are needed to identify which components of CBT work for which type of patient on which outcome/s, and to try to understand why.

Searching the internet for help with pain: adolescent search, coping, and medication behaviour

OBJECTIVES

To explore a community sample of adolescents for engagement with online pain resources. To assess if the use of the Internet to search for health information correlated with measures of coping, risk taking, catastrophizing about pain, and engaging in the self-management of pain.

DESIGN

A cross-sectional online study of community-based adolescents (n = 105) recruited via schools to examine their use of the Internet to seek pain-related information.

METHODS

Adolescents completed questionnaires of pain coping, catastrophic thinking, risk-taking behaviour, and medication use. Descriptive analyses were undertaken on event rates of pertinent behaviours, principally on information seeking and pain management behaviour. Correlational analyses were undertaken between coping and information seeking, and medication use.

RESULTS

Few participants engaged in online pain information seeking. Those who did were more likely to be female and scored higher on medication use, catastrophizing, risk taking, and the total score on the Pain Coping Questionnaire.

CONCLUSIONS

Although adolescents are high users of the Internet, paradoxically they do not appear to use the Internet for information about pain and pain management. Further research should assess inhibitory and disinhibitory factors associated with information seeking about pain and chronic illness on the Internet.

STATEMENT OF CONTRIBUTION

What is already known on this subject? Internet use in adolescents is common, mobile, and displays a level of technical awareness unparalleled by adults. The internet is postulated in previous research to present a platform for the delivery of health care, particularly information to aid health decision-making for young people. What does this study add? This study explores how adolescents use the internet to look for health information, particularly on pain and where this falls in a general profile of coping with illness. Interestingly and counterintuitively, adolescents did not use the internet to look for health or pain information. We hypothesize that there may be something about information on pain management that does not readily transfer to the digital world in a way that is useful to adolescent users.

Case study: ethical guidance for pediatric e-health research using examples from pain research with adolescents

OBJECTIVE

The Internet is a frequently used platform for research in pediatric and health psychology. However, there is little pragmatic guidance as to ethical best practice of this research. The absence of guidance is particularly prominent for online research with children. Our objective is to outline ethical issues in e-health research with children and adolescents using two exemplar studies in pediatric pain research.

METHODS

The first study is an asynchronous message board discussion amongst teenagers with pain who are frequent internet users.The second study is a web-based behavioral intervention for the management of adolescent pain.

RESULTS

Each exemplar study is discussed in the context of specific ethical considerations related to recruitment, informed consent and debriefing, privacy and confidentiality, and participant safety. Ethical issues regarding the evaluation of online psychological interventions are also discussed.

CONCLUSIONS

Guidance on optimal ethical practice in e-health research is summarized.

Keeping pain out of your mind: the role of attentional set in pain

BACKGROUND

The involuntary capture of attention by pain may, to some extent, be controlled by psychological variables. In this paper, we investigated the effect of attentional set (i.e., the collection of task-related features that a person is monitoring in order to successfully pursue a goal) on pain.

METHODS

Two experiments are reported in which the task relevance of the modality and spatial location of a target stimulus was manipulated. In both experiments, somatosensory and auditory stimuli were presented on each trial. In experiment 1, 29 participants were cued on each trial to localize either a somatosensory or an auditory target. In experiment 2, 37 participants were cued on each trial to identify either a somatosensory or an auditory target at a particular location.

RESULTS

In experiment 1, self-reported pain intensity and unpleasantness were reduced when participants had to localize the auditory target. The location of the painful stimulus relative to the location of the auditory target did not affect pain. In experiment 2, again, pain intensity and unpleasantness ratings were reduced when participants identified the auditory target. Now, the location of the painful stimulus relative to the location of the auditory target moderated the effect. Pain intensity was less when the painful stimulus was at a different location than the auditory target.

CONCLUSIONS

Results are discussed in terms of the attentional set hypothesis, and we argue that the effectiveness of distraction tasks depends on the degree to which the task-relevant features of the distraction task are distinct from pain-related features.

Psychological interventions for parents of children and adolescents with chronic illness

BACKGROUND

Psychological therapies have been developed for parents of children and adolescents with a chronic illness. Such therapies include parent only or parent and child/adolescent, and are designed to treat parent behaviour, parent mental health, child behaviour/disability, child mental health, child symptoms and/or family functioning. No comprehensive, meta-analytic reviews have been published in this area.

OBJECTIVES

To evaluate the effectiveness of psychological therapies that include coping strategies for parents of children/adolescents with chronic illnesses (painful conditions, cancer, diabetes mellitus, asthma, traumatic brain injury, inflammatory bowel diseases, skin diseases or gynaecological disorders). The therapy will aim to improve parent behaviour, parent mental health, child behaviour/disability, child mental health, child symptoms and family functioning.

SEARCH METHODS

We searched CENTRAL, MEDLINE, EMBASE and PsycINFO for randomised controlled trials (RCTs) of psychological interventions that included parents of children and adolescents with a chronic illness. The initial search was from inception of these databases to June 2011 and we conducted a follow-up search from June 2011 to March 2012. We identified additional studies from the reference list of retrieved papers and from discussion with investigators.

SELECTION CRITERIA

Included studies were RCTs of psychological interventions that delivered treatment to parents of children and adolescents (under 19 years of age) with a chronic illness compared to active control, wait list control or treatment as usual. We excluded studies if the parent component was a coaching intervention, the aim of the intervention was health prevention/promotion, the comparator was a pharmacological treatment, the child/adolescent had an illness not listed above or the study included children with more than one type of chronic illness. Further to this, we excluded studies when the sample size of either comparator group was fewer than 10 at post-treatment.

DATA COLLECTION AND ANALYSIS

We included 35 RCTs involving a total of 2723 primary trial participants. Two review authors extracted data from 26 studies. We analysed data using two categories. First, we analysed data by each medical condition across all treatment classes at two time points (immediately post-treatment and the first available follow-up). Second, we analysed data by each treatment class (cognitive behavioural therapy (CBT), family therapy (FT), problem solving therapy (PST) and multisystemic therapy (MST)) across all medical conditions at two time points (immediately post-treatment and the first available follow-up). We assessed treatment effectiveness on six possible outcomes: parent behaviour, parent mental health, child behaviour/disability, child mental health, child symptoms and family functioning.

MAIN RESULTS

Across all treatment types, psychological therapies that included parents significantly improved child symptoms for painful conditions immediately post-treatment. Across all medical conditions, cognitive behavioural therapy (CBT) significantly improved child symptoms and problem solving therapy significantly improved parent behaviour and parent mental health immediately post-treatment. There were no other effects at post-treatment or follow-up. The risk of bias of included studies is described.

AUTHORS' CONCLUSIONS

There is no evidence on the effectiveness of psychological therapies that include parents in most outcome domains of functioning, for a large number of common chronic illnesses in children. There is good evidence for the effectiveness of including parents in psychological therapies that reduce pain in children with painful conditions. There is also good evidence for the effectiveness of CBT that includes parents for improving the primary symptom complaints when available data were included from chronic illness conditions. Finally, there is good evidence for the effectiveness of problem solving therapy delivered to parents on improving parent problem solving skills and parent mental health. All effects are immediately post-treatment. There are no significant findings for any treatment effects in any condition at follow-up.

The Interruptive Effect of Pain on Attention

Pain is known to disrupt attentional performance in both healthy adults and patients with chronic pain. Exactly which aspects of attentional function are affected are, however, still to be determined. The primary aim of this investigation was to systematically examine the effects of experimentally induced pain on a range of attentional performance tasks. Following a review of tests of attentional disruption, seven best candidate tasks were selected and examined across seven experiments. The tasks were: continuous performance, flanker, endogenous precueing, n-back, inhibition, attentional switching, and divided attention. Healthy adult participants performed each of these tasks under three different conditions: a painful heat sensation, a warm heat sensation, and a nonheat control. Pain differentially affected attentional performance across these tasks; pain-related attentional impairment was found on the n-back, attentional switching, and divided attention tasks, but not on the other tasks. This finding suggests that the aspects of attention most affected by pain are those essential for the completion of complex tasks that require the processing of multiple cues and control over attentional deployment. These results are discussed in the context of an emerging view of pain as a demand for executive control and the development of measures that could be used to examine attentional disruption in the context of pain.

A comparison of the relative utility of coping and acceptance-based measures in a sample of chronic pain sufferers

Previous research suggests that to define the problem of chronic pain as a problem of coping may not be as useful as framing it as a problem of acceptance for some patients. The coping approach may encourage, or at least permit, a somewhat inflexible agenda of pain reduction or control while the acceptance approach may allow a more flexible agenda of willingness to have pain in some circumstances where that serves the goal of better life functioning. The purpose of this study was to continue to examine the relative utility of concepts of coping and acceptance of pain. Two hundred and thirty consecutive patients seeking assessment from a pain management service were the participants in the study. Patients completed the Coping Strategies Questionnaire (CSQ) and the Chronic Pain Acceptance Questionnaire (CPAQ). A revised scoring method was used for the CSQ (to correct for technical limitations noted in the past) and recently developed subscales of the CPAQ were examined. Correlation results showed that the acceptance variables were reliably stronger predictors of distress and disability compared with coping variables. Regression analyses confirmed that, compared with coping variables, acceptance accounted larger unique increments in variance in measures of patient functioning regardless of whether the coping variables were given priority in the regression equations. Increasing data support the view that the pain management field may benefit from evolving toward incorporating a less control-oriented and more accommodating view of aversive private experiences in some circumstances.