Attentional Biases Toward Sensory Pain Words in Acute and Chronic Pain Patients

Attentional biases towards pain-related words of chronic and acute low back pain (LBP) patients were compared with healthy pain-free controls. Specifically, the aims were to determine: 1) whether chronic LBP patients demonstrate attentional biases compared to pain-free controls; 2) whether observed biases are also present in those with acute LBP; and 3) whether observed biases are associated with pain-related fear among the pain groups. Four groups were recruited: 1) acute LBP patients; 2) chronic LBP patients from physiotherapy practices; 3) chronic LBP patients from a tertiary referral pain-management center; and 4) healthy pain-free controls. Participants were assessed on the dot-probe computer task for attentional bias to pain-related words. All 3 pain groups demonstrated biases compared to controls on sensory but not on affective, disability, or threat words. Among the pain groups, those with low and moderate levels of fear of (re)injury demonstrated biases towards sensory pain words that were absent in those with high levels of fear, which is counterintuitive to what the fear of (re)injury model suggests. These results suggest that the experience of pain, rather than duration, is the primary indicator of the presence of pain-related biases.     

Attentional and emotional mechanisms related to pain as predictors of chronic postoperative pain: A comparison with other psychological and physiological predictors

The present prospective longitudinal study on chronic postoperative pain was conducted to assess the predictive power of attentional and emotional variables specifically assumed to augment pain, such as pain hypervigilance, pain-related anxiety, pain catastrophizing and attentional biases to pain. Their relevance was determined in comparison with other psychological and physiological predictors (depression, anxiety, somatization, cortisol reactivity, pain sensitivity). In 84 young male patients the predictor variables were assessed one day before surgery (correction of chest malformation). Postoperative outcome (subjective pain intensity and pain-related disability) was assessed three (N = 84) and six months (N = 78) after surgery. Patients were classified into good and poor outcome groups. Patients with high pain intensity three (25%) or six months (14%) after surgery, differed significantly from those low in pain with regard to their preoperative performance in the dot-probe task (high attentional bias towards positive words). A sizeable portion (54%) of patients still felt disabled due to pain after three months and a few patients after six months (13%). These patients were those with high preoperative ratings in the Pain Vigilance and Awareness Questionnaire. The few subjectively disabled patients after six months could be identified in addition by low pressure pain and high cold pain thresholds before surgery. An attentional bias towards positive stimuli prior to surgery may indicate a maladaptive coping style, which avoids necessary confrontation with pain and predisposes patients to chronic postoperative pain. Lasting subjectively felt pain-related disability occurs predominantly in patients with high levels of pain hypervigilance before surgery.     

The predictive value of attentional bias towards pain-related information in chronic pain patients: A diary study

Theoretical accounts of chronic pain hypothesize that attentional bias towards pain-related information is a maintaining or exacerbating factor, fuelling further pain, disability, and distress. However, empirical research testing this idea is currently lacking. In the present study, we investigated whether attentional bias towards pain-related information predicts daily pain-related outcomes in a sample of chronic pain patients (n = 69; M_age = 49.64 years; 46 females). During an initial laboratory session, attentional bias to pain-related information was assessed using a modified spatial cueing task. In advance, patients completed a number of self-report measures assessing current pain intensity, current disability, and pain duration. Subsequently, daily pain outcomes (self-reported pain severity, disability, avoidance behaviour, and distractibility) were measured for 2 weeks by means of an electronic diary. Results indicated that, although an attentional bias towards pain-related information was associated with the current level of disability and pain severity, it had no additional value above control variables in predicting daily pain severity, avoidance, distractibility, and disability. Attentional bias towards pain-related information did, however, moderate the relationship between daily pain severity and both daily disability and distractibility, indicating that, particularly in those patients with a strong attentional bias, increases in pain were associated with increased disability and distractibility. The use of interventions that diminish attentional bias may therefore be helpful to reduce daily disability and the level of distraction from current tasks despite the presence of pain in chronic pain patients.     

Attentional bias to pain-related information: A meta-analysis

This meta-analysis investigated whether attentional bias, that is, the preferential allocation of attention to information that is related to pain, is a ubiquitous phenomenon. We also investigated whether attentional bias effects are related to the methodological quality of the study, to procedural differences in their measurement, or to individual differences in pain severity, pain-related fear, anxiety, and depression. Results indicated that individuals who experience chronic pain (n = 1023) display an attentional bias towards pain-related words or pictures, but this bias was of a small effect size (d = 0.134), and did not differ from that in control groups (d = 0.082; n = 1398). No evidence was found for an attentional bias towards pain-related words and pictures for acute pain (d = 0.049), procedural pain (d = 0.142), and experimental pain (d = 0.069). However, research in which attentional bias towards signals of impending experimental pain in healthy volunteers was investigated, revealed an attentional bias of medium effect size (d = 0.676). Moderator analyses in the chronic pain group identified important procedural variables that affected the presence and magnitude of an attentional bias towards pain-related words and pictures, that is, type and exposure time of pain-related information. None of the individual difference variables affected the magnitude of the attentional bias. Implications of current findings and future directions are discussed.     

Relationship between physical activity and disability in low back pain: a systematic review and meta-analysis

It is often assumed that patients with pain-related disability due to low back pain (LBP) will have reduced physical activity levels, but recent studies have provided results that challenge this assumption. The aim of our systematic review was to examine the relationship between physical activity and disability in LBP. The literature search included 6 electronic databases and the reference list of relevant systematic reviews and studies to May 2010. To be included, studies had to measure both disability (eg, with the Roland Morris Disability Questionnaire) and physical activity (eg, by accelerometry) in patients with non-specific LBP. Two independent reviewers screened search results and extracted data, and authors were contacted for additional data. Correlation coefficients were pooled using the random-effects model. The search identified 3213 records and 18 studies were eligible for inclusion. The pooled results showed a weak relationship between physical activity and disability in acute or subacute (<3 months) LBP (r = −0.08, 95% confidence interval = −0.17 to 0.002), and a moderate and negative relationship in chronic (>3 months) LBP (r = −0.33, 95% confidence interval = −0.51 to −0.15). That is, persons with acute or subacute LBP appear to vary in the levels of physical activity independent of their pain-related disability. Persons with chronic LBP with high levels of disability are also likely to have low levels of physical activity.     

Modification of attentional biases in chronic pain patients: a preliminary study

Research suggests that chronic pain patients demonstrate cognitive biases towards pain-related information and that such biases predict patient functioning. This study examined the degree to which a successful cognitive-behavioural program was able to reduce the observed attentional bias towards sensory pain words. Forty-two patients with chronic pain conditions for more than three months were recruited prior to commencing a cognitive-behavioural pain management program. Participants were assessed before the program, after the program and at one-month follow-up. Results confirmed that chronic pain patients exhibited biased attention towards sensory pain-related words at pre-treatment. These biases were still evident at post-treatment, but were no longer statistically significant at follow-up. Multiple regression analyses indicated that the changes in attentional bias towards sensory words between post-treatment and follow-up were predicted by pre- to post-treatment changes in fear of movement (Tampa Scale for Kinesiophobia) but not other relevant variables, such fear of pain or anxiety sensitivity. These results demonstrate that successful cognitive-behavioural treatments can reduce selective attention, thought to be indicative of hypervigilance towards pain. Moreover, these biases appear to be changed by reducing the fear associated with movement. Theoretically, these results provide support for the fear of (re)injury model of pain. Clinically, this study supports the contention that fear of (re)injury and movement is an appropriate target of pain management and that reducing these fears causes patients to attend less to pain-related stimuli.     

Time-course of attentional bias for pain-related cues in chronic daily headache sufferers

This study investigated attentional biases for linguistic pain-related stimuli in individuals suffering from chronic headaches and healthy controls. Attentional bias was assessed using a visual probe (also reported as dot probe in previous investigations) task which presented pain-related (sensory and affective) and neutral words at two exposure duration conditions, 500 and 1250 ms. The results indicated that individuals suffering from chronic headaches showed a significantly greater attentional bias at 1250 ms compared to the controls, which indicates a bias in maintained attention to pain cues in this group. No significant differences between groups were found in attentional bias scores at the shorter stimulus duration of 500 ms, which instead correlated significantly with trait anxiety. Results are discussed in relation to research into pain-related and anxiety-related biases in initial orienting and maintained attention.     

Efficacy and safety of tanezumab in the treatment of chronic low back pain

Increased nerve growth factor levels are associated with chronic pain conditions, including chronic low back pain (LBP). This study examined safety and analgesic efficacy of tanezumab, a humanized anti-nerve growth factor antibody, in adults with chronic LBP. Patients received intravenous tanezumab 200 μg/kg plus oral placebo (n = 88), intravenous placebo plus oral naproxen 500 mg twice a day (n = 88), or intravenous placebo plus oral placebo (n = 41). Primary outcome was average LBP intensity (aLBPI) at Week 6. Secondary outcomes were proportion of patients with ?30% or ?50% reduction in aLBPI, Roland-Morris Disability Questionnaire and Brief Pain Inventory-short form scores, Patients’ Global Assessment of LBP, Patients’ Global Evaluation of study medication, and rescue medication use. Mean aLBPI change from baseline to Week 6 was greater with tanezumab vs naproxen (P = 0.004) and placebo (P < 0.001). Greater proportions of patients reported ?30% and ?50% reduction in aLBPI with tanezumab vs naproxen (P ? 0.013) and placebo (P < 0.001), and greater improvements in Roland-Morris Disability Questionnaire (P < 0.001) and other secondary outcomes except rescue medication use. Tanezumab was associated with adverse events (AEs) of abnormal peripheral sensation that were generally mild and resolved before study completion; however, there were no serious AEs. Nine patients (4 of whom were tanezumab-treated) discontinued due to AEs. In conclusion, tanezumab resulted in analgesic efficacy that was clinically and statistically superior to placebo and naproxen in patients with chronic LBP. Tanezumab clinical development is on regulatory hold due to AEs in osteoarthritis patients.     

Attentional bias to pain and social threat in pediatric patients with functional abdominal pain and pain-free youth before and after performance evaluation

This study investigated attentional biases for pain and social threat versus neutral stimuli in 54 youth with functional abdominal pain (FAP) and 53 healthy control subjects (ages 10 to 16 years). We assessed attentional bias using a visual probe detection task (PDT) that presented pain and social threat words in comparison to neutral words at conscious (1250 ms) and preconscious (20 ms) presentation rates. We administered the PDT before and after random assignment of participants to a laboratory stressor—failure versus success feedback regarding their performance on a challenging computer game. All analyses controlled for trait anxiety. At the conscious rate of stimulus presentation, FAP patients exhibited preferential attention toward pain compared with neutral stimuli and compared with the control group. FAP patients maintained preferential attention toward conscious pain stimuli after performance feedback in both failure and success conditions. At the preconscious rate of stimulus presentation, FAP patients’ attention was neutral at baseline but increased significantly toward pain stimuli after performance feedback in both failure and success conditions. FAP patients’ somatic symptoms increased in both failure and success conditions; control youth’s somatic symptoms only increased after failure. Regarding social threat, neither FAP nor control youth exhibited attentional bias toward social threat compared with neutral stimuli at baseline, but both FAP and control youth in the failure condition significantly increased attention away from social threat after failure feedback. Results suggest that FAP patients preferentially attend to pain stimuli in conscious awareness. Moreover, performance evaluation may activate their preconscious attention to pain stimuli.     

Are prognostic indicators for poor outcome different for acute and chronic low back pain consulters in primary care?

Few studies have investigated whether prognostic indicators, which contribute to the transition from acute to chronic low back pain (LBP), are also those which contribute to continuing persistence of chronic LBP. We compared the contribution of physical, psychological and social indicators to predicting disability after one year between consulters with LBP of less than 3 months duration and more than 3 months duration. Data from two large prospective cohort studies of consecutive patients consulting with LBP in general practices were merged, providing complete data for 258 cases with acute/subacute LBP and 668 cases with chronic LBP at 12 months follow-up. There were significant differences between the two LBP groups in baseline characteristics and clinical course of disability, assessed by Roland Morris Disability Questionnaire, during the year of follow-up. Adjusted associations between potential prognostic indicators and disability at 12 months were carried out in the two LBP subgroups. The final multivariable regression models showed that being non-employed, having widespread pain, a high level of Chronic Pain Grade, and catastrophising were the strongest prognostic indicators for disability at 12 months in both LBP groups. Fear of pain was significantly associated with disability in chronic LBP. Importantly, beyond baseline disability, the effect size of the other prognostic indicators for poor outcome was rather low. These findings must continue to challenge researchers to identify useful early predictors of outcome in persons with disabling back pain, as screening and targeted treatment approaches are dependent upon prognostic indicators with clinical significance.     

Diagnostic uncertainty and recall bias in chronic low back pain

Patients’ beliefs about the origin of their pain and their cognitive processing of pain-related information have both been shown to be associated with poorer prognosis in low back pain (LBP), but the relationship between specific beliefs and specific cognitive processes is not known. The aim of this study was to examine the relationship between diagnostic uncertainty and recall bias in 2 groups of chronic LBP patients, those who were certain about their diagnosis and those who believed that their pain was due to an undiagnosed problem. Patients (N = 68) endorsed and subsequently recalled pain, illness, depression, and neutral stimuli. They also provided measures of pain, diagnostic status, mood, and disability. Both groups exhibited a recall bias for pain stimuli, but only the group with diagnostic uncertainty also displayed a recall bias for illness-related stimuli. This bias remained after controlling for depression and disability. Sensitivity analyses using grouping by diagnosis/explanation received supported these findings. Higher levels of depression and disability were found in the group with diagnostic uncertainty, but levels of pain intensity did not differ between the groups. Although the methodology does not provide information on causality, the results provide evidence for a relationship between diagnostic uncertainty and recall bias for negative health-related stimuli in chronic LBP patients.     

The emotional stroop task and chronic pain: what is threatening for chronic pain sufferers?

Using a computer version of the emotional stroop task, it was investigated whether chronic pain patients display an involuntary attentional shift towards pain-related information (sensory, affective pain words and injury related words). Multiple regression analyses were used to investigate which pain and psychosocial variables (pain severity, pain-related fear, pain catastrophizing and negative affect) were predictive of attentional bias. Results indicated: (1) that there was an attentional bias towards the sensory pain words; and (2) that current pain intensity was predictive of the effect. No other attentional effects were found. The results are discussed in terms of possible reasons for the difficulty of demonstrating attentional bias in chronic pain patients.     

Brain white matter structural properties predict transition to chronic pain

Neural mechanisms mediating the transition from acute to chronic pain remain largely unknown. In a longitudinal brain imaging study, we followed up patients with a single sub-acute back pain (SBP) episode for more than 1 year as their pain recovered (SBPr), or persisted (SBPp) representing a transition to chronic pain. We discovered brain white matter structural abnormalities (n = 24 SBP patients; SBPp = 12 and SBPr = 12), as measured by diffusion tensor imaging (DTI), at entry into the study in SBPp in comparison to SBPr. These white matter fractional anisotropy (FA) differences accurately predicted pain persistence over the next year, which was validated in a second cohort (n = 22 SBP patients; SBPp = 11 and SBPr = 11), and showed no further alterations over a 1-year period. Tractography analysis indicated that abnormal regional FA was linked to differential structural connectivity to medial vs lateral prefrontal cortex. Local FA was correlated with functional connectivity between medial prefrontal cortex and nucleus accumbens in SBPr. As we have earlier shown that the latter functional connectivity accurately predicts transition to chronic pain, we can conclude that brain structural differences, most likely existing before the back pain–inciting event and independent of the back pain, predispose subjects to pain chronification.     

Optimizing prediction of back pain outcomes

An accurate means of identifying patients at high risk for chronic disabling pain could lead to more cost-effective care, with more intensive interventions targeted to those likely to benefit most. The Chronic Pain Risk Score is a tool developed to predict risk for chronic pain. The aim of this study was to examine whether its predictive ability could be enhanced by: (1) improved measures of the constructs it assesses (Improved Chronic Pain Risk Model); and (2) adding other predictors (Expanded Chronic Pain Risk Model). Patients initiating primary care for back pain (N = 571) completed measures used in the Chronic Pain Risk Score, Improved Model, and Expanded Model, then completed the Graded Chronic Pain Scale (GCPS) 4 months later (n = 521; 91% response rate). In predicting 4-month GCPS grade III or IV (moderate or severe pain-related activity interference), the Improved Model performed better than did the Chronic Pain Risk Score (Net Reclassification Index [NRI] = 0.32, P = 0.003). The Expanded Model improved significantly on the prediction of the Improved Model (NRI = 0.56, P < 0.001) and demonstrated excellent discriminative ability (AUC = 0.84, 95% CI = 0.79-0.88). The Improved Model (AUC = 0.79, 95% CI = 0.75-0.84) and the Chronic Pain Risk Score (AUC = 0.76, 95% CI = 0.71-0.81) showed acceptable discriminative ability. A limited set of measures may be used to predict risk for future clinically significant pain in patients initiating primary care for back pain, but further evaluation of prognostic models is needed.     

Do main caregivers selectively attend to pain-related stimuli in the same way that patients do?

Despite increasing interest in the attentional biases of pain patients towards pain-related stimuli, there have been no investigations of whether the main caregivers of chronic pain patients also selectively attend to pain-related information. We compared the attentional biases to painful or happy faces of 120 chronic pain patients, 118 caregivers, and 50 controls. Analyses found that both patients and caregivers demonstrated biases towards painful faces that were not observed in control participants or to happy faces. Those patients and caregivers who were high in fear of pain demonstrated greater biases than those low in fear of pain, and the biases of the high-in-fear-of-pain group differed significantly from zero. When sub-groups of caregivers were compared, it was found that biases towards painful faces were not observed for those caregivers who accurately identified the level of pain the patient currently reported. In contrast, those caregivers who overestimated or underestimated the patients’ pain demonstrated biases that were significantly greater than zero. These results add to the growing weight of evidence suggesting that biases towards pain-related stimuli are observed in chronic pain patients, but that the nature of the stimuli is important. In addition, the results suggest that caregivers, particularly those who either under- or overestimate the level of pain that the patient reports, also demonstrate similar biases. Future research should investigate the links between caregivers’ biases and the way in which caregivers respond to pain.     

Attentional and Interpretational Biases Toward Pain-Related Stimuli in Children and Adolescents: ASystematic Review of the Evidence

This review investigated whether youth exhibit attention or interpretation biases toward pain-related information and whether such biases are more pronounced in youth with chronic pain. Three databases were searched to identify studies that assessed attention or interpretation biases using an accepted experimental paradigm. Ten studies were identified, 8 examining attentional biases and 2 examining interpretation biases. As in the adult literature, there was no evidence of attentional biases toward pain in youth without chronic pain. Three studies investigating youth without chronic pain found evidence for relationships between catastrophizing or anxiety and indicators of vigilance or avoidance (in 2 cases, for youth with low self-reported attentional control). For attentional biases, 5 studies compared youth with and without chronic pain. Two of these studies measured cortical correlates and found evidence of neurologic activity indicating a bias in orienting to pain-related stimuli. Three studies examined biases toward pain-related words or pictures. Of those, 2 found evidence of biases at subliminal presentation times, indicating vigilance (although 1 only after a stressful task). For supraliminal presentations, 1 study found evidence of avoidance, one of difficulty disengaging, and one of general slowing of responses. Only 1 study compared youth with and without pain for interpretation bias in adolescents, and interpretation biases were greater for youth with chronic pain. As with attention, no evidence for interpretation biases were found in youth without chronic pain. Overall, there is weak evidence to support vigilance in youth with chronic pain compared with those without. However, whether pain affects the subsequent deployment of attention is unclear. There is no evidence for biases toward pain in youth without chronic pain, but evidence suggests that anxiety or catastrophizing and attentional control may moderate pain-related attentional biases. There is also weak evidence of interpretation bias in youth with chronic pain compared with those without.

Chronic pain in the Republic of Ireland--community prevalence, psychosocial profile and predictors of pain-related disability: results from the Prevalence, Impact and Cost of Chronic Pain (PRIME) study, part 1

The aims of the PRIME study (Prevalence, Impact and Cost of Chronic Pain) were 3-fold: (1) to determine the point prevalence of chronic pain in Ireland; (2) to compare the psychological and physical health profiles of those with and without chronic pain; and (3) to explore a predictive model of pain-related disability. A postal survey of 3136 people was conducted with a representative community-based sample of adults. Measures were obtained for sociodemographic variables, physical and psychological well-being, depressive symptoms, presence of pain, pain severity, pain-related disability, and illness perceptions. Responses were received from 1204 people. The prevalence of chronic pain was 35.5% (95% CI = 32.8-38.2) (n = 428). No gender difference in prevalence was found. Prevalence of pain increased with age and was associated with manual employment. The most commonly reported site of pain was the lower back (47.6%); however, multiple pain sites was the norm, with more than 80% of participants reporting more than 1 pain site. Approximately 12% of participants were unable to work or were on reduced work hours because of pain. Of those with chronic pain, 15% met the criteria for clinically relevant depression compared with 2.8% of those without pain. A multiple regression analysis, predicting 67% of variance, showed that pain intensity was the strongest predictor of pain-related disability. Depression and illness perceptions were also predictive of pain-related disability, after controlling for the effects of pain intensity. Chronic pain is a prevalent health problem in Ireland and is associated with significant psychological and functional disability. Psychological factors appear to influence the level of pain-related disability.     

Randomized trial of a DVD intervention to improve readiness to self-manage joint pain

A DVD (digital video disk) intervention to increase readiness to self-manage joint pain secondary to hemophilia was informed by a 2-phase, motivational-volitional model of readiness to self-manage pain, and featured the personal experiences of individuals with hemophilia. The DVD was evaluated in a randomized controlled trial in which 108 men with hemophilia completed measures of readiness to self-manage pain (Pain Stages of Change Questionnaire) before and 6 months after receiving the DVD plus information booklet (n = 57) or just the booklet (n = 51). The effect of the DVD was assessed by comparing changes in Pain Stages of Change Questionnaire scores (precontemplation, contemplation, and action/maintenance) between groups. The impact on pain coping, pain acceptance, and health-related quality of life was tested in secondary analyses. Repeated-measures analysis of variance, including all those with complete baseline and follow-up data regardless of use of the intervention, showed a significant, medium-sized, group × time effect on precontemplation, with reductions among the DVD group but not the booklet group. Significant use × time effects showed that benefits in terms of contemplation and action/maintenance were restricted to those who used the interventions at least once. The results show that low-intensity interventions in DVD format can improve the motivational impact of written information, and could be used to help prepare people with chronic pain for more intensive self-management interventions. The findings are consistent with a 2-phase, motivational-volitional model of pain self-management, and provide the first insights to our knowledge of readiness to self-manage pain in hemophilia.     

Associations between daily chronic pain intensity,daily anger expression,and trait anger expressiveness: An ecological momentary assessment study

Links between elevated trait anger expressiveness (anger-out) and greater chronic pain intensity are well documented, but pain-related effects of expressive behaviors actually used to regulate anger when it is experienced have been little explored. This study used ecological momentary assessment methods to explore prospective associations between daily behavioral anger expression and daily chronic pain intensity. Forty-eight chronic low back pain (LBP) patients and 36 healthy controls completed electronic diary ratings of momentary pain and behavioral anger expression in response to random prompts 4 times daily for 7 days. Across groups, greater trait anger-out was associated with greater daily behavioral anger expression (P < 0.001). LBP participants showed higher levels of daily anger expression than controls (P < 0.001). Generalized estimating equation analyses in the LBP group revealed a lagged main effect of greater behavioral anger expression on increased chronic pain intensity in the subsequent assessment period (P < 0.05). Examination of a trait × situation model for anger-out revealed prospective associations between elevated chronic pain intensity and later increases in behavioral anger expression that were restricted largely to individuals low in trait anger-out (P < 0.001). Trait × situation interactions for trait anger suppression (anger-in) indicated similar influences of pain intensity on subsequent behavioral anger expression occurring among low anger-in persons (P < 0.001). Overlap with trait and state negative affect did not account for study findings. This study for the first time documents lagged within-day influences of behavioral anger expression on subsequent chronic pain intensity. Trait anger regulation style may moderate associations between behavioral anger expression and chronic pain intensity.