Pain expectations in neuropathic pain: Is it best to be optimistic?

BACKGROUND: Pain expectancy may be an important variable that has been found to influence the effectiveness of treatments for pain. Much of the literature supports a self-fulfilment perspective where expectations for pain relief predict the actual pain experienced. However, in conditions such as neuropathic pain (NeP) where pain relief is difficult to attain, expectations for pain relief could be unrealistic. The objective of this study was to investigate the relationship between realistic/unrealistic expectations and 6-month, post-treatment outcomes. METHODS: We performed a retrospective analysis of a large cohort of patients with NeP (n = 789) attending tertiary care centres to determine the association between unrealistic (both positive and negative) and realistic expectations with outcomes after multidisciplinary treatment. An expectation variable with three categories was calculated: realistic expectations were those whose expected reduction in pain was similar to the observed mean group reduction in pain, while optimistic and pessimistic expectations were those who over- or under-estimated the expected response to treatment, respectively. The association between baseline realistic/unrealistic expectations and 6-month pain-related disability, catastrophizing and psychological distress was assessed. RESULTS: Univariable analyses suggested that realistic expectations were associated with lower levels of disability, catastrophizing and psychological distress, compared to unrealistic expectations. However, after adjustment for baseline symptom severity, multivariable analysis revealed that patients with optimistic expectations had lower levels of disability, than those with realistic expectations. Those with pessimistic expectations had higher levels of catastrophizing and psychological distress at follow-up. CONCLUSIONS: These findings are largely congruent with the self-fulfilment perspective to expectations. SIGNIFICANCE: This study defined realistic pain expectations with patient data. Examining the relationship between expectations between pain and disability in a large cohort of patients with neuropathic pain.

The effect of pain on involuntary and voluntary capture of attention.

BACKGROUND: There is converging evidence for the notion that pain affects a broad range of attentional domains. This study investigated the influence of pain on the involuntary capture of attention as indexed by the P3a component in the event-related potential derived from the electroencephalogram. METHODS: Participants performed in an auditory oddball task in a pain-free and a pain condition during which they submerged a hand in cold water. Novel, infrequent and unexpected auditory stimuli were presented randomly in a series of frequent standard and infrequent target tones. P3a and P3b amplitudes were observed to novel, unexpected and target-related stimuli, respectively. RESULTS: Both electrophysiological components were characterized by reduced amplitudes in the pain compared with the pain-free condition. Hit rate and reaction time to target stimuli did not differ between the two conditions presumably because the experimental task was not difficult enough to exceed attentional capacities under pain conditions. CONCLUSIONS: These results indicate that voluntary attention serving the maintenance and control of ongoing information processing (reflected by the P3b amplitude) is impaired by pain. In addition, the involuntary capture of attention and orientation to novel, unexpected information (measured by the P3a) is also impaired by pain. Thus, neurophysiological measures examined in this study support the theoretical positions proposing that pain can reduce attentional processing capacity. These findings have potentially important implications at the theoretical level for our understanding of the interplay of pain and cognition, and at the therapeutic level for the clinical treatment of individuals experiencing ongoing pain.

Development and psychometric evaluation of a new measure of pain-related support preferences: the Pain Response Preference Questionnaire.

BACKGROUND: Behavioural conceptualizations of chronic pain posit that solicitous responses to pain behaviours are positively reinforcing and play a role in the development of chronic pain and disability. Recent research suggests that studies investigating this model were likely limited by the use of only a few narrowly defined categories of responses to pain behaviour. A measure of preferences regarding pain-related social support has the potential to improve behavioural models of chronic pain by identifying other potentially reinforcing responses to pain behaviour. OBJECTIVE: The Pain Response Preference Questionnaire (PRPQ) was created to assess preferences regarding pain-related social support. The purpose of the present study was to empirically develop PRPQ scales and examine their psychometric properties. METHODS: A large university student sample (n=487) free of chronic pain completed the 39-item PRPQ. Factor analysis was applied to the data from the present sample to empirically develop PRPQ scales. Using a second student sample (n=87), relationships between the PRPQ scales and theoretically related measures were examined to evaluate the construct validity of the scales. Factor analysis supported four factors that reflected preferences for emotional and instrumental support, assistance in managing pain and emotions, having one's pain ignored, and being encouraged to persist with one's activities. Based on this analysis, scales labelled solicitude, management, suppression and encouragement were created. Correlation analyses supported the construct validity of these scales. CONCLUSIONS: The PRPQ is a psychometrically sound measure of preferences of pain-related social support. Research with clinical samples is needed to further evaluate its psychometric properties and clinical utility.

Factors associated with chronic noncancer pain in the Canadian population.

Chronic noncancer pain (CNCP) is a prevalent health problem with pervasive negative effects on the individual's quality of life. Previous epidemiological studies of CNCP have suggested a number of individual biological, psychological and societal correlates of CNCP, but it has rarely been possible to simultaneously compare the relative strengths of many such correlates in a Canadian population sample. With data provided by the 1996/1997 Canadian National Population Health Survey, ordinal logistic regression was used to examine the extent to which a number of population variables are associated with CNCP in a large (n=69,365) dataset. The analysis revealed cross-sectional correlations of varying strengths between CNCP and 27 factors. Increasing age, low income, low educational achievement, daily cigarette smoking, physical inactivity and abstention from alcohol were among the factors found to increase CNCP risk. The considerable impact of distress and depression on CNCP are also highlighted. A number of comorbid medical illnesses increased CNCP risk, including some (such as chronic obstructive pulmonary disease, epilepsy and thyroid disease) that have not hitherto been associated with pain. White race and the affirmation of an important role for spirituality or faith reduced CNCP risk. In contrast to some previous studies, female sex did not emerge as an independent CNCP risk. The present exploratory analysis describes associations between CNCP and a number of characteristics from several domains, thus suggesting many areas for further research.

The disruptive effect of chronic pain on mismatch negativity.

OBJECTIVE: To investigate the effect of chronic pain on processes that generate the mismatch negativity (MMN). METHODS: Twelve participants with a diagnosis of chronic intractable pain were tested before and after pain treatment. During testing, event-related potentials were recorded while participants performed tasks of varying difficulty. RESULTS: The amplitude of the MMN was found to be greater following a nerve block procedure compared to MMN amplitude when participants were experiencing chronic pain. This effect was found to occur in the MMN for difficult-to-detect tones elicited while participants were performing a simultaneous cognitively demanding visual task. MMN amplitude was found to be greater with attention to difficult-to-detect deviants during pain but not in no pain conditions. CONCLUSIONS: These results provide an electrophysiological correlate of previous findings that high levels of pain disrupt cognition during the performance of demanding tasks.