The journal of pain : official journal of the American Pain Society
-
SCN9A is a key player in various rare monogenic pain disorders, including absence of pain or extreme pain, indicating that SCN9A is critical in human pain perception. This study aimed to investigate the association between the single-nucleotide polymorphisms (SNPs) in SCN9A and basal pain sensitivity variability in the general population. We used a combined tag and candidate SNP approach to explore possible associations between SCN9A SNPs and basal pain sensitivity in 309 healthy female Chinese undergraduates. Mechanical and heat pain sensitivity were measured, and a total of 28 SNPs were included in the final correlation analysis. Four candidate SNPs (rs6746030, rs7595255, rs12622743, and rs11898284) and 10 tag SNPs were associated (P < .05) with different pain perception phenotypes and exhibited opposite effects, resulting in either hypersensitivity or hyposensitivity. Furthermore, of all these SNPs, rs16851778 showed the strongest significant (P = .003) association with lower mechanical pain sensitivity, which was strengthened in a subsequent replication sample with 260 young patients scheduled for elective gynecological surgery. These findings provided evidence that the variability of basal pain sensitivity was associated with SCN9A polymorphisms in the general population. ⋯ This study demonstrated that several candidate and tag SCN9A SNPs were associated with hypersensitivity or hyposensitivity to basal experimental pain stimulation. Moreover, we identified a novel SNP, i,e,, rs16851778, that was associated with lower mechanical pain sensitivity and that was strengthened in a subsequent replication sample.
-
Self-report, the most widely used, gold standard measurement of pain, is crucial for pain research, diagnosis, and management. However, there are no accurate, reliable methods for detecting dishonesty in self-reports when there is incentive for pain deception. We introduce a novel approach to detecting pain deception by analyzing performance patterns of honest and dishonest psychophysical pain testing. Warmth sensation threshold (WST) and heat pain threshold (HPT) were measured in healthy individuals (N = 37) under 2 conditions: standard instruction (ie, provide sincere reports) and instructions to simulate intense pain (i.e., provide feigned reports) with the intention of deceiving. In the feigned compared with sincere condition, participants had significantly increased WST and decreased HPT. Repeatability and variability indices were indistinguishable between conditions. In a second, separate cohort (N = 24), measurements were repeated with the addition of a sensory interference to influence task performance. When sensory interference during HPT measurement was introduced, feigned pain reports had significantly higher variability and poorer repeatability compared with sincere reports and were distinguishable from sincere reports, with high sensitivity (83%) and specificity (84%). The statistical properties of psychophysical performance under sensory interference provide a method for identifying feigned performance and could be applied to evaluations of pain malingering. ⋯ This article introduces a method to detect whether individuals are being dishonest in psychophysical pain testing. The method could help clinicians to detect chronic pain malingering in contexts in which there is incentive to deceive.
-
There is little information regarding changes in placebo responsiveness with age, although first predictors of placebo responders such as psychological and physiological processes have been identified. Reviews and meta-analyses indicate that placebo response rates in randomized controlled trials (RCTs) are higher in children and adolescents compared with adults. As these studies cannot control for age-dependent differences in the natural course of the disease, biases might contribute to different placebo rates in RCTs. To avoid these biases, this study investigated age-related differences in placebo responsiveness between children and adults in a well-established experimental model of placebo analgesia combining classic conditioning and expectation. Our data confirm placebo analgesic responses in children, which did not differ in magnitude from those of adults. The influence of previous experience on subsequent treatment outcome was stronger in children than in adults, indicating an increased relevance of learning processes for treatment outcomes in children. Further studies are needed to understand the influence of treatment-related learning processes in children and adolescents, which might critically determine treatment responsiveness during adulthood. ⋯ This study is the first to experimentally explore placebo analgesia and influences of previous experience on placebo responses in children compared with adults. We found comparable placebo responses in both groups and an increased relevance of learning processes for treatment outcomes in children.
-
Data on the tolerability of opioids in patients with cancer-related pain are limited. Here, we report a systematic review that includes all published prospective studies reporting adverse events (AEs) of morphine, oxycodone, fentanyl, methadone, or hydromorphone for cancer-related pain in patients naive for these opioids. We included 25 studies describing 31 treatment cohorts, made an overview of study characteristics, and reported rates of AEs per type of opioid. The frequency of the most commonly reported AEs varied widely: nausea from 3 to 85%, vomiting from 4 to 50%, constipation from 5 to 97%, drowsiness from 3 to 88%, and dry mouth from 1 to 94%. There was a large heterogeneity among included studies, especially regarding the assessment and reporting of AEs. We describe how differences in assessment and reporting influence outcome rates. Although AEs are an important issue in daily clinical practice, realistic incidence rates of AEs per type of opioid are unknown because of the immense heterogeneity among studies. ⋯ Although opioid-related adverse events are an important issue when treating cancer-related pain, realistic rates of adverse events per type of opioid are unknown because of immense heterogeneity among studies and lack of systematic assessment and reporting. There is an urgent need for studies with standardized outcome measures and reporting.
-
Validation of the Hospital Anxiety and Depression Scale (HADS) in Patients with Acute Low Back Pain.
The Hospital Anxiety and Depression Scale (HADS) is a self-report instrument used to evaluate depression and anxiety in clinical research. The HADS has advantages over other assessments of anxiety and depression; it is efficient in assessing both anxiety and depression with a total of 14 items, and it was originally developed on a general medical rather than psychiatric sample. However, the HADS has not been evaluated specifically for use in clinical trials of acute pain. Validation analyses were conducted on data from a randomized, double-blind, parallel-group study of tapentadol immediate release vs oxycodone immediate release for acute low back pain (N = 666). Analyses of psychometric properties, internal consistency, convergent validity, assessments of bias, and confirmatory factor analysis were conducted on pretreatment data. Additional analyses were performed to test the responsiveness and predictive validity of the HADS. Both the Anxiety and Depression subscales (1) showed good psychometric properties, (2) had high internal consistency, (3) displayed good convergent validity, (4) had no unexpected biases, (5) fit the a priori factor structure, and (6) were highly sensitive to changes as a result of analgesic treatment. We conclude that the HADS is a valid instrument for efficient, low-burden assessment of anxiety and depression in clinical trials with an acute low back pain population. ⋯ Considered together with the results of other recent studies, the data suggest that the HADS can provide a valid, responsive, and efficient assessment of anxiety and depression in acute low back pain for clinical trials and other clinical research examining acute pain populations.