The journal of pain : official journal of the American Pain Society
-
National Pain Strategy population research objectives include: estimating chronic pain prevalence, studying pain treatment with electronic health care data, and developing metrics to assess progress in reducing chronic pain impact. In this article, the National Pain Strategy Population Research Workgroup reviews concepts relevant to achieving these aims. High-impact chronic pain was defined as persistent pain with substantial restriction of life activities lasting 6 months or more. In pilot work, we tested a brief assessment of high-impact chronic pain, and used electronic health records data to describe pain-related health care. A mail survey of adult health plan enrollees (N = 770) reported that 14% had high-impact chronic pain. Relative to persons with lower-impact chronic pain, those with high-impact chronic pain were more often frequent users of health care for pain, reported lower quality of life, greater pain-related interference with activities, and more often reported pain at multiple anatomic locations. Analyses of health care data (N = 289,464) reported that pain patients had higher health care costs compared with others and that pain services were typically delivered in primary care. These results support the feasibility of developing data on chronic pain through national health interview surveys and large electronic health care databases. ⋯ Pilot analyses supported the feasibility of brief chronic pain assessments suitable for national health surveys and use of electronic health care databases to develop data regarding trends in the delivery of pain treatments, costs, and effectiveness. These methods are relevant to achieving the aims of the US National Pain Strategy.
-
Cav2.3 (R-type) voltage-activated Ca(2+) channels (VACCs), encoded by the calcium channel, voltage-dependent, R-type, α1E subunit (CACNA1E) gene, are responsible for transmission of somatic inflammatory pain, and activation of antinociception elicited by visceral inflammatory pain stimuli. Carriers of the minor G allele of the rs3845446 single-nucleotide polymorphism (SNP) of the CACNA1E gene reportedly exhibit a decrease in opioid requirements to control typical somatic inflammatory pain after orthognathic surgery (ie, a painful cosmetic surgery), suggesting the downregulation of Cav2.3 VACC function that is responsible for transmission of somatic inflammatory pain in these carriers. Gastrointestinal surgery involves somatic and visceral inflammatory pain, in which visceral inflammatory pain stimuli activate Cav2.3 VACC-mediated antinociception. Unknown is whether pain-related phenotypes after gastrointestinal surgery are affected in these carriers. The present study used a correlational design to examine the effect of the rs3845446 SNP on postoperative pain-related phenotypes in 2 groups of patients who underwent gastrointestinal surgery. Carriers of the minor G allele had greater opioid requirements after laparoscopic colectomy when intravenous patient-controlled analgesia was used, and reported higher pain scores after open gastrointestinal surgery when postoperative analgesia was managed with continuous epidural analgesia and rescue analgesics. These results suggest that pain-related phenotypes after gastrointestinal surgery are enhanced in carriers of the minor G allele of the rs3845446 SNP, possibly through impairment of Cav2.3 VACC function that is responsible for the activation of visceral inflammatory pain stimulus-elicited antinociception. ⋯ Carriers of the minor allele of the rs3845446 SNP of the CACNA1E gene required more opioid or reported higher pain scores after gastrointestinal surgery, and required less opioid after orthognathic surgery. The difference may result from the presence of visceral inflammatory pain stimulus that activates Cav2.3 VACCs-mediated antinociception.
-
Previous studies have provided evidence for pain-alleviating effects of segmental tactile stimulation, yet the effect of social touch and its underlying mechanism is still unexplored. Considering that the soma affects the way we think, feel, and interact with others, it has been proposed that touch may communicate emotions, including empathy, interacting with the identity of the toucher. Thus, the goal of the current study was to examine the analgesic effects of social touch, and to test the moderating role of the toucher's empathy in analgesia using an ecological paradigm. Tonic heat stimuli were administered to women. Concurrently, their partners either watched or touched their hands, a stranger touched their hands, or no one interacted with them. The results revealed diminished levels of pain during partners' touch compared with all other control conditions. Furthermore, taking into account the dyadic interaction, only during the touch condition we found 1) a significant relationship between the partners' pain ratings, and 2) a significant negative relationship between the male touchers' empathy and the pain experience of their female partners. The findings highlight the powerful analgesic effect of social touch and suggest that empathy between romantic partners may explain the pain-alleviating effects of social touch. ⋯ Pain research mostly concentrates on different factors around a single pain target, without taking into account various social interactions with the observers. Our findings support the idea that pain perception models should be extended, taking into account some psychological characteristics of observers. Our conclusions are on the basis of advanced statistical methods.
-
Randomized Controlled Trial
An Exploratory Human Laboratory Experiment Evaluating Vaporized Cannabis in the Treatment of Neuropathic Pain from Spinal Cord Injury and Disease.
Using 8-hour human laboratory experiments, we evaluated the analgesic efficacy of vaporized cannabis in patients with neuropathic pain related to injury or disease of the spinal cord, most of whom were experiencing pain despite traditional treatment. After obtaining baseline data, 42 participants underwent a standardized procedure for inhaling 4 puffs of vaporized cannabis containing either placebo, 2.9%, or 6.7% delta 9-THC on 3 separate occasions. A second dosing occurred 3 hours later; participants chose to inhale 4 to 8 puffs. This flexible dosing was used to attempt to reduce the placebo effect. Using an 11-point numerical pain intensity rating scale as the primary outcome, a mixed effects linear regression model showed a significant analgesic response for vaporized cannabis. When subjective and psychoactive side effects (eg, good drug effect, feeling high, etc) were added as covariates to the model, the reduction in pain intensity remained significant above and beyond any effect of these measures (all P < .0004). Psychoactive and subjective effects were dose-dependent. Measurement of neuropsychological performance proved challenging because of various disabilities in the population studied. Because the 2 active doses did not significantly differ from each other in terms of analgesic potency, the lower dose appears to offer the best risk-benefit ratio in patients with neuropathic pain associated with injury or disease of the spinal cord. ⋯ A crossover, randomized, placebo-controlled human laboratory experiment involving administration of vaporized cannabis was performed in patients with neuropathic pain related to spinal cord injury and disease. This study supports consideration of future research that would include longer duration studies over weeks to months to evaluate the efficacy of medicinal cannabis in patients with central neuropathic pain.
-
There is increasing recognition that many if not most common chronic pain conditions are heterogeneous with a high degree of overlap or coprevalence of other common pain conditions along with influences from biopsychosocial factors. At present, very little attention is given to the high degree of overlap of many common pain conditions when recruiting for clinical trials. As such, many if not most patients enrolled into clinical studies are not representative of most chronic pain patients. The failure to account for the heterogeneous and overlapping nature of most common pain conditions may result in treatment responses of small effect size when these treatments are administered to patients with chronic overlapping pain conditions (COPCs) represented in the general population. In this brief review we describe the concept of COPCs and the putative mechanisms underlying COPCs. Finally, we present a series of recommendations that will advance our understanding of COPCs. ⋯ This brief review describes the concept of COPCs. A mechanism-based heuristic model is presented and current knowledge and evidence for COPCs are presented. Finally, a set of recommendations is provided to advance our understanding of COPCs.