Hooten, W. Michael

Background The past two decades have witnessed a surge in the use of lumbar facet blocks and radiofrequency ablation (RFA) to treat low back pain (LBP), yet nearly all aspects of the procedures remain controversial. Methods After approval by the Board of Directors of the American Society of Regional Anesthesia and Pain Medicine, letters were sent to a dozen pain societies, as well as representatives from the US Departments of Veterans Affairs and Defense. A steering committee was convened to select preliminary questions, which were revised by the full committee. Questions were assigned to 4–5 person modules, who worked with the Subcommittee Lead and Committee Chair on preliminary versions, which were sent to the full committee. We used a modified Delphi method, whereby the questions were sent to the committee en bloc and comments were returned in a non-blinded fashion to the Chair, who incorporated the comments and sent out revised versions until consensus was reached. Results 17 questions were selected for guideline development, with 100% consensus achieved by committee members on all topics. All societies except for one approved every recommendation, with one society dissenting on two questions (number of blocks and cut-off for a positive block before RFA), but approving the document. Specific questions that were addressed included the value of history and physical examination in selecting patients for blocks, the value of imaging in patient selection, whether conservative treatment should be used before injections, whether imaging is necessary for block performance, the diagnostic and prognostic value of medial branch blocks (MBB) and intra-articular (IA) injections, the effects of sedation and injectate volume on validity, whether facet blocks have therapeutic value, what the ideal cut-off value is for a prognostic block, how many blocks should be performed before RFA, how electrodes should be oriented, the evidence for larger lesions, whether stimulation should be used before RFA, ways to mitigate complications, if different standards should be applied to clinical practice and clinical trials and the evidence for repeating RFA (see table 12 for summary). Conclusions Lumbar medial branch RFA may provide benefit to well-selected individuals, with MBB being more predictive than IA injections. More stringent selection criteria are likely to improve denervation outcomes, but at the expense of more false-negatives. Clinical trials should be tailored based on objectives, and selection criteria for some may be more stringent than what is ideal in clinical practice.

Background Smoking adversely impacts pain-related outcomes of spinal cord stimulation (SCS). However, the proportion of SCS patients at risk of worse outcomes is limited by an incomplete knowledge of smoking prevalence in this population. Thus, the primary aim of this systematic review is to determine the prevalence of smoking in adults with chronic pain treated with SCS. Methods A comprehensive search of databases from 1 January 1980 to 3 January 2019 was conducted. Eligible study designs included (1) randomized trials; (2) prospective and retrospective cohort studies; and (3) cross-sectional studies. The risk of bias was assessed using a tool specifically developed for prevalence studies. A total of 1619 records were screened, 19 studies met inclusion criteria, and the total number of participants was 10 838. Results Thirteen studies had low or moderate risk of bias, and six had a high risk of bias. All 19 studies reported smoking status and the pooled prevalence was 38% (95% CI 30% to 47%). The pooled prevalence in 6 studies of peripheral vascular diseases was 56% (95% CI 42% to 69%), the pooled prevalence of smoking in 11 studies of lumbar spine diagnoses was 28% (95% CI 20% to 36%) and the pooled prevalence in 2 studies of refractory angina was 44% (95% CI 31% to 58%). Conclusions The estimated prevalence of smoking in SCS patients is 2.5 times greater than the general population. Future research should focus on development, testing and deployment of tailored smoking cessation treatments for SCS patients.

Objective: Experts cautioned that patients affected by the November 2010 withdrawal of the opioid analgesic propoxyphene might receive riskier prescriptions. To explore this, we compared drug receipts and outcomes among propoxyphene users before and aftermarket withdrawal. Study Design: Using OptumLabs data, we studied 3 populations: commercial, Medicare Advantage (MA) aged (age 65+ y) and MA disabled (age below 65 y) enrollees. The exposed enrollees received propoxyphene in the 3 months before market withdrawal (n=13,622); historical controls (unexposed) received propoxyphene 1 year earlier (n=9971). Regression models estimated daily milligrams morphine equivalent (MME), daily prescription acetaminophen dose, potentially toxic acetaminophen doses, nonopioid prescription analgesics receipt, emergency room visits, and diagnosed falls, motor vehicle accidents, and hip fractures. Principal Findings: Aged MA enrollees illustrate the experience of all 3 populations examined. Following the market withdrawal, propoxyphene users in the exposed cohort experienced an abrupt decline of 69% in average daily MME, compared with a 14% decline in the unexposed. Opioids were discontinued by 34% of the exposed cohort and 18% of the unexposed. Tramadol and hydrocodone were the most common opioids substituted for propoxyphene. The proportion of each group receiving ≥4 g of prescription acetaminophen per day decreased from 12% to 2% in the exposed group but increased from 6% to 8% among the unexposed. Adverse events were rare and not significantly different in exposed versus unexposed groups. Conclusions: After propoxyphene market withdrawal, many individuals experienced abrupt discontinuation of opioids. Policymakers might consider supporting appropriate treatment transitions and monitoring responses following drug withdrawals.

Abstract Objective Electronic (eHealth) and mobile (mHealth) technologies may be a useful adjunct to clinicians treating patients with chronic pain. The primary aim of this study was to investigate the effects of eHealth and mHealth interventions that do not require clinician contact or feedback on pain-related outcomes recommended by the Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials (IMMPACT) guidelines in adults with chronic pain. Methods We searched four databases and included English language randomized controlled trials of ambulatory adults with chronic pain from January, 1 2000, to January 31, 2018, with interventions that are independent of clinician contact or feedback. In the meta-analysis, outcomes were assessed at short- (three months or less), intermediate- (four to six months), and long-term (seven or more months) follow-up. Results Seventeen randomized controlled trials (N = 2,496) were included in the meta-analysis. Both eHealth and mHealth interventions had a significant effect on pain intensity at short- and intermediate-term follow-up. Similarly, a significant but small effect was observed for depression at short- and intermediate-term follow-up and self-efficacy at short-term follow-up. Finally, a significant effect was observed for pain catastrophizing at short-term follow-up. Conclusions eHealth and mHealth interventions had significant effects on multiple short- and intermediate-term outcome measures recommended in the IMMPACT guidelines. Given widespread availability and low cost to patients, clinicians treating patients with chronic pain could consider using eHealth and mHealth interventions as part of a multidisciplinary pain treatment strategy.

The catechol-O-methyltransferase Val158Met polymorphism has been associated with alterations in pain perception, but the influence of the polymorphism on pain perception in patients with chronic pain receiving daily opioid therapy has not been previously reported. The primary aim of this study was to investigate the effects of the catechol-O-methyltransferase Val158Met polymorphism on heat pain perception in a cohort of adults receiving daily opioid therapy for chronic pain. Adults with chronic pain consecutively admitted to an outpatient pain rehabilitation program who met inclusion criteria and were receiving daily opioid therapy were recruited for study participation (N = 142). Individuals were genotyped for catechol-O-methyltransferase Val158Met (rs4680), and the polymorphism was analyzed using an additive and codominant genotype models. The distribution of the Val158Met genotypes was 25% for Val/Val, 41% for Val/Met and 34% for Met/Met (Hardy–Weinberg, P > 0.05). A main effect of genotype was observed for heat pain perception ( P = 0.028). Under the codominant model of allele effects, exploratory post hoc pairwise comparisons adjusted for morphine equivalent dose and pain catastrophizing demonstrated that individuals with the Val/Met genotype were hyperalgesic compared to individuals with the Val/Val ( P = 0.039) and Met/Met ( P = 0.023) genotypes. No significant association was observed between heat pain perception and genotype under the additive model of allele effects. Among patients with chronic pain who were receiving daily opioids, the Val/Met genotype was associated with hyperalgesia using a measure of heat pain perception that has been previously indicative of opioid-induced hyperalgesia in other heterogeneous samples of adults with chronic pain. This study contributes to the emerging understanding of how catechol-O-methyltransferase activity affects pain perception in the context of daily opioid use, and these findings may be useful in the design of future trials aimed at investigating the potential efficacy of ß-2 adrenergic receptor antagonism for opioid-induced hyperalgesia.

ABSTRACT Background Vaginal diazepam is frequently used to treat pelvic floor tension myalgia and pelvic pain despite limited knowledge of systemic absorption. Aim To determine the pharmacokinetic and adverse event profile of diazepam vaginal suppositories. Methods We used a prospective pharmacokinetic design with repeated assessments of diazepam levels. Eight healthy volunteers were administered a 10-mg compounded vaginal diazepam suppository in the outpatient gynecologic clinic. Serum samples were collected at 0, 45, 90, 120, and 180 minutes; 8, 24, and 72 hours; and 1 week following administration of a 10-mg vaginal suppository. The occurrence of adverse events was assessed using the alternate step and tandem walk tests, the Brief Confusion Assessment Method, and numerical ratings. Plasma concentrations of diazepam and active long-acting metabolites were measured. Pharmacokinetic parameters were calculated by standard noncompartmental methods. Results The mean peak diazepam concentration (Cmax) of 31.0 ng/mL was detected at a mean time (Tmax) of 3.1 hours after suppository placement. The bioavailability was found to be 70.5%, and the mean terminal elimination half-life was 82 hours. The plasma levels of temazepam and nordiazepam peaked at 0.8 ng/mL at 29 hours and 6.4 ng/mL at 132 hours, respectively. Fatigue was reported by 3 of 8 participants. Clinical Implications Serum plasma concentrations of vaginally administered diazepam are low; however the half-life is prolonged. Strengths & Limitations Strengths include use of inclusion and exclusion criteria aimed at mitigating clinical factors that could adversely impact diazepam absorption and metabolism, and the use of an ultrasensitive LC-MS/MS assay. Limitations included the lack of addressing the efficacy of vaginal diazepam in lieu of performing a pure pharmacokinetic study with healthy participants. Conclusion Vaginal administration of diazepam results in lower peak serum plasma concentration, longer time to peak concentration, and lower bioavailability than standard oral use. Providers should be aware that with diazepam’s long half-life, accumulating levels would occur with chronic daily doses, and steady-state levels would not be reached for up to 1 week. This profile would favor intermittent use to allow participation in physical therapy and intimacy.