What should be the entry pain intensity criteria for chronic pain clinical trials? An IMMPACT update

Mean of Daily Versus Single Week Recall-Based Pain Quality Assessments in Neuropathic Pain Trials: Implications for Assay Sensitivity

Patients with neuropathic pain often present with variable pain and nonpainful sensory qualities that could serve as outcomes in randomized clinical trials (RCTs). This study aimed to investigate the within-participant variability in the severity of these sensory qualities and whether the means of 7 daily pain quality assessments provide better assay sensitivity (ie, more sensitivity to treatment effects) than single-week recall-based assessments. This secondary analysis used data from an RCT of transcutaneous electrical nerve stimulation for chemotherapy-induced peripheral neuropathy (N = 142). Participants rated the severity of painful and nonpainful sensory qualities using 0 to 10 numeric rating scales daily for 1 week (24-hour recall) and 1 time at the end of each week (week recall) at trial baseline and endpoint (after 6 weeks of treatment). For pain quality assay sensitivity analyses, the 2 types of measures were used to 1) define the study sample (ie, how many participants met minimum baseline pain quality severity) and 2) calculate the observed effect sizes (ie, between-group differences in mean pain qualities) using analysis of covariances. The projected sample sizes required to detect the observed effect sizes in future clinical trials for hot/burning pain and cramping were substantially smaller using the daily mean outcome compared with week recall (ie, hot/burning pain: 153 vs 388, cramping: 121 vs 349), and only marginally larger for sharp/shooting pain (22 participants) with the daily mean outcome. Compared with single-week recall-based assessments of pain qualities, the mean of daily assessments may improve RCT assay sensitivity when used to define entry criteria and assess outcomes. PERSPECTIVE: This study suggests that means of daily pain quality assessments may improve assay sensitivity when used to define entry criteria and assess outcomes in clinical trials. This work may inform design of future clinical trials evaluating the intensity of different pain qualities.

8. Herpes zoster and post herpetic neuralgia

INTRODUCTION

Patients suffering from postherpetic neuralgia (PHN) report unilateral chronic pain in one or more dermatomes after an acute herpes zoster (HZ) infection. The incidence of acute HZ ranges between three and five patients per 1000 person-years. In one out of four patients, acute HZ-related pain will transition into PHN. PHN can be very disabling for patients and reduce quality of life. Additionally, the treatment of PHN is characterized by high failure rates. The aim of this review is to give an update on the previous practical guideline published in 2011 and revised in 2015 (published in 2019) and to provide an overview of current interventional treatment options for HZ infection and PHN.

METHODS

The literature on the diagnosis and treatment of HZ and PHN was systematically reviewed and summarized.

RESULTS

The most important treatment for acute HZ-related pain is antiviral therapy within 72 h of symptom onset. Additional symptomatic treatment options are analgesic drugs according to the WHO pain ladder, tricyclic antidepressants (eg, nortriptyline), and antiepileptic drugs (eg, gabapentin). If pain is not sufficiently reduced, interventional treatment such as an epidural injection with local anesthetics and corticosteroids or pulsed radiofrequency of the dorsal root ganglion (DRG) are options. Treatment for PHN is preferably transdermal capsaicin, lidocaine, or oral drugs such as antidepressants or antiepileptics.

CONCLUSIONS

Treatment of acute HZ-related pain especially PHN is challenging. Besides the conventional treatment for PHN, interventional management is considered a new treatment option. PRF of DRG seems to be the most promising interventional management.

Topical amitriptyline in burning mouth syndrome: A retrospective real-world evidence study

OBJECTIVE

To evaluate the effectiveness, tolerability, and safety of topical amitriptyline as a potential route of administration for the management of burning mouth syndrome.

BACKGROUND

Burning mouth syndrome is a complex, idiopathic, and debilitating orofacial pain disorder that impairs quality of life, with a prevalence of up to 18% in menopausal women. Available drugs to alleviate its burning sensation have inconsistent and limited efficacy. Given its physicochemical properties, excellent tolerability, and ability to target peripheral pathways, topical amitriptyline seems a promising mechanistically specific analgesic drug for burning mouth syndrome.

METHODS

In this retrospective cross-sectional real-world evidence study, patients with burning mouth syndrome who were prescribed topical amitriptyline for 8 weeks were identified. Eligibility criteria stemmed from ICHD-3, ICOP, and consensus definitions. The primary outcome measure was mean daily pain intensity (on a 0-10 scale); secondary outcomes included adverse events and patient global impression of improvement. Data are given as the mean ± SD.

RESULTS

A total of 15 patients fulfilling the eligibility criteria were included and analyzed. Mean daily pain was 6.7 ± 2.1 at baseline and 3.7 ± 2.3 after treatment, with a mean reduction of 3.1 ± 2.8 (p = 0.002). Half of the patients experienced a decrease in pain by at least 50% (p = 0.008). Several mild adverse events were reported, such as somnolence or dry mouth.

CONCLUSIONS

Topical amitriptyline may be a safe and potent route of administration in the treatment of burning mouth syndrome, a hypothesis to be tested in further controlled trials.

Effect of esketamine combined with pregabalin on acute postsurgical pain in patients who underwent resection of spinal neoplasms: a randomized controlled trial

ABSTRACT

Moderate-to-severe acute postsurgical pain (APSP) can prolong the recovery and worsen the prognosis of patients who undergo spinal surgery. Esketamine and pregabalin may resolve APSP without causing hyperpathia or respiratory depression after surgery. However, there are other risks, such as dissociative symptoms. We designed a randomized controlled trial to investigate the effect of the combination of these 2 drugs on the incidence of APSP in patients who underwent resection of spinal neoplasms. Patients aged 18 to 65 years were randomized to receive esketamine (a bolus dose of 0.5 mg·kg -1 and an infusion dose of 0.12 mg·kg -1 ·h -1 for 48 hours after surgery) combined with oral pregabalin (75-150 mg/day, starting 2 hours before surgery and ending at 2 weeks after surgery) or an identical volume of normal saline and placebo capsules. The primary outcome was the proportion of patients with moderate-to-severe APSP (visual analog scale score ≥ 40) during the first 48 hours after surgery. Secondary outcomes included the incidence of drug-related adverse events. A total of 90 patients were randomized. The incidence of moderate-to-severe APSP in the combined group (27.3%) was lower than that in the control group (60.5%) during the first 48 hours after surgery (odds ratio = 0.25, 95% CI = 0.10-0.61; P = 0.002). The occurrence of mild dissociative symptoms was higher in the combined group than in the control group (18.2% vs 0%). In conclusion, esketamine combined with pregabalin could effectively alleviate APSP after spinal surgery, but an analgesic strategy might increase the risk of mild dissociative symptoms.