A systematic literature review of the epidemiology and burden of herpes zoster in selected locales in Asia Pacific

Herpes zoster (HZ) is a painful rash which typically affects older adults. This is of concern in Asia-Pacific given its aging population. As HZ epidemiology and burden are evolving, this systematic literature review aimed to update the current understanding of HZ burden and associated costs for selected Asia-Pacific locales. MEDLINE and Embase were searched for English articles of HZ studies conducted in Australia, China, Hong Kong, Japan, Korea, New Zealand, Singapore, and Taiwan. Eligible outcomes included HZ incidence and prevalence, occurrence of HZ-related complications, healthcare resource utilization, costs, and HZ-associated quality of life outcomes. This paper focused on HZ data in the general adult population (N = 90 articles). Substantial HZ-related disease and economic burden were observed in these locales, consistent with global trends. These findings reinforce the increasing burden of HZ and need for preventive strategies, which may include raising awareness and encouraging timely vaccination.

Association of the incidence of postherpetic neuralgia with early treatment intervention of herpes zoster and patient baseline characteristics: A systematic review and meta-analysis of cohort studies

OBJECTIVES

To conduct a meta-analysis of the association between postherpetic neuralgia (PHN), baseline characteristics of patients with herpes zoster (HZ), and early interventions.

METHODS

Literature searches were conducted in seven databases, in June 2021 and updated in June 2022. Two investigators independently conducted literature screening and data extraction, and the studies were evaluated according to the Newcastle-Ottawa scale.

RESULTS

A total of 53 cohort studies were included. The meta-analyses identified skin lesions, timing of initial treatment (≥3 days), and comorbidities as potential risk factors for PHN. In contrast, female sex (odds ratio [OR] = 1.13, 95% confidence interval [CI]: 0.99-1.29), cervical herpes (OR = 0.80, 95% CI: 0.21-2.99), lumbar herpes (OR = 1.29, 95% CI: 0.61-2.74), and immunosuppressive therapy (OR = 1.96, 95% CI: 0.22-17.12), were not significantly associated with PHN. In addition, glucocorticoid use (OR = 0.61, 95% CI: 0.22-1.70) may be a protective factor for the development of PHN; however, the difference was not statistically significant.

CONCLUSION

A series of baseline characteristics were identified among populations at high risk of developing PHN from HZ. Additionally, the timing of initial treatment is associated with PHN occurrence. The preventive effect of glucocorticoids warrants further validation.

Bidirectional two-sample Mendelian randomization analysis reveals a causal effect of interleukin-18 levels on postherpetic neuralgia risk

Background

Postherpetic neuralgia (PHN) is a debilitating complication of herpes zoster, characterized by persistent neuropathic pain that significantly impairs patients' quality of life. Identifying factors that determine PHN susceptibility is crucial for its management. Interleukin-18 (IL-18), a pro-inflammatory cytokine implicated in chronic pain, may play a critical role in PHN development.

Methods

In this study, we conducted bidirectional two-sample Mendelian randomization (MR) analyses to assess genetic relationships and potential causal associations between IL-18 protein levels increasing and PHN risk, utilizing genome-wide association study (GWAS) datasets on these traits. Two IL-18 datasets obtained from the EMBL's European Bioinformatics Institute database which contained 21,758 individuals with 13,102,515 SNPs and Complete GWAS summary data on IL-18 protein levels which contained 3,394 individuals with 5,270,646 SNPs. The PHN dataset obtained from FinnGen biobank had 195,191 individuals with 16,380,406 SNPs.

Results

Our findings from two different datasets of IL-18 protein levels suggest a correlation between genetically predicted elevations in IL-18 protein levels and an increased susceptibility to PHN.(IVW, OR and 95% CI: 2.26, 1.07 to 4.78; p = 0.03 and 2.15, 1.10 to 4.19; p =0.03, respectively), potentially indicating a causal effect of IL-18 protein levels increasing on PHN risk. However, we did not detect any causal effect of genetic liability to PHN risk on IL-18 protein levels.

Conclusion

These findings suggest new insights into identifying IL-18 protein levels increasing at risk of developing PHN and may aid in the development of novel prevention and treatment approaches for PHN.

HSV-1 infection-induced herpetic neuralgia involves a CCL5/CCR5-mediated inflammation mechanism

Herpetic-related neuralgia (HN) caused by varicella-zoster virus (VZV) infection is one of the most typical and common neuropathic pain in the clinic. However, the potential mechanisms and therapeutic approaches for the prevention and treatment of HN are still unclear. This study aims to provide a comprehensive understanding of the molecular mechanisms and potential therapeutic targets of HN. We used an HSV-1 infection-induced HN mouse model and screened the differentially expressed genes (DEGs) in the DRG and spinal cord using an RNAseq technique. Moreover, bioinformatics methods were used to figure out the signaling pathways and expression regulation patterns of the DEGs enriched. In addition, quantitative real-time RT-PCR and western blot were carried out to further confirm the expression of DEGs. HSV-1 inoculation in mice resulted in mechanical allodynia, thermal hyperalgesia, and cold allodynia, following the infection of HSV-1 in both DRG and spinal cord. Besides, HSV-1 inoculation induced an up-regulation of ATF3, CGRP, and GAL in DRG and activation of astrocytes and microglia in the spinal cord. Moreover, 639 genes were upregulated, 249 genes were downregulated in DRG, whereas 534 genes were upregulated and 12 genes were downregulated in the spinal cord of mice 7 days after HSV-1 inoculation. GO and KEGG enrichment analysis suggested that immune responses and cytokine-cytokine receptor interaction are involved in DRG and spinal cord neurons in mice after HSV-1 infection. In addition, CCL5 and its receptor CCR5 were significantly upregulated in DRG and spinal cord upon HSV-1 infection in mice. And blockade of CCR5 exhibited a significant analgesic effect and suppressed the upregulation of inflammatory cytokines in DRG and spinal cord induced by HSV-1 infection in mice. HSV-1 infection-induced allodynia and hyperalgesia in mice through dysregulation of immune response and cytokine-cytokine receptor interaction mechanism. Blockade of CCR5 alleviated allodynia and hyperalgesia probably through the suppression of inflammatory cytokines. Therefore, CCR5 could be a therapeutic target for the alleviation of HSV-1 infection-induced HN.

Efficacy of different acupuncture therapies on postherpetic neuralgia: A Bayesian network meta-analysis

Background

Postherpetic neuralgia (PHN) is a common, complex, and refractory type of neuropathic pain. Several systematic reviews support the efficacy of acupuncture and related treatments for PHN. Nevertheless, the efficacy of various acupuncture-related treatments for PHN remains debatable.

Objective

We aimed to assess the efficacy and safety of acupuncture-related treatments for PHN, identify the most effective acupuncture-related treatments, and expound on the current inadequacies and prospects in the applications of acupuncture-related therapies.

Methods

We searched PubMed, Cochrane Central Register of Controlled Trials, Embase, Web of Science, Google Scholar, four Chinese databases (China National Knowledge Infrastructure, China Biomedical, Chongqing VIP, and Wan Fang databases), clinical research registration platform (World Health Organization International Clinical Trial Registration platform, China Clinical Trial Registration Center) for relevant studies. We also examined previous meta-analyses; gray literature; and reference lists of the selected studies. We then evaluated the risk of bias in the included studies and performed a Bayesian multiple network meta-analysis.

Results

We included 29 randomized controlled trials comprising 1,973 patients, of which five studies showed a high risk of bias. The pairwise meta-analysis results revealed that the efficacy of all acupuncture-related treatments for pain relief related to PHN was significantly better than antiepileptics. The network meta-analysis results showed that pricking and cupping plus antiepileptics were the most effective treatment, followed by electroacupuncture (EA) plus antiepileptics for pain relief in patients with PHN. EA plus antiepileptics ranked the best regarding reduced Pittsburgh Sleep Quality Index (PSQI) and Self-Rating Depression Scale (SDS) scores in patients with PHN. No results were found regarding the total response rate or quality of life in this study. Acupuncture-related treatments showed a lower incidence of adverse events than that of antiepileptics.

Conclusion

Acupuncture-related therapies are potential treatment options for PHN and are safe. Pricking and cupping plus antiepileptics, are the most effective acupuncture-related techniques for pain relief, while EA plus antiepileptics is the best acupuncture-related technique for improving PHN-related insomnia and depression symptoms. However, owing to the limitations of this study, these conclusions should be cautiously interpreted, and future high-quality studies are needed.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021226422, identifier CRD42021226422.

A Guide to Preclinical Models of Zoster-Associated Pain and Postherpetic Neuralgia

Reactivation of latent varicella-zoster virus (VZV) causes herpes zoster (HZ), which is commonly accompanied by acute pain and pruritus over the time course of a zosteriform rash. Although the rash and associated pain are self-limiting, a considerable fraction of HZ cases will subsequently develop debilitating chronic pain states termed postherpetic neuralgia (PHN). How VZV causes acute pain and the mechanisms underlying the transition to PHN are far from clear. The human-specific nature of VZV has made in vivo modeling of pain following reactivation difficult to study because no single animal can reproduce reactivated VZV disease as observed in the clinic. Investigations of VZV pathogenesis following primary infection have benefited greatly from human tissues harbored in immune-deficient mice, but modeling of acute and chronic pain requires an intact nervous system with the capability of transmitting ascending and descending sensory signals. Several groups have found that subcutaneous VZV inoculation of the rat induces prolonged and measurable changes in nociceptive behavior, indicating sensitivity that partially mimics the development of mechanical allodynia and thermal hyperalgesia seen in HZ and PHN patients. Although it is not a model of reactivation, the rat is beginning to inform how VZV infection can evoke a pain response and induce long-lasting alterations to nociception. In this review, we will summarize the rat pain models from a practical perspective and discuss avenues that have opened for testing of novel treatments for both zoster-associated pain and chronic PHN conditions, which remain in critical need of effective therapies.

Effect and safety of extracorporeal shockwave therapy for postherpetic neuralgia: A randomized single-blind clinical study

Objective

To evaluate the efficacy and safety of extracorporeal shockwave therapy (ESWT) for postherpetic neuralgia.

Design

Randomized single-blind clinical study.

Patients

Patients with postherpetic neuralgia.

Methods

Patients were randomly divided into the control group and the ESWT group. The control group received conventional treatment while the ESWT group received conventional treatment and ESWT. The primary outcome is pain degree as assessed by the numeric rating scale (NRS), and secondary outcomes include brief pain inventory (BPI), Self-rating Anxiety Scale (SAS), Self-rating Depression Scale (SDS), and Pittsburgh Sleep Quality Index (PSQI). Data were collected at baseline and at weeks 1, 4, and 12. Linear mixed-effects models were applied to repeated measurement data.

Results

The scores on the NRS, BPI, SAS, SDS, and PSQI decreased over time in both groups. The NRS and SDS scores of the ESWT group were statistically lower than the control group. There was no time × group interaction in the mixed model analysis. Baseline age was correlated with NRS scores and BPI scores, and invasive treatment was related to PSQI scores, with no interaction effect for baseline confounders observed. No adverse events were observed during the process of this trial.

Conclusion

Extracorporeal shockwave therapy combined with conventional treatment could relieve pain and improve the psychological state in patients with postherpetic neuralgia without serious adverse effects.

Clinical Characteristics, Treatment Effectiveness, and Predictors of Response to Pharmacotherapeutic Interventions Among Patients with Herpetic-Related Neuralgia: A Retrospective Analysis

BACKGROUND

The treatment for herpetic-related neuralgia focuses on symptom control by use of antiviral drugs, anticonvulsants, and tricyclic antidepressants. We aimed to explore the clinical characteristics associated with medication responsiveness, and to build a classifier for identification of patients who have risk of inadequate pain management.

METHODS

We recruited herpetic-related neuralgia patients during a 3-year period. Patients were stratified into a medication-resistant pain (MRP) group when the pain decrease in the visual analogue scale (VAS) is < 3 points, and otherwise a medication-sensitive pain (MSP) group. Multivariate logistic regression was performed to determine the factors associated with MRP. We fitted four machine learning (ML) models, namely logistic regression, random forest, supporting vector machines (SVM), and naïve Bayes with clinical characteristics gathered at admission to identify patients with MRP.

RESULTS

A total of 213 patients were recruited, and 132 (61.97%) patients were diagnosed with MRP. Subacute herpes zoster (HZ) (vs. acute, OR 8.95, 95% CI 3.15-29.48, p = 0.0001), severe lesion (vs. mild lesion, OR 3.84, 95% CI 1.44-10.81, p = 0.0084), depressed mood (unit increase OR 1.10, 95% CI 1.00-1.20, p = 0.0447), and hypertension (hypertension, vs. no hypertension, OR 0.36, 95% CI 0.14-0.87, p = 0.0266) were significantly associated with MRP. Among four ML models, SVM had the highest accuracy (0.917) and receiver operating characteristic-area under the curve (0.918) to discriminate MRP from MSP. Phase of disease is the most important feature when fitting ML models.

CONCLUSIONS

Clinical characteristics collected before treatment could be adopted to identify patients with MRP.

Efficacy and Safety of Moxibustion for Postherpetic Neuralgia: A Systematic Review and Meta-Analysis

Background: Postherpetic neuralgia (PHN) is one of the most common complications of herpes zoster (HZ), and there is still a lack of effective therapies. An increasing number of studies have found that compared to traditional therapy, moxibustion treatment is beneficial for the treatment of PHN, although current evidence remains inconclusive. This systematic review and meta-analysis of randomized controlled trials (RCTs) aimed to evaluate the efficacy and safety of moxibustion for PHN.

Methods: We conducted a broad literature review of a range of databases from inception to December 2020, including the Cochrane Library, PubMed, EMBASE, Web of Science, Clinical Trails, China National Knowledge Infrastructure (CNKI), VIP Database for Chinese Technical Periodicals (VIP), China Biomedical Network Information, and Wanfang databases. We included RCTs that compared moxibustion to pharmacological therapies, herbal medicine, or no treatment for treating PHN. The main outcome measure was efficacy rate and Visual Analog Scale (VAS); the secondary outcome measure was adverse events. Data accumulation and synthesis included meta-analysis, publication bias, sensitivity analysis, risk-of-bias assessment, and adverse events.

Results: We included 13 RCTs involving 798 patients. Compared with the controls (pharmacological therapies, herbal medicine, or no treatment), moxibustion achieved a significantly higher efficacy rate (odds ratio [OR]: 3.65; 95% [confidence interval]: [2.32, 5.72]; P < 0.00001). Subgroup analysis of the distinct moxibustion modalities showed that both Zhuang medicine medicated thread and thunder-fire moxibustions obtained higher clinical efficacy than the control group. Compared with the controls, moxibustion resulted in significantly lower scores on the VAS (Weighted Mean Difference (MD) = −1.79; 95% CI: [−2.26, −1.33]; P < 0.00001). However, there was no significant difference in terms of safety between moxibustion and the controls (OR = 0.33; 95% CI [0.06, 1.77]; P = 0.19).

Conclusion: Due to the lack of methodological quality as well as the significant heterogeneity of the included studies, it remains difficult to draw a firm conclusion on the efficacy and safety of moxibustion for the treatment of PHN. Future high-quality studies are urgently needed.

Different dosages of valaciclovir for the treatment of herpes zoster in adults: A randomized clinical study

WHAT IS KNOWN AND OBJECTIVE

The dosages of valaciclovir used for herpes zoster treatment recommended by Chinese pharmaceutical companies can differ considerably from those reported in the literature. This randomized clinical study compares the efficacy and safety of different oral valaciclovir doses for the treatment of herpes zoster in adults.

METHODS

A total of 214 patients with herpes zoster were enrolled and randomized into two groups according to age: 98 patients in the 18-44-year group (younger patients) and 116 patients in the 45-74-year group (middle-aged and elderly patients). Patients in the two age groups were then prescribed different doses of valaciclovir. The high-dose group was administered 900 mg of valaciclovir, three times daily for 10 days, whereas the low-dose group was administered 300 mg of valaciclovir, two times daily for 10 days. The efficacy and side effects of these regimens were recorded on days 6, 11 and 30.

RESULTS

In total, 207 (of 214 enrolled) patients completed the study. Of the seven patients who discontinued the study, five discontinued because their follow-up time was not fixed and two withdrew after moving to other cities. At the 11th day after treatment, the clinical effect of high-dose valaciclovir groups were significantly better than that of the low-dose valaciclovir groups in middle-aged and elderly patients (p < 0.05). The difference in visual analog scale (VAS) pain scores between the two dose groups was statistically significant in middle-aged and elderly patients at the 6th day(p < 0.05), whereas there was no difference in younger patients (p > 0.05). The VAS scores were significantly lower in high-dose group than in low-dose group at day 11 in both groups of patients(p < 0.05).There was no statistically significant difference in the time to skin scab improvement between the two different dose groups in younger patients (p > 0.05). Among middle-aged and elderly patients, the incidence of postherpetic neuralgia (PHN) was significantly lower in the high-dose group than in the low-dose group (p < 0.05). The difference in the incidence of adverse reactions between the high-dose and low-dose groups was not statistically significant (p > 0.05). Overall, the main side effect was headache.

WHAT IS NEW AND CONCLUSION

The present study indicates that early treatment with high-dose valaciclovir can significantly reduce pain in patients, especially in elderly patients, in whom it can also reduce the incidence of PHN. In terms of safety, no significant difference was noted in the incidence of adverse reactions between high- and low-dose groups.

Intravenous Administration of Vitamin C in the Treatment of Herpes Zoster-Associated Pain: Two Case Reports and Literature Review

Background

Herpes zoster (HZ) is an acute inflammatory neurocutaneous disease caused by the reactivation of varicella-zoster virus. It is estimated that the incidence of postherpetic neuralgia following HZ is 10–20%. The leading risk factors of the prognosis are aging and immunity dysfunction. Vitamin C plays a pivoted role in enhancing white blood cell function. Epidemiological evidence and clinical studies have indicated an association between pain and suboptimal vitamin C status. At present, vitamin C has been used as an additional option in the treatment of HZ-associated pain. Despite the current controversy, case reports and randomized controlled studies have indicated that both acute- and postherpetic neuralgia can be dramatically alleviated following intravenous vitamin C infusions. Case Presentation. Two patients (male aged 72 and female 78 years) with HZ did not respond well to antiviral therapy and analgesics. Skin lesions in the right groin and front thigh healed after early antiviral therapy, but the outbreak of pain persisted in the male patient. The female patient presented to our clinic with clusters of rashes in the right forehead with severe edema of her right upper eyelid. Because nerve blockade could not be conducted for both patients, intravenous infusion of vitamin C was applied and resulted in an immediate remission of the breakthrough pain in the male patient and cutaneous lesions in the female patient.

Conclusions

The use of vitamin C appears to be an emerging treatment alternative for attenuating HZ and PHN pain. Hence, we recommend the addition of concomitant use of intravenously administered vitamin C into therapeutic strategies in the treatment of HZ-associated pain, especially for therapy-resistant cases. Furthermore, animal studies are required to determine analgesic mechanisms of vitamin C, and more randomized clinical trials are essential to further determine the optimal dose and timing of administration of vitamin C.

Predicting Postherpetic Neuralgia in Patients with Herpes Zoster by Machine Learning: A Retrospective Study

Introduction

Postherpetic neuralgia (PHN) is a neuropathic pain secondary to shingles. Studies have shown that early pain intervention can reduce the incidence or intensity of PHN. The aim of this study was to predict whether a patient with acute herpetic neuralgia will develop PHN and to help clinicians make better decisions.

Method

Five hundred two patients with shingles were reviewed and classified according to whether they had PHN. The risk factors associated with PHN were determined by univariate analysis. Logistic regression and random forest algorithms were used to do machine learning, and then the prediction accuracies of the two algorithms were compared, choosing the superior one to predict the next 60 new cases.

Results

Age, NRS score, rash site, Charlson comorbidity index (CCI) score, antiviral therapy and immunosuppression were found related to the occurrence of PHN. The NRS score was the most closely related factor with an importance of 0.31. As for accuracy, the random forest was 96.24%, better than that of logistic regression in which the accuracy was 92.83%. Then, the random forest model was used to predict 60 newly diagnosed patients with herpes zoster, and the accuracy rate was 88.33% with a 95% confidence interval (CI) of 77.43–95.18%.

Conclusions

This study provides an idea and a method in which, by analyzing the data of previous cases, we can develop a predictive model to predict whether patients with shingles will develop PHN.