Assessment of pain in herpes zoster: lessons learned from antiviral trials

Antiviral Therapy in Herpes Zoster: A Review

Herpes zoster is a disease caused by reactivation of the latent form of the varicella zoster virus (VZV). It is usually seen in adults, occurring mainly in the elderly. The acute phase of the disease is characterized by a rash, which is typically accompanied by pain. In some patients the pain may persist after the rash has healed, and may last for many months or years. Three antiviral agents are currently available to treat herpes zoster: aciclovir, its prodrug valaciclovir, and famciclovir. All three are effective in accelerating healing of the rash, and reducing the patient's period of infectivity. These antiviral agents also impact on the chronic pain associated with herpes zoster but appear to differ in their efficacy. Two different measures of chronic pain have been used in clinical studies: post-herpetic neuralgia (PHN) which refers to the pain occurring after the rash has healed, and zoster-associated pain (ZAP), defined as the continuum of pain occurring after the onset of herpes zoster (i.e. making no distinction between acute pain and PHN). Famciclovir has been shown to significantly reduce the risk and duration of PHN in patients over 50 years old. In another study famciclovir was shown to be significantly more effective than aciclovir in relieving ZAP when treatment was taken within 48 h of the onset of herpes zoster. Valaciclovir was also found to be better than aciclovir in reducing the duration of ZAP, but it is unclear whether this improvement over aciclovir also applied to PHN. Elderly patients therefore benefit from antiviral therapy, which should be initiated as early as possible, and can significantly reduce the risk and duration of the chronic pain associated with herpes zoster.

Systematic review of incidence and complications of herpes zoster: towards a global perspective

OBJECTIVE

The objective of this study was to characterise the incidence rates of herpes zoster (HZ), also known as shingles, and risk of complications across the world.

DESIGN

We systematically reviewed studies examining the incidence rates of HZ, temporal trends of HZ, the risk of complications including postherpetic neuralgia (PHN) and HZ-associated hospitalisation and mortality rates in the general population. The literature search was conducted using PubMed, EMBASE and the WHO library up to December 2013.

RESULTS

We included 130 studies conducted in 26 countries. The incidence rate of HZ ranged between 3 and 5/1000 person-years in North America, Europe and Asia-Pacific, based on studies using prospective surveillance, electronic medical record data or administrative data with medical record review. A temporal increase in the incidence of HZ was reported in the past several decades across seven countries, often occurring before the introduction of varicella vaccination programmes. The risk of developing PHN varied from 5% to more than 30%, depending on the type of study design, age distribution of study populations and definition. More than 30% of patients with PHN experienced persistent pain for more than 1 year. The risk of recurrence of HZ ranged from 1% to 6%, with long-term follow-up studies showing higher risk (5-6%). Hospitalisation rates ranged from 2 to 25/100 000 person-years, with higher rates among elderly populations.

CONCLUSIONS

HZ is a significant global health burden that is expected to increase as the population ages. Future research with rigorous methods is important.

Neurodermatology

Since the skin and the central and/or peripheral nervous system share a common source (the ectoderm), numerous genetic and acquired diseases (infectious, tumoral or autoimmune disorders) equally affect both. Neurologic diseases or symptoms such as stroke, cerebral or medullary vascular malformations, peripheral, brain or medullary tumors, epilepsy, ataxia, neurologic infections, or cognitive disorders (dementia, mental retardation) may be associated with specific cutaneous manifestations of which the discovery can facilitate the final diagnosis, thereby leading to specific treatment and/or genetic investigations. Careful examination of the skin, hair, and nails by the neurologist is consequently of the utmost importance; when unusual abnormalities of the skin are discovered or when greater expertise is required, consultation with a dermatologist is frequently advisable.

Vaccination against herpes zoster and postherpetic neuralgia in France: a cost-effectiveness analysis

This study assesses the cost-effectiveness of vaccination against herpes zoster (HZ) and postherpetic neuralgia in France, using a published Markov model. The cost-effectiveness of vaccinating individuals aged from 65 years or between 70 and 79 years was evaluated over their lifetime, from a third-party payer perspective. French-specific data were combined with results from clinical studies and international quality-of-life-based (EuroQol five-dimension questionnaire) utilities from the literature. HZ vaccination was highly cost effective in both populations. Incremental cost-effective ratios were estimated between €9513 and 12,304 per quality-adjusted life year gained, corresponding to €2240-2651 per HZ case avoided and €3539-4395 per postherpetic neuralgia case avoided. In addition to epidemiological and clinical evidence, economic evidence also supports the implementation of HZ vaccination in France.

Recent developments in anti-herpesvirus drugs

Background Herpesviruses notably establish lifelong infections, with latency and reactivation. Many of the known human herpesviruses infect large proportions of the population worldwide. Treatment or prevention of herpes infections and recurrent disease still pose a challenge in the 21st century. Sources of data Original papers and review articles, meeting abstracts, a book (Clinical Virology; DD Richman, RJ Whitley & FG Hayden eds) and company web sites. Areas of agreement For herpes simplex types 1 and 2 and for varicella zoster, acyclovir (ACV; now increasingly replaced by its prodrug valacyclovir, VACV) and famciclovir (FCV) have greatly reduced the burden of disease and have established a remarkable safety record. Drug-resistance, in the otherwise healthy population, has remained below 0.5% after more that 20 years of antiviral use. In immunocompromised patients, drug resistance is more common and alternative drugs with good safety profiles are desirable. For human cytomegalovirus disease, which occurs in immunocompromised patients, ganciclovir and increasingly its prodrug valganciclovir are the drugs of choice. However, alternative drugs, with better safety, are much needed. Areas of controversy Various questions are highlighted. Should the new 1-day therapies for recurrent herpes labialis and genital herpes replace the current standard multi-day therapies? The marked differences between VACV and FCV (e.g. triphosphate stability, effect on latency) may not yet be fully exploited? Do current antivirals reduce post-herpetic neuralgia (PHN)? For immunocompromised patients with varicella zoster virus (VZV) disease, should the first-line treatment be FCV, not ACV or VACV? Should there be more support to explore new avenues for current antivirals, for example in possibly reducing herpes latency or Alzheimer's disease (AD)? Should primary Epstein-Barr virus (EBV) disease in adolescents be treated with antivirals? How can new compounds be progressed when the perceived market need is small but the medical need is great. FCV was reclassified from prescription-only to pharmacist-controlled for herpes labialis in New Zealand in 2010; should this be repeated more widely? This article reviews new drugs in clinical trials and highlights some of the problems hindering their progress.

[Burden of herpes zoster and postherpetic neuralgia: Incidence, proportion, and associated costs in the French population aged 50 or over]

BACKGROUND

Despite the perspective of vaccination against herpes zoster, there are few recent data available on the incidence of this disease, the proportion of postherpetic neuralgia cases, and associated disease management costs. This study was performed to evaluate these parameters in a representative sample of French physicians.

METHODS

It was a retrospective, declarative study conducted from the medical files of patients who presented with herpes zoster and consulted in 2005, based on a random sample of GPs, dermatologists, neurologists, and physicians in pain clinics, weighted by demographic departmental distribution of patients aged 50 years and above. The analysis was performed on cases diagnosed by physicians themselves (incident cases).

RESULTS

The annual incidence of herpes zoster was estimated at 8.99/1000 [8.34-9.64], all types of physicians pooled and at 8.67/1000 for GPs. This represents about 182,500 cases of herpes zoster in France in 2005 in patients aged 50 years and above. Incidence was slightly higher amongst women (1.3 times) and increased with age. Amongst the 777 cases of incident herpes zoster, 343 were complicated by postherpetic neuralgia one month after diagnosis. The proportion of patients presenting postherpetic neuralgia at 3 and 6 months was 32.1% and 17.6%, respectively. The annual cost of management of herpes zoster and postherpetic neuralgia was estimated at 170 [109-249] million euros, of which 61.0 million euros were covered by the national health insurance.

CONCLUSION

In this study, the incidence of herpes zoster observed in France in subjects aged 50 years and above is close to that already estimated in France and Europe. The proportion of postherpetic neuralgia is high and this painful complication may persist for several months after diagnosis of herpes zoster. To our knowledge, EPIZOD is the first study conducted in France to assess the cost of herpes zoster and of postherpetic neuralgia, the most frequent complication of this viral disease.

Predictors of pain intensity and persistence in a prospective Italian cohort of patients with herpes zoster: relevance of smoking, trauma and antiviral therapy

BACKGROUND

Herpes zoster (HZ) is a common disease, characterized by rash-associated localized pain. Its main complication, post-herpetic neuralgia (PHN), is difficult to treat and may last for months to years in the wake of rash resolution. Uncertainties remain as to the knowledge of predictors of HZ-related pain, including the role of antiviral therapy in preventing PHN in ordinary clinical practice. This prospective cohort study was aimed at investigating pain intensity at HZ presentation and its correlates, as well as the incidence of PHN and its predictors.

METHODS

Patients diagnosed with HZ were consecutively enrolled by a network of Italian General Practitioners and Hospital Units in the health district of Pescara, Italy, over two years. Uncertain cases were referred for microbiological investigation. Data were collected through electronic case report form (e-CRFs) at enrollment and at 1, 3, 6 and 12 months after enrollment. Pain intensity was coded on a five-degree semi-quantitative scale at each time point. PHN was defined as pain of any intensity during follow-up and quantified using an area-under-the-curve (AUC) method.

RESULTS

Four hundred and forty-one patients composed the final sample. Mean age was 58.1 years (SD = 20.4 years); 43.5% of patients were males; 7.9% did not receive prescription of antivirals. Intense/very intense pain at presentation was reported by 25.2% of patients and was significantly associated with female gender, older age, cigarette smoking, trauma and/or surgery at HZ site (logistic regression). PHN was diagnosed in 51.2% of patients at one month and in 30.0% of patients at three months. PHN was significantly associated with pain intensity at presentation, age, smoking, trauma and missed antiviral prescription (generalized estimating equations model). The same factors were also independent predictors of the overall pain burden as described by the AUC method (linear regression).

CONCLUSIONS

Smoking, traumas and surgery at the HZ site emerged as new predictors of both HZ-related pain intensity and persistence, opening new perspectives in the prevention of HZ-related pain. An independent line of evidence was provided for the efficacy of antiviral therapy in preventing PHN and reducing total pain burden.

Plasma vitamin C is lower in postherpetic neuralgia patients and administration of vitamin C reduces spontaneous pain but not brush-evoked pain

OBJECTIVES

Plasma vitamin C concentrations have been suggested to be related to pain modulation in postherpetic neuralgia (PHN), an intractable neuropathic pain syndrome. In this study, we first compared plasma concentrations of vitamin C between healthy volunteers and PHN patients and then designed a symptom-based and mechanism-based approach to assess the analgesic effect of intravenous vitamin C on spontaneous and brush-evoked pain.

METHODS

Study 1 was cross-sectional that enrolled 39 healthy volunteers and 38 PHN patients. Study 2 was a double-blinded, placebo-controlled intervention study, which comprised 41 patients randomly allocated into the ascorbate group and placebo. Each patient received normal saline infusion with or without ascorbate on days 1, 3, and 5 and answered questionnaires that included side effects; numeric rating pain scale (NRS) on spontaneous and brush-evoked pain on days 1, 3, 5, and 7; and patient global impression of change on spontaneous and brush-evoked pain on day 7.

RESULTS

Study 1 revealed that plasma concentrations of vitamin C were significantly lower in patients with PHN than in healthy volunteers (P<0.001). Study 2 showed that ascorbate treatment effectively restored plasma vitamin C concentrations in the patients and decreased spontaneous pain by 3.1 in NRS from baseline to day 7, as compared with a decrease of 0.85 in NRS by placebo treatment (P<0.001). Conversely, ascorbate treatment did not significantly affect brush-evoked pain. Ascorbate treatment also resulted in a better efficacy than placebo in patient global impression of change on spontaneous pain (P<0.001) on day 7 and did not affect brush-evoked pain. No side effects were observed.

CONCLUSIONS

Plasma vitamin C status plays a role in PHN, and intravenous ascorbate helps relieve spontaneous pain in PHN.

Incremental 1-year medical resource utilization and costs for patients with herpes zoster from a set of US health plans

BACKGROUND

Nearly 1 million new episodes of herpes zoster (HZ) occur annually in the US, yet little is known about the medical resource utilization (RU) and costs associated with HZ and its complications.

OBJECTIVES

To describe the medical RU and cost burden of HZ in the first 90 days and the first year after diagnosis from the health insurer perspective and to stratify this burden for patients diagnosed with post-herpetic neuralgia (PHN) and those who are immunocompromised. In addition, this study explores costs from the societal perspective as a result of work loss in the first year after diagnosis.

METHODS

The medical RU and cost data were obtained from the MarketScan Research Database for the years 1998-2003. This database contains inpatient, outpatient and prescription drug data for approximately 14 million individuals of all ages, covered under a variety of fee-for-service and capitated provider reimbursement arrangements, including those with Medicare and private insurance. The work loss estimates were based on the MarketScan Health and Productivity Management Database. Claims for services incurred between 1 January 1998 and 31 December 2003 were screened to identify a cohort of HZ patients based on the presence of at least one International Classification of Diseases, 9th Revision (ICD-9) diagnosis code 053.xx. Each patient was assigned an index date based on the earliest observed occurrence of an HZ diagnosis. A cohort of PHN patients was identified as a subset of the HZ cohort with ICD-9 codes 053.12, 053.13, 053.19 or 729.2x in the period of 90 days to 12 months after the index date. Multivariable regression was used to compare HZ cases with matched controls after adjusting for demographic characteristics, insurance status, co-morbidities and medical expenditure in the 6 months prior to diagnosis for each of the endpoints. Separate regression models were developed, in which age and immune status were stratified. All costs were adjusted to March 2008 values using the medical care component of the Consumer Price Index. The average per patient cost of all HZ cases was $US605 in the first 90 days after diagnosis and $US1052 at 1 year. For the subset with PHN, the average per patient cost of HZ at 1 year was $US3815. For the subset with an immunocompromising condition, the average HZ cost at 1 year was $US1745. The majority of the costs were the result of outpatient visits and prescription drugs. The subset of HZ cases that had both absence hour and short-term disability (STD) records available had 26.5 absence hours and 2.9 STD days. Healthcare utilization, medical care costs and work loss all increased with age for all HZ cases. Based on the results from the present study, the direct medical cost burden of HZ in the US is high, exceeding $US1000 per HZ patient. This direct medical cost may be nearly twice as high in immunocompromised patients and four times as high in the subset of HZ cases with PHN. The direct medical cost burden of HZ may exceed $US1 billion annually in the US. The majority of medical RU and cost burden is incurred by the elderly. Although many people with HZ may no longer be in the workforce, HZ does contribute to lost work time.

Diagnosis and assessment of pain associated with herpes zoster and postherpetic neuralgia

Accurate evaluation of pain plays a critical role in identifying new interventions for the treatment and prevention of herpes zoster and postherpetic neuralgia (PHN). Different types of pain and other sensory symptoms are found in patients with herpes zoster, and these vary greatly with respect to their presence, location, duration, intensity, and quality. The results of recent studies of herpes zoster and PHN and the development of new methods for assessing neuropathic pain provide a foundation for diagnosing and assessing the pain associated with herpes zoster. We review the results of recent research to identify the essential components that must be considered in developing an evidence-based description of pain associated with herpes zoster and PHN.

PERSPECTIVE

Comprehensive assessments of pain are necessary for clinical research on the epidemiology, natural history, pathophysiologic mechanisms, treatment, and prevention of pain in herpes zoster and PHN.

Postherpetic neuralgia: epidemiology, pathophysiology and management

Postherpetic neuralgia (PHN) is a neuropathic pain syndrome and is the most common complication of herpes zoster (HZ; shingles). PHN occurs mainly in HZ patients 60 years of age and older, in particular in those suffering from more severe acute pain and rash. Administration of antiviral drugs reduces the duration of pain associated with HZ. The pathophysiology of PHN may be distinctly different between patients with either reduced or increased skin sensitivity. Therapy is with tricyclic drugs (e.g., nortriptyline), alpha 2 delta-ligands (e.g., gabapentin) or opiates with adjunctive topical lidocaine or capsaicin. Mechanism-based therapy is a desirable goal but so far proves elusive. The incidence of HZ, and therefore that of PHN, is likely to increase as a result of greater longevity and increasing numbers of patients receiving treatment that compromises cell-mediated immunity. A zoster vaccine for administration to adults reduces the incidence of HZ and PHN, as well as the burden of illness associated with these conditions.

A population-based study of the incidence and complication rates of herpes zoster before zoster vaccine introduction

OBJECTIVE

To establish accurate, up-to-date, baseline epidemiological data for herpes zoster (HZ) before the introduction of the recently licensed HZ vaccine.

METHODS

Using data from January 1, 1996, to October 15, 2005, we conducted a population-based study of adult residents (Greater than or equal to 22 years) of Olmsted County, MN, to determine (by medical record review) the incidence of HZ and the rate of HZ-related complications. Incidence rates were determined by age and sex and adjusted to the US population.

RESULTS

A total of 1669 adult residents with a confirmed diagnosis of HZ were identified between January 1, 1996, and December 31, 2001. Most (92%) of these patients were immunocompetent and 60% were women. When adjusted to the US adult population, the incidence of HZ was 3.6 per 1000 person-years (95% confidence interval, 3.4-3.7), with a temporal increase from 3.2 to 4.1 per 1000 person-years from 1996 to 2001. The incidence of HZ and the rate of HZ-associated complications increased with age, with 68% of cases occurring in those aged 50 years and older. Postherpetic neuralgia occurred in 18% of adult patients with HZ and in 33% of those aged 79 years and older. Overall, 10% of all patients with HZ experienced 1 or more nonpain complications.

CONCLUSIONS

Our population-based data suggest that HZ primarily affects immunocompetent adults older than 50 years; 1 in 4 experiences some type of HZ-related complication.

Tolerability of treatments for postherpetic neuralgia

Herpes zoster occurs in up to 20% of people infected with varicella-zoster virus, due to reactivation of the virus from latently infected sensory ganglia. Although pain is a typical feature of acute zoster, pain persisting for more than a month after resolution of the rash is less common and is termed postherpetic neuralgia (PHN). The pain associated with PHN is neuropathic in origin and is notoriously difficult to treat. The incidence of herpes zoster and its associated complications both increase with age, so PHN should be seen more commonly in an aging population. Vaccination with live, attenuated varicella vaccine is safe and efficacious, particularly in children. It decreases the incidence of acute varicella and subsequent herpes zoster. Aciclovir is well tolerated, with renal toxicity only at high intravenous doses. Treatment of acute varicella with aciclovir attenuates acute illness but does not prevent herpes zoster. Treatment of herpes zoster with aciclovir or its derivatives minimises symptoms and may reduce the rate of PHN. Foscarnet is an alternative for an aciclovir-resistant virus but its use is limited by renal and CNS toxicity. Corticosteroids reduce acute pain in herpes zoster but do not affect the incidence of PHN. Their use in some patients may be limited by adverse effects such as gastritis and impaired glucose tolerance. Treatment of established PHN is difficult and may require a holistic approach. Tricyclic antidepressants and gabapentin are the systemic agents with the most proven benefit, although opioids such as oxycodone and NMDA receptor antagonists such as ketamine may be useful in some people. Adverse effects from tricyclic antidepressants are common but usually mild, while gabapentin is generally well tolerated. Although effective, the relatively common adverse effects of opioids and ketamine limit their usefulness in treating PHN. Topical treatment with 5% lidocaine patch or capsaicin is of benefit in some patients and is generally well tolerated. Intrathecal methyl prednisolone may be considered for intractable pain but efficacy and safety have not been confirmed.

Brivudin compared with famciclovir in the treatment of herpes zoster: effects in acute disease and chronic pain in immunocompetent patients. A randomized, double-blind, multinational study

OBJECTIVE

This was a double-blind, randomized multicentre trial comparing efficacy and safety of brivudin (125 mg, once a day) and famciclovir (250 mg, three times a day), both given orally for 7 days, in the treatment of herpes zoster.

METHODS

A total of 2027 immunocompetent zoster patients>or=50 years with zoster-related pain at presentation were included. Outcome measures embraced prevalence of postherpetic neuralgia (PHN), defined as at least moderate pain 3 months after treatment initiation, duration of PHN, prevalence and duration of zoster-associated pain (ZAP), duration of vesicle formation and rash healing.

RESULTS

The prevalence of PHN at month 3 was 11.3% with brivudin and 9.6% with famciclovir [per-protocol (PP) population]. Equivalence of the two drugs could be demonstrated (P=0.01, PP and intention-to-treat analysis). The median duration of PHN was 46.5 days with brivudin and 58 days with famciclovir (P=0.54, PP analysis). Prevalence and duration of ZAP did not differ significantly between treatment groups. The prevalence of PHN was higher in patients>or=65 years (brivudin: 16.4%, famciclovir: 16.4%), and in patients with severe rash (brivudin: 13.4%, famciclovir: 15.7%), without significant differences between treatment groups. In patients>or=65 years, median duration of PHN was shorter with brivudin than with famciclovir (39.5 vs. 57.5 days), although the difference was not statistically significant. The two drugs had equivalent efficacy in being able to accelerate the stop of vesicle formation, and lesion healing. Adverse events were similar in nature and prevalence among groups.

CONCLUSIONS

The study demonstrated equivalent efficacy of brivudin and famciclovir in the treatment of herpes zoster regarding the prevention of chronic pain and the resolution of signs and symptoms of acute herpes zoster. Compared with famciclovir, brivudin provides equivalent efficacy and safety at a more convenient once-daily dose schedule.

[Varicella-zoster virus infections]

The primary infection with varicella-zoster virus (VZV) is manifest clinically as varicella. It is a common very contagious disease, normally appearing in childhood. VZV is a ubiquitous virus with a high prevalence. Clinically it is characterized by pleomorphic skin lesions. Normally antiviral therapy is necessary only in severe cases, in adults or in immunosuppressed patients. Herpes zoster, also caused by (VZV), is a neurodermal disease representing the endogenous relapse of the primary varicella infection. Herpes zoster is characterized by lesions concentrated in the innervation region of a cranial or spinal nerve. One of the most feared manifestations of herpes zoster is pain. Several antiviral drugs are approved and many studies have shown that antiviral therapy, started early in the course of disease, can significantly reduce risk and duration of postherpetic neuralgia in elderly patients. Therefore, antiviral therapy in combination with an adequate pain management should be given to all elderly patients as soon as herpes zoster is diagnosed.

Treatment of postherpetic neuralgia: a review of therapeutic options

Postherpetic neuralgia (PHN) is a disabling consequence of the reactivation of the varicella zoster infection. The observation that patients with PHN experience various types of pain suggests that multiple pathophysiologic mechanisms are involved, which may include the peripheral and central nervous systems. A reasonable initial strategy would involve selecting from among multiple agents that have complementary mechanisms of action and that have been proven effective in controlled clinical trials, such as the lidocaine patch 5%, gabapentin, tricyclic antidepressants, and opioids. Based on initial assessment and ongoing reassessment, sequential trials should be undertaken until adequate pain relief is achieved. This may ultimately lead to therapy with more than one medication. Safety and tolerability are important considerations in choosing initial therapy, particularly in older patients. Physicians can either add another agent to the current regimen or switch to a new type of monotherapy if there is inadequate response to initial therapy. Alternative therapies, (i.e., ketamine, intrathecal corticosteroid injections) have not been adequately studied. Well-designed, multicenter, controlled clinical trials are needed to develop a treatment algorithm that provides an evidence-based, rational approach to treating PHN.

The role of antivirals in the management of neuropathic pain in the older patient with herpes zoster

Herpes zoster has been known since ancient times. It is a ubiquitous disease, occurring sporadically without any seasonal preference and is caused by the varicella-zoster virus. It may be defined as an endogenous relapse of the primary infection varicella. Herpes zoster is characterised by typical efflorescences in the innervation region of a cranial or spinal nerve and starts and ends with pain of varying intensity. Currently, several antiviral drugs are approved and many studies have shown that antiviral therapy, started early in the course of disease, can significantly reduce the risk and the duration of postherpetic neuralgia in elderly patients. The effects of all antivirals discussed in this article, given either orally or intravenously, are comparable with regards to the resolution of virus replication, prevention of dissemination of skin lesions and reduction of acute herpes zoster pain. Valaciclovir (valacyclovir), famciclovir and brivudine (brivudin) are comparably effective in the reduction of the incidence and/or prevention of zoster-associated pain and postherpetic neuralgia. Brivudine 125mg once daily is as effective as famciclovir 250mg three times daily in reducing the prevalence and the duration of zoster-associated pain and postherpetic neuralgia, especially if therapy is combined with a structured-pain therapy. The intensity of the therapy for pain should depend on the intensity of the pain that it is treating. Famciclovir and brivudine offer an advantage over other antivirals because they are administered less frequently; this is particularly relevant for elderly patients who may already be taking a number of medications for other diseases. Therefore, antiviral therapy in combination with adequate pain management should be given to all elderly patients as soon as herpes zoster is diagnosed.

The PINE study: rationale and design of a randomised comparison of epidural injection of local anaesthetics and steroids versus care-as-usual to prevent postherpetic neuralgia in the elderly [ISRCTN32866390]

BACKGROUND: Postherpetic neuralgia (PHN) is by far the most common complication of herpes zoster (HZ) and one of the most intractable pain disorders. Since PHN is seen most often in the elderly, the number of patients with this disorder is expected to increase in our ageing society. PHN may last for months to years and has a high impact on the quality of life. The results of PHN treatment are rather disappointing. Epidural injection of local anaesthetics and steroids in the acute phase of HZ is a promising therapy for the prevention of PHN. Since randomised trials on the effectiveness of this intervention are lacking, the PINE (Prevention by epidural Injection of postherpetic Neuralgia in the Elderly) study was set up. The PINE study compares the effectiveness and cost-effectiveness of a single epidural injection of local anaesthetics and steroids during the acute phase of HZ with that of care-as-usual (i.e. antivirals and analgesics) in preventing PHN in elderly patients. METHODS / DESIGN: The PINE study is an open, multicenter clinical trial in which 550 elderly (age >/= 50 yr.) patients who consult their general practitioner in the acute phase of HZ (rash < 7 days) are randomised to one of the treatment groups. The primary clinical endpoint is the presence of HZ-related pain one month after the onset of the rash. Secondary endpoints include duration and severity of pain, re-interventions aiming to treat the existing pain, side effects, quality of life, and cost-effectiveness. CONCLUSION: The PINE study is aimed to quantify the (cost-) effectiveness of a single epidural injection during the acute phase of HZ on the prevention of PHN.

Tramadol in post-herpetic neuralgia: a randomized, double-blind, placebo-controlled trial

The efficacy and safety of sustained-release tramadol compared to placebo in the treatment of post-herpetic neuralgia were evaluated in a multicenter, randomized, double-blind, parallel-group study in 127 outpatients. Treatment was administrated for 6 weeks. The dose of tramadol could be increased from 100 mg/day to 400 mg/day (300 mg/day in patients more than 75 years old). Groups were compared on changes in pain intensity on a Visual Analogue Scale (VAS) between inclusion and the 6th week of treatment (covariance analysis as main analysis and repeated measures analysis as complementary analysis) in the per protocol (PP) population. The randomized population comprised 127 patients aged 35-85 years, mostly females (72.4%). Groups were comparable at inclusion both in the intent to treat (ITT) population (63 patients in the tramadol group and 62 patients in the placebo group) and in the PP population (53 patients in the tramadol group and 55 patients in the placebo group). Mean pain intensity on day 43 adjusted on day 1 (covariance analysis) was significantly lower in the tramadol group than in the placebo group in both the PP (P=0.0499), and the ITT (P=0.031) populations. The two groups significantly differed on change in pain intensity over time (repeated measures analysis) in the ITT population (P=0.012). The percentage of pain relief over the 6th week was significantly higher in the tramadol group than in the placebo group (P=0.017). During the 6th week, patients in the tramadol group required less rescue medication than patients in the placebo group (P=0.022). No significant difference was found between groups either in pain intensity on a 5-point Verbal Scale (VRS) or in quality of life measurements. Tramadol was administered at an average dosage of 275.5 (89.7) mg/day after a 1-week dose-adaptation period. Tramadol was well tolerated. No notable difference appeared between groups either in the percentage of patients with treatment-associated adverse events (TAAE) (29.7% in the tramadol group and 31.8% in the placebo group) or in the total number of TAAE (31 in the tramadol group and 28 in the placebo group).

Oral antivirals revisited in the treatment of herpes zoster: what do they accomplish?

Oral antiviral agents currently represent the most important therapeutic keystone in the treatment of herpes zoster. Three oral antiviral agents are available for the treatment of herpes zoster: acyclovir, its derivative valacyclovir, and famciclovir. Meta-analysis of published data has shown that oral acyclovir significantly reduces various herpes zoster-related symptoms as well as the duration, intensity and prevalence of zoster-associated pain (ZAP). However, this drug does not influence postherpetic neuralgia. The newer agents famciclovir and valacyclovir exhibit a better oral bioavailability than acyclovir. These agents have demonstrated similar efficacy to acyclovir with ZAP and they require less frequent administration. When initiated within 72 hours, oral antiviral therapy of herpes zoster is beneficial in selected, elderly immunocompetent patients, reducing the duration and intensity of ZAP and providing more rapid skin lesion healing. Oral antivirals are also of benefit in immunocompromised patients with uncomplicated herpes zoster. However, signs of cutaneous and visceral dissemination should be monitored; if signs occur, intravenous antiviral therapy is indicated.

Herpes zoster guideline of the German Dermatology Society (DDG)

Varicella zoster virus (VZV) causes varicella (chickenpox), remains dormant in dorsal root and cranial nerve ganglia and can be reactivated as a consequence of declining VZV-specific cellular immunity leading to herpes zoster (shingles). Patients older than 50 years of age affected by herpes zoster may suffer a significant decrease of quality of life. These patients and immunocompromised individuals are at increased risks for severe complications, involving the eye, the peripheral and the central nervous system (prolonged pain, postherpetic neuralgia). Such complications occur with and without cutaneous symptoms. The German Dermatology Society (DDG) has released guidelines in order to guarantee updated management to anyone affected by herpes zoster. Diagnosis is primarily clinical. The gold standard of laboratory diagnosis comprises PCR and direct identification of VZV in cell cultures. Detection of IgM- and IgA-anti VZV antibodies may be helpful in immunocompromised patients. Therapy has become very effective in the last years. Systemic antiviral therapy is able to shorten the healing process of acute herpes zoster, to prevent or to alleviate pain and other acute and chronic complications, particularly, when given within 48 h to a maximum of 72 h after onset of the rash. Systemic antiviral therapy is urgently indicated in patients beyond the age of 50 years and in patients at any age with herpes zoster in the head and neck area, especially in patients with zoster ophthalmicus. Further urgent indications are severe herpes zoster on the trunk and on the extremities, herpes zoster in immunosuppressed patients and in patients with severe atopic dermatitis and severe ekzema. Only relative indications for antiviral therapy exist in patients younger than 50 years with zoster on the trunk and on the extremities. In Germany acyclovir, valacyclovir, famciclovir and brivudin are approved for the systemic antiviral treatment of herpes zoster. These compounds are all well tolerated by the patients and do not differ with regard to efficacy and safety. Brivudin has a markedly higher anti-VZV potency than oral acyclovir, valacyclovir and famciclovir and thus offers a simpler dosing regimen. It must be given only once daily during 7 days in comparison to three and five times dosing per day of valacyclovir, famciclovir and acyclovir, respectively. Brivudin is an antiviral agent with no nephrotoxic properties, which is an advantage when compared to acyclovir. The most important aim of therapy of herpes zoster is to achieve painlessness. Appropriately dosed analgesics in combination with a neuroactive agent (i.e. amitriptylin) are very helpful when given together with antiviral therapy. The additive therapy with corticosteroids may shorten the degree and duration of acute zoster pain, but has no essential effect on the development of postherpetic neuralgia, which is a very difficult condition to treat. Thus early presentation to a pain therapist is recommended in specific cases.

Prevention of postherpetic neuralgia with varicella-zoster hyperimmune globulin

Recovery after an acute attack of herpes zoster is followed by postherpetic neuralgia (PHN) in 9-14% of all patients. Depending on the patient's age, the severity of the acute attack of herpes zoster and the dermatome involved, the incidence of PHN may be as high as 65%. The purpose of our study was to ascertain the incidence of PHN after a prophylactic intravenous injection of varicella-zoster hyperimmune globulin (VZV-IG) (Varitect Biotest Pharma). For this double-blind placebo-controlled randomised investigation we defined PHN as pain confined to the dermatome previously affected by herpes zoster, and we required a pain intensity of at least 15% points on a visual analogue scale (VAS) for this dermatome. The inclusion criteria were the dermatological diagnosis of herpes zoster together with age over 50 years. On Day 1, 20 patients received a single intravenous infusion of VZV-IG in a dose of 2mL/kg body weight, 20 patients (control group) received a single infusion of human albumin 5% in a dose of 2mL/kg body weight. All patients received acyclovir intravenously in a dose of 15mg/kg body weight per 24h for 5 days. The patients were followed up for a total of 42 days. The incidence of PHN at Day 42 was selected as the main outcome criterion for assessing the efficacy of prophylaxis. On reaching a significant difference between the groups (t test; alpha<0.05) in favour of the active treatment group, prophylaxis of PHN by VZV-IG was assessed as effective. Pain was assessed on a VAS and a NAS. As auxiliary outcome criteria, we used the McGill Pain-Rating Questionnaire in its German version, the revised multidimensional pain scale (RMSS) and the Freiburg symptom list (FBL). All results were assessed by the t test (alpha<0.05). The frequency of PHN in the placebo group was 70% (14/20), in the active treatment group it was 35% (7/20) at Day 42. The results of the McGill test showed the variability of the perception of pain in the placebo group significantly greater. No significant group differences were found in the FBL. Being tested with the RMSS, the patients of the placebo group assessed their pains as significantly "more obstinate" (p=0.047). The results can be summed up by saying that VZV-IG not only reduces the incidence of PHN, but also that in certain respects the patients' assessments of their pain experience were different. In our study we found a 50% reduction in PHN incidence However, the outcome time point of our trial was so close to the acute phase of the zoster illness that spontaneous remissions of PHN still have to be taken into account. Despite the widely varied approaches to the problem, reliably effective therapy, let alone 100% prevention of PHN, is still not feasible.

Lidocaine Patch 5% Reduces Pain Intensity and Interference with Quality of Life in Patients With Postherpetic Neuralgia: An Effectiveness Trial

OBJECTIVE

To assess the effectiveness of the lidocaine patch 5% (Lidoderm), a targeted peripheral analgesic, in reducing pain intensity/interference with quality of life (QOL) among patients with postherpetic neuralgia (PHN).

DESIGN

Open-label, nonrandomized, effectiveness study; up to three patches applied to area of greatest pain for 12 hours per day for 28 days.

SETTING

Forty-two centers consisting of large institutional primary care programs and academic centers, including pain centers, neurologists, and pain specialists affiliated with a university.

PATIENTS

Patients with PHN (N = 332).

OUTCOME MEASURES

Patients completed the Brief Pain Inventory Short Form and global pain assessments at baseline, Days 7 and 14, and study conclusion. Physicians completed global assessments at baseline and study conclusion.

RESULTS

The mean time from onset of herpes zoster to treatment was 28 months. Use of the lidocaine patch 5% was associated with reductions in all mean pain intensity, pain interference with QOL, and composite scores at all time points (P = 0.0001). Overall, 66% of patients reported improvement in pain intensity, and 74% reported improved QOL by Day 7; approximately 43% who did not respond by Day 7 experienced improvement in pain intensity by Day 14. For all measures of pain intensity, relief, and interference with QOL, improvements from baseline were equally significant regardless of time since shingles onset. In all, approximately 60% of patients reported moderate to complete pain relief at final evaluation. The lidocaine patch 5% was well tolerated.

CONCLUSIONS

Based on results of previous randomized, controlled trials and the current study, designed to gauge response in the clinical practice setting, the lidocaine patch 5% should be considered a first-line therapy, alone or in combination with other agents, for PHN due to its efficacy, safety, minimal systemic side effects and drug interactions, and ease of administration. Although the lidocaine patch 5% was equally effective in longstanding PHN, it would appear prudent to begin therapy as early in the course of PHN as possible.

10: Herpes simplex and varicella-zoster virus infections

Any new patient with suspected genital herpes should have diagnostic testing with virus identification. Type-specific serological tests that distinguish between antibodies for type 1 and type 2 herpes simplex virus (HSV) may be useful to determine previous exposure but cannot be used to diagnose recurrences of genital herpes. Initial episodes of genital herpes usually require antiviral therapy, while recurrences may be treated with continuous antiviral suppression (if frequent) or episodic therapy; patient counselling and education (including how to recognise lesions) are essential. Topical or systemic therapy is available for initial and recurrent non-genital herpes simplex. Primary varicella infection (chickenpox) and herpes zoster (shingles) are usually diagnosed clinically, but can be confirmed by detection of varicella-zoster virus antigens or nucleic acid from swabs of lesions or by antibody tests. Antiviral therapy should be considered in chickenpox if disease is complicated or the patient is immunocompromised. In herpes zoster, antiviral therapy should be given within 72 hours of onset to patients aged over 50 years or with severe pain or neurological abnormalities to reduce the likelihood and duration of postherpetic neuralgia. The availability of effective antiviral therapy makes early diagnosis vital

Rash severity in herpes zoster: correlates and relationship to postherpetic neuralgia

Baseline and follow-up data from 4 samples of immunocompetent patients with herpes zoster who participated in clinical trials of the antiviral agent famciclovir were examined (N = 1778). In both univariate and multivariate analyses, severe rash (ie, >50 lesions, defined as papules, vesicles, or crusted vesicles) was significantly associated with older age, male sex, severe pain, primary involvement of nontrigeminal dermatomes, and a greater number of affected dermatomes. In addition, severe rash predicted the presence of pain 3 months later. The results indicate that severe rash is more common in patients with herpes zoster who are older and who have more severe acute pain and confirm that severe rash is a risk factor for prolonged pain.

Neuropathic pain

Damage to peripheral nerves triggers a cascade of events in axotomized sensory neurones that are generally believed to be responsible for the generation of neuropathic pain. Recent data in animal models show that alterations in the properties of undamaged neurones that project into a damaged nerve can also play an important role. These new findings could explain some of the enigmatic clinical signs and symptoms of pain following nerve injury such as the spread of symptoms into areas not affected by the primary lesion. The basis by which uninjured nerves could be affected is a reduced supply of neurotrophic factors, an abnormal interaction in the Remak bundles of partially denervated Schwann cells and unmyelinated axons, or the byproducts of Wallerian degeneration.

Acute pain in herpes zoster: the famciclovir database project

The results of a considerable number of recent prospective studies have demonstrated that greater acute pain severity in herpes zoster patients is associated with a significantly greater risk of developing postherpetic neuralgia (PHN). Only a few studies have examined the relationships between acute pain severity and demographic characteristics and clinical features of patients with herpes zoster, however, and the results of these studies have been inconsistent. To clarify these relationships, data from 1778 herpes zoster patients studied within 72 h of rash onset in four clinical trials of the antiviral agent famciclovir were examined. Univariate and multivariate analyses indicated that greater acute pain severity was significantly associated with greater age, female sex, greater rash severity, the presence of a prodrome, and primary involvement of non-trigeminal dermatomes. These results demonstrate that three of the established risk factors for PHN - older age, greater rash severity, and the presence of a prodrome - are also associated with more severe acute pain assessed soon after rash onset in patients with herpes zoster. The results of this study are consistent with the recommendation that herpes zoster patients who are older, who have had a prodrome, or who have severe rash or severe acute pain should be targeted for interventions designed to prevent PHN.

Risk and prognostic factors of postherpetic neuralgia and focal sensory denervation: a prospective evaluation in acute herpes zoster ophthalmicus

OBJECTIVES

To determine the general risk and the prognostic factors of postherpetic neuralgia and focal sensory denervation in ophthalmic zoster disease.

STUDY DESIGN

A prospective clinical study.

SETTING

An ophthalmic practice participating in an eye-care network.

PATIENTS

A cohort of 81 immunocompetent adult patients with herpes zoster ophthalmicus and referred by their general practitioner during the acute phase of the disease.

METHODS

Various acute phase clinical parameters were determined via patient history and regular ophthalmic examinations. At a 2-month follow-up, the intensity of postherpetic neuralgia, rated on a 4-point verbal scale, and focal sensory denervation was determined. Skin tactile sensation within the ophthalmic dermatomes was tested with use of a cotton-wool tip, and corneal sensitivity was measured with use of a Cochet-Bonnet esthesiometer by comparing each eye. Statistical analysis was performed via chi2 analysis or Fisher exact test to identify prognostic factors of postherpetic neuralgia and focal sensory denervation at a 2-month follow-up.

RESULTS

At a 2-month follow-up, pain of varying intensity was reported by 38 participants (47%). Of these patients, 25 patients (31%) rated their pain as mild, 8 patients (10%) rated their pain as moderate pain, and 5 patients (6%) rated their pain as severe. At that time, focal loss of normal skin or corneal sensation was detected in 49 patients (60%). Patient age, acute neuralgia score, manifestation and extent of acute skin rash, signs of ocular inflammation, and nontrigeminal cranial nerve involvement were all associated with prolonged pain and tactile sensory loss.

CONCLUSIONS

The severity of acute skin rash, based on a specific manifestation of cutaneous herpes zoster eruptions, and the extent of infection to other neural pathways were clearly associated with postherpetic neuralgia and focal sensory denervation at a 2-month follow-up. These findings suggest that the inability of the immune system to control the spread of replicating varicella-zoster virus in the initial phase of the disease is an important factor in the pathogenesis of chronic zoster-related neuropathy.

Prevalence of postherpetic neuralgia after a first episode of herpes zoster: prospective study with long term follow up

OBJECTIVE

To estimate the frequency, duration, and clinical importance of postherpetic neuralgia after a single episode of herpes zoster.

DESIGN

Prospective cohort study with long term follow up.

SETTING

Primary health care in Iceland.

PARTICIPANTS

421 patients with a single episode of herpes zoster.

MAIN OUTCOME MEASURES

Age and sex distribution of patients with herpes zoster, point prevalence of postherpetic neuralgia, and severity of pain at 1, 3, 6, and 12 months and up to 7.6 years after the outbreak of zoster.

RESULTS

Among patients younger than 60 years, the risk of postherpetic neuralgia three months after the start of the zoster rash was 1.8% (95% confidence interval 0.59% to 4.18%) and pain was mild in all cases. In patients 60 years and older, the risk of postherpetic neuralgia increased but the pain was usually mild or moderate. After three months severe pain was recorded in two patients older than 60 years (1.7%, 2.14% to 6.15%). After 12 months no patient reported severe pain and 14 patients (3.3%) had mild or moderate pain. Seven of these became pain free within two to seven years, and five reported mild pain and one moderate pain after 7.6 years of follow up. Sex was not a predictor of postherpetic neuralgia. Possible immunomodulating comorbidity (such as malignancy, systemic steroid use, diabetes) was present in 17 patients.

CONCLUSIONS

The probability of longstanding pain of clinical importance after herpes zoster is low in an unselected population of primary care patients essentially untreated with antiviral drugs.

The role of sympathetic nerve blocks in herpes zoster and postherpetic neuralgia

The most common complication of herpes zoster in immunocompetent patients is postherpetic neuralgia (PHN). Sympathetic blocks have been traditionally used for patients with herpes zoster and PHN with three different therapeutic goals: pain relief during acute herpes zoster, pain relief during PHN, and prevention of PHN by treating patients with acute zoster. The role of sympathetic blocks in herpes zoster and PHN remains controversial due to methodologic shortcomings in published studies and the limited current understanding of the role of the sympathetic nervous system in mediating pain. Current theories of the pathophysiology of PHN, the role of the sympathetic nervous system in herpes zoster and PHN, and published studies investigating use of sympathetic nerve blocks in herpes zoster and PHN are reviewed.

Allodynia and pinprick hypesthesia in acute herpes zoster, and the development of postherpetic neuralgia

Sensory loss and allodynia are hallmark signs of postherpetic neuralgia (PHN). We set out to investigate how frequently these signs are present in patients with acute herpes zoster (HZ) and what their prognostic value might be. We assessed pain, mechanical allodynia, and sensitivity to pinprick in 113 immunocompetent patients with HZ of a median duration of 5 days. Follow-up visits took place at 2 weeks, 6 weeks, 3 months, and 6 months. When first seen, 87 (77%) patients reported ongoing pain and 48/107 (45%) had allodynia. Twenty-eight (25%) patients had pain at 3 months (and were considered to have developed PHN), while 14 (12%) patients had pain at 6 months. Allodynia tended to subside quickly in most patients. Reduced sensitivity to pinprick was less common. Mechanical allodynia and pinprick hypesthesia were strongly associated with the development of PHN. They merit addition to the list of potential risk factors for PHN although they cannot be used as a predictive rule for an individual patient. By contrast, lack of allodynia in the early stages of HZ predicts good recovery by three months.

Valaciclovir: a review of its use in the management of herpes zoster

Varicella zoster virus (VZV), the pathogen responsible for herpes zoster, belongs to the herpesvirus family and is sensitive to the antiviral drug aciclovir. However, the low oral bioavailability of aciclovir has to some extent limited its efficacy in the treatment of herpes zoster and has prompted the development of the more readily absorbed oral prodrug valaciclovir. In a large comparative study valaciclovir, (1000 mg 3 times daily for 7 days) was at least as effective as aciclovir (800 mg 5 times daily for 7 days) in controlling the symptoms of acute herpes zoster. Importantly, valaciclovir alleviated zoster-associated pain and postherpetic neuralgia significantly faster than aciclovir. A 14-day regimen of valaciclovir showed no significant advantage over the 7-day regimen. A smaller trial in Japanese patients focusing primarily on the cutaneous (rash) signs of herpes zoster confirmed the similar efficacy of valaciclovir and aciclovir in the 7-day regimen. This study did not follow all patients for a formal analysis of postherpetic neuralgia. Valaciclovir and aciclovir demonstrated similar efficacy for the control of cutaneous lesions and ocular complications in patients with zoster ophthalmicus. Preliminary results of a large controlled trial indicate that valaciclovir 1000 mg 3 times daily and famciclovir (the prodrug of penciclovir) 500 mg 3 times daily are of similar efficacy in speeding resolution of acute herpes zoster rash and shortening the duration of postherpetic neuralgia. Starting treatment later than 72 hours after rash onset did not significantly reduce the beneficial effect of valaciclovir on duration of zoster-associated pain (a continuum of pain that encompasses both acute pain and postherpetic neuralgia) in a large observational study, suggesting that valaciclovir might be effective when given later than previously thought. However, valaciclovir should ideally be given as soon as possible after symptoms appear. With the recommended regimen for the treatment of herpes zoster (1000 mg 3 times daily for 7 days) valaciclovir was well tolerated, with nausea and headache being the most commonly reported adverse events. The adverse events profile of the agent was similar to that seen with aciclovir or famciclovir.

CONCLUSION

The efficacy of valaciclovir for the treatment of herpes zoster has been confirmed and extended by follow-up studies in herpes zoster ophthalmicus, in Japanese patients, and in the wider primary care setting. Valaciclovir is at least equivalent to, and better in certain parameters than, aciclovir and appears to have similar efficacy to famciclovir 500 mg 3 times daily. Valaciclovir is a well tolerated first-line therapy with an established place in the treatment of immunocompetent patients with herpes zoster.

Pain and its Assessment in Herpes Zoster

Pain typically accompanies acute herpes zoster. In a proportion of patients, herpes zoster pain persists well beyond rash healing. This persisting pain is termed post-herpetic neuralgia (PHN). Because of the substantial personal and economic burdens caused by PHN, studies of the pathophysiology of herpes zoster pain and of the efficacy of antiviral treatment in reducing prolonged pain are of great importance. Different methods have been used to examine pain in research on herpes zoster and in clinical trials, making it difficult to compare across studies. There is substantial evidence, however, that demonstrates the importance of distinguishing acute pain from PHN. Several differences have been found between acute herpes zoster pain and PHN, including pathophysiological findings, risk factors and pain quality. Recommendations for the design and analysis of future trials of antiviral agents in herpes zoster have been recently proposed. These include a definition of PHN and recommended secondary end points for future trials. Adopting these recommendations in future research on herpes zoster pain, and in the design and analysis of future trials, will facilitate comparisons across studies of the pathophysiology and prevention of PHN.