The impact of herpes zoster and post-herpetic neuralgia on quality-of-life

Abstract

Background: The potentially serious nature of herpes zoster (HZ) and the long-term complication post-herpetic neuralgia (PHN) are often underestimated. One in four people will contract herpes zoster in their lifetime, with this risk rising markedly after the age of 50 years, and affecting one in two in elderly individuals. Pain is the predominant symptom in all phases of HZ disease, being reported by up to 90% of patients. In the acute phase, pain is usually moderate or severe, with patients ranking HZ pain as more intense than post-surgical or labour pains. Up to 20% of patients with HZ develop PHN, which is moderate-to-severe chronic pain persisting for months or years after the acute phase. We review the available data on the effect of HZ and PHN on patients' quality-of-life.

Discussion: Findings show that HZ, and particularly PHN, have a major impact on patients' lives across all four health domains--physical, psychological, functional and social. There is a clear correlation between increasing severity of pain and greater interference with daily activities. Non-pain complications such as HZ ophthalmicus can increase the risk of permanent physical impairment. Some elderly individuals may experience a permanent loss of independence after an acute episode of HZ. Current challenges in the management of HZ and PHN are highlighted, including the difficulty in administering antiviral agents before pain becomes established and the limited efficacy of pain treatments in many patients. We discuss the clinical rationale for the HZ vaccine and evidence demonstrating that the vaccine reduces the burden of the disease. The Shingles Prevention Study, conducted among >38,000 people aged >or=60 years old, showed that the HZ vaccine significantly reduces the burden of illness and the incidence of both HZ and PHN. In the entire study population, zoster vaccination reduced the severity of interference of HZ and PHN with activities of daily living by two-thirds, as measured by two questionnaires specific to HZ.

Summary: A vaccination scheme may positively impact the incidence and course of HZ disease, thereby improving patients' quality-of-life.

Figure 1

Association between 'worst pain' score and some interference with individual activities of daily living [36]. Fifty patients with HZ were asked to rate their level of pain on a scale from 0 (no pain) to 10 (pain as bad as you can imagine). Interference of pain with seven activities of daily living was measured by the Wisconsin Brief Pain Inventory (four of seven daily activities are shown). Some interference was defined as a score of ≥3. There is a clear correlation between increased pain intensity and greater interference with daily activities and the enjoyment of life. Approximately 20%-30% of those with moderate pain (score 4) reported that the pain affected their daily activities. At least 51% of those who experienced high levels of pain (score 9-10) reported that pain interfered with each activity. Adapted with permission from Lydick et al. [31].

Figure 2

Impact of post-herpetic neuralgia (PHN) across different aspects of quality-of-life (QoL) [13]. A study assessed the impact of pain, medication use and QoL in 385 patients with PHN aged >65 years. Pain causes disruption across many aspects of life for PHN patients. As many as 40% of respondents said that pain moderately or severely affected their ability to carry out general activities. Forty-eight percent of patients commented that pain interfered moderately or severely with their enjoyment of life. Adapted with permission from Oster et al. [13].

Figure 3

Quality-of-life (QoL) scores in a French general population cohort versus patients with herpes zoster (HZ) or post-herpetic neuralgia (PHN) (Leplège, unpublished data; adapted from Figure 2 in Chidiac 2001 [38]). The French general population cohort comprised healthy individuals and individuals with various chronic diseases (n = 3656). Average Short-Form-36 (SF-36) scores (eight domains) were calculated for the general French population and for patients with acute HZ, HZ-related complications, and PHN. The differences in scores between each patient group and the general French population are presented. Patients with HZ and PHN have poorer QoL scores than the general-population group. Clinically meaningful differences (scores below -0.5) are observed for some domains in patients with HZ, and for all domains in patients with complicated HZ or PHN. All three groups of patients scored low for the SF-36 domains of vitality and mental health.

Figure 4

Number needed to treat with common pain therapies to obtain 50% pain relief in one patient [68]. Data highlight the limited relief from pain obtained in patients with post-herpetic neuralgia (PHN). For some treatments, approximately four patients with PHN need to be treated to achieve 50% pain relief in one patient.

Figure 5

Duration of pain in vaccine recipients in the Shingles Prevention Study [70]. The graph compares vaccine recipients who developed herpes zoster and post-herpetic neuralgia (PHN; 315/19,254 recipients) with placebo recipients who developed disease (641/19,247 recipients). Compared with placebo, Zostavax reduced PHN incidence defined as pain at different cut-off times for the duration of pain. Pain persisting at 90 days was reduced by 67%. * For the total population and the sub-groups stratified according to sex, the incidence of PHN in each treatment group (vaccine or placebo) was the weighted average of the observed incidence of PHN stratified according to age group, with weights proportional to the total number of person-years of follow-up in each age group.