Herpes zoster and quality of life

Although herpes zoster is a self-limited disease, usually resolving in under 2 months, the pain can be severe and intractable. This pain markedly interferes with the patient's ability to perform normal daily activities and with quality of life.

Methods.

This study enrolled 50 patients with herpes zoster from four multispecialty practices, two each from the east and west coasts of the United States. Mean age was 70 years (range, 54 to 94). Approximately one-half were enrolled within a week of the onset of pain or rash and 80% within 2 weeks of onset.

We collected information on demographics and comorbidities at baseline and data on the extent and site of the lesions weekly. Extent of lesions was determined by tracing the involved area for each patient and calculating the actual area (in cm²) by computer and digitizing pad. Questions on comorbidities were used to compute the Charlson Comorbidity Index, ^[1] a commonly used index of comorbidity that was originally developed as a predictor of mortality.

The Wisconsin Brief Pain Inventory (BPI) ^[2] was administered daily in the first week and weekly thereafter. The BPI is a short, simple questionnaire on pain which takes about 5 minutes to complete. There are four questions on pain over the past 24 hours. The patient is asked to score his worst pain, least pain, average pain, and pain right now, from 0 to 10-zero being no pain at all and 10 being "pain as bad as you can imagine.'' In addition, there is one question on the location of pain and seven questions on how the pain interferes with daily activities (also scored from 0 to 10).

The MOS SF-36, ^[3] a standard health-related quality-of-life questionnaire, was given every 2 weeks. The 36 questions of the SF-36 are divided into seven domains and a single general healthperception question. ^[3] A global question on self-reported health ("How do you rate your own health? Is it excellent, very good, good, fair, or poor?'') was also asked of each patient at baseline.

Results.

Table 1 shows the impact of pain on activities of daily living. In this table, a score of 3 or more represents interference with activities of daily living, and a score of 2 or less represents no interference. At a pain level of 3, only a few patients reported interference with activities. At 4, 20 to 30% of patients reported interference. And at a pain level of 9 and 10, almost all individuals reported interference on all activities, with certain activities like work and general activity being influenced more by pain, and others, such as walking and relationships with others, being less affected by pain.

Weekly mean scores for the seven domains of the SF-36 are shown in Table 2. Each individual's score has been normalized, with 0 being the least value and 100 indicating the highest level of functioning or the best quality of life. At study week 2 (third or fourth week of the episode), patients tended to report the worst quality of life for all domains. The effects of herpes zoster are particularly apparent in the domains of physical functioning, emotional functioning, and vitality. Four patients were discontinued from the study before week 8 because of no rash, no symptoms, and no pain. Thus, the values in Table 2 in weeks 4, 6, and 8 are biased slightly downward.

The relationships between quality-of-life domain scores and a number of other variables were examined using multivariate linear regression. The dependent variables were the individual SF-36 domain scores at week 2. Pain, rash, response to the global health question, Comorbidity Index score, and age were entered as independent variables. Pain is that reported on week 2 for the "worst pain'' question of the BPI. Rash area is the maximum rash area at weeks 0, 1, or 2. The worst pain as reported by these patients was the most important determinant of self-reported quality of life for all domains. This variable alone explained 25% of the variance.

Discussion.

Herpes zoster, which is an episodic infectious disease, can have a devastating effect on quality of life, even though the individual is aware that in most cases it will resolve completely. At week 8, scores from the zoster patients rebounded to close to mean scores from the general US population of similar age in most domains except for role functioning-physical and role functioning-emotional. ^[4] However, during the peak of the episode, the impact of herpes zoster on quality of life is at least as great as that seen with chronic diseases such as congestive heart failure, diabetes, myocardial infarction, and clinical depression. ^[3] The symptom that leads to this profound quality-of-life change is the associated pain. Certainly, as the pain ameliorates, patients' self-reported health status and their ability to carry out daily activities rebound to age- and sex-specific values within the general population.