The clinical course of herpes zoster: A prospective study in primary care

Objectives: To determine the incidence of herpes zoster (HZ) and frequency of complications, mainly the incidence of postherpetic neuralgia (PHN). Design: Prospective follow-up study. Setting: Primary health care in Iceland. Main outcome measures: Incidence of HZ, age and sex distribution of patients and discomfort or pain 1, 3 and 12 months after the rash. Results: During an observation period of 229,547 person years, 462 episodes of acute zoster developed (incidence equals; 2.0/1,000/year) in 457 patients. End points were gained for all (100%) after 12 months follow up. Those still having pain after 12 months were followed further, 23 to 57 months more. Systemic acyclovir was used in less than 4%. A fourth of all HZ cases occurred in children and teenagers. PHN was rare in patients younger than 60 years of age; 2% and 1% experienced only mild pain at 3 and 12 months respectively. No patient had moderate or severe pain in this age group at these time points. In contrast pain was experienced by 19% and 8% of patients 60 years of age and older at 3 and 12 months respectively. However, after 12 months only two patients (0.4%) had moderate pain, none had severe pain. Potential immuno-modulating conditions (diabetes mellitus, cancer, HIV-infection, steroid treatment) were present in 24 patients (5%), 4 (1%) of whom were diagnosed with a malignancy within 6 months of contracting HZ. Conclusions: HZ is more common in younger age groups than has previously been reported. In patients younger than 60, the probability of PHN is very low. Malignancy is seldom associated with zoster rash in the primary care setting. The use of routine computerised medical records increases the possibility of collecting epidemiological information on the clinical course of a disease.