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 first episode of herpes tester. Design Prospective cohort study with long term follow up. Setting Primary health care in Iceland. Participants 421 patients with a first episode of herpes tester. Main outcome measures Age and sex distribution of patients with herpes tester, point prevalence or 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 tester 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 It patients. Conclusions The probability of longstanding pain of clinical importance after herpes tester is lo it in an unselected population of primary care patients essentially untreated with antiviral drugs.