A study of shingles and the development of postherpetic neuralgia in East London.

The incidence of post-herpetic neuralgia following shingles and the factors that are known to predict it were examined in a prospective observational community study of patients with acute shingles presenting to their family doctors. The detection of viral DNA in the blood at presentation as a prognostic indicator for pain was also evaluated. Patients were followed for one year and the persistence of pain following rash assessed. Among 165 patients who had completed 6 months, and 139 one-year follow-up, the prevalence of post herpetic neuralgia was 30% at 6 weeks 27% at 12 weeks, 15.9% at 6 months, and 9% at one year. Age and severity of pain were significantly associated with the persistence of pain beyond 3 months. Viremia at presentation was detected in 66% of patients and was significantly associated with the presence of pain at six months or beyond. Antiviral agents were administered to only 50% of those at highest risk of post-herpetic neuralgia (PHN) mainly because of presentation longer than 72 hours after the onset of rash. Few patients were prescribed the more potent prodrugs, Valaciclovir and Famciclovir. In conclusion, treatment of acute shingles in this observational community-based study was suboptimal in 50% of cases. More accurate prediction of which subset of elderly patients are most at risk of PHN may enable targeted prescribing of the most potent drugs to those most likely to benefit.