To characterise predisposition to post herpetic neuralgia following herpes zoster.
Design: Late follow up of patients originally admitted with acute zoster to a double blind randomised placebo controlled study of oral acyclovir over 60 years of age.
Setting: Two UK cities of 1.5 million population.
Results: 158 of the 298 patients from the original study were available for evaluation at a mean follow up of 9 years. Thirty four (21%) described experiencing pain from the zoster within the previous 12 months. Pain at follow up was associated with characteristics at the time of acute zoster of: moderate or severe acute pain (p = 0.006), prodromal pain >72 h before rash (p = 0.006), severity of rash (p = 0.033) and female gender (p = 0.046). There was no association between pain at 9 year follow up and use of placebo or aciclovir nor with the presence or absence of pain at the point of discharge from the original study. Further analysis of 17 of the 34 patients with long term pain who have full data available, the median pain score was 4 out of 10 and more than 50% described persistent pain and interference with sleep.
Conclusion: Long term pain in the elderly following zoster is associated with identifiable characteristics during the acute illness.