Clinical correlates of prolonged pain in Japanese patients with acute herpes zoster.

To determine which risk factors are relevant to the occurrence of post-herpetic neuralgia in Japanese patients with acute herpes zoster, correlations between the prolongation of pain and various disease factors were examined in 263 adult patients presenting within 10 days of the onset of rash at 17 institutions in the Hyogo region of Japan. All patients in whom pain persisted for more than 3 months were over 60 years of age. The pain also tended to be more prolonged in those with clustered vesicles, disturbed sleep and hypanaesthesia. Other factors such as underlying disease states, critically involved regions, scar tissue, generalized rash and allodynia were not relevant to the duration of pain. Although decreased pain persistence was observed in patients in whom acyclovir therapy was initiated within 72 h of the onset of symptoms in comparison with those in whom it was initiated after this time, the difference between the two groups of patients was not statistically significant. Our results suggest that advanced age, the presence of clustered vesicles, and disturbed sleep and hypanaesthesia influence the prolongation of herpes zoster pain.