Factors influencing pain outcome in herpes zoster: an observational study with valaciclovir

Aim of the study An observational study with valaciclovir was conducted to assess clinical outcome in herpes tester, especially pain and associated neurological signs and symptoms in relation to a series of demographic and disease characteristics discernible at presentation. The safety and acceptability of valaciclovir for treatment of tester was assessed in a wide variety of primary care and clinic referral settings. Methods In total, 1897 immunocompetent adults with clinically diagnosed, localized acute herpes tester were enrolled in this international, open-label study of valaciclovir. AU subjects received treatment with oral valaciclovir (1000 mg three times daily) for 7 days from entry to the study and were asked to record the presence of tester-associated pain and abnormal sensations throughout treatment and 6 months follow-up. They were seen frequently in clinic to verify subjective assessments and for evaluation of rash healing. Safety and tolerability were assessed by adverse event monitoring. Results Overall, 1191 subjects (63%) were aged greater than or equal to 50 years, and 203 (11%) had ophthalmic tester. Cessation of tester-associated pain was significantly faster in the younger age group; median times to loss of tester-associated pain were 23 days and 9 days in the greater than or equal to 50 and < 50 years age groups, respectively. Similarly, abnormal sensations resolved significantly more rapidly in the younger subjects; the median duration of abnormal sensations was 31 days in the greater than or equal to 50 year olds and 16 days in those aged < 50 years. In cases of ophthalmic tester, the rate of pain resolution was not different from those with tester in other dermatomes (median duration of pain 18 vs. 16 days). However, abnormal sensations persisted significantly longer in subjects with ophthalmic tester than in those with tester at other sites (47 vs. 22 days). In addition to advancing age, subjects suffering moderate to severe prodromal pain or acute pain during the rash phase were at significantly greater risk of zoster-associated pain and abnormal sensations persisting for longer. Subjects with concomitant neurological disorders were also more likely to develop prolonged abnormal sensations. Valaciclovir treatment was well tolerated, and adverse events were rare and generally mild. Conclusion This study confirmed the prognostic importance of advancing age and the intensity of prodromal or acute pain as risk factors for prolonged tester-associated pain and persisting abnormal sensations in the affected dermatome. Ophthalmic tester and pre-existing neurological disorders are also identified as highly significant risk factors for prolonged abnormal sensations in herpes tester.