Background: This is a retrospective study of the epidemiology and morbidity of herpes zoster and the risk factors for herpes zoster morbidity in Singapore.
Results: The mean age of 164 patients with herpes zoster seen at our dermatology clinic between January 1994 and December 1995 was 48.8 years, with a sex ratio of 1:1. The common presenting symptoms were pain (90%), feelings of helplessness and depression (20%), and flu-like symptoms (12%). The commonest prodromes were pain (41%), itching (27%), and paresthesia (12%). Prodromal pain was more frequently experienced by patients aged more than 50 years (42%) than by patients aged less than 30 years (25%). The thoracic (45%) and cervical (23%) dermatomes were the most commonly affected in all age groups. There was no statistically significant difference in the frequency of dermatomal distribution among the different age groups and between the sexes. Pain was experienced by almost all (95%) patients during the course of their disease. It tended to be more severe in older patients. Burning (26%), stabbing (15%), and shooting (15%) pain were the most common types experienced. Post-herpetic neuralgia was significantly more common in older patients. The prevalence of post-herpetic neuralgia decreased over time in all age groups. A higher proportion of older patients (more than 50 years of age) (20%) suffered from post-herpetic neuralgia compared with younger patients (less than 30 years of age) (7%) (not significant). Patients in all age groups considered acute pain (46%) and persistent pain (25%) to be their most unbearable symptoms during the course of herpes zoster. The most significant problems caused by herpes zoster pain were insomnia (25%), misery (feeling helpless and depressed) (20%), limitation of movement (9%), and inability to continue work (8%). Insomnia was significantly more commonly experienced by patients more than 50 years of age (36%) than those less than 30 years of age (P = 0.026). Few patients (9%) consulted their general practitioner (GP) during the prodrome or on the day of appearance of skin eruptions. Most patients (45%) consulted their GP within the first 3 days of the onset of skin eruptions; 33% sought treatment more than 3 days after the appearance of zoster symptoms. Only 30% of patients were willing to pay more than S$200 for antiviral therapy. Most (43%) were only prepared to pay for antiviral treatment if it cost less than S$200. The most important features the patients wished to derive from antiviral therapy were a shortening of the duration of skin lesions (55%) and a reduction in the severity of pain (acute and chronic) (30%).
Conclusions: Our study indicated that older patients (aged more than 50 years) were at a higher risk of developing post-herpetic neuralgia. They were also more likely to suffer morbidity, e.g. insomnia. There is a need to educate patients at risk to identify the prodrome and skin eruptions of herpes zoster so that early antiviral therapy can be considered.