Immunity and the burden of herpes zoster.

The burden of herpes zoster may be related to patients' immunity, although this has not been studied extensively. This hypothesis was tested in a matched case-control study of patients with herpes zoster who sought treatment at one of seven university hospitals in Korea from January 1, 2007, to December 31, 2010. Patients diagnosed with herpes zoster were placed into three groups based on their immune status: severely immunocompromised, mild-to-moderately immunocompromised, and normal immunity. Each patient in the severely immunocompromised group was matched with one patient in the mild-to-moderately immunocompromised group and one patient in the normal immunity group in the same hospital based on age, sex, and date of herpes zoster onset. A total of 582 patients with herpes zoster were included in the analysis: 194 in each of the three groups. Patients in the severely immunocompromised group had the highest herpes zoster-related hospitalization rate as compared to patients in the mild-to-moderately immunocompromised and normal immune groups (P < 0.01). The length of hospital stay and herpes zoster-related medical cost increased significantly with the deterioration of patients' immunity (P < 0.01, respectively). Cutaneous complications occurred more frequently in the severely immunocompromised group than in the other two groups (P < 0.01). An increase in herpes zoster burden was observed as the patients' immunity decreased. Therefore, effective measures are necessary to prevent herpes zoster and reduce its burden in severely immunocompromised patients.