Complications and cost estimations in herpes zoster – a retrospective analysis at a Swiss tertiary dermatology clinic

Abstract

INTRODUCTION: Herpes zoster is the common reactivation of latent varicella zoster virus infection and is associated with substantial morbidity and costs. Age, immunosuppression, diabetes and active cancer are important risk factors for developing herpes zoster. The recombinant herpes zoster vaccine is highly effective in preventing this infection. To inform cost-effectiveness analyses of vaccination in risk groups, it is important to define the rates of complications, mortality, and hospitalisation and its costs. METHODS: In this single-centre, investigator-initiated, retrospective study we analysed herpes zoster patients treated in our tertiary dermatology referral centre between 2005 and 2019. Case costs were calculated using health insurance invoices and by estimating the drug-related costs. The associations between patients' characteristics and complications were assessed using logistic regression models. RESULTS: A total of 355 herpes zoster patients were analysed (mean age 61.5 ± 18.8 years; 56.6% women). The complication rate was 30.1% (n = 107) with post-herpetic neuralgia being the most frequent (37/355, 10.4%). The herpes zoster-related hospitalisation rate was 19.2% (n = 68), the herpes zoster-related mortality rate 0.85% (n = 3). Of all patients, 22.8% (n = 81) had herpes zoster risk factors. The odds ratio for complications (multivariate analysis) was 2.5 (95% confidence interval [CI] 1.12–5.72) in cancer patients and 1.04 (1.02–1.05) for each additional year of age (1.41 for 10 years). The cost ratio (median) of in- vs outpatient treatment was 26.9 (CHF/case 9029 vs 335), of all complicated vs non-complicated herpes zoster patients 6.6 (CHF/case 2203 vs 332) and of complicated vs non-complicated herpes zoster outpatients 4.3 (CHF/case 1331 vs 306). CONCLUSION: In this herpes zoster population at a university hospital, one in three patients was affected by herpes zoster-related complications. Age and cancer were independently associated with a high complication rate, suggesting a need to vaccinate cancer patients. Herpes zoster-related complications and the need for inpatient treatment escalated the costs per case.