The Incidence of Herpes Zoster Complications: A Systematic Literature Review

INTRODUCTION: The objective of this work was to summarize the incidence of herpes zoster (HZ) complications in different populations. METHODS: Systematic literature review of PubMed, Embase, and Virtual Health Library records between January 1, 2002 and October 20, 2022 using search strings for HZ, complications, and frequency measurements. RESULTS: The review included 124 studies, most conducted in the general population (n = 93) and on individuals with comorbidities (n = 41) ≥ 18 years of age. Most studies were conducted in Europe (n = 44), Asia (n = 40), and North America (n = 36). Postherpetic neuralgia (PHN) was the most studied neurological complication. Variable relative PHN incidence was found in the general population (2.6-46.7%) or based on diagnosis: immunocompromised (3.9-33.8%), depression (0-50%), and human immunodeficiency virus (HIV) (6.1-40.2%). High incidence rates were observed in hematological malignancies (HM) and solid organ malignancies (132.5 and 93.7 per 1000 person-years, respectively). Ocular complications were frequently reported with herpes zoster ophthalmicus (HZO). The relative incidence (incidence rate) of HZO in the general population was reported as 1.4-15.9% (0.31-0.35 per 1000 person-years). High relative incidence was observed in HIV (up to 10.1%) and HM (3.2-11.3%). Disseminated HZ was the most frequently reported cutaneous complication. The relative incidence of disseminated HZ was 0.3-8.2% in the general population, 0-0.5% in the immunocompetent, and 0-20.6% in patients with comorbidities. High relative incidence was reported in HM and solid organ transplant (up to 19.3% and 14.8%, respectively). DISCUSSION: Most reported complications were neurological (n = 110), ocular (n = 48), and cutaneous (n = 38). Few studies stratified complications by age or gender (or both). Incidence appeared higher in select immunocompromised populations. Higher incidence was associated with older age in several studies; the general association with gender was unclear. CONCLUSIONS: Variable incidence of HZ complications was reported by population subgroup. Further research is required to quantitatively analyze incidence by age, gender, and location.