Incidence of herpes zoster and postherpetic neuralgia in Italian adults aged ≥50 years: A prospective study ☆

Herpes zoster (HZ) mainly affects older adults and immunocompromised individuals and is usually characterized by a unilateral painful skin rash. Its most common complication, postherpetic neuralgia (PHN), may cause chronic debilitating pain lasting for months or years. This study ( ClinicalTrials.gov Identifier: NCT01772160 ) aimed to estimate the HZ incidence and the proportion of HZ patients with PHN in the Italian population aged 50 years or older. From 2013 to 2016, HZ-patients were recruited when presenting with acute HZ at 75 reporting general practitioners in Italy, covering 43,875 persons aged ≥50 years. PHN was defined as ‘worst pain’ rated ≥ 3 on the Zoster Brief Pain Inventory persisting or appearing over 90 days after rash onset. The overall HZ incidence rate per 1000 person-years (PY) was estimated as 6.46 (95% confidence interval [CI]: 5.99–6.95), increasing with age to 9.12/1000 PY (95% CI: 7.50–10.99) in 75–79 year-olds. Among 391 HZ-patients who completed the study, the overall proportion with PHN was 10.23% (95% CI: 7.41–13.67) and the highest proportion was 15.56% (95% CI: 6.49–29.46) for the 75–79 year-olds. Among the 128 patients (32.7%) who reported at least one pre-existing medical condition, 35.9% reported diabetes mellitus and 32.0% reported emotional problems, stress or depression. The study confirms previous findings that HZ and PHN cause an important clinical burden in older Italian adults. It also confirmed the age-related increasing risk of HZ and PHN. Highlights • HZ has a strong incidence in the Italian population, the 2nd oldest worldwide. • The estimated overall HZ incidence rate was 6.46 per 1000 person-years. • The most common complication, PHN, was encountered by 10.23% of HZ patients. • Strengths of the study are its prospective design and its large sample. • Limitation: incidence may be underestimated due to cases missed in primary care.