Epidemiology and economic burden of herpes zoster and post-herpetic neuralgia in Italy: A retrospective, population-based study

BACKGROUND: Data on the epidemiology and cost of herpes zoster (HZ) and post-herpetic neuralgia (PHN) in Italy are limited. This retrospective, population-based study was designed to determine the incidence of HZ and the proportion developing PHN in Italy and the associated medical resource utilisation and costs. It focused primarily on immunocompetent patients aged ≥50 years who would be eligible for preventive vaccination. METHOD: Data were extracted from a primary-care database and national hospital-discharge records covering four major regions in Italy for 2003-2005. Cases of HZ and PHN (1 and 3 months' duration; PHN1 and PHN3) were identified by ICD9-CM codes and, additionally for PHN, prescription of neuropathic pain medication. RESULTS: Over 3 years, 5675 incident cases of HZ were documented in adults, of which 3620 occurred in immunocompetent patients aged ≥50 years (incidence of 6.31 per 1000 person-years [95% CI: 6.01-6.62]). Of the immunocompetent patients aged ≥50 years with HZ, 9.4% (95% CI: 8.2-10.7) and 7.2% (95% CI: 6.2-8.2) developed PHN1 and PHN3, respectively. Increasing age, female sex, and being immunologically compromised conferred increased risk for both HZ and PHN. Overall, about 1.3% of HZ and almost 2% of PHN cases required inpatient care, with 16.9% of all HZ-related hospitalisations due specifically to PHN. In patients aged ≥50 years, mean stay was 7.8 ± 5.4 days for HZ and 10.2 ± 8.6 days for PHN, and direct costs associated with inpatient care were more than 20 times outpatient costs per HZ case (mean ± SD: €2592 ± €1313 vs. €122.68 ± €97.51) and over 5 times more per episode of PHN (mean ± SD: €2806 ± €2641 vs. €446.10 ± €442.97). Total annual costs were €41.2 million, of which €28.2 million were direct costs and €13.0 million indirect costs. CONCLUSIONS: This study, the largest to date on the epidemiology and economic impact of HZ and PHN in Italy, confirms the considerable disease and economic burden posed by HZ. As HZ and PHN disproportionately affect the elderly, without intervention this problem is likely to grow as the proportion of elderly in the Italian population continues to increase.