Monitoring the rate of hospitalization before rotavirus immunization in Italy utilizing ICD9-CM regional databases

Background: Recently, two Rotavirus (RV) vaccines were licensed in Italy, rendering RV illness a vaccine preventable disease. To assess the RV hospitalization rate in Italy, a study focused on the Regional hospital discharge forms (HDD) databases was carried out. Results: Regional HDD databases from Piemonte, Veneto, Friuli-Venezia-Giulia and Marche were analyzed. A total of 434,335 hospitalizations were counted in the study timeframe and 13,234 VE diagnoses (3% of hospitalizations) were collected. A total of 8546 RVE cases (2% of hospitalizations, 64% of all VE) were observed, of which 1.2% were primary diagnoses (PD) and 0.8% secondary diagnosis (SD). The RVE hospitalization peak (4.9%) was observed at the age of 1 year (4.5% in 7–12 months of age) with a median hospital stay of 4.4 days (s.d ± 4.2). Two deaths (out of 8546 RVE cases) were identified. Patients and methods: Regional HDD databases with the diagnosis of viral enteritis (VE) and RV enteritis (RVE) (ICD9-CM code 00861-69 and 008.8) in any position of the first 20 discharge diagnoses in children aged less or equal to 5 years between 2001 and 2005 were requested. Conclusion: Despite some limitations due to the HDD synthetic contents and low potential for clinical interpretation, the Regional HDD databases, including PD and SD, may be a useful tool for monitoring the clinical impact of RV vaccination introduction in Italy