Hospital rates for compliated and uncomplicated chickenpox in a poorly vaccined pediatric population

Background: A retrospective study was conducted to provide epidemiological data on hospitalization for complicated and uncomplicated chickenpox in a pediatric population. Methods: The study analyzed hospitalization cases for chickenpox, among all the 31 Tuscan hospitals, during the period 1997-2003. Results: Globally, 650 cases were recorded (306 = 47.07% for uncomplicated and 344 = 52.92% for complicated chickenpox). Total hospitalization rate was 22.66 per 100,000 living Tuscan children and 11.52 per 1,000 notified chickenpox cases. Hospitalization rates for complicated chickenpox were 12.00 per 100,000 Living children and 6.09 per 1,000 notified cases. Notably, significantly increased hospitalization rates for complicated chickenpox were evidenced over years (p = 0.011 per 100,000 Living children and p = 0.001 per 1,000 notified cases), due to the increased proportion of neurological (p = 0.043 per 100,000 Living children and p = 0.025 per 1,000 notified cases) and respiratory (p = 0.021 per 100,000 living children and p = 0.008 per 1,000 notified cases) complications, whereas hospitalization rates for other complications as well as for uncomplicated chickenpox remained constant (p = 0.25 per 100,000 living children and p = 0.09 per 1,000 notified cases). Conclusions: Chickenpox complications, requiring hospitalization, occurred at a substantial rate in our pediatric population. In particular, increasing hospitalization rates for neurological and respiratory complications were evidenced over the study period. Our epidemiological data may provide additional information white planning a vaccination strategy for Italy.