Estimating incidence of bacterial meningitis with capture-recapture method, Lazio Region, Italy

To estimate the incidence of bacterial meningitis in the Lazio Region, incl uding the city of Rome, and to assess the quality of the surveillance syste ms, we adopted a multiple-capture model by merging cases from three sources available in 1995-1996: the Notifiable Disease Surveillance (NDS) system, the Special Hospital Surveillance (SHS) system and the Hospital Discharge ( HD) registry. A medical record revision was carried out to confirm the case s of bacterial meningitis. A total of 199 individuals was classified as pro bable or confirmed cases of bacterial meningitis in 1995-1996. In this peri od, the incidence of reported meningitis was 3.8/100,000 (population = 5,20 9,633). The log-linear model yielded a total estimated number of 236 cases (95% confidence interval (CI): 206-306), the estimate of incidence reaching the value of 4.5/100,000. Hospital Discharge registry showed the highest s ensitivity (77%), the SHS system the highest positive predictive value (83% ). In 1997-1998, the meningitis surveillance was integrated with an additio nal laboratory-based source and yielded 326 cases, with an incidence of rep orted cases of 6.3/100,000. Laboratory surveillance, involving 115 (92%) pu blic hospitals and 84 (57%) private clinics, contributed 35 (27%) cases in addition to those notified to NDS (n = 130). Multiple-capture models, in ou r experience could estimate the bacterial meningitis incidence with a very good approximation. In order to improve both sensitivity and positive predi ctive value of surveillance, hospital and public health sources should be i ntegrated with laboratory-based system.