VALIDATION OF THE SURVEILLANCE SYSTEM FOR NEW CASES OF TUBERCULOSIS IN A PROVINCE OF NORTHERN ITALY

In Italy tuberculosis (TB) surveillance is hampered by several problem s (inconsistency of data and underreporting), A tuberculosis surveilla nce system was established in Varese Province (VSS) in 1992, The aim o f the present study was, using VSS, to estimate: 1) coverage and valid ity of data collected by the national Compulsory Surveillance System ( CSS); 2) validity of diagnosis and risk factors for tuberculosis; 3) t uberculosis incidence. A specifically designed form, including the sam e items as the CSS form and 10 more questions on risk factors and diag nostic issue, was completed in all the existing health facilities in t he province for each new tuberculosis case diagnosed, collected by the study co-ordinator during monthly supervision after a review of clini cal records, and stored in a database at the co-ordinating centre, Rou tine notifications collected at national level by CSS for the province were nominally linked with VSS data, To evaluate coverage and data va lidity, a comparison was made between VSS and CSS data after removal o f duplicates, Quality of data, risk factors I tors and incidence were evaluated on VSS data (gold standard). CSS coverage was 63% with a sig nificant underreporting of extrapulmonary cases, Within CSS, 20% of da ta were missing (particularly diagnostic information: 42-72%). Accordi ng to VSS, smear was performed on 88% of cases and culture on 66%. Hal f of the cases had no risk factors, The overall incidence of tuberculo sis in Varese Province was 15 per 100,000. We estimated the coverage a nd validity of the data collected by CSS, validity of diagnosis, risk factors for and incidence of tuberculosis and proposed several suggest ions to improve CSS nationwide.