[Epidemiologic surveillance of measles and rubella in Campinas (SP), Brazil: the reliability of the data].

OBJECTIVE

To evaluate and validate the information concerning measles and rubella from the Brazilian National Disease Notification System (BNDNS) (Sistema Nacional de Informação de Agravos de Notificação, or SINAN) for Campinas, a large city in the state of São Paulo, Brazil, using as a reference the data from a control system, the Syndromic Surveillance System for Fever and Exanthem (SSSFE) (Sistema de Vigilância Sindrômica de Febre e Exantema, or VigiFEx), which operated from May 2003 through June 2004.

METHOD

In our study we compared: (1) annual data from BNDNS for the years 1999 through 2003 and (2) data from BNDNS and data from SSSFE for the period of June 2003 through May 2004. We analyzed the rate of completion for key fields (record number, date of notification, and city of notification) as well as for name of disease, date of first symptoms, name of patient, birth date and age, sex, city of residence, date of investigation, immunization history, presence of exanthem, date at start of exanthem, presence of fever, suspected cases among pregnant women, signs and symptoms, date of collection of first sample, results with the sample, virus isolation, final classification, criteria for confirmation/exclusion of cases, diagnosis of excluded patients, development of the case, and date of closure. The level of agreement between the recorded cases in the two data banks was also analyzed.

RESULTS

From June 2003 through May 2004, 211 suspected cases of measles or rubella were identified in SSSFE and 275 in BNDNS. All the records had complete information concerning the three key fields. The rate of completion was also 100% for patient name, disease, and city of residence. The completion rate was higher than 95% for date of investigation, measles vaccine, measles and rubella vaccine, and rubella vaccine. A lower completion rate was found for other vaccination variables (number of doses and date of last dose) and for exanthem, fever, and date of start of exanthem. The two information systems were not completely consistent, particularly in terms of variables related to epidemiologic background, clinical data, and case closure. The quality of the SSSFE data was higher.

CONCLUSIONS

Epidemiologic surveillance, immunization, and laboratory information systems need to undergo routine evaluation to ensure that the data are reliable and can support the planning of public health efforts.