Quality of reporting on birth defects in birth certificates: case study from a Brazilian reference hospital

The aim of this study was to evaluate the coverage, validity and reliability of Brazil's Information System on Live Births (SINASC) for birth defects in a hospital in the city of Campinas (São Paulo State). The study population consisted of 2,823 newborn infants delivered in 2004 at the Women's Integrated Health Care Center (CAISM). A birth defect registry (ECLAMC) was used as the gold-standard. All birth defect cases reported at CAISM in 2004 (92 cases) were selected from SINASC data files. All 168 birth defect cases from the same city and year registered at ECLAMC were also retrieved. An underreporting of 46.8% was observed for all birth defects, and 36.4% when considering only the major birth defects. The ascertained sensitivity and specificity were, respectively, 54.2% and 99.8%. The reliability of three and four-digit ICD-10 coding for birth defects was 0.77 and 0.55 respectively (kappa statistic). These results suggest that information provided by birth certificates in Campinas still presents limitations when seeking to ascertain accurate estimates of the prevalence of birth defects, hence indicating the need for improvements in the SINASC database to enable it to portray birth defect prevalence at birth in this city.