Reliability of data from a very low birth weight population in the Live Birth Information System 2005-2006

The objective of the present study was to evaluate the completeness and agreement between data obtained from the Live Birth Information System (SINASC) and hospital records for high neonatal risk situations. Using RecLink III software, a probabilistic data linkage was carried out using databases from a Public Health Neonatal Intensive Care Unit and SINASC (years 2005-2006), which made possible the analysis of data from 170 live births with very low birth weight (between 500g and 1,499g), present at both databases. Variables evaluated were: maternal age, number of antenatal care visits, delivery type, sex, birth weight, Apgar score at 1st and 5th minutes and gestational age. Completeness in SINASC varied from 91.8% (1st minute Apgar Score) to 100% (variables sex, delivery type and maternal age). To evaluate agreement, kappa coefficient was used for dichotomous variables, weighted kappa was used for ordinal variables and intraclass correlation coefficient (ICC) and Bland-Altman graphic approach were used for continuous variables. Agreement was considered good to excellent for 1ST minute Apgar score (weighted kappa = 0.98), delivery type (kappa = 0.96), maternal age (ICC = 0.95), 5TH minute Apgar Score (weighted kappa = 0.93), sex (kappa = 0.92) and antenatal care visits (weighted kappa = 0.76), but only fair for gestational age (weighted kappa = 0.50) and birth weight (ICC = 0.57). Although birth weight might be more prone to registry errors in high risk neonatal populations, the elevated reliability observed for most variables analyzed corroborates SINASC importance as a source of information for perinatal epidemiology studies, even when dealing with high risk neonatal situations.