Underreporting of unfavorable outcomes of congenital syphilis on the Notifiable Health Conditions Information System in the state of São Paulo, Brazil, 2007-2018.

Objective: to describe the frequency of underreporting of unfavorable outcomes of congenital syphilis in the state of São Paulo, Brazil, 2007-2018.
Methods: this was a descriptive study of cases of abortion, fetal and non-fetal deaths due to congenital syphilis reported on the Notifiable Health Conditions Information System (Sistema de Informação de Agravos de Notificação - SINAN), and those of congenital syphilis registered in any line in the Death Certificate, on the Mortality Information System (Sistema de Informações sobre Mortalidade - SIM), by means of probabilistic and deterministic linkage.
Results: of the 27,713 cases of congenital syphilis reported, 1,320 progressed to death (871 fetal deaths, 449 infant deaths) and were matched to the SIM; 355 deaths (259 fetal deaths, 96 infant deaths) were not included on SINAN; there was an increase in unfavorable outcomes,11.4% for infant deaths due to congenital syphilis, 3.0% for fetal deaths and 1.9% for abortions.
Conclusion: the use of different relationship techniques proved to be adequate to identify the frequency of underreporting of unfavorable outcomes of congenital syphilis in the state of São Paulo.