Abstract

Objective:

To evaluate the completeness and concordance of infant deaths from congenital syphilis in the Metropolitan Region of Sao Paulo, Brazil, between 2010 and 2017.

Methods:

This was a descriptive study based on linkage between the Mortality Information System (SIM) and the Live Birth Information System (SINASC). Deaths with mention of congenital syphilis in multiple causes of death were analyzed. The completeness of 11 SIM variables was analyzed and SINASC was adopted as the reference. The Kappa statistic was used to analyze concordance.

Results:

There were 134 recorded congenital syphilis deaths, 132 of which were linked. 67 had congenital syphilis as the underlying cause, while 65 involved multiple causes of death, indicating underestimated congenital syphilis mortality. After linkage, the number of variables with excellent completeness increased from two to ten.

Conclusion:

Linking SIM with SINASC data improved completeness. The magnitude of congenital syphilis mortality was found to be underestimated, and the use of multiple causes improved its measurement.

Keywords:
Syphilis, Congenital; Infant Mortality; Cause of Death; Information Systems; Epidemiology, Descriptive

Introduction

Congenital syphilis results from the transmission of Treponema pallidum from a pregnant woman to her baby.¹1. Ministério da Saúde (BR), Secretaria de Vigilância em Saúde. Sífilis: 2019.Boletim epidemiol. 2019;(n. especial):1-44. Untreated or inadequate treatment of infected pregnant women can lead to complications such as early fetal death, neonatal death, premature birth, and congenital infection in infants.²2. Gomez GB, Kamb ML, Newman LM, Mark J, Broutet N, Hawkes SJ. Untreated maternal syphilis and adverse outcomes of pregnancy: a systematic review and meta-analysis. Bull World Health Organ. 2013 Mar 1;91(3):217-26. doi: https://doi.org/10.2471/BLT.12.107623.
https://doi.org/https://doi.org/10.2471/...

Although it is an easily preventable and treatable disease, congenital syphilis is the second most common infectious cause of stillbirth worldwide.³3. Lawn JE, Blencowe H, Waiswa P, Amouzou A, Mathers C, Hogan D, et al. Stillbirths: rates, risk factors, and acceleration towards 2030. Lancet. 2016 Feb 6;387(10018):587-603. doi: https://doi.org/10.1016/S0140-6736(15)00837-5.
https://doi.org/https://doi.org/10.1016/... In Brazil, mortality due to congenital syphilis increased 431% in the period 2008-2018, reaching 8.2 per 100,000 live births.¹1. Ministério da Saúde (BR), Secretaria de Vigilância em Saúde. Sífilis: 2019.Boletim epidemiol. 2019;(n. especial):1-44. These deaths represent an undesirable event in Public Health, since they are preventable.

Quality health information systems are needed in order to be able to act to reduce these deaths. The proper maintenance of these systems is important to ensure data reliability and to support actions that improve Public Health.⁴4. Lima CRA, Schramm JMA, Coelhi CM, Silva MEM. Revisão das dimensões de qualidade dos dados e métodos aplicados na avaliação dos sistemas de informação em saúde. Cad Saude Publica. 2009;25(10):2095-109. doi: https://doi.org/10.1590/S0102-311X2009001000002.
https://doi.org/https://doi.org/10.1590/... ^,55. Naidoo H, Avenant T, Goga A. Completeness of the road-to-health booklet and road-to-health card: results of cross-sectional surveillance at a provincial tertiary hospital. South Afr J HIV Med. 2018 Apr 10;19(1):765. doi: https://doi.org/10.4102/sajhivmed.v19i1.765.
https://doi.org/https://doi.org/10.4102/...

The objective of this study was to evaluate the completeness and concordance of infant deaths from congenital syphilis in the Metropolitan Region of Sao Paulo, Brazil, between 2010 and 2017.

Methods

This was a descriptive study of infant deaths due to congenital syphilis in the Metropolitan Region of São Paulo city. This is an important economic region, with 20,996,747 inhabitants and responsible for 53.8% of the gross domestic product (GDP) of the entire state of São Paulo.⁶6. Fundação Sistema Estadual de Análise de Dados. Informações dos municípios paulistas [Internet]. São Paulo: SEADE; 2020 [acesso 28 jul. 2020]. Disponível em: Disponível em: https://www.seade.gov.br/
https://www.seade.gov.br/... Between 2007 and 2018, this region recorded 57.3% of the state’s congenital syphilis cases.⁷7. Secretaria de Estado da Saúde de São Paulo. Coordenadoria de Controle de Doenças. Centro de Referência e Treinamento em DST/Aids. Programa Estadual de IST/Aids de São Paulo. Boletim Epidemiológico de HIV-AIDS-IST. 2019;36(1):1-291.

We included deaths of children under 1 year old, between 2010 and 2017, for which congenital syphilis (codes A50.0-A50.9 of the Tenth Revision of the International Statistical Classification of Diseases and Related Health Problems - ICD-10) was mentioned in the multiple cause of death lines of their death certificates.

We used data from the Mortality Information System (SIM) and the Live Birth Information System (SINASC), obtained from the Brazilian National Health System Information Technology Department (DATASUS) website (accessed on October 23, 2020) and from the São Paulo State Health Department Center for Strategic Health Information (CIEVS/SES/SP).⁸8. Ministério da Saúde (BR). DATASUS [Internet]. Brasília, DF: MS; 2020 [acesso 28 jul. 2020]. Disponível em: Disponível em: https://datasus.saude.gov.br/
https://datasus.saude.gov.br/...

The following SIM and SINASC variables were analyzed:

The deaths identified were linked to the live birth data using the deterministic linkage technique, which identifies the same individual in different databases. The first stage of this process was carried out by means of the common unifying variable, 'live birth certificate number', available in the databases obtained from DATASUS. The second step was carried out by CIEVS/SES/SP, which used the 'name of the deceased', 'date of birth' and 'mother's name' identification variables to identify the live birth certificate number, with manual checking of pairs.

Completeness was measured by the proportion of completed variables, excluding blank and unknown records, according to the following criteria: excellent (>95.0%); good (90.1-95.0%); fair (80.1-90.0%); poor (50.1-80.0%); and very poor (≤50.0%).⁹9. Romero DE, Cunha CB. Avaliação da qualidade das variáveis epidemiológicas e demográficas do sistema de informações sobre nascidos vivos, 2002. Cad Saude Publica. 2007;23(3):701-14. doi: https://doi.org/10.1590/S0102-311X2007000300028.
https://doi.org/https://doi.org/10.1590/... The live birth certificate was used as the reference to check whether the information had been added to the death certificate.

The difference in completeness was analyzed according to the death certificate issuer: hospital physician (attending or on duty) and physician from other services (Medical Examiner-Coroner; Death Verification Service; other services).

Concordance analysis allows us to identify whether the filling out of a given variable has been done identically on both databases. The proportion of concordant records was calculated for the categorical variables common to the live birth certificates and the death certificates, and the Kappa statistic was used according to the following criteria: no agreement (<0); poor agreement (0.00-0.19); reasonable agreement (0.20-0.39); moderate agreement (0.40-0.59); substantial agreement (0.60-0.79); and excellent agreement (0.80-1.00).¹⁰10. Landis JR, Koch GG. The measurement of observer agreement for categorical data. Biometrics. 1977;33(1):159-74. doi: https://doi.org/10.2307/2529310.
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The data were processed using SPSS17.0 and Microsoft Excel 2016.

The study project was approved by the University of São Paulo Faculty of Public Health Research Ethics Committee: Certificate of Submission for Ethical Appraisal No. 17870819.1.0000.5421; Opinion No. 3.525.067, issued on August 22, 2019.

Results

We identified 134 deaths due to congenital syphilis, 132 (98.5%) of which were linked to the SINASC system. In the first stage of the study, 96 deaths (71.6%) were paired with live birth certificates, plus a further 36 (26.9%) in the second stage. Two unlinked deaths (1.5%) were excluded (Figure 1).

Initially, 54 deaths were recorded as having congenital syphilis as their original underlying cause. After analyzing the (final) ‘underlying cause’ field, a further 13 deaths (24.1%) were added, totaling 67. After analyzing multiple causes, a further 65 deaths (+97.0%) were added, totaling 132.

Of the 132 death certificates, the ‘issuer’ field was complete on 120 of them, 97 (80.8%) of whom were hospital physicians and 23 physicians from other services. Most of the variables were more complete on the death certificates issued by the hospitals. It is noteworthy that before linkage, two variables had excellent completeness; and five variables had good completeness. After linkage with SINASC, the excellent variables increased from two to ten. 'Maternal schooling', 'birth weight' and 'number of stillborn children' were the variables that had the highest increase in information (>10.0%) (Table 1).

When analyzing concordance, the Kappa statistic was poorest for race/skin color (0.49), occupation (0.46) and maternal schooling (0.52) (Table 2).

Discussion

The completeness of SIM system data was enhanced through linkage with the SINASC system. Death certificates were filled out better at hospitals, and concordance was excellent or moderate for most variables. Significant underestimation of mortality due to congenital syphilis was only identified when the underlying cause of death was analyzed.

A limitation of the study is the possibility of congenital syphilis not being mentioned on the death certificate, especially in the case of deaths that occurred later, due to failure to identify the disease at childbirth or due to lack of follow-up after hospital discharge, which may have led to under-recording of this cause. All possibly infected newborns should be investigated with complementary tests for congenital syphilis until they are negative, since most are asymptomatic at birth.

All fields referring to multiple causes of death were used, for all diseases, morbid states, and injuries that contributed to or produced the death.¹¹11. Ministério da Saúde (BR). A declaração de óbito: documento necessário e importante. Brasília, DF: MS ; 2009. (Série A, normas e manuais técnicos). This criterion allowed us to identify that congenital syphilis was not classified as the underlying cause in half of the deaths for which the disease was present in the causal chain leading to death. Analyzing only the underlying cause would result in around half of the infant deaths due to congenital syphilis being underestimated. A study conducted using the same strategy found 25.0% additional deaths for Brazil as a whole, in 2001/2002 and 2012/2013.¹²12. Machado CJ, Simão AB, Gonçalves RV, Azevedo AC, Drumond EF, Faria MG. Sífilis congênita no Brasil em 2001/2002 e 2012/2013: estudo de causas múltiplas de óbito. Rev Faculdade Cienc Med Sorocaba. 2018;20(2):98-103. doi: https://doi.org/10.23925/1984-4840.2018v20i2a8.
https://doi.org/https://doi.org/10.23925... Selecting the underlying cause of death alters the magnitude of some diseases, and analyzing this cause alone underestimates the magnitude of congenital syphilis mortality.¹³13. Azevedo AC, Drumond EF, Gonçalves RV, Machado CJ. Evolução da qualidade das informações das declarações de óbito com menções de sífilis congênita nos óbitos perinatais no Brasil. Cad Saude Colet. 2017;25(3):259-67. doi: https://doi.org/10.1590/1414-462X201700030214.
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Under-recording can be minimized by means of investigations carried out by Infant Death Surveillance Committees. This study found that the work of these committees increased identification of these deaths by 24.0%; in a similar study conducted in Recife in 2014, 63.9% of investigated deaths had their underlying cause redefined.¹⁴14. Marques LJP, Pimentel DR, Oliveira CM, Vilela MBR, Frias PG, Bonfim CV. Concordância da causa básica e da evitabilidade dos óbitos infantis antes e após a investigação no Recife, Pernambuco, 2014. Epidemiol Serv Saude. 2018;27(1):e20170557. doi: https://doi.org/10.5123/S1679-49742018000100007.
https://doi.org/https://doi.org/10.5123/...

Use of the linkage technique allows for an increase in the quantity and quality of information, in addition to it being easy to perform and its low operational cost.¹⁵15. Romaguera AA, Guimarães ALS, Oliveira CM, Cardoso MD, Bonfim CV. Concordância e completude dos dados sobre nascidos vivos e óbitos infantis. Acta Paul Enferm. 2020;33:1-8. doi: http://dx.doi.org/10.37689/acta-ape/2020AO0309.
https://doi.org/http://dx.doi.org/10.376... The success of its use depends on good data coverage and quality, so that correct identification of the same individual in different databases can occur. An excellent percentage of linkage was obtained, reflecting the excellent coverage and regularity rates of the SIM and SINASC systems in the Metropolitan Region of São Paulo, as well as improvements in the filling out of the single identifier (live birth certificate number) for infant deaths.

Analysis of the completeness of variables is important for evaluating the quality of vital statistics, because incomplete data can generate distortions and biases in health indicators.¹⁶16. Maia LVS, Souza WV, Mendes ACG. A contribuição do linkage entre o SIM e Sinasc para a melhoria das informações da mortalidade infantil em cinco cidades brasileiras. Rev. Bras. Saude Mater Infant. 2015;15(1)57-66. doi: https://doi.org/10.1590/S1519-38292015000100005.
https://doi.org/https://doi.org/10.1590/... It is necessary to reinforce training and raise awareness among physicians about the importance of filling out death certificates as a generator of epidemiological information.

Linking deaths with the SINASC system increased the filling out of variables common to both systems, allowing for improved analysis of maternal characteristics. This is consistent with the results of other studies.¹⁵15. Romaguera AA, Guimarães ALS, Oliveira CM, Cardoso MD, Bonfim CV. Concordância e completude dos dados sobre nascidos vivos e óbitos infantis. Acta Paul Enferm. 2020;33:1-8. doi: http://dx.doi.org/10.37689/acta-ape/2020AO0309.
https://doi.org/http://dx.doi.org/10.376... The recovery of information on maternal education is noteworthy, as its completeness increased from regular to excellent. Low schooling is a factor associated with infant mortality and incidence of syphilis among pregnant women.¹⁷17. Geib LTC, Fréu CM, Brandão M, Nunes ML. Determinantes sociais e biológicos da mortalidade infantil em coorte de base populacional em Passo Fundo, Rio Grande do Sul. Cienc Saude Colet. 2010;15(2):363-70. doi: http://dx.doi.org/10.1590/S1413-81232010000200011.
https://doi.org/http://dx.doi.org/10.159... ^,1818. Moreira KFA, Oliveira DM, Alencar LN, Cavalcante DFB, Pinheiro AS, Orfão NH. Profile of notified cases of congenital syphilis. Cogitare Enferm. 2017;22(2): e48949. doi: http://dx.doi.org/10.5380/ce.v22i1.48949.
https://doi.org/http://dx.doi.org/10.538...

Death certificates filled out by hospital physicians were more complete, probably because of access to information on hospital medical records, which is not the case for Medical Examiner-Coroner/Death Verification Service physicians. A study of fetal deaths in the city of São Paulo, in 2008, also found better completion of death certificates issued by hospitals.¹⁹19. Almeida MF, Alencar GP, Schoeps D, Minuci EG, Silva ZP, Ortiz LP, et al. Qualidade das informações registradas nas declarações de óbito fetal em São Paulo, SP. Rev Saude Publica. 2011;45(5):845-53. doi: https://doi.org/10.1590/S0034-89102011005000058
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The concordance results indicate an improvement in the quality of death data and reaffirm the usefulness of these systems as instruments for measuring the health status of children.²⁰20. Maia LTS, Souza WV, Mendes ACG, Silva AGS. Uso do linkage para a melhoria da completude do SIM e do Sinasc nas capitais brasileiras. Rev Saude Publica. 2017;51:112. doi: https://doi.org/10.11606/S1518-8787.2017051000431.
https://doi.org/https://doi.org/10.11606... However, the race/skin color variable showed the poorest concordance, possibly due to the fact that the color of the newborn child is reported by its mother while the color of a deceased person is reported by someone else. In Brazil, race/skin color is a social construct, associated with socioeconomic and health inequalities, including infant mortality, which makes it even more important to fill out this field properly.²¹21. Victora CG, Aquino EML, Leal MC, Monteiro CA, Barros FC, Szwarcwald CL. Maternal and child health in Brazil: progress and challenges. Lancet. 2011 May 28;377(9780):1863-76. doi: https://doi.org/10.1016/S0140-6736(11)60138-4.
https://doi.org/https://doi.org/10.1016/... ^,2222. Lafetá KRG, Martelli Júnior H, Silveira MF, Paranaíba LMR. Maternal and congenital syphilis, underreported and difficult to control. Rev Bras Epidemiol. 2016;19(1):63-74. doi: https://doi.org/10.1590/1980-5497201600010006.
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Although the SIM system has improved over the years, the need exists to improve the selection of the underlying cause in deaths due to congenital syphilis and maintain continuous evaluation of its quality in order to obtain reliable indicators. Incidence of congenital syphilis, as well as incidence of deaths due to it, has been increasing continuously, and quality information is an important tool in the efforts to reduce it.²³23. Rêgo AS, Costa LC, Rodrigues LS, Garcia RAS, Silva FMAM, D’eça Junior A, et al. Congenital syphilis in Brazil: distribution of cases notified from 2009 to 2016. Rev Soc Bras Med Trop. 2020 Nov 25;53: e20200338. doi: https://doi.org/10.1590/0037-8682-0338-2020.
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