Abstract

Objective:

to evaluate the application of a deterministic routine for identifying multiple pregnancies on the Brazilian Live Birth Information System (SINASC).

Methods:

SINASC data deduplication and linkage with the mortality database (fetal deaths) for Rio de Janeiro state for the period 2007-2008; we used a deterministic routine, using a key based on SINASC maternal and birth information, complemented by manual review.

Results:

of the 433,874 SINASC records, 9,036 (2.1%) were classified as multiple pregnancy newborns; after implementing the routine, we reclassified 385 records as twins, and 286 as singletons; accuracy of multiple pregnancy information on the SINASC database was high (sensitivity=95.8%; specificity=99.9%); applying the routine without the manual review process increased sensitivity by 4.2%, with no significant change of specificity.

Conclusion:

despite the accuracy of information regarding multiple pregnancy held on SINASC, we suggest the use of this routine as an option for improving classification of twins.

Keywords:
Health Information Systems; Systems Integration; Health Evaluation; Pregnancy, Multiple

Introduction

The Live Birth Information System (SINASC) was implemented in order to bring together information on births in the entire country. With effect from 1990, SINASC has shown itself to be relevant regarding characterization and status of child deliveries and births, as well as for identifying at risk/vulnerable groups of mothers and children.¹1. Theme Filha MM, Gama SGN, Cunha CB, Leal MC. Confiabilidade do Sistema deInformações sobre Nascidos Vivos Hospitalares no Município do Rio de Janeiro,1999-2001. Cad Saúde Pública [Internet]. 2004 [citado 2019 out 21];20(Supl.1):S83-91. Disponível em: Disponível em: http://www.scielo.br/pdf/csp/v20s1/09.pdf . doi:10.1590/S0102-311X2004000700009
http://www.scielo.br/pdf/csp/v20s1/09.pd... ^,22. Costa JMBS, Frias PG. Avaliação da completitude das variáveis da Declaração de Nascido Vivo de residentes em Pernambuco, Brasil, 1996 a 2005. Cad Saúde Pública [Internet]. 2009 mar [citado 2019 out 21];25(3):613-24. Disponível em: Disponível em: http://www.scielo.br/pdf/csp/v25n3/16.pdf . doi: 10.1590/S0102-311X2009000300016
http://www.scielo.br/pdf/csp/v25n3/16.pd...

Multiple pregnancy is a risk factor for negative outcomes at birth.3-6 The risk of multiple babies dying can be 12 times greater, when compared to the same risk for single pregnancy babies. The main explanation for this difference lies in the increased proportion of prematurity and restricted intrauterine growth in the case of twins.⁷7. Shinwell ES, Haklai T, Eventov-Friedman S. Outcomes of mMultiplets. Neonatology [Internet]. 2009 [cited 2019 Oct 21];95(1):6-14. Available from: Available from: https://www.karger.com/Article/Abstract/151750 . doi: 10.1159/000151750
https://www.karger.com/Article/Abstract/... ^,88. Cooke RWI. Does neonatal and infant neurodevelopmental morbidity of multiples and singletons differ? Seminars in Fetal & Neonatal MedicineSemin Fetal Neonatal Med [Internet]. 2010 Dec [cited 2019 Oct 21];15(6):362-6. Available from: Available from: https://www.sfnmjournal.com/article/S1744-165X(10)00047-8/fulltext . doi:10.1016/j.siny.2010.06.003
https://www.sfnmjournal.com/article/S174... .

Multiple pregnancy children also have greater risk of developing undesirable conditions in the long term, such as cerebral palsy, cognitive dysfunction, language development disorders, learning difficulties, as well as psychiatric and socio-behavioral problems.⁷7. Shinwell ES, Haklai T, Eventov-Friedman S. Outcomes of mMultiplets. Neonatology [Internet]. 2009 [cited 2019 Oct 21];95(1):6-14. Available from: Available from: https://www.karger.com/Article/Abstract/151750 . doi: 10.1159/000151750
https://www.karger.com/Article/Abstract/... ^,88. Cooke RWI. Does neonatal and infant neurodevelopmental morbidity of multiples and singletons differ? Seminars in Fetal & Neonatal MedicineSemin Fetal Neonatal Med [Internet]. 2010 Dec [cited 2019 Oct 21];15(6):362-6. Available from: Available from: https://www.sfnmjournal.com/article/S1744-165X(10)00047-8/fulltext . doi:10.1016/j.siny.2010.06.003
https://www.sfnmjournal.com/article/S174... It is therefore important to identify multiple births in studies that use vital statistics databases.

Each twin is registered separately on the births database and has its own identification number. In addition, SINASC has a variable that indicates the number of children in the same pregnancy; however data completion errors lead to incorrect classification of information about twinning.¹1. Theme Filha MM, Gama SGN, Cunha CB, Leal MC. Confiabilidade do Sistema deInformações sobre Nascidos Vivos Hospitalares no Município do Rio de Janeiro,1999-2001. Cad Saúde Pública [Internet]. 2004 [citado 2019 out 21];20(Supl.1):S83-91. Disponível em: Disponível em: http://www.scielo.br/pdf/csp/v20s1/09.pdf . doi:10.1590/S0102-311X2004000700009
http://www.scielo.br/pdf/csp/v20s1/09.pd... ^,99. Barbuscia DM, Rodrigues-Júnior AL. Completeness of data on live birth certificates and death certificates for early neonatal and fetal deaths in the Ribeirão Preto Region, São Paulo State, Brazil, 2000-2007. Cad Saúde Pública [Internet]. 2011 Jun [cited 2019 Oct 21]; 27(6):1192-200. Available from: Available from: http://www.scielo.br/pdf/csp/v27n6/16.pdf . doi: 10.1590/S0102-311X2011000600016
http://www.scielo.br/pdf/csp/v27n6/16.pd... ^,1010. Oliveira MM, Andrade SSCA, Dimech GS, Oliveira JCG, Malta DC, Rabelo Neto DL, et al. Avaliação do Sistema de Informações sobre nascidos vivos. Brasil, 2006 a 2010. Epidemiol Serv Saúde [Internet]. 2015 out-dez [citado 2019 out 21];244(4):629-40. Disponível em: Disponível em: http://www.scielo.br/pdf/ress/v24n4/2237-9622-ress-24-04-00629.pdf . doi: 10.5123/S1679-49742015000400005
http://www.scielo.br/pdf/ress/v24n4/2237... Database linkage is used to improve data information quality by retrieving it and confirming it in a single database (data duplication identification process) or comparing different databases.¹¹11. Méray N, Reitsma JB, Ravelli AC, Bonsel GJ. Probabilistic record linkage is a valid and transparent tool to combine databases without a patient identification number. Journal of Clinical Epidemiology [Internet]. 2007 Sep [cited 2019 Oct 21];60(9):883-91. Available from: Available from: https://www.jclinepi.com/article/S0895-4356(06)00500-2/fulltext .doi: 10.1016/j.jclinepi.2006.11.021
https://www.jclinepi.com/article/S0895-4...

12. Silva LP, Moreira CMM, Amorim MHC, Castro DS, Zandonade E. Avaliação da qualidade dos dados do Sistema de Informações sobre Nascidos Vivos e do Sistema de Informações sobre Mortalidade no período neonatal, Espírito Santo, Brasil, de 2007 a 2009. Ciênc Saúde Coletiva [Internet]. 2014 jul [citado 2019 out 21];19(7):2011-20. Disponível em: Disponível em: http://www.scielo.br/pdf/csc/v19n7/1413-8123- csc-19-07-02011.pdf . doi: 10.1590/1413-81232014197.0892201313.
http://www.scielo.br/pdf/csc/v19n7/1413-...

13. Bartholomay P, Oliveira G.P, Pinheiro RS, Vasconcelos AMN. Melhoria da qualidade das informações sobre tuberculose a partir do relacionamento entre bases de dados. Cad Saúde Pública [Internet]. 2014 nov [citado 2019 out 21];30(11):2459-70. Disponível em: Disponível em: http://www.scielo.br/pdf/csp/v30n11/0102- 311X-csp-30-11-2459.pdf doi: 10.1590/0102-311X00116313
http://www.scielo.br/pdf/csp/v30n11/0102... ^-1414. Souza MaiaMaia LTS, Souza WV, MendesCruz ACG.M. A contribuição do linkage entre SIM e SINASC para a melhoria das informações da mortalidade infantil em cinco cidades brasileiras. Revista Brasileira de Saúde Mater rno-Infant [Internet]il. 2015 mar [citado 2019 out 21];15(1):57-66. Disponível em: Disponível em: http://www.scielo.br/pdf/rbsmi/v15n1/1519-3829-rbsmi-15-01-0057.pdf . doi: 10.1590/S1519-38292015000100005
http://www.scielo.br/pdf/rbsmi/v15n1/151...

The objective of this study was to evaluate the application of a deterministic routine in order to identify multiple pregnancies on the SINASC database for Rio de Janeiro state for the years 2007 and 2008.

Methods

We conducted a descriptive study to evaluate improvement of information about multiple pregnancies held on the SINASC database by applying a deterministic routine (internal linkage).

We used SINASC data (N=433,882) for Rio de Janeiro state for the years 2007 and 2008. We also examined fetal death records (N=372) on the Mortality Information System (SIM), searching manually for twins, when multiple pregnancy was indicated on SINASC but with only one live birth recorded.

The deterministic routine was based on four processes: (i) record comparison (internal database linkage), using a deterministic key comprised of maternal information (soundex of mother’s first name, soundex of mother’s second name; soundex of mother’s last name) and information about birth (full date of birth; code of the health establishment where birth occurred); (ii) automatic comparison of residential address, using a routine based on the Levenshtein edit distance; (iii) manual search for twins on the SIM system; and (iv) manual reviewing.

First of all the SINASC database was pre-processed with the aim of eliminating records with duplicated Live Birth Certificate numbers.

Records that had the same deterministic key were assessed according to information about pregnancy (single; multiple) held on SINASC. In the case of records having classification in agreement. i.e. with coinciding keys and indicating multiple pregnancy (key+/Sinasc+), and records having classification in disagreement, i.e. with coinciding keys but indicating single pregnancy (key+/Sinasc-), their addresses were compared automatically. When addresses coincided completely, the records were classed as being multiple pregnancy. When addresses were in disagreement, a manual review was performed in order to achieve final classification. During this manual stage, information regarding mother’s name, maternal age, place of birth, type of delivery and type of pregnancy were used by the researcher to define classification as being or not being multiple pregnancy.

When the key did not identify twins and the information held on SINASC was for single pregnancy (key-/Sinasc-), records were classified as not being twins. In the case of records indicating multiple pregnancy but for which the key did not identify a record of twins (key-/Sinasc+), we performed a manual search on the SIM fetal deaths database to confirm for twins, given that babies from the same pregnancy might be found on different information systems. Those that were not found on the fetal deaths database underwent a manual review.

We assessed records that had their classification changed (multiple or single pregnancy) following application of the complete routine (deterministic key, address comparison, fetal deaths database search and manual review of pairs). Classification following application of the complete routine was considered to be gold standard for accuracy analyses, both for information on twins registered on SINASC and also for classified obtained by applying a reduced routine, based solely on information held on SINASC and deterministic key agreement, without performing the remaining procedures (address comparison, fetal deaths database search and manual review of pairs). In this case, SINASC records that indicated multiple pregnancy or had deterministic key record agreement were classified as multiple pregnancy. SINASC records with no information on multiple pregnancy and with no pairs indentified simultaneously by the deterministic key were considered not to be twins. We calculated sensitivity, specificity and positive predictive value and respective 95% confidence intervals (95%CI).

We used PostgreSQL 9.2 and Stata12 applications, respectively, to carry out the deterministic linkage routine and for analysis.

The study project, based on secondary data provided by the Rio de Janeiro State Health and Civil Defense Department and developed in accordance with research ethics principles, was submitted to the IESC/UFRJ Research Ethics Committee as an amendment to the project entitled ‘Integrated Health Records: longitudinal evaluation of morbidity and mortality in a cohort of live born babies and their mothers - Phase 1’ and was approved on October 3^rd 2012 - Certification of Submission for Ethical Appraisal (CAAE) No. 07534512.9.0000.5286.

Results

Eight of the 433,882 records of live births in Rio de Janeiro state in 2007 and 2008 were excluded because of duplication and 9,036 (2.1%) were classified as multiple pregnancy on the SINASC system; 8,136 of these latter records had deterministic key agreement (key+/Sinasc+). Following application of the routine and following automatic address comparison, 6,508 records that had the same address were automatically classified as twins, and a further 1,628 that had different addresses were classified as twins following manual review (Figure 1).

All 385 records having key+/Sinasc- were classified as twins: 260 with the same address were classified automatically, and 125 following manual review (Figure 1).

We identified 816 records for which the routine did not indicate twins but for which the information held on SINASC referred to multiple pregnancy (key-/Sinasc+). Seventy-eight of these were found after searching on the SIM system. With regard to the other 738, manual review identified 452 twins and 286 non-twins.

There were 424,537 records in key-/Sinasc- category; 9,051 were classified as twins and 424,823 as non-twins, with change of initial status in 671.

Accuracy of multiple pregnancy information held on SINASC, when compared to the classification derived by applying the complete routine, was as follows: sensitivity=95.8% (95%CI 95.3;96.2%), specificity=99.9% (95%CI 99.9;99.9%) and positive predictive value=95.9% (95%CI 95.5;96.3%) (Table 1).

When applying the routine without manual review, accuracy was as follows: sensitivity=100.0%, specificity=99.9% (95%CI 99.9;99.9%) and positive predictive value=96.9% (95%CI 96.6;97.3%) (Table 2).

Discussion

The study used a deterministic routine which enabled better classification of multiple pregnancy information held on the SINASC system, avoiding both false-positive errors and also false-negative errors. Incorrect classification of a multiple pregnancy, such as duplications in data linkage processes, is a challenge for the development of algorithms for electronic health records.¹⁵15. Baldwin E, Johnson K, Berthoud H, Dublin S. Linking mothers and infants within electronic health records: a comparison of deterministic and probabilistic algorithms. Pharmaco epidemiology and Drug Safety [Internet]. 2015 Jan [cited 2019 Oct 21];24(1):45-51. Available from: Available from: https://onlinelibrary.wiley.com/doi/abs/10.1002/pds.3728 . doi: 10.1002/pds.3728
https://onlinelibrary.wiley.com/doi/abs/...

16. Harron KL, Doidge JC, Knight HE, Gilbert RE, Goldstein H, Cromwell DA, Meulen JH, et al. A guide to evaluating linkage quality for the analysis of linked data. International Journal of Epidemiology [Internet]. 2017 Oct [cited 2019 Oct 21]; 46(5):1699-710. Available from: Available from: https://academic.oup.com/ije/article/46/5/1699/4107250 . doi: 10.1093/ije/dyx177
https://academic.oup.com/ije/article/46/... ^-1717. Harper G. Linkage of maternity hospital episode statistics data to birth registrationand notification records for birth sin England 2005-2014: qQuality assurance of linkage of routine data for singleton and multiple births. BMJ Open [Internet]. 2018 Mar [cited 2019 Oct 21];8(3):e017898. Available from: Available from: https://bmjopen.bmj.com/content/8/3/e017898.long . doi: 10.1136/bmjope n-2017- 017898
https://bmjopen.bmj.com/content/8/3/e017...

SINASC data coverage and quality are fundamental for its reliability as a source of substantial information for health evaluation and research.¹⁸18. Silva RS, Oliveira CM, Ferreira DKS, Bonfim CV. Avaliação da completitude das variáveis do Sistema de Informações sobre Nascidos Vivos -- SINASC - nos12 Estados da região Nordeste do Brasil, 2000 e 2009. Epidemiol Serv Saúde[Internet]. 2013 abr-jun [citado 2019 out 21];22(2):347-52. Disponível em: Disponível em: http://scielo.iec.gov.br/pdf/ess/v22n2/v22n2a16.pdf . doi: 10.5123/S1679-49742013000200016
http://scielo.iec.gov.br/pdf/ess/v22n2/v... ^,1919. Mello Jorge MHP, Laurenti R, Gotlieb SLD. Análise da qualidade das estatísticas vitais brasileiras: a experiência de implantação do SIM e do SINASC. Ciênc Saúde Coletiva [Internet]. 2007 maio-jun [citado 2019 out 21];12(3):643-54. Disponível em: Disponível em: http://www.scielo.br/pdf/csc/v12n3/14.pdf . doi: 10.1590/S1413- 81232007000300014
http://www.scielo.br/pdf/csc/v12n3/14.pd...

Although good quality information was found about pregnancy type on the Rio de Janeiro state SINASC system, a result in agreement with the literature,¹1. Theme Filha MM, Gama SGN, Cunha CB, Leal MC. Confiabilidade do Sistema deInformações sobre Nascidos Vivos Hospitalares no Município do Rio de Janeiro,1999-2001. Cad Saúde Pública [Internet]. 2004 [citado 2019 out 21];20(Supl.1):S83-91. Disponível em: Disponível em: http://www.scielo.br/pdf/csp/v20s1/09.pdf . doi:10.1590/S0102-311X2004000700009
http://www.scielo.br/pdf/csp/v20s1/09.pd... ^,2020. Gabriel GP, Chiquetto L, Morcillo AM, Ferreira MC, Bazan IG, Daolio LD, et al. Evaluation of data on live birth certificates from the Information System on Live Births (Sinasc) in Campinas, São Paulo, 2009. Revista Paulista de Pediatria [Internet]. 2014 Sep [cited 2019 Oct 21];32(3):183-8. Available from: Available from: http://www.scielo.br/pdf/rpp/v32n3/en_0103-0582-rpp-32-03-0183.pdf . doi: 10.1590/0103-0582201432306
http://www.scielo.br/pdf/rpp/v32n3/en_01... ^,2121. Bonilha EA, Vico ESR, Freitas M, Barbuscia DM, Galleguillos TGB, Okamura MN, et al. Cobertura, completude e confiabilidade das informações do Sistema de Informações sobre Nascidos Vivos de maternidades da rede pública no município de São Paulo, 2011. Epidemiol Serv Saúde [Internet]. 2018 [citado 2019 out 21];27(1):e201712811. Disponível em: Disponível em: http://www.scielo.br/pdf/ress/v27n1/2237- 9622-ress-27-01-e201712811.pdf . doi: 10.5123/s1679-49742018000100011
http://www.scielo.br/pdf/ress/v27n1/2237... applying the routine is nevertheless useful and easy to perform. However, given the peculiar characteristics of twins, in general studies of neonatal outcomes exclude records of this group, which should be analyzed separately.²²22. Gardner MO, Goldenberg RL, Cliver SP, Tucker JM, Nelson KG, Copper RL. The origin and outcome of preterm twin pregnancies. Obstetrics and Gynecology. 1995 Apr;85(4):553-7.^,2323. Garite TJ, Clark RH, Elliott JP,Thorp JA. Twins and triplets: the effect of plurality and growth on neonatal outcome compared with singleton infants. American Journal of Obstetrics and Gynecology [Internet]. 2004 Sep [cited 2019 Oct 21]1;191(3):700-7. Available from: Available from: https://www.ajog.org/article/S0002- 9378(04)00286-8/fulltext . doi: 10.1016/j.ajog.2004.03.040
https://www.ajog.org/article/S0002- 9378... Low frequency of twins in relation to total births results in changes in the number of cases being relatively important, even when small in absolute terms. Moreover, the Robson classification is now publicized on the sinasc system, since accurate information about twins is necessary for adequate categorization of women.²⁴24. Brasil. Ministério da Saúde. Secretaria de Vigilância em Saúde. Departamento de Vigilância de Doenças e Agravos não Transmissíveis e Promoção da Saúde. Saúde Brasil 2017: uma análise da situação de saúde e os desafios para o alcance dos objetivos de desenvolvimento sustentável. Brasília, 2018.

Database linkage techniques, whether deterministic or probabilistic, are being used to improve information quality.¹²12. Silva LP, Moreira CMM, Amorim MHC, Castro DS, Zandonade E. Avaliação da qualidade dos dados do Sistema de Informações sobre Nascidos Vivos e do Sistema de Informações sobre Mortalidade no período neonatal, Espírito Santo, Brasil, de 2007 a 2009. Ciênc Saúde Coletiva [Internet]. 2014 jul [citado 2019 out 21];19(7):2011-20. Disponível em: Disponível em: http://www.scielo.br/pdf/csc/v19n7/1413-8123- csc-19-07-02011.pdf . doi: 10.1590/1413-81232014197.0892201313.
http://www.scielo.br/pdf/csc/v19n7/1413-... ^,2525. Pedraza DF. Quality of the Information System on Live Births/Sinasc: a critical analysis of published studies. Ciênc Saúde Coletiva. 2012;17(10):2729-37. Deterministic routines have excellent performance when data quality is good:²⁶26. Coeli CM, Pinheiro RS, Camargo Jr KR. Conquistas e desafios para o emprego das técnicas de record linkage na pesquisa e avaliação em saúde no Brasil. Epidemiol Serv Saúde. 2015;24:795-802.^,2727. Oliveira GP, Bierrenbach AL, Camargo Jr. KR, Coeli CM, Pinheiro RS. Acurácia das técnicas de relacionamento probabilístico e determinístico: o caso da tuberculose. Rev Saúde Pública. 2016;50(49) their processing is rapid and they can be used without manual review of the links formed.

The routine developed in our study included a manual review stage which is only feasible for small or medium volume databases in situations of information disagreement. In situations involving databases with a larger volume of records, only applying the key without doing manual review increases sensitivity for identifying twins without significant alteration of specificity or positive predictive value. A midway alternative would be to manually process only records not identified by the key, although for these records multiple pregnancy information exists on the SINASC system.

A limitation of this study is that not all cases were manually reviewed. However, the likelihood of mistaken pregnancy type classification is very low when there is agreement between the key and the Live Birth Information System - SINASC.

Although the increase as a result of recovering twins appears small, the cost of doing this is low in view of the possibility of improving information. We suggest that the routine proposed be used habitually, especially in studies of neonatal outcomes among twins.

References

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