Abstracts

INTRODUCTION

Mortality indicators are important for understanding the epidemiological profile of a population; they support both the planning and evaluation of health actions and are, therefore, relevant to analyze the health situation to direct public policies. However, due to problems with information quality, the analysis of trends and main causes in mortality in many low- and middle-income countries is generally restricted to either areas with a higher socioeconomic level or larger cities. In fact, the places with major problems related to the quality of information about deaths have the heaviest disease burden.⁹9  Mathers CD, Fat DM, Inoue M, Rao C, Lopez AD. Counting the dead and what they died from: an assessment of the global status of cause of death data. Bull World Health Organ. 2005;83(3):171-7. DOI:10.1590/S0042-96862005000300009
https://doi.org/10.1590/S0042-9686200500... Therefore, some methodological proposals for indirect estimates and analyses of corrected data from vital statistics systems have been used in Brazil⁴4  França E, Rao C, Abreu DMX, Souza MFM, Lopez AD. Comparison of crude and adjusted mortality rates from leading causes of death in northeastern Brazil. Rev Panam Salud Publica. 2012;31(4):275-82. DOI:10.1590/S1020-49892012000400002
https://doi.org/10.1590/S1020-4989201200... ^,66  Gamarra CJ, Valente JG, Silva GA. Correção da magnitude da mortalidade por câncer do colo do útero no Brasil, 1996-2005. Rev Saude Publica. 2010;44(4):629-38. DOI:10.1590/S0034-89102010000400006
https://doi.org/10.1590/S0034-8910201000... to include the population groups most at risk from death and disease.

The high proportions of deaths from ill-defined causes in Brazil are worrisome, as they indicate problems related to the access and quality of medical care received by the population, in addition to compromising the reliability of mortality statistics for causes of death.⁸8  Laurenti R, Mello Jorge MHP, Gotlieb SL. A confiabilidade dos dados de mortalidade e morbidade por doenças crônicas não-transmissíveis. Cienc Saude Coletiva. 2004;9(4):909-21. DOI:10.1590/S1413-81232004000400012
https://doi.org/10.1590/S1413-8123200400... ^,1010  Mello Jorge MHP, Gotlieb SLD, Laurenti R. O sistema de informações sobre mortalidade: problemas e propostas para o seu enfrentamento I - Mortes por causas naturais. Rev Bras Epidemiol. 2002;5(2):197-223. DOI:10.1590/S1415-790X2002000200008
https://doi.org/10.1590/S1415-790X200200... ^,2020  Teixeira CLS, Klein CH, Bloch KV, Coeli CM. Reclassificação dos grupos de causas prováveis dos óbitos de causa mal definida, com base nas Autorizações de Internação Hospitalar no Sistema Único de Saúde, Estado do Rio de Janeiro, Brasil. Cad Saude Publica. 2006;22(6):1315-24. DOI:10.1590/S0102-311X2006000600020
https://doi.org/10.1590/S0102-311X200600... These deaths corresponded to 14.3% of the total in 2000, with wide variability between cities and even regions: proportions ranged from 28.4% in the Northeast to 6.3% in the South.^aa Ministério da Saúde. Datasus. Brasília (DF); [s.d.] [cited 2013 Jun]. Available from: www.datasus.gov.br

The ideal method for clarifying a cause listed as ill-defined on the death certificate (DC) is investigating records from hospitals and other health services, or interviews with family and health professionals. However, few Brazilian researchers reported field investigations reclassifying causes of death that were listed as ill-defined on the death certificate,¹1  Campos D, França E, Loschi RH, Souza MFM. Uso da autópsia verbal na investigação de óbitos com causa mal definida em Minas Gerais, Brasil. Cad Saude Publica. 2010;26(6):1221-33. DOI:10.1590/S0102-311X2010000600015
https://doi.org/10.1590/S0102-311X201000... ^,1010  Mello Jorge MHP, Gotlieb SLD, Laurenti R. O sistema de informações sobre mortalidade: problemas e propostas para o seu enfrentamento I - Mortes por causas naturais. Rev Bras Epidemiol. 2002;5(2):197-223. DOI:10.1590/S1415-790X2002000200008
https://doi.org/10.1590/S1415-790X200200... or cross-checking records to reclassify these causes.²⁰20  Teixeira CLS, Klein CH, Bloch KV, Coeli CM. Reclassificação dos grupos de causas prováveis dos óbitos de causa mal definida, com base nas Autorizações de Internação Hospitalar no Sistema Único de Saúde, Estado do Rio de Janeiro, Brasil. Cad Saude Publica. 2006;22(6):1315-24. DOI:10.1590/S0102-311X2006000600020
https://doi.org/10.1590/S0102-311X200600...

Beginning in 2005, the Ministry of Health initiated a project to upgrade the mortality information with a focus on the country’s Northern and Northeastern regions. The main actions were: contracting supporters for the states; developing instruments to investigate deaths, as well as applications to support and monitor municipalities in the process of investigating deaths from ill-defined causes; linking records from the Sistema de Informações de Mortalidade (SIM – Mortality Information System) with other information systems; setting investigation goals; continuous monitoring of investigation results and the “percentage of deaths from ill-defined causes” indicator in each state.^bb Ministério da Saúde. Manual para investigação do óbito com causa mal definida. Brasília (DF): 2009. (Série A. Normas e Manuais Técnicos). Since issuing a DC is an integral part of medical care,^cc Conselho Federal de Medicina. Resolução 1779. Diario Oficial Uniao. 5 Dez 2005;Seção1:121. a new instruction manual for completing it was widely publicized,^dd Ministério da Saúde. Secretaria de Vigilância em Saúde. Departamento de Análise de Situação de Saúde. Manual de Instruções para o preenchimento da Declaração de Óbito. Brasília (DF); 2011. to raise physicians’ awareness of the importance of DC.

The proportion of ill-defined causes of death (IDCD) decreased from 8.6% to 7.0% among reported deaths, after including the results of IDCD reclassification in the official statistics published in Brazil in 2010. However, this proportion is relatively high and there are still great differentials between the states and regions. This variation also occurs intra-regionally, with IDCD proportions close to 30.0% in some states’ macro-regions.^aa Ministério da Saúde. Datasus. Brasília (DF); [s.d.] [cited 2013 Jun]. Available from: www.datasus.gov.br^,bb Ministério da Saúde. Manual para investigação do óbito com causa mal definida. Brasília (DF): 2009. (Série A. Normas e Manuais Técnicos). It has thus become important that analyses cause-specific mortality include methods for correcting deaths through the remaining IDCD. The rates’ magnitude is affected by these causes, introducing bias into comparisons between places with different proportions of IDCD and in studies of temporal trends.

Redistributing IDCD into defined causes represents a proposal to minimize this problem. Statistical methods for this correction are used based on the behavior of the defined causes that were reported.¹³13  Paes NA, Gouveia JF. Recuperação das principais causas de morte do Nordeste do Brasil: impacto na expectativa de vida. Rev Saude Publica. 2010;44(2):301-9. DOI:10.1590/S0034-89102010000200010
https://doi.org/10.1590/S0034-8910201000... More common is the use of proportional redistribution according to the defined causes, registered by sex and age, considering all causes¹¹11  Oliveira GMM, Klein CH, Silva NAS. Mortalidade por doenças cardiovasculares em três estados do Brasil de 1980 a 2002. Rev Panam Salud Publica. 2006;19(2):85-93. DOI:10.1590/S1020-49892006000200003
https://doi.org/10.1590/S1020-4989200600... ^,1212  Oliveira GMM, Silva NAS, Klein CH. Mortalidade Compensada por Doenças Cardiovasculares no Período de 1980 a 1999 – Brasil. Arq Bras Cardiol. 2005;85(5):305-13. DOI:10.1590/S0066-782X2005001800002
https://doi.org/10.1590/S0066-782X200500... ^,1414  Périssé G, Medronho RA, Escosteguy CC. Espaço Urbano e a Mortalidade por Doença Isquêmica do Coração em Idosos no Rio de Janeiro. Arq Bras Cardiol. 2010;94(4):463-71. DOI:10.1590/S0066-782X2010005000009
https://doi.org/10.1590/S0066-782X201000... ^,1919  Soares GP, Brum JD, Oliveira GMM, Klein CH, Silva NAS. Mortalidade por todas as causas e por doenças cardiovasculares em três estados do Brasil, 1980 a 2006. Rev Panam Salud Publica. 2010;28(4):258-66. DOI:10.1590/S1020-49892010001000004
https://doi.org/10.1590/S1020-4989201000... or only the non-external causes, as proposed in the 1990 Global Burden of Disease Study.¹⁶16  Porapakkham Y, Rao C, Pattaraarchachai J, Polprasert W, Vos T, Adair T, et al. Estimated causes of death in Thailand, 2005: implications for health policy. Popul Health Metr. 2010;8(1):14. DOI:10.1186/1478-7954-8-14
https://doi.org/10.1186/1478-7954-8-14...

17  Silva GA, Gamarra CJ, Girianelli VR, Valente JG. Tendência da mortalidade por câncer nas capitais e interior do Brasil entre 1980 e 2006. Rev Saude Publica. 2011;45(6):1009-18. DOI:10.1590/S0034-89102011005000076
https://doi.org/10.1590/S0034-8910201100... ^-1818  Soares DA, Gonçalves MJ. Mortalidade cardiovascular e impacto de técnicas corretivas de subnotificações e óbitos mal definidos. Rev Panam Salud Publica. 2012;32(3):199-206. DOI:10.1590/S1020-49892012000900005
https://doi.org/10.1590/S1020-4989201200... ^,ee Murray CJL, Lopez AD. Estimating causes of death: new methods and global and regional applications for 1990. Boston: Harvard School of Public Health; 1996. The global burden of disease. p. 118-200. However, these redistribution methodologies are not considered satisfactory.¹⁰10  Mello Jorge MHP, Gotlieb SLD, Laurenti R. O sistema de informações sobre mortalidade: problemas e propostas para o seu enfrentamento I - Mortes por causas naturais. Rev Bras Epidemiol. 2002;5(2):197-223. DOI:10.1590/S1415-790X2002000200008
https://doi.org/10.1590/S1415-790X200200... The redistribution methodology based on death distribution of non-external causes is particularly questionable, after findings of violence and accidents among the IDCD investigated.¹1  Campos D, França E, Loschi RH, Souza MFM. Uso da autópsia verbal na investigação de óbitos com causa mal definida em Minas Gerais, Brasil. Cad Saude Publica. 2010;26(6):1221-33. DOI:10.1590/S0102-311X2010000600015
https://doi.org/10.1590/S0102-311X201000... ^,1010  Mello Jorge MHP, Gotlieb SLD, Laurenti R. O sistema de informações sobre mortalidade: problemas e propostas para o seu enfrentamento I - Mortes por causas naturais. Rev Bras Epidemiol. 2002;5(2):197-223. DOI:10.1590/S1415-790X2002000200008
https://doi.org/10.1590/S1415-790X200200... ^,2020  Teixeira CLS, Klein CH, Bloch KV, Coeli CM. Reclassificação dos grupos de causas prováveis dos óbitos de causa mal definida, com base nas Autorizações de Internação Hospitalar no Sistema Único de Saúde, Estado do Rio de Janeiro, Brasil. Cad Saude Publica. 2006;22(6):1315-24. DOI:10.1590/S0102-311X2006000600020
https://doi.org/10.1590/S0102-311X200600...

The investigation of IDCD represents an important gain in clarifying the cause of death. From this perspective, this study proposes a method for redistributing IDCD based on an investigation of these causes.

METHODS

Cross-sectional study on the IDCD allocated in chapter 18 (Symptoms, Signs and Abnormal Clinical and Laboratory Findings, Not Elsewhere Classified) of the International Classification of Diseases and Health-Related Problems, 10^th Revision (ICD-10). All deaths registered in the SIM in 2010 were considered.

Investigations of IDCD comprises collecting information about the deceased’s terminal illness in health services, such as the basic health units in the Family Health Strategy or health facilities, in the case of hospitalization; as well as collecting information obtained from other sources, such as the Disease Notification Information System, Hospital Information System, Serviço de Verificação de Óbito (SVO – Death Verification Service), and Instituto Médico Legal (IML – Forensic Institute). In cases where the information obtained from the health services prohibits the cause of death to be identified, an investigation should be conducted through a home interview by a health professional; data should be collected on a standardized verbal autopsy form, which seeks to obtain information about the signs and symptoms presented by the patient in the period prior to death and were observed by family members who lived with the deceased during this period. Analyzing all the information present on the form, an accredited physician should determine the sequence of causes that led to the death, as well as its underlying cause, and then complete the DC.^bb Ministério da Saúde. Manual para investigação do óbito com causa mal definida. Brasília (DF): 2009. (Série A. Normas e Manuais Técnicos). An evaluation study of the process of investigating IDCD in Alagoas in 2010 indicates that the professionals responsible for conducting the interviews are mostly nurses; the presence of the physician responsible for certifying the underlying cause after investigation was listed on the forms in approximately 1/3 of the verbal autopsies conducted. A physician defined the underlying cause of death in 12 out of the 18 randomly selected municipalities; in four cities, this task was the responsibility of a multidisciplinary technical team that included the participation of physicians.³3  França EB, Cunha CC, Vasconcelos AMN, Escalante JJC, Abreu DMX, Lima RB, et al. Avaliação da implantação do programa “Redução do percentual de óbitos por causas mal definidas” em um estado do Nordeste do Brasil. Rev Bras Epidemiol. 2014;17(1):119-134. DOI: 10.1590/1415-790X201400010010.
https://doi.org/ 10.1590/1415-790X201400...

The DC that originally showed IDCD were categorized into: (i) IDCD investigated and reclassified (cause clarified/changed after investigation): certificates that ended up having a defined underlying cause of death, i.e., belonging to any chapter of ICD-10 except chapter 18; the new causes were arranged in the respective classes, in this case, the chapters and groups of ICD-10; (ii) IDCD not reclassified (an investigation of the IDCD was not performed or the cause was not clarified/changed after investigation): certificates that continued to be included in chapter 18 of ICD-10. This category also encompasses deaths from causes not originally classified under any chapter of ICD-10 or from chapters of defined causes (usually deaths of women of childbearing age or children) that were moved to chapter 18 after investigation. The total comprises the group that is, here, called remaining IDCD.

Investigated IDCD are reported in a specific field in the SIM application. The underlying causes presented by the system, called final causes, include the investigated and reclassified cases (when the IDCD is replaced by an underlying cause not belonging to chapter 18 of ICD-10 in the SIM). The cause of death (COD) before investigation is called the original COD. The CODs of the DC originally classified as IDCD were analyzed by crosschecking the classifications of the original COD with the final ones.

The proposed method includes redistributing the remaining IDCD according to the reclassification obtained in the first group. The assumption is that the profile of causes among the remaining IDCD will be similar to those of the reclassified IDCD. The redistribution should be performed according to the proportional distribution of causes observed among the investigated and reclassified IDCDs, i.e., according to the redistribution coefficient RC-IDCD, which provides a redistribution factor of the remaining IDCDs for the ICD-10 chapters that concern defined causes. This redistribution was performed according to the following steps:

1. Calculation of the RC-IDCD based on the IDCD reclassified for each chapter of the ICD-10, by age and sex;

2. The RC-IDCD obtained were applied to the non-reclassified IDCD, and redistributed into the chapters of defined causes;

3. The total number of deaths corrected with a defined cause was calculated by the sum of the deaths registered in the chapter with a defined cause after including the deaths reclassified in IDCD investigation plus the deaths redistributed in the prior step. As an example, the number of deaths corrected by the RC-IDCD for neoplasms (Corrected Deaths RC-IDCD_neo) was estimated, by age and sex:

The method of using the RC-IDCD was compared with two other commonly used redistribution methods: a) according to the distribution of all defined causes (IDCD redistributed according to the proportional distribution of the originally defined causes by sex and age – redistribution coefficient called RC-Total); b) according to the distribution of the non-external defined causes (IDCD redistributed according to the proportional distribution of the originally defined causes by sex and age, excluding external causes – redistribution coefficient RC-Non-external).

The corrections were made according to sex and quinquennial age group. The data with unknown sex and age were redistributed proportionally among the data with known sex and age. Mortality rates for uncorrected selected causes were calculated from the number of deaths reported in the SIM in 2010; those with correction were calculated from the number of deaths corrected by the RC-IDCD and other redistribution coefficients evaluated. The population considered was the 2010 Brazilian Census.

RESULTS

In 2010, 8.6% of 1,136,947 deaths that were reported to the SIM were originally classified as IDCD. Investigations of these causes occurred in all regions of the country, particularly in the Midwest and Northeast, which also had proportionately more cases of IDCD reclassified. The proportions of the remaining IDCD were different among the regions (from 11.8% in the North to 4.0% in the Midwest) (Table 1).

About 20.0% of IDCD were reclassified in all age groups and both sexes, with a small increase among women of childbearing age and smaller proportions in the extreme age groups (Table 2).

Among those reported, 1,037,967 deaths resulted from defined causes and 97,314 were from IDCD. After investigating these causes, 19.8% of the deaths were reclassified as defined causes of death. These were added to the other defined causes, totaling 1,057,325 deaths from defined causes in the SIM database. In addition to the 78,011 IDCD that were not reclassified (67,827 were originally IDCD and were not investigated and 10,183 were investigated and not reclassified), 1,611 more deaths were added to the IDCD group for two main reasons: 1) deaths originally not classified in any chapter of the ICD-10; 2) deaths from other chapters and not in chapter 18 of ICD-10, and which changed to IDCD after investigation. Therefore, 79,622 deaths continued to be IDCD, to be subsequently redistributed (Figure).

The proportions of defined causes among the IDCD that were reclassified and represented by RC-IDCD were different from the proportions among the reported deaths, with a higher proportion of endocrine diseases, mental disorders, nervous system diseases, circulatory diseases and maternal causes among the IDCD. Infectious diseases, neoplasms, respiratory diseases, genitourinary diseases, perinatal disorders and congenital malformations occurred in a relatively smaller proportion (Table 3). Neoplasms showed different proportions in different parts of the country (higher in the North and Northeast and lower in the South, Southeast, and Midwest) (data not presented). There was a relatively significant proportion of external causes among the IDCD (9.3% of the IDCDs reclassified for Brazil), higher in men (10.5%). While, the proportion of endocrine diseases among the IDCD was higher in women (13.1%), the proportion of mental and behavioral disorders was higher in men (8.7%) (data not presented). There was an increase in the number of deaths for all the chapters of defined causes according to the three criteria considered, without implying changes in the rank of leading causes of death (Table 3).

With the exception of perinatal diseases, congenital malformations, and external causes, there was a similar percentage increase for risk of death for almost all causes when using RC-Total and RC-Non-external, unlike the proposed new criterion based on RC-IDCD, which corrected the different causes of death with different weights. By this criterion, endocrine diseases, particularly diabetes, diseases of the circulatory system and, particularly, maternal causes and mental disorders, had greater representation than they did using the other two criteria. In contrast, neoplasms, infectious diseases, and genitourinary diseases showed smaller relative increases. External causes were not addressed in the redistribution process using RC-Non-external and only had a small increase among the redistributed causes due to correction for unknown age and sex. RC-IDCD considered a relatively smaller weight for them among the IDCD when compared to RC-Total (Table 4).

DISCUSSION

This study indicates that the proportional distribution of causes among the IDCD reclassified after investigation differed from the original distribution of defined causes. Therefore, we consider that the method proposed here for redistributing IDCD based on the results of investigations conducted by the health services enables more reliable estimates of mortality risk for specific causes, when compared to the usual redistribution methods.

Pro rata distribution is the most commonly used method for redistributing IDCD. The redistribution coefficient is calculated based on the distribution of underlying causes of death by sex and age group, considering all defined causes¹¹11  Oliveira GMM, Klein CH, Silva NAS. Mortalidade por doenças cardiovasculares em três estados do Brasil de 1980 a 2002. Rev Panam Salud Publica. 2006;19(2):85-93. DOI:10.1590/S1020-49892006000200003
https://doi.org/10.1590/S1020-4989200600... ^,1212  Oliveira GMM, Silva NAS, Klein CH. Mortalidade Compensada por Doenças Cardiovasculares no Período de 1980 a 1999 – Brasil. Arq Bras Cardiol. 2005;85(5):305-13. DOI:10.1590/S0066-782X2005001800002
https://doi.org/10.1590/S0066-782X200500... ^,1414  Périssé G, Medronho RA, Escosteguy CC. Espaço Urbano e a Mortalidade por Doença Isquêmica do Coração em Idosos no Rio de Janeiro. Arq Bras Cardiol. 2010;94(4):463-71. DOI:10.1590/S0066-782X2010005000009
https://doi.org/10.1590/S0066-782X201000... ^,1919  Soares GP, Brum JD, Oliveira GMM, Klein CH, Silva NAS. Mortalidade por todas as causas e por doenças cardiovasculares em três estados do Brasil, 1980 a 2006. Rev Panam Salud Publica. 2010;28(4):258-66. DOI:10.1590/S1020-49892010001000004
https://doi.org/10.1590/S1020-4989201000... or only non-external causes.¹⁶16  Porapakkham Y, Rao C, Pattaraarchachai J, Polprasert W, Vos T, Adair T, et al. Estimated causes of death in Thailand, 2005: implications for health policy. Popul Health Metr. 2010;8(1):14. DOI:10.1186/1478-7954-8-14
https://doi.org/10.1186/1478-7954-8-14...

17  Silva GA, Gamarra CJ, Girianelli VR, Valente JG. Tendência da mortalidade por câncer nas capitais e interior do Brasil entre 1980 e 2006. Rev Saude Publica. 2011;45(6):1009-18. DOI:10.1590/S0034-89102011005000076
https://doi.org/10.1590/S0034-8910201100... ^-1818  Soares DA, Gonçalves MJ. Mortalidade cardiovascular e impacto de técnicas corretivas de subnotificações e óbitos mal definidos. Rev Panam Salud Publica. 2012;32(3):199-206. DOI:10.1590/S1020-49892012000900005
https://doi.org/10.1590/S1020-4989201200... On the other hand, redistribution based on empirical studies is less used in Brazil, having been reported for specific causes such as cancer as well as maternal and external causes.⁴4  França E, Rao C, Abreu DMX, Souza MFM, Lopez AD. Comparison of crude and adjusted mortality rates from leading causes of death in northeastern Brazil. Rev Panam Salud Publica. 2012;31(4):275-82. DOI:10.1590/S1020-49892012000400002
https://doi.org/10.1590/S1020-4989201200... ^,66  Gamarra CJ, Valente JG, Silva GA. Correção da magnitude da mortalidade por câncer do colo do útero no Brasil, 1996-2005. Rev Saude Publica. 2010;44(4):629-38. DOI:10.1590/S0034-89102010000400006
https://doi.org/10.1590/S0034-8910201000... ^,1717  Silva GA, Gamarra CJ, Girianelli VR, Valente JG. Tendência da mortalidade por câncer nas capitais e interior do Brasil entre 1980 e 2006. Rev Saude Publica. 2011;45(6):1009-18. DOI:10.1590/S0034-89102011005000076
https://doi.org/10.1590/S0034-8910201100...

Some authors propose statistical methods for correcting information, such as Cavalini et al²2  Cavalini LT, Ponce de Leon ACM. Correção de sub-registros de óbitos e proporção de internações por causas mal definidas. Rev Saude Publica. 2007;41(1):85-93. DOI:10.1590/S0034-89102007000100012
https://doi.org/10.1590/S0034-8910200700... (2007), which used the Bayesian estimators of James-Stein to correct underreporting and redistribute IDCD for deaths and hospitalizations; they observed an increase in the number of deaths and a modification in the structure of proportional mortality in the North and Northeast. Paes & Gouveia¹³13  Paes NA, Gouveia JF. Recuperação das principais causas de morte do Nordeste do Brasil: impacto na expectativa de vida. Rev Saude Publica. 2010;44(2):301-9. DOI:10.1590/S0034-89102010000200010
https://doi.org/10.1590/S0034-8910201000... (2010) employed the Lederman method to redistribute IDCD to non-external causes, with greater gains for circulatory diseases and smaller gains for infectious and parasitic diseases.

Few published Brazilian studies exists on clarifying IDCD. Mello Jorge et al¹⁰10  Mello Jorge MHP, Gotlieb SLD, Laurenti R. O sistema de informações sobre mortalidade: problemas e propostas para o seu enfrentamento I - Mortes por causas naturais. Rev Bras Epidemiol. 2002;5(2):197-223. DOI:10.1590/S1415-790X2002000200008
https://doi.org/10.1590/S1415-790X200200... investigated 294 IDCD in hospitals, Forensic Institutes (IML), and households in 13 municipalities in the states of Sergipe, Sao Paulo, and Mato Grosso, in 2000. Of these, 61.9% were reclassified into defined causes after investigation. Campos et al¹1  Campos D, França E, Loschi RH, Souza MFM. Uso da autópsia verbal na investigação de óbitos com causa mal definida em Minas Gerais, Brasil. Cad Saude Publica. 2010;26(6):1221-33. DOI:10.1590/S0102-311X2010000600015
https://doi.org/10.1590/S0102-311X201000... (2010) investigated 202 IDCD in households, using the verbal autopsy method, in health services and IML, in a sample of 10 municipalities in the macro-region of Minas Gerais, Southeastern Brazil, in 2007; the COD was reclassified in 63.9% of the cases. Teixeira et al²⁰20  Teixeira CLS, Klein CH, Bloch KV, Coeli CM. Reclassificação dos grupos de causas prováveis dos óbitos de causa mal definida, com base nas Autorizações de Internação Hospitalar no Sistema Único de Saúde, Estado do Rio de Janeiro, Brasil. Cad Saude Publica. 2006;22(6):1315-24. DOI:10.1590/S0102-311X2006000600020
https://doi.org/10.1590/S0102-311X200600... (2006) sought to clarify IDCD in Rio de Janeiro, Southeastern Brazil, in 1998 by relating data from the SIM and Hospital Information System. Of the 12,633 IDCD, 16.3% were reclassified, which diminished the importance of IDCD in proportional mortality by causes. Similar findings were observed in this study: 65.5% of IDCD investigated in the country had their cause reclassified after investigation (19.8% of IDCD reported in 2010).

The project to qualify the Brazilian Mortality Information System has enabled the clarification of IDCD, with a significant reduction in its proportion since 2005.^bb Ministério da Saúde. Manual para investigação do óbito com causa mal definida. Brasília (DF): 2009. (Série A. Normas e Manuais Técnicos). 132,056 IDCD between 2006 and 2010 were investigated in the country, and 64.2% of IDCD investigated were reclassified into a defined group of causes of death and included in the official statistics available on the Internet. The profile of causes of death among the reclassified IDCD differs from those observed among the defined causes that were reported,⁵5  França EB, Souza FM, Ishitani LH, Teixeira R, Szwarcwald CL. Strengthening vital statistics in Brazil: investigation of ill-defined causes of death and implications on mortality statistics. Lancet. 2013;381(Suppl2):17-9. DOI:10.1016/S0140-6736(13)61305-7
https://doi.org/10.1016/S0140-6736(13)61... confirming previous findings¹⁰10  Mello Jorge MHP, Gotlieb SLD, Laurenti R. O sistema de informações sobre mortalidade: problemas e propostas para o seu enfrentamento I - Mortes por causas naturais. Rev Bras Epidemiol. 2002;5(2):197-223. DOI:10.1590/S1415-790X2002000200008
https://doi.org/10.1590/S1415-790X200200... and those of this study.

Despite the importance of correction for IDCD, there is no standardization in the redistribution methods or terminology used, which hinders its routine use in mortality statistics. The very definition of grouping IDCD is not consensual. Various codes considered incomplete or “garbage codes” from chapters other than chapter 18 of ICD-10 have been added to the IDCD group, since they do not characterize the cause of death.⁹9  Mathers CD, Fat DM, Inoue M, Rao C, Lopez AD. Counting the dead and what they died from: an assessment of the global status of cause of death data. Bull World Health Organ. 2005;83(3):171-7. DOI:10.1590/S0042-96862005000300009
https://doi.org/10.1590/S0042-9686200500... The present study only considered IDCD with codes from chapter 18, which have more recognized redistribution methodologies.

Various terms are used for IDCD with a defined COD after investigation, such as reallocated, recovered, clarified, altered or reclassified IDCD.¹1  Campos D, França E, Loschi RH, Souza MFM. Uso da autópsia verbal na investigação de óbitos com causa mal definida em Minas Gerais, Brasil. Cad Saude Publica. 2010;26(6):1221-33. DOI:10.1590/S0102-311X2010000600015
https://doi.org/10.1590/S0102-311X201000... ^,1010  Mello Jorge MHP, Gotlieb SLD, Laurenti R. O sistema de informações sobre mortalidade: problemas e propostas para o seu enfrentamento I - Mortes por causas naturais. Rev Bras Epidemiol. 2002;5(2):197-223. DOI:10.1590/S1415-790X2002000200008
https://doi.org/10.1590/S1415-790X200200... ^,2020  Teixeira CLS, Klein CH, Bloch KV, Coeli CM. Reclassificação dos grupos de causas prováveis dos óbitos de causa mal definida, com base nas Autorizações de Internação Hospitalar no Sistema Único de Saúde, Estado do Rio de Janeiro, Brasil. Cad Saude Publica. 2006;22(6):1315-24. DOI:10.1590/S0102-311X2006000600020
https://doi.org/10.1590/S0102-311X200600... We opted to use the term reclassified IDCD, which was considered more appropriate for this analysis since the allocation of the new COD was performed using an existing classification, the ICD-10. The term redistributed IDCD refers to the certificates that underwent processing after redistribution among the defined causes of death.

When comparing the IDCD redistribution method used in this study with the usual methods, a greater relative proportion of endocrine diseases, mental disorders, and maternal causes exists. This suggests a possible underestimation of these causes when using the usual redistribution methods. Results similar to those of this study were observed in 13 Brazilian municipalities in 2000,¹⁰10  Mello Jorge MHP, Gotlieb SLD, Laurenti R. O sistema de informações sobre mortalidade: problemas e propostas para o seu enfrentamento I - Mortes por causas naturais. Rev Bras Epidemiol. 2002;5(2):197-223. DOI:10.1590/S1415-790X2002000200008
https://doi.org/10.1590/S1415-790X200200... which also found a higher incidence of deaths from mental disorders among the investigated IDCD (6.6%) than among the reported deaths (1.1%). The same occurred for maternal causes (0.8% of IDCD) and endocrine diseases, mainly diabetes. However, a study in Thailand¹⁵15  Polprasert W, Rao C, Adair T, Pattaraarchachai J, Porapakkham Y, Lopez AD. Cause-of-death ascertainment for deaths that occur outside hospitals in Thailand: application of verbal autopsy methods. Popul Health Metr. 2010;8(1):13. DOI:10.1186/1478-7954-8-13
https://doi.org/10.1186/1478-7954-8-13... found that verbal autopsy may overestimate the importance of diabetes post-investigation.

The increase in the number of deaths due to maternal causes when using RC-IDCD is likely related to the investigations conducted by maternal death prevention committees, active in most municipalities. On the other hand, proportional mortality by neoplasms decreased with the use of correction based on this coefficient, possibly due to a better certification of these causes than the others among IDCD.⁶6  Gamarra CJ, Valente JG, Silva GA. Correção da magnitude da mortalidade por câncer do colo do útero no Brasil, 1996-2005. Rev Saude Publica. 2010;44(4):629-38. DOI:10.1590/S0034-89102010000400006
https://doi.org/10.1590/S0034-8910201000... ^,1010  Mello Jorge MHP, Gotlieb SLD, Laurenti R. O sistema de informações sobre mortalidade: problemas e propostas para o seu enfrentamento I - Mortes por causas naturais. Rev Bras Epidemiol. 2002;5(2):197-223. DOI:10.1590/S1415-790X2002000200008
https://doi.org/10.1590/S1415-790X200200... The finding is consistent with the different proportions among the regions, higher in the North and Northeast and lower in the South, Southeast, and Midwest, where the coverage of deaths and access to diagnosis are probably better.

External causes are considered to be well recorded and, therefore, would not be part of the IDCD group.¹³13  Paes NA, Gouveia JF. Recuperação das principais causas de morte do Nordeste do Brasil: impacto na expectativa de vida. Rev Saude Publica. 2010;44(2):301-9. DOI:10.1590/S0034-89102010000200010
https://doi.org/10.1590/S0034-8910201000... ^,1717  Silva GA, Gamarra CJ, Girianelli VR, Valente JG. Tendência da mortalidade por câncer nas capitais e interior do Brasil entre 1980 e 2006. Rev Saude Publica. 2011;45(6):1009-18. DOI:10.1590/S0034-89102011005000076
https://doi.org/10.1590/S0034-8910201100... ^,1818  Soares DA, Gonçalves MJ. Mortalidade cardiovascular e impacto de técnicas corretivas de subnotificações e óbitos mal definidos. Rev Panam Salud Publica. 2012;32(3):199-206. DOI:10.1590/S1020-49892012000900005
https://doi.org/10.1590/S1020-4989201200... However, there was a relatively significant proportion of these causes among IDCD (9.3% of the reclassified IDCD for Brazil in 2010), probably related to the active search for clarifying IDCD that was conducted in the IML in various municipalities. Studies in Brazilian municipalities also showed significant proportions of external causes among IDCD.¹1  Campos D, França E, Loschi RH, Souza MFM. Uso da autópsia verbal na investigação de óbitos com causa mal definida em Minas Gerais, Brasil. Cad Saude Publica. 2010;26(6):1221-33. DOI:10.1590/S0102-311X2010000600015
https://doi.org/10.1590/S0102-311X201000... ^,1010  Mello Jorge MHP, Gotlieb SLD, Laurenti R. O sistema de informações sobre mortalidade: problemas e propostas para o seu enfrentamento I - Mortes por causas naturais. Rev Bras Epidemiol. 2002;5(2):197-223. DOI:10.1590/S1415-790X2002000200008
https://doi.org/10.1590/S1415-790X200200... ^,2020  Teixeira CLS, Klein CH, Bloch KV, Coeli CM. Reclassificação dos grupos de causas prováveis dos óbitos de causa mal definida, com base nas Autorizações de Internação Hospitalar no Sistema Único de Saúde, Estado do Rio de Janeiro, Brasil. Cad Saude Publica. 2006;22(6):1315-24. DOI:10.1590/S0102-311X2006000600020
https://doi.org/10.1590/S0102-311X200600... Khosravi et al⁷7  Khosravi A, Rao C, Naghavi M, Taylor R, Jafaria N, Lopez AD. Impact of misclassification on measures of cardiovascular disease mortality in the Islamic Republic of Iran: a cross-sectional study. Bull World Health Organ. 2008;86(9):688-96. DOI:10.2471/BLT.07.046532
https://doi.org/10.2471/BLT.07.046532... (2008) observed that 9.6% of IDCD in adults referred to external causes in Iran.

The redistribution of deaths from ill-defined causes may result in overestimating or underestimating specific mortality rates by causes. However, while the quality of information is “questionable”, it will be necessary to provide more reliable estimates of mortality rates by age and sex. As information quality improves, the contribution of this correction will diminish. Therefore, it is necessary to decrease the proportion of IDCD cases that need to be reclassified and redistributed, which can be achieved with better care and better completion of DC by physicians.

This study did not seek to define a cutoff point for the proportion of IDCD to which the redistribution method should be applied, which would require another type of design. In general, it is considered that the proportion of IDCD from chapter 18 of ICD-10, together with other selected, poorly designed codes (I46.1, I46.9, I95.9, I99, J96.0, J96.9, P28.0, C76, C80, C97, Y10-Y34, and Y87.2), should not exceed 5.0% for deaths of non-elderly individuals (< 65 years),^ff AbouZahr C, Mikkelsen L, Rampatige R, Lopez A. Mortality statistics: a tool to enhance understanding and improve quality. Brisbane: Health Information Systems Knowledge Hub; 2010 [cited 2014 Feb]. (Working Paper Series, 13). Available from: http://www.uq.edu.au/hishub/docs/WP13/HISHUB-WP13-KP-05-WEB-9Mar12.pdf which was not achieved in either Brazil or its regions in 2010.

This study, by proposing the use of empirical data to redistribute IDCD, allows more suitable estimates for risk of cause-specific mortality, and values and encourages the health services’ enormous effort to investigate deaths with an undefined underlying cause. Strategies to improve information quality should be encouraged, including the role of physicians and their participation in the appropriate completion of DC.

HIGHLIGHTS

This study proposes a methodology for redistributing ill-defined causes of death (IDCD), based on empirical data from investigations conducted in 2010, in health services and households, using standardized verbal autopsy forms.

The redistribution of IDCD using the proposed methodology not only improves the quality of mortality statistics in Brazil but also increases the potential for using mortality indicators to make decisions based on evidence.

The distribution of reclassified IDCD differs from that observed among deaths with defined causes, with a higher proportion of endocrine diseases, mental disorders, nervous system diseases, circulatory diseases, and maternal causes among the IDCD.

The results of this research can be incorporated by the managers of the Mortality Information System and by Health Surveillance professionals, in the three spheres of government, to redistribute IDCD and produce epidemiological indicators with corrected mortality rates in the states and, therefore, with more appropriate estimates for mortality risk by specific causes.

Professor Rita de Cássia Barradas Barata

Scientific Editor

REFERENCES

Publication Dates

History