ABSTRACT

Introduction:

Unspecified stroke (UnST) is of great importance in mortality statistics, as it is the fourth leading cause of death in Brazil. The objective of this study was to identify the profile of reclassified causes of death after investigation of deaths caused by UnST in Brazil.

Methods:

All deaths registered as UnST in 2017 in the Mortality Information System (SIM) were considered as garbage codes. The specific causes, detected after investigation in 60 selected cities, were analyzed by age and sex.

Results:

Of the total deaths due to UnST identified in these 60 cities (n = 11,289), 25.8% were investigated. Of these, 56.3% were reclassified to ischemic stroke, 12.7% to hemorrhagic stroke, and 23.3% to other specific causes, such as diabetes and chronic kidney disease, in both sexes.

Discussion:

The higher proportion of deaths due to ischemic stroke in comparison to hemorrhagic stroke was expected. However, the detection of other specific causes outside the stroke group indicates possible quality problems in the filling of death certificate (DC).

Conclusion:

The investigations allowed the identification of subgroups of deaths due to stroke. In addition to the research, however, it is important to conduct physician training in the adequate filling in of the DC, in order to improve estimates of specific stroke mortality, and to enable appropriate targeting of health actions and services.

Keywords:
Death certificates; Cause of death; Stroke; Health information systems

INTRODUCTION

Stroke is defined as a sudden neurological deficit resulting from a vascular lesion. This lesion has an acute, variable-duration installation and can lead to death. Its severity varies according to the site and intensity with which the vascular lesion occurs¹1. André C. Manual de AVC. 2ª ed. Rio de Janeiro: Revinter; 2006.. There are three major subgroups of stroke, classified as follows: ischemic stroke, intracerebral hemorrhage, and subarachnoid hemorrhage²2. Organização Mundial da Saúde. O Manual STEPS de Acidentes Vascular Cerebrais da OMS: enfoque passo a passo para a vigilância de acidentes vascular cerebrais/doenças não-transmissíveis e saúde mental, Organização Mundial da Saúde. Genebra; 2005.. Ischemic stroke subtypes are classified as lacunar, atherosclerotic, and embolic³3. Chaves MLF. Acidente vascular encefálico: conceituação e fatores de risco. Rev Bras Hipertens. 2000;7(4):372-82.^{), (4}4. Radanovic M. Características do atendimento de pacientes com acidente vascular cerebral em hospital secundário. Arq Neuropsiquiatr. 2000;58(1):99-106. http://dx.doi.org/10.1590/S0004-282X2000000100015
http://dx.doi.org/10.1590/S0004-282X2000... .

Between 2003 and 2013, stroke ceased to occupy an anonymous position, covered by the term “cardiovascular disease”, and became recognized as an autonomous non-transmissible disease, with great implications for global health⁵5. Mensah GA, Norrving B, Feigin VL. Global burden of stroke. Neuroepidemiology. 2015;45(3):143-5. https://doi.org/10.1161/CIRCRESAHA.116.308413
https://doi.org/10.1161/CIRCRESAHA.116.3... . There is still no country in the world where the stroke burden, in terms of the absolute number of people affected or who died from stroke, has declined in the last two decades⁶6. Feigin VL, Krishnamurthi RV, Parmar P, Norrving B, Mensah GA, Bennett DA, et al. Update on the global burden of ischaemic and haemorrhagic stroke (1990-2013): the GBD 2013 Study. Neuroepidemiology. 2015;45(3):161-76. https://dx.doi.org/10.1159%2F000441085
https://dx.doi.org/10.1159%2F000441085... .

Stroke is a disease influenced by several factors, with more than 150 known causes⁷7. Amarenco P, Bogousslavsky J, Caplan LR, Donnan GA, Hennerici MG. Classification of stroke subtypes. Cerebrovasc Dis. 2009;27(5):493-501. https://doi.org/10.1159/000210432
https://doi.org/10.1159/000210432... . Diabetes constitutes a risk factor for stroke through direct atherogenic mechanisms and by interacting with other risk factors, such as hypertension and hyperlipidemia⁸8. Mortel KF, Meyer JS, Sims PA, McClintic K. Diabetes mellitus as a risk factor for stroke. South Med J. 1990;83(8):904-11. https://doi.org/10.1097/00007611-199008000-00014
https://doi.org/10.1097/00007611-1990080... . Cerebral atherosclerosis is the main cause of ischemic stroke. In the 1930s, a study of autopsies indicated that more than 70% of ischemic stroke cases were due to atherosclerosis, and only 3% to embolism⁹9. Aring CD, Merritt HH. Differential diagnosis between cerebral hemorrhage and cerebral thrombosis. Arch Intern Med. 1935;56(3):435-54. https://doi.org/10.1001/archinte.1935.00170010023002
https://doi.org/10.1001/archinte.1935.00... . Hypertension is the main risk factor for hemorrhagic stroke, consequent to rupture of a vessel in the intimacy of the cerebral parenchyma. Other causes of hemorrhagic stroke are coagulation alterations, subarachnoid hemorrhages due to the existence of arteriovenous malformations or aneurysm ruptures, among others¹⁰10. Sacco RL, Wolf PA, Gorelick PB. Risk factors and their management for stroke prevention: outlook for 1999 and beyond. Neurology. 1999;53(7 Suppl 4):S15-24.^{), (11}11. Kannel WB. Framingham study insights into hypertensive risk of cardiovascular disease. Hypertens Res. 1995;18(3):181-96. https://doi.org/10.1291/hypres.18.181
https://doi.org/10.1291/hypres.18.181... .

Although it has been demonstrated the importance of recognizing stroke as a vascular disease to be faced in particular and of great importance in vital statistics¹²12. Murray CJ, Lopez AD. Mortality by cause for eight regions of the world: global burden of disease study. Lancet. 1997;349(9061):1269-76. https://doi.org/10.1016/S0140-6736(96)07493-4
https://doi.org/10.1016/S0140-6736(96)07... , unspecified stroke (UnST) still has great relevance in statistics in Brazil, being the fourth cause of death recorded in the Mortality Information System (Sistema de Informação sobre Mortalidade - SIM) in 2015, surpassed only by ischemic heart disease, pneumonia and ill-defined causes¹³13. Brasil. Ministério da Saúde. Informações de saúde (Tabnet): estatísticas vitais: mortalidade geral [Internet]. Brasília, DF; 2008 [atualizado em 25 jan. 2016; citado em 27 ago. 2019]. Disponível em: http://www2.datasus.gov.br/DATASUS/index.php?area=0205&id=6937
http://www2.datasus.gov.br/DATASUS/index... .

A difficulty found in mortality statistics for knowing the real magnitude of the types of stroke is the certification of UnST, cause included in the list of garbage codes (GC). The garbage causes of death are considered inadequate or of no use for public health purposes¹⁴14. GBD 2015 Mortality and Causes of Death Collaborators. Global, regional, and national life expectancy, all-cause mortality, and cause-specific mortality for 249 causes of death, 1980-2015: a systematic analysis for the Global Burden of Disease Study 2015. Lancet. 2016;388(10053):1459-544. https://doi.org/10.1016/S0140-6736(16)31012-1
https://doi.org/10.1016/S0140-6736(16)31... ^{)- (17}17. Naghavi M, Makela S, Foreman K, O'Brien J, Pourmalek F, Lozano R. Algorithms for enhancing public health utility of national causes-of-death data. Popul Health Metrics. 2010;8:9. https://doi.org/10.1186/1478-7954-8-9
https://doi.org/10.1186/1478-7954-8-9... .

In the Global Burden of Disease study (GBD) the codes of the International Statistical Classification of Diseases and Health-Related Problems, 10^th Revision (ICD-10) for UnST are redistributed by statistical methods to ischemic and hemorrhagic subgroups¹⁴14. GBD 2015 Mortality and Causes of Death Collaborators. Global, regional, and national life expectancy, all-cause mortality, and cause-specific mortality for 249 causes of death, 1980-2015: a systematic analysis for the Global Burden of Disease Study 2015. Lancet. 2016;388(10053):1459-544. https://doi.org/10.1016/S0140-6736(16)31012-1
https://doi.org/10.1016/S0140-6736(16)31... , but the fractions of redistribution are not presented. There are few studies that present the UnST fractions used for redistribution to the hemorrhagic, ischemic, and subarachnoid stroke subtypes¹⁸18. Truelsen T, Krarup LH, Iversen HK, Mensah GA, Feigin VL, Sposato LA, et al. Causes of death data in the Global Burden of Disease estimates for ischemic and hemorrhagic stroke. Neuroepidemiology. 2015;45(3):152-60. https://doi.org/10.1159/000441084
https://doi.org/10.1159/000441084... . On the other hand, empirical methods may represent new and more accurate strategies in evaluating the actual occurrence of deaths by these subgroups. Thus, this study aimed to identify the fractions of specific causes detected after investigation of deaths from UnST in adults.

METHODS

This is a cross-sectional study on the profile and reclassification of deaths of people aged 30 years or over, whose underlying causes recorded in the death certificate (DC) were classified as UnST in Brazil in 2017. The study is part of the project “Improvement of the diagnosis of cause of death in Brazil”, conducted in partnership between the Ministry of Health and the Universidade Federal de Minas Gerais (UFMG), with the external partnership of Vital Strategies and the University of Melbourne by the Bloomberg Foundation. The project was implemented in 60 cities of the five regions of Brazil that adhered to the study voluntarily, tacking into consideration the structure of their epidemiological surveillance teams. In this study, the term city was used as a synonym for the municipality and covers all its territorial extension, including deaths occurred in urban and rural areas.

More than 85% of deaths from UnST to be investigated in the 60 cities occurred in those with more than 500,000 inhabitants, possibly with greater access to healthcare services, quality of care, and qualified health professionals involved in the process. In fact, in the analysis of deaths according to the population size of cities (> 500,000 inhabitants; from 100,001 to 500,000; and 100,000 or less), according to the medical assistance variable and also according to R98 and R99 codes, it was observed that the strata of larger cities had lower proportions of deaths without care and also with R98 or R99 codes. These data indicate that these cities would tend to have more structured health facilities with higher capacity for investigation.

The following ICD-10¹⁹19. Organização Mundial de Saúde. Classificação Estatística Internacional de Doenças e Problemas Relacionados à Saúde: CID-10. 8ª ed. São Paulo: Editora da Universidade de São Paulo; 2012. codes were considered as UnST, according to the 2015 GBD study list: I64, I67.4, I67.9, I69.4, I69.8¹⁴14. GBD 2015 Mortality and Causes of Death Collaborators. Global, regional, and national life expectancy, all-cause mortality, and cause-specific mortality for 249 causes of death, 1980-2015: a systematic analysis for the Global Burden of Disease Study 2015. Lancet. 2016;388(10053):1459-544. https://doi.org/10.1016/S0140-6736(16)31012-1
https://doi.org/10.1016/S0140-6736(16)31... . The I67.8 code was excluded from the GC list, considering that in Brazil this code is used for ischemic stroke²⁰20. Abreu DMX, Drumond EF, França EB, Ishitani LH, Malta DC, Machado CJ. Análise comparativa de classificações de causas evitáveis de morte em capitais brasileiras: o caso das doenças cerebrovasculares. Rev Bras Estud Popul. 2010;27(2):447-55. http://dx.doi.org/10.1590/S0102-30982010000200014
http://dx.doi.org/10.1590/S0102-30982010... . For this reason, for the reclassification of deaths, the I67.8 code was added to specific causes.

The data referring to deaths of residents of the 60 cities occurring in 2017 were obtained from the SIM, which is fed from information contained in the DC. Deaths were selected according to the following criteria: residence of the deceased person in some of the 60 cities under study, age ≥ 30 years, and original underlying cause encoded as UnST. Based on these eligible deaths (n = 11,289) we initially estimated the frequencies (absolute and relative) of the main sociodemographic characteristics (sex, age group, race, educational level, region of residence) and other selected variables, such as the place of death, certifier physician, and whether the death was investigated or not.

The investigations were conducted by the epidemiological surveillance teams of the municipal health departments. Initially, the DCs were reviewed to correct possible inadequacies in the typing or coding of the underlying cause. The teams selected hospital deaths of residents of the city and searched for information in hospital records and, when necessary for supplementation, in health services such as the Death Verification Service (SVO) and the Forensic Medical Institute (IML). After, the teams changed the cause of death in the SIM. This process of investigation and registration in the SIM followed the guidelines contained in the “Protocol for investigating deaths with causes classified as garbage codes - 60 cities in Brazil” ⁽²¹21. Brasil. Ministério da Saúde, Melhoria do Diagnóstico de Casa de Morte no Brasil. Protocolo de investigação de óbitos com causas classificadas como códigos "garbage": sessenta cidades do Brasil. Brasília, DF; 2017 [citado em 3 set. 2019]. Disponível em: http://www1.saude.ba.gov.br/dis/arquivos_pdf/Protocolo-Investigacao-Codigos-Garbage-60-Cid-Abril-2017.pdf
http://www1.saude.ba.gov.br/dis/arquivos... . It should be noted that the hospital investigations were not proposed for all deaths from UnST, as recommended in the protocol, which established the strategy of prioritizing the conduct of investigations in hospitals with a higher volume of garbage causes. Some cities prioritized hospitals with a positive history of collaboration with surveillance services.

For all deaths investigated in hospitals, an investigation form containing variables was filled in enabling reclassification of the underlying cause originally defined as GC. The variables used in hospital investigation include: date of hospitalization, circumstance of referral to hospitalization, information on pre-hospital care, findings and clinical evolution, more relevant exams to reclassify the cause of death, procedures performed during hospitalization, and information about comorbidities that may have contributed to death. The data collected in the hospital investigation of each death were submitted to review and certification by physicians who reclassified or not the original underlying cause of death. In general, the physicians were part of the epidemiological surveillance team of the municipal health department and had experience in the certification of causes of death.

The new underlying causes of death after investigation were categorized according to the level of certainty of the diagnosis, according to criteria adapted from Serina et al. ⁽²²22. Serina P, Riley I, Stewart A, Flaxman AD, Lozano R, Mooney MD, et al. A shortened verbal autopsy instrument for use in routine mortality surveillance systems. BMC Med. 2015;13:302. https://doi.org/10.1186/s12916-015-0528-8
https://doi.org/10.1186/s12916-015-0528-... , namely: (1) definitive: diagnosis with the highest level of certainty for certain health condition, confirmed through laboratory examination or imaging, and/or clinical history documented by specific signs and symptoms in those clinical conditions in which there are no supplementary evidentiary exams; (2) probable: diagnosis with a high level of certainty for a given health condition through the documented clinical history by specific signs and symptoms, in the absence of specific supplementary exams; (3) possible: diagnosis that does not reach the previous criteria for a given health condition.

The new underlying causes were included in the municipal SIM and in an online database called Collect, created by the Brazilian Ministry of Health to include the causes investigated in hospitals. This database allows the evaluation of criteria used in the reclassification of causes of death, specifying the level of certainty of the diagnosis of the cause defined after investigation. Thus, in this study, the selection of deaths from UnST was based on two complementary information systems, SIM and Collect. In the SIM, among the eligible deaths of the 60 cities (n = 11,289), we selected those that had the variable investigation filled in with a “yes” (n = 2,910) and in which the underlying cause had changed after investigation (n = 2,116). For comparison, we selected the SIM deaths that had the data from investigations inserted into Collect, and which had the level of certainty of diagnosis of the underlying cause in this system identified as “definitive” or “probable” (n = 616), as shown in Figure 1.

We calculated the absolute and relative frequencies of the deaths investigated and reclassified to a specific cause per federation unit (FU). The underlying causes of death after investigation, registered in SIM (n = 2,116) and Collect with a level of certainty of diagnosis as “definitive” or “probable” (n = 616), were grouped according to the 2015 GBD study list of causes, and calculated proportions according to sex and age groups (from 30 to 69 years; 70 years and over). To check the difference in proportions between information in SIM and Collect, the chi-square test was used.

This study was approved by the Research Ethics Committee of UFMG (CAEE 7555317.0.0000.51 49) and developed according to the ethical precepts established in Ordinance No. 466/2012 of the National Health Council.

RESULTS

Of the total deaths from UnST of the 60 cities (n = 11,289), 25.8% (n = 2,910) were investigated, 53.3% of which were female. Overall, investigated and non-investigated deaths presented relatively similar frequency distributions for the variables sex, age group, race, educational level and certifier physician (Table 1).

Of the investigated deaths, 69.8% occurred in the age group of 70 years and over, and 30.2% in the age group from 30 to 69 years. Whites and blacks (black and brown) had 47.9% and 46.8% of the deaths from UnST investigated, respectively. Almost half (48.2%) of the investigated deaths were uneducated people or with an education of up to three years (data not presented). Concerning the region of residence, 6.9% and 3.6% of the total deaths from UnST were of residents of the South and Midwest regions, which contributed with 17.8% and 6.4% of the investigated deaths, respectively. The opposite was observed in the Southeast region, which, despite contributing to almost half of the total number of deaths (46.6%), had only one third (34.9%) investigated. Regarding the place of occurrence, 84.9% of the investigated deaths occurred in hospitals, and 8.2% at home. Most of the investigated deaths were certified by substitute physicians (38.9%), followed by other physicians (29.2%), and assistant physicians (24.5%) (Table 1).

Of 2,910 deaths from UnST investigated in the SIM (25.8%), it was observed that three states investigated more than 70% of deaths: Acre (100%), Santa Catarina (77.2%), and Tocantins (71.3%). Sergipe, Mato Grosso, Roraima, Paraná and Alagoas investigated between 40% and 70% of the deaths (Table 2).

Regarding reclassification, 67.1% (n = 1,952) of the deaths from UnST had the underlying cause changed to specific causes after investigation. Most of the states reclassified more than half of the investigated deaths, highlighting Acre, where 100% of the deaths due to UnST were investigated and all were reclassified. However, it should be noted that this state had the lowest total number of deaths from UnST. Other states with higher frequencies of deaths from UnST had a lower percentage of cases investigated, such as Amazonas (5.5%), Bahia (8.1%), and Rio de Janeiro (8.9%), but showing a much higher proportion of reclassification to specific causes: 64.7%, 47.9%, and 45.5%, respectively (Table 2).

We have observed similarities in the percentage distribution by sex and age group of deaths from UnST investigated and which changed the underlying cause registered in the SIM and Collect (p > 0.05). The percentage of reclassification increased with age in both sexes, with the highest percentages being found in those older than 80 years. In this age group, approximately half of the female deaths were reclassified (51.7% in the SIM and 47.6% in Collect), whose values were higher than those of males (33.6% in SIM and 33.9% in Collect) (Chart 1).

Regarding the reclassification of underlying cause of death after investigation, it was found that, of the UnST, 49.1% (male) and 56.0% (female) were reclassified to ischemic stroke, and 14.0% and 11.5% to hemorrhagic stroke in men and women, respectively. For both sexes, these percentages were 56.3% for ischemic stroke and 12.7% for hemorrhagic stroke. The reclassification of deaths from UnST to ischemic stroke was more frequent in the age group of 70 years and over. However, the reclassification to hemorrhagic stroke was more frequent in the age group of 30 to 69 years. In these two situations, there was little difference between the sexes (Table 3).

Among the deaths from UnST in both sexes, 7.7% remained as GC even after investigation, being 5.4% as UnST and 2.3% as other GC not associated with UnST (Table 3). In addition, 23.3% in both sexes migrated to other specific causes that do not belong to the stroke group, such as diabetes (5.4%), atrial flutter (2.2%), chronic kidney disease (2.0%), Alzheimer’s and other dementia (1.7%), ischemic heart disease 1.7%), and falls, with 1.5% (data not presented).

DISCUSSION

Through the investigations of deaths from UnST in 60 cities, it was found that 67% were reclassified to specific underlying causes in the SIM and there was a higher proportion of reclassification for ischemic stroke (49% in males and 56% in females), being much lower for hemorrhagic stroke (14% and 12% for men and women, respectively). In global estimates for 2016, the risk of occurrence of first ischemic stroke among people aged from 25 years is about 2.2 times higher than the risk of first hemorrhagic stroke²³23. GBD 2015 Risk Factors Collaborators. Global, regional, and national comparative risk assessment of 79 behavioural, environmental and occupational, and metabolic risks or clusters of risks, 1990-2015: a systematic analysis for the Global Burden of Disease Study 2015. Lancet. 2016;388(10053):1659-724. https://doi.org/10.1016/S0140-6736(16)31679-8
https://doi.org/10.1016/S0140-6736(16)31... . In Brazil, an increase has also been observed in the incidence of ischemic stroke in young adults²⁴24. Cabral NL, Freire AT, Conforto AB, Santos N, Reis FI, Nagel V, et al. Increase of stroke incidence in young adults in a middle-income country: a 10-year population-based study. Stroke. 2017;48(11):2925-30. https://doi.org/10.1161/STROKEAHA.117.018531
https://doi.org/10.1161/STROKEAHA.117.01... . Ours is the first study of reclassification of deaths from UnST, therefore no results of Brazilian studies were found for comparison. Worldwide indirect estimates based on the GBD 2013 study, however, confirm higher proportions of redistribution of UnST to ischemic stroke (64.7%) and lower for hemorrhagic stroke (30.8%), with variable fractions according to age groups and regions of the world¹⁸18. Truelsen T, Krarup LH, Iversen HK, Mensah GA, Feigin VL, Sposato LA, et al. Causes of death data in the Global Burden of Disease estimates for ischemic and hemorrhagic stroke. Neuroepidemiology. 2015;45(3):152-60. https://doi.org/10.1159/000441084
https://doi.org/10.1159/000441084... .

High proportions of UnST as underlying causes of death reduce the quality of information about the causes of death and hinder the planning and adequate definition of health actions and assistance. Therefore, some studies have demanded efforts to correct ill-defined causes and GC, using indirect methods¹⁴14. GBD 2015 Mortality and Causes of Death Collaborators. Global, regional, and national life expectancy, all-cause mortality, and cause-specific mortality for 249 causes of death, 1980-2015: a systematic analysis for the Global Burden of Disease Study 2015. Lancet. 2016;388(10053):1459-544. https://doi.org/10.1016/S0140-6736(16)31012-1
https://doi.org/10.1016/S0140-6736(16)31... . Correcting these causes of death with field-research, using data from medical records of hospitals and other health facilities, represents a possible alternative, as found in this study and in others conducted in the country²⁵25. 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 Saúde Pública. 2010;26(6):1221-33. http://dx.doi.org/10.1590/S0102-311X2010000600015
http://dx.doi.org/10.1590/S0102-311X2010... ^{), (26}26. França EB, Teixeira RA, Ishitani LH, Duncan BB, Cortez-Escalante JJ, Morais Neto OL, et al. Causas mal definidas de óbito no Brasil: método de redistribuição baseado na investigação do óbito. Rev Saúde Pública. 2014;48(4):671-81. http://dx.doi.org/10.1590/S0034-8910.2014048005146
http://dx.doi.org/10.1590/S0034-8910.201... .

Deaths that had the underlying cause changed in the SIM (n = 2,116) were equivalent to 72.7% of the number of investigated deaths in the SIM. This value was higher than that found in a study on investigation of ill-defined causes in Brazil in 2010, when 65.5% of deaths were reclassified²⁶26. França EB, Teixeira RA, Ishitani LH, Duncan BB, Cortez-Escalante JJ, Morais Neto OL, et al. Causas mal definidas de óbito no Brasil: método de redistribuição baseado na investigação do óbito. Rev Saúde Pública. 2014;48(4):671-81. http://dx.doi.org/10.1590/S0034-8910.2014048005146
http://dx.doi.org/10.1590/S0034-8910.201... . With regard to the 27.3% (n = 794) that did not have the underlying cause changed in this study, this was probably due to the difficulties in obtaining the necessary information for reclassification, difficulties in accessing the healthcare network, and the low quality of provided care and medical records in some establishments²⁷27. Silva FG, Tavares-Neto J. Avaliação dos prontuários médicos de hospitais de ensino do Brasil. Rev Bras Educ Med. 2007;31(2):113-26. http://dx.doi.org/10.1590/S0100-55022007000200002
http://dx.doi.org/10.1590/S0100-55022007... ^{), (28}28. Alves MA, Szpilman ARM, Poton WL. Avaliação do registro médico nos prontuários de um ambulatório de ensino, Vila Velha, ES. Rev Bras Pesqui Saúde, Vitória. 2015;17(3):69-77. https://doi.org/10.21722/rbps.v17i3.14138
https://doi.org/10.21722/rbps.v17i3.1413... . It is noted that some states had a low percentage of investigation, however they had a higher percentage of reclassification of underlying causes. This result is possibly related to the selection in this study of cities with a large population, in which the number of deaths is high, which hinders the investigation of all cases. In this situation, it is essential to structure surveillance teams to recover data that qualifies cause-of-death information.

An unexpected result in this study was the reclassification of deaths from UnST to causes of death that are different from specific types of stroke, such as diabetes, atrial flutter, chronic kidney disease, Alzheimer’s, ischemic heart disease and falls. These results indicate difficulties found in the quality of DC completion, in coding and selection of underlying causes of death, in investigation of death, in recertification of underlying cause of death, as well as in supply of technologies capable of providing physicians with the possibility of better diagnosis.

Regarding the two databases evaluated, it was observed that the deaths inserted in Collect are similar to the total number of investigated deaths inserted in the SIM relative to sex and age groups. On the other hand, a higher percentage of other specific causes that are different from stroke in the Collect system relative to the SIM can be noted. This result may be explained by the fact that, in the first, the investigation was performed only in hospitals, allowing the reclassification of cause of death in a more consistent way as a consequence of greater access to information and diagnostic exams. It is to be expected that in hospital services more information will be found clarifying causes of death by searching through medical records²⁵25. 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 Saúde Pública. 2010;26(6):1221-33. http://dx.doi.org/10.1590/S0102-311X2010000600015
http://dx.doi.org/10.1590/S0102-311X2010... ^{), (26}26. França EB, Teixeira RA, Ishitani LH, Duncan BB, Cortez-Escalante JJ, Morais Neto OL, et al. Causas mal definidas de óbito no Brasil: método de redistribuição baseado na investigação do óbito. Rev Saúde Pública. 2014;48(4):671-81. http://dx.doi.org/10.1590/S0034-8910.2014048005146
http://dx.doi.org/10.1590/S0034-8910.201... .

In summary, the results presented here reinforce the importance of strategies to qualify the causes of death, which include both the training of physicians to adequately fill in the DC and in the investigation of these deaths. According to Ishitani et al. ⁽¹⁵15. Ishitani LH, Teixeira RA, Abreu DMX, Paixão LMMM, França EB. Qualidade da informação das estatísticas de mortalidade: códigos garbage declarados como causas de morte em Belo Horizonte, 2011-2013. Rev Bras Epidemiol. 2017;20(Suppl 1):34-45. http://dx.doi.org/10.1590/1980-5497201700050004
http://dx.doi.org/10.1590/1980-549720170... , it is necessary to invest in raising the awareness of health professionals about the importance of the DC as an instrument for producing health statistics to contribute to the development of actions and programs for prevention and treatment of diseases and problems that should receive intervention¹⁵15. Ishitani LH, Teixeira RA, Abreu DMX, Paixão LMMM, França EB. Qualidade da informação das estatísticas de mortalidade: códigos garbage declarados como causas de morte em Belo Horizonte, 2011-2013. Rev Bras Epidemiol. 2017;20(Suppl 1):34-45. http://dx.doi.org/10.1590/1980-5497201700050004
http://dx.doi.org/10.1590/1980-549720170... .

Thus, aiming at prevention, it becomes extremely important to recommend that, in addition to the diagnosis of UnST, physicians try to reach a distinction between the diagnosis of hemorrhagic or ischemic stroke. Considering the prevention of new cases, it is important that information about the type of stroke is presented in the DC, since ischemic stroke has a cause most often related to atherosclerosis, while hemorrhagic stroke has a close relation with systemic arterial hypertension and rupture of cerebral aneurysms. Several options of prevention and primary care policies are now available to act on the main risks¹⁴14. GBD 2015 Mortality and Causes of Death Collaborators. Global, regional, and national life expectancy, all-cause mortality, and cause-specific mortality for 249 causes of death, 1980-2015: a systematic analysis for the Global Burden of Disease Study 2015. Lancet. 2016;388(10053):1459-544. https://doi.org/10.1016/S0140-6736(16)31012-1
https://doi.org/10.1016/S0140-6736(16)31... .

CONCLUSION

It was observed that deaths from UnST after investigation were reclassified with higher percentage to ischemic stroke, followed by hemorrhagic stroke. In addition, ischemic stroke was reclassified more frequently in more advanced age groups (70 years and over), while hemorrhagic stroke was reclassified more frequently in the age group of 30 to 69 years.

Moreover, a considerable amount of UnST was reclassified to other specific causes that are different from the stroke group, which shows difficulties related to the quality found both in the completion of DC and in the process of coding and selecting the underlying cause of death, or in the investigation of deaths, as well as in the availability of technologies for better medical diagnosis. Therefore, health service management needs to implement training of physicians to raise awareness on the importance of adequate DC completion. Reducing causes of death from GCs may contribute to improving estimates of mortality from ischemic and hemorrhagic stroke, in order to plan and implement health actions and assistance aimed at preventing atherosclerosis and controlling arterial hypertension, capable of reducing the incidence of these impairing events that are so costly for public health.

Acknowledgements

The authors of this manuscript thank all health professionals who made feasible and carried out investigations in hospitals and other health services of the 60 cities participating in the project “Melhoria do Diagnóstico de Causa de Morte no Brasil”. (Improvement in the Diagnosis of Cause of Death in Brazil).

References

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