epidemiology of cerebrovascular …hist.library.paho.org/english/bul/ev17n3p292.pdflessa and bastes...

EPIDEMIOLOGY OF CEREBROVASCULAR ACCIDENTS IN THE CITY OF SALVADOR, BAHIA, BRAZIL’

Ines Lessa and Carlos Ant8nio G. Bastos3

Few data are available on the ebidemiology of cerebrovascular accidents in developing countries. The following article provides a detailed analysis of the situation in Salvador, Brazil, based on a review of all known cerebrovascular accidents occurring in that city between I Jub 1979 and 30 June 1980.

Introduction

The generally recognized importance of cerebrovascular accidents (CVAs) as a cause of death has prompted the World Health Or- ganization to sponsor centers in Europe, Asia, and Africa to study this problem (I). Both CVA incidence and the mortality resulting from CVAs exhibit wide geographic variations, even within a single country (l-.5), variations that have not yet been satisfactorily ex- plained (4,s). In the United States these rates vary according to location and are higher among blacks (7-10); in Europe the average incidence is 200 cases per 100,000 population per year (4); and in Japan, where CVAs have been a leading cause of death since 195 1, the rates are higher and also variable (S,ll-15).

Despite a wide variety of risk factors described for CVAs (2,6,16-22), arterial hypertension is generally accepted as the principal predisposing factor (4,19-24). In Japan, where the incidence of hypertension is very high, CVAs are also very prevalent (S), while in places where the prevalence of hypertension is low, CVAs are virtually unknown (25).

‘Also appearing in Portuguese in the Bolelin de la Of;- cina Sanitaria Panamericana.

ZAssociate Professor, Department of Preventive Med- icine, Federal University of Bahia; Fellow, Brazilian Na- tional Research Council.

3Fellow, Brazilian Ministry of Education and Culture; medical student, Federal University of Bahia.

In Brazil, an analysis of historical trends over 30 years (1940-1969) in Slo Paulo revealed a sharp increase in mortality from CVAs during that period (26). Also, a 1962- 1964 study of mortality in 10 Latin American cities, Bristol (England), and San Francisco (United States) suggested that SBo Paulo and another Brazilian city (Ribeirso P&o) had the highest CVA mortalities (for both sexes) of all the cities studied (27). More recently, a survey of a district in the city of Salvador revealed the presence of CVA sequelae in 2.9 per cent of the survey subjects 50 years of age or older

(28). At present, the developed countries consti-

tute the main source of information about CVA epidemiology. However, it is difficult to apply such information to Brazil because of that country’s distinct ethnic composition, geography, climate, economy, and environ- mental conditions. Therefore, the study reported here was undertaken for the purpose of investigating such basic epidemiologic matters as CVA incidence and mortality, rates of death among CVA victims, common characteristics of CVA victims, seasonal variations, principal diseases associated with CVAs, the types of CVAs involved (and their prevalence and impact), the principal clinical features of CVAs, and possible conclusions of value in health planning. Only the first three of these subjects (incidence and mortality, victims’ characteristics, and seasonal variations) are discussed here.

292

Lessa and Bastes l CEREBROVASCULAR ACCIDENTS IN SALVADOR, BRAZIL 293

Materials and Methods

Defining a CVA as an acute complication of certain chronic diseases with clinical mani- festations requiring immediate medical care and hospitalization, we collected data on all pktients who experienced CVAs between 1 July 1979 and 30 June 1980 who were living within the city limits of Salvador, Bahia. Cases of temporary cerebral ischemia were excluded.

These data were obtained from the medical records of patients receiving care at 10 hospitals and eight emergency services in the city, after excluding clinics that did not admit CVA patients. Of the 18 medical facilities involved (which included institutions providing private, public, and social welfare services), 16

r were found to be dealing with patients from all social strata and virtually every part of the city. This diversity of admissions is a result of agreements entered into by the National Medical Care and Social Welfare Institute (INAMPS); various private, municipal, state, and federal medical services; and various private and public enterprises. The other two facilities (a military hospital and a prepaid ser- vice clinic) were found to be serving specific clienteles. The demand for prompt medical care was greatest at the eight emergency services and at one emergency hospital. CVA patients were generally admitted to the other hospitals via transfers, since most of these hospitals, including the one university hospital, had no emergency departments.

All death certificates for the period 1 July 1979-31 July 1980 that cited a CVA as the cause of death were examined. The relevant data were collected at the Data Processing Center (CEPRO) of the Bahia State Depart- ment of Health in order to supplement the data from individual facilities. The reason for doing this was to gather data on four specific kinds of victims, namely (a) those who died at home after being discharged from the hospital; (b) those who died at home without receiving any inpatient care; (c) those who experienced sudden death and who were autop-

sied at the Medico-Legal Institute; and (d) those experiencing a CVA toward the end of the survey period and who died between 1 and 31 July 1980.

All the diagnoses upon which the medical records were based were made by the physicians who treated the patients. In the vast majority of cases these diagnoses were clinical; however, in all cases where patients were given laboratory examinations or were sub- sequently autopsied, the initial diagnosis was confirmed.

It should also be mentioned that all the data obtained were transferred to an appropriate record form (see Annex 1). No additional in- vestigations were pursued with the patients’ families or with physicians.

. . .

Most of the Salvador population data used to calculate incidence and mortality rates were those from the 1980 census, which found the Salvador population over 14 years of age to total 783,642 inhabitants. However, since these data were only classified by sex, and not by age group, the size of various age groups in Salvador was estimated by using a hypothet- ical projection presented as “Hypothesis III” in a publication on possible demographic trends from 1940 to 2000 (29). The reason for selecting this particular projection was that it closely matched the actual 1980 census figures for both sexes.

The incidence of CVAs was calculated in two ways-by including all CVA patients and, alternatively, by excluding CVA patients with a previous CVA history. This latter incidence is referred to as the “corrected incidence. ” The first calculation, where all CVA cases were included, followed the cri- teria of Aho et al. (Z,), whereby a recurrence is considered important from a public health standpoint because it requires the same type of medical care as an initial occurrence. The second calculation (that of corrected incidence) was made by finding the percentage of

294 PAHO BULLETIN l vol. 17, no. 3.1983

hospitalized CVA cases with prior CVA occurrences and then using that percentage to estimate the frequency of prior occurrences among CVA victims who died at home without receiving hospital care. In this regard, it should be noted that most of the CVA patients (82.5 per cent) were hospitalized. Student’s t test was applied to compare the average ages of both sexes. The test of difference between two proportions was used to compare the mortality among males and females.

Results

Between 1 July 1979 and 30 June 1980 a total of 1,089 patients suffering from acute CVA episodes were admitted to the 18 medical facilities covered by this study. Another 232 episodes are known to have occurred in Salvador during this period, six being cases of sudden death with subsequent autopsy and the others being cases involving death at home. In all, 1,321 CVA cases were found to have occurred in Salvador during the one- year study period.

The patients involved ranged in age from one year to 91 years. However, the one-year- old (who had CVA resulting from sickle cell anemia) was excluded from the analysis (see Table 1) because of the rarity of the problem at that age. Therefore, the age groups of the

subjects whose ages were known and whose cases were included ranged from 15-24 years to 65 years and over.

Within all the groups up to 65 years of age the incidence of CVAs was similar for both sexes. However, cases among women pre- dominated in the 65 and over group. Overall, the average age at onset was 62.4 years for men and 64.5 for women.

Table 2 shows the incidences and corrected incidences found for different Salvador age groups, by sex. In calculating the overall corrected incidences for men and women, an estimated 104 men and 97 women with previous occurrences of CVA were excluded from the calculations. Both the incidence and the corrected incidence among both sexes were found to be high in the 45-54 and 55-64 age groups and very high in the group over 64 years old. In addition, the subjects’ sex appeared to have little influence upon the incidence or corrected incidence in any age group, the relatively smaller number of males over 64 years old more than compensating for the larger number of cases among women in that age group. It should be noted, however, that the incidences and corrected incidences for particular age groups were slightly underesti- mated, because the ages of 55 men and 48 women were unknown. This underestimation was somewhat greater for men than for

Table 1. Distribution of the 1,320 Salvador CVA cases recorded between 1 July 1979 and 30 .June 1980 that were included in the study, by age group and sex.

Male.?= F~tIl&S= Total Age group (in years) NO. % NO. % NO. %

15-24 7 1.15 8 1.12 15 1.14 25-34 21 3.46 14 1.97 35 2.65 35-44 34 5.59 48 6.74 82 6.21 45-54 83 13.65 92 12.93 175 13.26 55-64 129 21.21 115 16.15 244 18.49 265 279 45.89 387 54.35 666 50.45

Unknown 55 9.05 48 6.74 103 7.80

Total 608 100 712 100 1,320 100

aAverage ages of subjects f one standard deviation: 62 4 f 14.24 years (males); 64.5 f 14 2 years (females). t(d.f.=1,215) =2.!jg; p<O.~i.

Table 2. Incidence of CVA cases and corrected incidence (new cases) per 100,000 inhabitants in Salvador, Bahia, from I July 1979 through 30 June 1980, by age group and sex.

Age group (in years)

No. of Population cases

Corrected Corrected incidence incidence

Incidence (new case.3 Incidence (new cases (cases per No. of Per No. of (cases per No. of Per 100,000) new cases 100,000) Population cases 100,000) new cases 100,000)

15-24 132,487 7 5.3 7 5.3 152,959 8 5.2 8 5.2 25-34 92,317 21 22.7 18 19.5 110,392 14 12.7 13 11.8 35-44 56,394 34 60.3 30 53.2 65,149 48 73.7 46 70.6 45-54 40,171 83 206.6 74 184.2 46,094 92 199.6 81 175.7 55-64 22,274 129 579.2 106 475.9 27,939 115 411.6 87 311.4 265 14,291 279 1,952.3 223 1,560.4 23,175 387 1,670.0 334 1,441.2

Unknown 55 46 48 46

Total 357,934 608 169.9 504 140.8 425,708 712 167.3 615 144.5

Table 3. Mortality among the 1,320 CVA victims and the 1,088 CVA victims who were hospitalized, by age group and sex.

Age group No. of (in years) cases

15-24 7 25-34 21 35-44 34

45-54 83 55-64 129

265 279

Unknown 55

Total 608

aZ = 2.76; p<O.Ol.

bz = 1.22; p>o.o5.

General mortality among CVA victims Mortality among hospttahzed CVA victims

M&S F.XW.kS Males F,3IX3kS

No of % mor- No. of No. of % mor- No. of No. of % mor- No. of No. of % mor- deaths tality cases deaths tality cases deaths tality cases deaths tality

3 42.86 8 8 100.00 5 1 20.00 7 7 100.00 13 61.90 14 8 57.14 20 12 60.00 14 8 57.14

- 14 41.18 48 26 54.17 32 12 37.50 43 21 48.84

48 57.83 92 50 54.35 79 44 55.70 85 43 50.59 76 58.91 115 72 62.61 111 58 52.25 104 61 58.65

186 66.67 387 288 74.42 231 138 59.74 257 158 61.48

10 18.18 48 11 22.92 54 9 16.67 46 9 19.57

350 57.57a 712 463 65.03a 532 274 51.50b 556 307 55.22b

296 PAHO BULLETIN l vol. 17, no. 3, 1983

women because there were fewer men than women in the Salvador population.

The rate of fatalities was high among CVA victims of both sexes in all age groups. Table 3 shows fatality data, by age and sex, for all known cases and, separately, for hospital cases. The two breakdowns are provided because of the possible existence of CVA cases where the subject neither died nor received inpatient care, thereby leading to a possible overestimation of the rate of fatalities. Over- all, the general rate of fatalities observed among CVA patients was 53.40 per cent among hospitalized subjects and 61.59 per cent among all subjects.

As indicated in Table 4, overall CVA mortality per 100,000 inhabitants of Salvador was slightly higher among females than among males. The main reason why this was so, despite higher male mortality in most age groups, was that females greatly outnumbered males in the oldest age group (23,175 to 14,291) where CVA mortality was highest, and so the female population as a whole experienced a higher proportion of CVA-related deaths.

Of the 581 recorded deaths among hospitalized patients, 31.4 per cent occurred within the first day after the CVA episode, 36.9 per cent occurred between the second and seventh days, and 2 1.0 per cent occurred between the eighth and twenty-ninth days.

Table 4. Mortality among the inhabitants of Salvador attributed to CVAs during the period 1 July 1979-30

June 1980, by age group and sex.

Age group (in years)

Mortahty (deaths per 100,000) among:

M&S Females

15-24 2.26 5.23 25-34 14.08 7.25 35-44 24.83 39.91 45-54 119.49 108.47

55-64 341.20 257.70 ~65 1,301.52 1,242.72

Total 97.78 108.76

Data relating to the subjects’ race, marital status, and occupation were hard to analyze for a variety of reasons. The information obtained indicated that 27.2 per cent of the patients were white, 52.2 per cent were mulat- toes, and 20.6 per cent were black. However, elimination of ethnic information from the 1980 census made it difficult to assess the racial composition of the general population. Marital data were also difficult to analyze because the “single” category (including 37.0 per cent of the female subjects and 18.7 per cent of the male subjects) contained a large number of people living together. Likewise, occupational data were hard to analyze because of the wide variety of occupations listed. Most of the men were listed as “retired” and most of the women as “homemakers”; the largest single group of actively employed subjects were “stone-workers and painters” (4.3 per cent) and “drivers” (3.0 per cent). Monthly variations in the rate of CVAs were slight, considering the small number of cases involved, with the percentage of cases occurring in any given month ranging from 6.6 to 10.1 per cent. No seasonal bunching of cases was detected, perhaps because the seasons are not clearly defined in the Brazilian northeast (11,12).

Discussion

These findings indicate that CVAs are a public health problem in Salvador for individ- uals 45 years of age and over. It should be noted, however, that our approach of collect- ing data on all CVA cases occurring in the city of Salvador within a one-year period could in- troduce small distortions in the following ways:

1) Some people in the city could have experienced mild, nonfatal CVAs for which no inpatient care was provided. These cases would not have been recorded. We have as- sumed that such cases would be uncommon, since the mortality among hospitalized patients was high and most of the deaths (89.3

Lessa and Bastos l CEREBROVASCULAR ACCIDENTS IN SALVADOR, BRAZIL 297

per cent) occurred within a month of the onset of illness. Moreover, home medical care would not appear a viable alternative to inpatient care for most patients, since it is always private, extremely costly, and so beyond the reach of the vast bulk of CVA patients who are not members of the social elite. Never- theless, any mild, unhospitalized cases occurring would have led to an underestimation of CVA incidence and an overestimation of the fatality rate among CVA patients.

2) A small number of home deaths occurring among CVA victims who received no hospital care may not have been included in the study because of a failure by one of the civil registries to forward death certificates to the State Health Department’s Data Process- ing Center (CEPRO). The result of this would be a slight underestimation of both CVA incidence and CVA mortality.

3) It is conceivable that a few cases may have been improperly diagnosed. However, the typical signs and symptoms of an acute CVA make the clinical diagnosis easy (2,19, 30); and in all cases where a laboratory examination or autopsy was performed, the diagnosis was confirmed. The major difficulty encountered was not diagnosing the problem but arriving at a correct differential diagnosis of the type of CVA involved. This matter will be covered in a later work.

Considering all these possible sources of er- ror, therefore, we believe the errors that may have been introduced in these various ways were small, and that they had little effect upon the findings reported here.

. . .

In the United States and Europe, the period of high CVA incidence has been described as beyond age 55 or, more frequently, beyond age 65 (7,8,18,31). However, the average age of CVA patients studied by Eisenberg et al. (7) in Connecticut (USA) was about 10 years above the average age of CVA patients in Salvador. As far as the Salvador population is

concerned, the situation appears to become critical in the 45-54 year age group, where the observed annual incidence in our study rose to 206.6 cases per 100,000 inhabitants among men and 199.6 per 100,000 among women (see Table 2).

The rate of fatality among CVA victims is always described as being high in the indus- trialized countries, where it generally ranges from 25 to 56 per cent within the first three months of onset, depending upon the type of CVA involved (7,20,3.2). In Japan, relatively high mortality (25 per cent) typically occurs on the first day of the episode; many of these fatalities result from a hemorrhagic CVA, the most lethal form of the illness, a form which is common in that country (19). The observed fatality rates in Salvador (61.59 per cent among all subjects and 53.40 per cent among hospitalized subjects) do not appear to depart radically from CVA fatality rates observed in developed countries. The major and serious difference lies in the time elapsing between the episode and death; that is, 31.4 per cent of the Salvador fatalities occurred on the first day of the episode and 89.3 per cent occurred during the first month. These very high percentages of early deaths reflect the low standard of medical care being provided for these patients, who typically need costly and continuing treatment to survive.

A large majority of the CVA patients in Salvador receive medical care at one of three emergency posts operated by the Medical Care and Social Welfare Institute (INAMPS). These posts are small facilities with six to 10 beds and a high bed-turnover rate, each post having a load of 300 to 400 patients per day. Patients with severe disease cases are generally admitted to these small facilities while they wait for admission to one of the city hospitals. However, a CVA patient is only rarely as- signed to a hospital bed. This is brought out clearly by the fact that the two INAMPS hospitals in Salvador, taken together, admitted fewer than 70 inpatients in one year.

In this vein, it is worth noting that the observed CVA mortality in Salvador was higher


than CVA mortality observed in the 1960s in

RibeirZo P&o and Slao Paulo, rates which at

that time were regarded as “exceptionally

high’ ’ for the Americas (27). Information

available up to now concerning CVAs in these

three Brazilian cities suggests that CVAs tend

to be more common there than in other Latin

American cities studied and are high up on the

list of noninfectious causes of death. In sum,

the patterns of CVA incidence and mortality

observed in Salvador and elsewhere appear to

pose a very serious disease problem; and so,

despite the continuing need to devote a sub-

stantial portion of available health resources to

combating infectious and parasitic diseases,

the CVA situation underscores the need to

adopt a health policy capable of dealing effec-

tively with noncommunicable disease prob-

lems as well.

SUMMARY

A review of acute cerebrovascular accidents (CVAs) was conducted in Salvador, Bahia, Brazil, in order to assess the basic epidemiology of the problem in that city and to provide information needed for health planning. To perform that review, the authors collected data from the records of all the health facilities in Salvador (10 hospitals and eight emergency services) that provided care for CVA victims between 1 July 1979 and 30 June 1980. To complete their data base, they also sought to review all death certificates citing a CVA as the cause of death.

According to 1980 census data, the city of Sal- vador had 783,642 inhabitants over 14 years of age; and according to the available medical records and death certificates, 1,321 people experienced cerebrovascular accidents during the one-year study period. The average age of onset was 62.4 years among men and 64.5 years among women. Around age 45 the CVA incidence started to rise quickly;

this incidence became very high in the oldest (over 64) age group, reaching a level of 1,952 cases per 100,000 among men and 1,670 per 100,000 among women. The apparent CVA mortality during the study period was 97.78 deaths per 100,000 male inhabitants and 108.76 deaths per 100,000 female in- h3bitants.

The mortality among hospitalized CVA victims in Salvador was extremely high on the first day of the episode, with 31.4 per cent of the 581 deaths coming within 24 hours. Overall, 89.3 per cent of these deaths occurred within a month of the episode. These very high percentages of early deaths (in terms of comparable percentages in developed countries) reflects the low standards of medical care being provided for CVA victims in the study area and underscores the need to adopt a health policy capable of dealing effectively with this and similar noncommunicable disease problems.


Annex 1: Form Used to Record Data on CVA Patients

Department of Preventive Medicine, School of Medicine, Federal University of Bahia

Cerebrovascular Accident (CVA) Clinical-epidemiological Record)

Name of medical facility:

Date of admission:

A. Patient Information:

Name:

Age: Sex:

Profession or occupation:

Address:

City:

Race:

Registration:

Marital status:

Nationality:

District:

Indigent ( ) INAMPS or similar ( ) Private ( )

B. Diagnosis of CVA

1. CVA was due to: 2. Diagnosis was based on:

( ) Thrombosis

( ) Cerebral hemorrhage

( ) Embolism

( ) SAH-rupture of aneurysm

( ) Temporary ischemia

( ) Ischemia

( ) Other (specify)

( ) No answer given

( ) Clinical history

( ) Physical examination

( ) Spinal tap

( ) Arteriography

( > Autopsy

( ) Other (specify)

( ) No answer given

C. Related Factors (Epidemiologic Data)

1. Past hypertension

( ) Yes

( )No

1.1 Current hypertension ( 2 160 x 95)

( )Yes

( )No

( ) No answer given

2. Past CVA

( ) No answer given

2.1 No. of past CVAs

( 1 Yes

( >No

( ) No answer given

( 11 ( )4

( 12 ( )5

( )3 (I>5


2.2 Interval between first CVA and current CVA

( ) <imonth ( ) 6-8 months ( ) No answer given

( ) l-2 months ( ) 9-11 months

( ) 3-5 months ( ) 1-4 years

3. Past cardiac disease 3.1 Current cardiac disease

( )Yes ( )No

( )Yes ( )No

( ) No answer given

3.2 Specification of cardiac disease, if any:

( ) No answer given

3.3 Past infarct 3.4 Current infarct

( > Yes

( )No

( ) Yes

( )No ( ) No answer given

3.6 Fibrillation

( ) No answer given

( )Yes

( )No

( ) No answer given

4. Past history of diabetes 4.1 Current diabetes diagnosed

( )Yes ( > Yes

( )No ( )No

( ) No answer given ( ) No answer given

5. Other disease or clinical condition present (specify):

6. Smoking habit

( ) Yes

( )No

( ) No answer given

7. Patient’s physique

( ) Slight

( ) Normal

( ) Corpulent

( ) No answer given

D. Neurologic Condition of Patient (First Day of Hospitalization)

1. ( ) Conscious

( ) Sluggish

( ) Unconscious (coma)

( ) No answer given

2. ( ) Aphasia

( ) Dysarthria

( ) No answer given

( ) No impairment

Lessa and Bastes l CEREBROVASCULAR ACCIDENTS IN SALVADOR, BRAZIL 301

3. Motor condition

( ) Right hemiplegia

( ) Left hemiplegia

( ) Hemiplegia, side not specified

( ) Monoplegia

( ) Tetraplegia

( ) Deviation of right corner of mouth

( ) Deviation of left corner of mouth

( ) No signs

( ) No answer given

4. Other neurologic signs (specify):

5. Other neurologic symptoms (specify):

6. Sensory condition

Hemiparesis:

Muscular weakness:

Other (specify):

( ) right ( ) left

( 1 yes ( >no

E. Laboratory Examinations

Examination

Spinal fluid

Arteriography

Complete tomography

Electrocardiogram

Blood lipids

Blood sugar

Transaminases

Other (specify)

Results normal Abnormality detected No answer given

F. Outcome of Case

( ) Patient still in hospital

( ) Patient discharged

( ) Patient transferred to date :

( ) Patient died in hospital with confirmed diagnosis, date:

( ) Patient died and was autopsied at the Medico-Legal Institute, date of death:

( ) Patient died at home, date:

302 PAHO BULLETIN l vol. 17, no. 3.1983

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