Transcript specified populations

Approaches to Reducing Sudden Death
in the Workforce of the OAU, Ile-Ife
Kayode Ijadunola, MD, MSc, FWACP
Associate Professor, Department of Community Health
OAU, October 30, 2013
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An Exercise in Epidemiology?

Epidemiology is the study of the distribution and
determinants of health-related states or events in
specified populations and the application of study
findings to the control of health problems.
So the words to watch are:
 Distribution – who is affected by sudden death, where,
when, under what circumstances?
 Determinants – causes, risk factors, associated factors?
 Specified population – Humans (OAU community)
 Control – eliminate, reduce the burden, prevent
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An Exercise in Epidemiology?

Although, hazard prevention/risk elimination and
reduction is the ultimate goal of Epidemiology and is
most desirable, it should be tempered by the recognition
that death can only be deferred, but cannot prevented on
the long run
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What is Sudden Death?
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Sudden (cardiac) death [SCD] is typically defined as an
unexpected death in a person with or without preexisting heart disease, involving an abrupt loss of
consciousness due to blood circulatory collapse and
occurring within 1 hour of the onset of symptoms
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SCD is witnessed in only two-thirds or less of cases, the
rest happens when no one is there, making the
diagnosis and time of onset difficult to establish
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Global Burden of Sudden Death
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In the developed countries, SCD represents the single
largest cause of natural death, accounting for 12-18% of
the total deaths, and 50% of heart related deaths
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Each year in the United States alone, 300,000 people
die from (cardiac arrest) heart attacks (range 184,000462,000); in Canada, deaths number tens of thousands
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In recent studies using multiple sources of data in the
United States, Netherlands, Ireland, and China, SCD
rates ranged from 50 to 100 deaths per 100 000 people
in the general population
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Global Burden of Sudden Death
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The average age of sudden death in Seattle,
Washington, and Maastricht, Holland is 66 years and 62
years respectively, and incidence increases with age
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Age adjusted death rate figures show that men are 2-4
times more affected compared with women
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African-Americans are twice as likely as whites to
experience (cardiac arrest) heart attack, and half as
likely to survive an event of cardiac arrest
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Global Burden of Sudden Death
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A survey of sudden death among a working population in
Japan revealed an incidence of 22 deaths/100,000
among men and 8 deaths/100,000 among women
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The incidence increased with age from 2 deaths/100,000
among men aged 20-24 yrs to 97 deaths/100,000 among
men over 60 years
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Global Burden of Sudden Death
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There are hardly any population based studies of
sudden death in the African literature
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Two hospital based studies from autopsies in pathology
departments were found, one in South Africa and one in
Ile-Ife, Nigeria
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The Nigerian study determined among other variables,
the circumstances of death and related causal variables
in cases of sudden cardiac death among Nigerians
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Global Burden of Sudden Death
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The records of 2,529 medico-legal autopsies over a tenyear period were reviewed, of which 79 were found to be
cases of sudden cardiac deaths (SCD)
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The SCD cases consisted of 59 males (74.7%) and 20
females (25.3%), with age ranging from 27 to 80 years
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The average age at death was 54 yrs for males and 52
yrs for females
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Global Burden of Sudden Death
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Hypertensive heart disease was the cause of death in 66
cases (83.5%), of which only 20 (30.3%) were previously
diagnosed!
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Diseases of the heart vessels and heart muscle of
unknown origin ranked next as the most common cause
of death with 5 cases (6.3%) each
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Global Burden of Sudden Death
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A previous study among a working population of Japan,
showed that 58% of sudden death was due to diseases
of the heart and the blood vessels
30% was due to diseases of the blood vessels of the
brain (cerebro-vascular diseases or stroke)
6% was due to diseases of the chest such as pneumonia
and asthma
1% was due to bleeding in the food canal (GIT)
1% was due to epilepsy
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Global Burden of Sudden Death
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Despite the large numbers of SCDs in the general
population, the overall incidence is only 0.1% per year.
That is any population-based preventive measure would
have to be applied to 1000 people to prevent one
sudden death!
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Therefore, to reduce the incidence of SCD, we must
-either accurately identify those at risk; or
-develop safe, low-cost interventions that can be
applied to the population at large
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Risk factors: Individual and Population
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The critical challenge for scientific and clinical
investigators of SCD is that the patient group
contributing the highest deaths is comprised not of
individuals who are at risk due to a prior sudden heart
related disease or those with some other identified
disease processes (in whom the estimated one-year risk
reaches 30% or greater);
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Rather, the group contributing the highest number of
sudden deaths is the general population with an
estimated risk of only 1-2/1000 people!
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Fig. 1. Incidence of sudden cardiac death in specific
populations and annual sudden cardiac death numbers
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Risk factors: Individual and Population
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SCD is the first manifestation of disease in almost 50% of
patients with heart blood vessel (coronary artery) disease
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For example, in the Quebec Cardiovascular Study, 42% of
all heart vessel disease deaths in men fulfilled the criteria
for sudden death or were in individuals found dead in bed
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Approximately 55% of male and 63% of female SCD
victims have no previous history of heart disease, and
therefore SCD is often the initial manifestation of heart
disease
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Risk factors: Individual and Population
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Information from trials of patients put on continuous
monitors showed that only approximately 1 in 3 sudden
deaths occurs in patients with known risk factors
(markers).
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That the majority of sudden cardiac deaths occur in
individuals who have not been identified as being at high
risk necessitates new measures and modalities for
recognizing predisposition and stratifying risk
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Risk factors: Individual and Population
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The most powerful predictor of sudden cardiac death is
disease on the left side of the heart (poor left ventricular
function) .
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Other risk factors are similar to the risk factors for heart
vessel (coronary) disease which are well known
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Risk factors: Individual and Population
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Public health efforts to significantly reduce mortality from
SCD through identification of persons at risk face
numerous challenges
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First, the incidence of SCD in the population is low, even
in common high risk clinical populations
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Second, the current risk factors have low positive
predictive value (i.e. most of the patients with the risk
factors will not experience sudden death in a particular
year)
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Risk factors: Individual and Population
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The risk factors also have low sensitivity (many victims
of SCD do not have the particular risk factor)
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Therefore, the use of the currently identified risk factors
to characterize high risk groups comes at the cost of
(decreasing sensitivity) i.e. overlooking large numbers of
SCD victims
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A number of additional (complex) factors are currently
being explored for their potential in identifying individuals
at risk
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Risk factors: Individual and Population
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The clarification of genetic risk is critical; studies are
revealing that SCD tends to aggregate in families
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It is becoming increasingly clear, for instance, that
genetic factors may play a role in the development of the
heart muscle disease that is associated with SCD
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Risk factors: Individual and Population
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Evidence
from
epidemiologic
studies,
animal
experiments and clinical research implicates a part of the
nervous system (autonomic) in the cause of SCD
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Emotional stress and vigorous physical exertion may be
important triggers for SCD
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There also appears to be a (circadian) pattern to the
timing of SCD, with significantly more events occurring in
the morning (6am through 12 noon), perhaps due to
increased autonomic nervous system activity
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Strategies to decrease mortality from SCD
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Strategies to decrease the burden of SCD must aim at both
reduction in event rate and improvement in event survival
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First are the primary preventive measures in the general
population targeting reductions in known heart and blood
vessel (cardiovascular) risk factors and risk factors for
stroke
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Because of the low incidence of SCD in the general
population, these interventions will have to be broadbased, safe, easily administered, acceptable to the
population and inexpensive
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Strategies to decrease mortality from SCD
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Second is primary prevention of SCD in patients with
known heart disease with a focus on drug therapies
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Many of the traditional risk factors associated with the
development of heart vessel (coronary) disease are also
associated with SCD; clinical and public health efforts
that promote effective treatment of these risk factors are
likely to reduce the incidence of out-of-hospital cardiac
arrest in the general population
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Strategies to decrease mortality from SCD
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Eating right is key. The consumption of at least one fatty
fish meal per week is associated with a 48% reduction
in the risk of SCD; avoid animal fat as much as possible!
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Given the observation that the risk of cardiac arrest is
particularly large among current smokers, and declines
rapidly after stopping smoking, smoking cessation will
likely impact a reduction in the risk of SCD
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Strategies to decrease mortality from SCD
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Regular exercise is associated with an overall reduction
in the risk of SCD; some exercise is better than none,
regardless of the intensity, but there is a transient
increase in risk during strenuous exercise
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In the physicians health study, men who had two to four
drinks of alcohol per week had a significantly reduced
risk for SCD, compared to men who never drank, but
heavy alcohol consumption (six or more drinks per day)
or binge drinking increased the risk of SCD
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Strategies to decrease mortality from SCD
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You must check your blood and BP numbers
(parameters) at intervals, especially once you are 40
years and above
BP monthly, if you are hypertensive, and at least yearly if
you are not, especially if there is family history
Blood sugar at least yearly if not diabetic, and daily if
diabetic using home based measures
Blood cholesterol profile at least yearly
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Strategies to decrease mortality from SCD
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Will benefit from other specialized tests that might reveal
the status of other organs periodically, if over 40 years
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Pap’s smear for women yearly if no abnormal tests;
more frequently if tests are abnormal
Self breast examination, clinical breast examination and
mammography as indicated
Blood urea nirtogen and creatinine for the kidneys
Rectal examination and Prostate Specific Antigen
periodically for men over 40 years
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Strategies to decrease mortality from SCD
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Pharmacological treatment of patients with known heart
disease and processes for improving event survival is the
business of the physicians
However, they must receive the cooperation of the patients
who must come to the hospital, accept to be treated, adhere
to drug therapy, and follow-up on treatment
The hospitals must also be sufficiently equipped with staff and
necessary infrastructure to respond to emergencies (the
health center specifically here)
There must also be a critical mass of trained paramedics who
can respond in little or no time to emergencies at the
community level
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Prognosis
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For patients who suffer out-of-hospital cardiac arrest due
to heart disease, survival rates are low, even in the
setting of witnessed arrests
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Long-term survival rates of 20% have been reported
from urban centers with the ability to provide rapidresponse and defribillator-equipped emergency services
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However, national averages of successful resuscitation
from out-of-hospital cardiac arrest due to heart disease
are much lower (1-2%)
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References
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Deo R, Albert CM. Epidemiology and Genetics of Sudden Cardiac
Death. Circulation. 2012; 125: 620-637 doi:
10.1161/​CIRCULATIONAHA.111.023838
Tiemensma M, Burger EH. Sudden and unexpected deaths in an
adult population, Cape Town, South Africa, 2001-2005.S Afr Med J.
2012 Jan 27;102(2):90-4
Rotimi O, Fatusi AO, Odesanmi WO. Sudden cardiac death in
Nigerians--the Ile-Ife experience.West Afr J Med. 2004 JanMar;23(1):27-31
Zipes DP. Epidemiology and mechanism of sudden cardiac death.
Can J Cardiol; 21(Suppl A): 37A-40A
Sotoodehniaa N, Zivina A, Bardya GH, Siscovick DS. Reducing
mortality from sudden cardiac death in the community: lessons from
epidemiology and clinical applications research. Cardiovascular
Research 2001; 50: 197–209
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Thank you!
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