Lecture 19: Overview of the epidemiology of cardiovascular disease Flashcards
what are the challenges that come with data sources of CVD?
- diagnosis is often based on symptoms, not always histological
- need standard case definitions
- no registry of cardiovascular (unlike cancer)
- rely on self report, hospital or primary care data, surveys and mortality data
- there are many different ways of defining cardiovascular disease, so it needs to be clear how things are defined when you interpret and measure things
what can population surveys be useful for?
- can be used due to limitations due to hospital and primary care data
- can measure blood pressure and conduct an electrocardiogram
how do population surveys normally work?
often use self-report
e.g. Have you ever been admitted to hospital with a heart attack?
what are the limitations of a self-report population survery?
- access to healthcare
- understanding of communication from healthcare providers
- social desirability bias
- representation in survey
- adequate explanatory power
what are some of the findings of the population survey?
- in 2020/21 the prevalence was 4.2% which is ~175,000 aduls
- ischemic heart disease is more prevalent in older age grops
- more prevalent in older age groups
- more in males than females
- more in maori than non-maori
what is some of the historial data about CVDs?
- it wasn’t a major health problem until the early 20th century
- in 1935-1947: Sweden, USA, Finland and Norway all had increased rates of death from ateriosclerosis
- USA continued to rise, but Finland and Norway decreased in 1940’s
- At the time, Europe had WW2 so the european countires CVD rates declined as people had a different lifestyle to the war. Had to ration, had less reports of death, people died of of other things
- in america 80% of men smoked, cigarettes were being given out to men as rations during war, fast food was starting, people drove everywhere, new suburbs didn’t have footpaths
what are the origins of the framingham study?
- government bodies were concerned about increase in CVD mortality
- in the US, US National Heart Institute funded the Framingham heart study
- was a cohort study with 5209 men and women aged 30-62 years old with no symptoms or history of CVD
- it is still going on today by examing the offspring of the original cohort
what were the key events/dates of the Framingham heart study?
1948 - Framingham heart study begins
1956 - Findings on progression of rheumatic heart disease reported
1957 - identification of association between high blood pressure and cholesterol with coronary heart disease
1960 - cigarette smoking found to increase the risk of heart disease
1961 - term ‘risk factor’ used for the first time
1967 - physical activity found to reduce the risk of heart disease and obesity to increase the risk of heart disease
1970 - high blood pressure found to increase the risk of stroke
1978 - psychosocial factors found to affect heart disease
what did the Seven Countries Study (Keys et al) look at?
risk factors and dietary risk factors in relation to the prevalence of coronary heart disease in Greece, Itality, Spain, South Africa, Japan, Finland
what did the British Doctors Study look at?
they looked at the association between smoking and coronary heart disease
- this was quite surprising at the time
what was the earliest clinical trial for CVD?
“Effects of Treatment on Morbidity in Hypertension”
- done using the health insurance database
- looked at the effect of treatment in those with hypertension
what did the framingham heart study do in 1998?
development of simple coronary disease prediction algorithm involving risk factor categories to allow physicians to predict multivariate coronary heart disease risk patients without overt CHD.
what does this show?
- death continued to increase from 1990 - 2019
- higher death rates in males
- China, India, Russia and USA had the highest rates in 2019 (consider the population size of india and china)
- ischaemic heart disease has almost 50% of CVD deaths
- both types of stroke are also significant for CVD deaths proportion (haemorrhagic and ischemic)
what does this show?
DALYs due to CVD in 2019 vary around the world.
- eastern europe, russia, asia, africa, middle east have highest disability due to CVD
what does this show?
- disability is more prevalent in older age groups
- disability more prevalent in males during early adulthood
- more prevalent in females during late adulthood
what does this show?
- DALYs due to CVD in 2019 varies by region
- high DALYs in Asia, Oceania and middle east
what does this show?
blue = decrease is age-standardised CVD deaths red = increase in age standardised CVD deaths
between 2010-2019
most of the world has seen a decreased death rate, but important inequities can be seen among and within countries
some regions are seeing CVD death rates increase by more than 15%
what does this show?
trends in death rates for coronary heart disease (ischaemic heart disease) in australia 1940-2006.
- this was in a post-was period in high-income countries
- CHD deaths increased dramatically until 1960-70s, saw a decline after this
- similar pattern in UK, USA, western european countires and NZ
- the decline coincided with increased knowledge we had for risk factors of CHD and available treatment
what does this show?
a 2007 study showing why coronary heart disease mortality decreased
- due to treatments and risk-factor changes
treatments included: bypass grafting, stents in coronary arteries
risk factor changes: changing diet, stop smoking, taking BP and cholesterol pills, primary and secondary preventions
1968-76 in the US, 40% of decrease in death was due to treatment, 54% due to RF
1974-81 in NZ, 60% due to RF, 40% due to treatment
1972-92 in Finland, 24% due to treatment, 76% due to RF
- USA is very treatment focused, not prevention focused
what does this show?
the number of DALYs due to IHD are going up globally
the age-standardised DALYs due to IHD are going down globally
similar patterns seen for deaths
what does this show?
age-standardised DALYs due to IHD are low in north and south america, and higher in russia, mongolia, south asia and middle east
- maps don’t give a good picture of the pacific region
what does this show?
myocardial infarction incidence rates in 1990-2015
many variations among countries
- some regions are coming down
- some are going up
what does this show?
the total number of prevalent strokes, deaths and DALYs due to stroke increased steadily from 1990, reaching 143million DALYs due to stroke
globally, age-standardised rates for deaths and DALYs due to stroke substantially declined over the same period of time
on average, global increases in stroke burden have been largely due to population growth and aging.
what does this show?
lots of variability of age-standardised incidence rates for stroke between regions
what does this show?
number of deaths and mortality rates from ischaemic heart disease by sex. 1950-2012
from 1950 there was a steady increase until about 1970’s
- higher increase for men
- lower increase for women
- from 1970 there was a decrease, and appears to continue to decrease
what does this show?
highlights inequalities for maori and non maori for ischemic heart disease
what does this show?
compares CVD to other chronic health disorders
- CVD and cancer are the leading cause of DALYs in NZ
what does this show?
- Maori mortality rates from IHD are higher than non Maori
- Rates are decreasing overtime
- Inequities persist
shows the story of NZ health system
- Justification of the Maori health authority (the inequities)
- People who suggest MHA point to data like this
- The NZ health structure does not eliminate inequities
what does this show?
death and mortality rates due to stroke 1950-2012 by sex globally
male death rate due to stroke was increasing slightly from 1950-1970. From 1970 onwards a steady decline in death rates took place for males
female death rates due to stroke was decreasing slowing from 1950-1970. From 1970 onwards, death rates declined at a similar rate to males
what does this show?
from 1996-2012 inequities are seen between maori and non maori mortality rates for stroke mortality.
- rates are declining but the inequities are still seen
- not as big as for IHD
what does this show?
from 1950’s-1970’s, both IHD and stroke mortality rates increased (differently)
- but from 1970’s we have seen a continuous decline from both.
