Epidemiology: Principles and Practices

This study material explores the principles and practices of epidemiology. It covers topics such as incidence rates, risk factors, and more. It is suitable for students studying epidemiology.

Running Head: EPIDEMIOLOGY: PRINCIPLES AND PRACTICES
Epidemiology: Principles and Practices
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1Epidemiology: Principles and Practices
A. Question 1-
a. 19
 Age specific incidence rates of prostate cancer in city A-
Incidence rate- count
total population *100,000
0-44 years = 50/500,000* 100,000=10
45- 65 years = 250/75,000*100,000= 333.33
65+ = 350/25,000*100,000=100,000.014
Crude rate=
650/600,000*100,000= 108.33
 Age specific incidence rate of prostate cancer in city B-
Incidence rate- - count
total population *100,000
0-44 years = 80/1,500,000*100,000= 5.33
45- 65 years = 1000/600,000*100,000= 166.66
65+ =2500/400,000*100,000=625
Crude rate=
3580/2,500,000*100,000= 143.2
The age specific incidence rate of prostate cancer in age group 0-44 years and
45-64 years is more in cities A as compared to city B, whereas, the incidence rate of
prostate cancer in old age people of 65 years and above is more in city B as compared
to city A.
The crude incidence rate of prostate cancer in males of city B is more as
compared to the incidence rate of prostate cancer in males of city A.

2Epidemiology: Principles and Practices
b. The crude incidence rate of prostate cancer of age group 0-44 years in city A is
more than as compared city B, which might be due to the poor eating habits and
family history of prostate cancer. However, in both the cities (city A and city B),
the risk of prostate cancer is less in age group 0-44 years as compared to other age
groups, which is valid. Incidence rate of prostate cancer in people of age 45- 64
years are more in city A as compared to city B, but the incidence rate in both the
cities is less than that of the old age group and more than that of adult age group.
The risk of prostate cancer increase with the age, which is analysed from the data.
The people belonging to age group 65 years and are the most effected population.
c. Standardised incidence rate of prostate cancer in city A
0-44 years= 50/74,000*100,000=67.57
45-64 years= 250/19,000*100,000=1315.79
65+ above= 350/7,000*100,000=5000
Standardised incidence rate of prostate cancer in city B
0-44 years= 80/74,000*100,000= 108.1
45-64 years= 1000/19,000*100,000= 5263.16
65+ above= 2500/7,000*100,000= 35,714.29
The incidence crude rate is less than that of the standardised rate of incidence.
d. The crude incidence rate of prostate cancer of age group 0- 44 years in city A is
more than as compared city B, hence it can be said that the children and adult
males of city B have high risk of prostate cancer. The reason behind this can be the
unhealthy eating habits in males of city A. The family history of prostate cancer
can also be one of the cause (Wu et al, 2016). The risk of prostate cancer increases
with age hence, the incidence rate of prostate cancer in old adults (45- 64 years)

3Epidemiology: Principles and Practices
and old age people (65+ years) is more than that of the previous age group (0-44
years). Risk factor associated are tall heights and lack of exercise in old age males.
In addition poor eating habit also increases the risk of prostate cancer in elderly
people (Graffouillere et al., 2015).
B. Question 2-
a. Prevalence rate = number of women with cervical cancer/ total number of
screened women* 100
Prevalence rate of cervical cancer in 2000= 92/5458*100= 1.69%
Women without cervical cancer are again screened in 2005
Prevalence rate of cervical cancer in 2005= 60/5366*100= 1.28%
b. Incidence rate= new cases of cervical cancer/ total patient years
60/(60*5)
60/300= 0.2
This is a measure of incidence rate, because instead of year (in case of cumulative
frequency), patient year is considered.
c. Each 60 women are diagnosed with cervical carcinoma were followed up half-
way during five year period.
The incidence rate of cervical cancer in these women during the period off five
years is
60/(5/2*60)=
60/150= 0.4
C. Question 3-
a. The study design is cohort risk assessment study.
Cohort study is a type of longitudinal study that expresses a group of people
sharing a particular characteristics in a specific period of time. The reason of

4Epidemiology: Principles and Practices
choosing cohort study is that it expresses a large group of population considering
the risk factors. Another reason for assessing cohort study is that it have two
variables (heavy drinkers and patient with CHD) and have two population group,
one with CHD and one without CHD (Reeves et al., 2018).
b. Risk ratio of drinkers= 198/310= 0.64
Risk ratio of non- drinkers= 87/260= 0.33
Risk difference between drinkers and non- drinkers= 0.64- 0.33= 0.31
Risk percentage= 0.31*100= 31
In case of heavy alcohol drinkers, the likeliness of developing CHD is 31% higher
than the occasional and non-alcohol drinkers.
Patient with CHD Residents without
CHD
Total
Heavy drinkers 198 112 310
Non-drinkers 87 173 260
Total 285 285 570
c. Total population = 285+285= 570
Population which drinks and have CHD= 198
Percentage of people suffering from CHD could have been prevented if alcohol is
not consumed = 198/570*100= 34.74%
The correct measure is proportion.
34.74% of the total population could be prevented from having CHD if alcohol is
not consumed.
D. Question 4-
Data in 2016 Australia India Nigeria

5Epidemiology: Principles and Practices
1. Population
(thousands)
25,294 1,362,216 199,485
2. Population
proportion
Under 15 (%) 19% 29% 44%
Over 60 (%) 20% 8% 5%
3. Crude mortality
(per 1000)
6.5 7.3 12.5
4. Under 5
mortality rate (per
1000 live births)
3.7 41.6 103.8
5. Maternal
mortality ratio (per
100,000 live births)
(2015)
41 164 542
6. Life expectancy
(years), 2016
At birth (Both
sexes)
76.9 years 69.5 years 61.2 years
At age 60 (Both
sexes)
21.0 years 18.2 years 1.6 years
7. Healthy
(Disability-free) life
expectancy, 2016

6Epidemiology: Principles and Practices
At birth (Both
sexes)
68.9 years 60.4 years 53.8 years
Table – 1
Source- (WHO, 2019)
a. The population of the three countries Australia, India and Nigeria is 25,294, 1,362,216
and 199,485 respectively. The crude mortality rate of Australia is 6.5 per 1000 live births,
whereas the crude mortality rate of India and Nigeria is 7.3 and 12.5 respectively per
1000 live births. From the data it is observed that, the crude mortality of Nigeria is
maximum and that of Australia is minimum with India being on average. Crude mortality
rate is the effective measure in comparing the health status of Australia, India and
Nigeria. As crude mortality rate species the number of death in particular population,
throughout the year per 1000 population. Hence by the help of calculating the death rate
the heath status of a particular country is estimated, as death status is correlated with the
health status. The better the health status the less the crude mortality rate (Laursen et al.,
2016). Hence, the health care facility in Australia is better than other both countries.
b. The life expectancy data at birth and life expectancy in Australia, India and Nigeria is
76.9, 69.5 and 61.2 years respectively and 21.0, 18.2 and 1.6 years respectively. The life
expectancy at birth states that and life expectancy at 60 differs because life expectancy
states the expected year a new-born can live, whereas the life expectancy at 60 denotes
the average number of years a person of that age can live (Laursen et al., 2016). Hence,
the life expectancy at 60 is less than that of the life expectancy at birth as a person of age
60 years is expected to leave less than that of a new born.
Healthy life expectancy at birth of Australia, India and Nigeria is 68.9, 60.4 and
53.8 years and healthy life expectancy at 60 of the three countries which is different than
the life expectancy at birth (Australia, India and Nigeria is 76.9, 69.5 and 61.2 years

7Epidemiology: Principles and Practices
respectively). Healthy life expectancy at birth is less than that of the life expectancy at
birth because healthy life expectancy is defined to as the estimated years a person can live
in healthy state, whereas life expectancy is defined as the expected year a person can live
(Singh et al., 2017). As the disease increase with the age hence, so a person cannot live in
healthy state throughout their whole life (Graffouillere et al., 2015). Hence, life
expectancy at birth and healthy life expectancy differs.
c. The general health of a country is defined by considering the mortality arte, life
expectancy rate, healthy life expectancy rate and maternal mortality ratio (Singh et al.,
2017). The mortality rate, maternal mortality ratio, life expectancy rate at birth, life
expectancy rate at 60 and healthy life expectancy rate of Australia is 3.7, 41, 76.9, 21.0,
and 68.9 years respectively. The mortality rate, maternal mortality ratio, life expectancy
rate at birth, life expectancy rate at 60 and healthy life expectancy rate of India is 41.6,
164, 69.5, 18.2 and 60.5 respectively and of Nigeria is 103.8, 542, 61.2 years, 1.6 years
and 53.8 years respectively.
From the data, it is concluded that mortality rate and maternal mortality ratio in
Australia is minimum and maximum in Nigeria. Life expectancy both at birth and 60 and
the healthy life expectancy is more in Australia, whereas minimum in Nigeria. Hence it
can be stated that, the health status of Australia is superlative as compared to two other
countries, whereas it is poorest in Nigeria and needs improvisation.

8Epidemiology: Principles and Practices
References
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