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Clinical Epidemiology and Clinical Research

Dr. Nancy Agens, Head,

Technical Operations, Pubrica

sales@pubrica.com

In Brief

Clinical epidemiology aims at preventing,

detecting and treating diseases in an

efficient manner. John R Paul coined the

term “clinical epidemiology” about fifty

years ago. Clinical epidemiology focuses

on medicines to improve health,

especially in the present world, when

individuals are encouraged to take care

of their own health. Here, a population is

chosen to study the health related

phenomena of different diseases. Either a

patient population could be chosen or

some other community based population

can also be considered which has the

conventional numerator and denominator

values of an epidemiological

study(Ehrenstein et al., 2017).

The image given below illustrates what is

done in clinical epidemiology:

Fig 1. Distribution and

Determinants of Diseases in Human Population

The distribution and determinants of

diseases in human population is

investigated in these studies and clinical

epidemiology serves as the right tool in

this respect. However, clinical

epidemiology cannot be considered as an

independent science because several skill

sets are required in this field such as

biostatistics, health social science and

clinical economics. A gold standard testing

procedure is used in clinical epidemiology.

Results are the strength of relationship

between two events which are measured

through ratios, rates and proportion tests in

clinical epidemiology. This relationship

data is presented in a table wherein the

number of false positive and true positive

diagnostic test results is visualized. This

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table also gives an idea about the number

of patients actually having and not having

this disease(Huang et al., 2020).

Fig 2. False Positive and True Positive Diagnostic Test Results

Fig 3. Illustrating Clinical Epidemiology Study Results of Patients Suffering from Covid-19

in Wuhan, China

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Given below are a few figures illustrating

clinical epidemiology study results of

patients suffering from Covid-19 in

Wuhan, China. The graphs depict their

clinical features.

Clinical epidemiology studies three

kinds of diseases:

a. Endemic disease - it affects the

population at a relatively constant and

expected rate within a specific region.

The spread of pathogens and vectors,

which are the reservoirs of disease is

the main cause of an endemic disease.

Geographical features, climate

changes, poor living conditions such as

dull houses, improper sewage systems

and hazardous work conditions are

other responsible factors for an

endemic disease. Example includes

Malaria in Africa.

b. Epidemic disease -the population is

affected at an unusually fast or

unexpected rate.It occurs due to the

increase in infectivity of a pathogen,

poor living conditions such as crowded

areas and improper sanitation systems,

spreading and introduction of the

pathogen in a new geographical

condition. Example includes Ebola

fever in West Africa.

c. Pandemic - it is defined as a worldwide

epidemic, the reasons being global

trade and worldwide travelling and the

increased infectivity of pathogens due

to antigenic shift and gene mutations.

Example includes Covid-19.

Clinical epidemiology calls in for

clinical research, so that the population

affected in the epidemic get the required

treatments to eradicate the disease as fast

as possible(Adhikari et al., 2020).

Clinical research is defined as “a

careful study and an investigation in order

to discover new facts and information”.

Unbiased, reliable and valid measurements

are required to carry out a clinical research

programme. Clinical research addresses a

specific question in an organized and

objective manner(Magnin et al., 2019).

The different types of clinical researches

are described below.

1. Treatment research : It involves an

intervention such as medication,

psychotherapy, new devices, new

approaches to surgery and radiation

therapy

2. Prevention research: Finds out better

ways to prevent the development or the

return of diseases. Medicines,

vitamins, vaccines, minerals and

lifestyle changes are usually studied

here.

3. Diagnostic research: This refers to the

practice to look out for better ways for

the identification of a particular

disorder or condition

4. Screening research: It aims to find the

best possible ways for the detection of

particular disorders or typical health

conditions

5. Quality of life research: This explores

ways to improve comfort levels and the

quality of life for individuals suffering

from a chronic illness

6. Genetic studies: These studies aim to

improve the prediction of disorders

through identification and

understanding of the relationship

between genes and ill health. The

different ways in which genes of an

individual is more likely to develop a

disorder is explored in this research

domain. This in turn leads to the

development of tailor-made treatments

which are based on a person’s genetic

make-up

7. Epidemiological studies:They seek to

identify the patterns, causes and

control of disorders in different groups

of people. “Outpatient” clinical

research requires that participants do

not stay overnight at the treatment

centre. “Inpatient” clinical research

requires the participants to stay for at

least one night in the hospital or

research centre.

Given below is an illustration of

clinical research study results on the

causes, clinical manifestation,

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epidemiology, control and prevention of

Covid-19 at the outbreak of the

disease(Magnin et al., 2019):

Figure 4: Illustration of Clinical Research

Study Results

Clinical research involves conducting of

clinical trials. These are done in four

phases:

Phase I: An experimental drug or

treatment is tested in a small group

(about 20-80) of people for the first

time. The safetyof treatment is

determined by the researchers and they

suggest a safe dosage range of the

drug, with the identificationof side

effects

Phase II :The experimental drug or

treatment is given to a larger group

(about 100-300) of people to see if it is

effective and to further evaluate its

safety

Phase III:The experimental drug or

treatment is given to large groups

(about 1000 -3000) of people. The

effectiveness is confirmed, side effects

are monitored, and these are compared

to commonly used treatments.

Information is collected that

allowssafe use ofthe experimental drug

or treatment

Phase IV: Post marketing studies are

conducted after a treatmentis

FDAapproved.It provides additional

information about the risks, benefits

and best usage of the drug or treatment.

CONCLUSION

The factors considered in a clinical

research studyinclude age, gender,

underlying disease and health history.

Clinical trials are carried out in hospitals,

clinics, individual physician’s chambers,

university health centres and community

health centres, and patient privacy is

essentially maintained during any clinical

trial.

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REFERENCES

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R.-X., Wang, Q.-Z., Sun, C., Sylvia, S., Rozelle,

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