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Epidemiological Research


Epidemiology is defined as the study of the distribution and determinants of health related states or events in specified populations and the application of this study to control health problems. Epidemiological studies are of primary importance in a large developing country like ours where the natural history, incidence, prevalence and impact on morbidity and mortality of a variety of diseases are not known. It has usually been considered that epidemiology of infectious diseases is of prime importance in our country. However, the evolving pattern of change in the society with upward economic mobility and increasing number of middle classes would mean that a significant number of life style related diseases such as Ischaemic Heart Disease are increasing. There is very little information about this and it would be useful to undertake long term cohort studies in different population groups.

Epidemiological studies are generally considered into two categories - observational and experimental. Designs of these studies are based on cross-sectional, case-control or cohort approaches. Epidemiological studies cover research, programme evaluation and surveillance. Scope of ethical guidelines for epidemiological studies is concerned with epidemiological research. Ethics in epidemiological studies is multidimensional covering clinical medicine, public health and the social millieau.

Perhaps code of ethics is much better understood for clinical research, where the interaction between a patient and a clinical researcher is of supreme importance.In epidemiological research the researcher is dealing with group of individuals and the questions faced by an epidemiologist are more of professional nature. These questions would pertain to interactions with individual subjects, sources of funding or employer, fellow epidemiologist and the society at large. Need for code of ethics for epidemiologists is being recognised globally and the issues for such a code in the context of epidemiological research in India deserve attention.

Epidemiological research differs from clinical research in the context of large number of study subjects and generally a long time frame. If some mistakes or aberrations get detected during the course of conduct of such studies, repeating the whole exercise will be expensive, time consuming and may not even be feasible. Hence utmost care needs to be taken for various aspects, technical, practical and ethical.

I. Observational Epidemiology:

Observational Epidemiological Research includes the following type:-

a. Cross Sectional Studies (Surveys):
This is primarily population based and involves selecting stratified random samples of the population to be representative based on census data and then applying questionnaires to understand the prevalence of various diseases. Its aim is to assess aspects of the health of a population or to test hypotheses about possible cause of disease or suspected risk factors.

b. Case Control Studies:
This usually compares the past history of exposure to risks among patients who have a specified condition/disease (cases) with the past history of exposure to this among persons who resemble the cases in such respects as age, sex socioeconomic status, geographic location, but who do not have the disease. (controls) Case control studies can be done by following up available records, usually records in a hospital, but in the context of a country like ours it may require direct contact between research workers and study subjects and informed consent to participation in the study is necessary. However, if it entails only a review of medical records, informed consent may not be required and indeed may not be feasible.

c. Cohort Studies:
These are longitudinal or prospective studies of a group of individuals with differing exposure levels to suspected risk factors. They are observed over a long period usually several years. The rate of occurrence of the condition of interest are measured and compared in relation to identified risk factors. It requires a study of large number of subjects for a long time and involves asking questions, usually routine medical examination and sometimes laboratory investigations. Individuals are being followed up as the cohort and it is essential to identify precisely every individual to be studied. Protection of individual rights is an important issue.

II. Experimental Epidemiology:

In experimental epidemiology the investigators alter one or more parameters under controlled conditions to study the effects of the intervention. These are usually randomised controlled trials done to test a preventive or therapeutic regimen or the efficacy of a diagnostic procedure. Although these are strictly speaking epidemiological studies they come under the purview of clinical evaluation of drugs/devices/products etc.


The C.I.O.M.S/W.H.O guidelines for epidemiological research assumes that the individuals or population being studied are capable of giving informed consent understanding the implications of the study. With large segments of our population, given their level of education, the full understanding in the sense of industrialised countries may not be achievable. How the principle of "do no harm" is ensured under such circumstances without being paternalistic is a major issue which has to be taken into consideration in ethical guidelines.

In cohort or survey techniques for incidence and prevalence of various diseases, a major issue that has to be considered is how much of intervention is justified and whether one is justified in withholding interventions. For example, if you are looking at longitudinal morbidity in a population group, should you give them health education which is well established with regard to preventive aspects, or should you leave them alone so that the natural evolution of the disease can be studied? Health education or other interventions including non-health interventions can be quite expensive. An alternate strategy that may be followed is to make curative therapy available to the population at their own request. This usually involves running a clinic which is readily accessible to the population without any other intervention.However, it is generally considered unethical to withhold intervention or services.

General Ethical Principles:

General ethical principles of respect for persons, duty to maximise possible benefits and minimise possible harm are important considerations in ethical guidelines. At the same time it is essential that all individuals in an epidemiological research are treated alike keeping in mind the rules of distributive justice.The welfare of the individual has to be balanced against the welfare of the community and society at large.

Specific Ethical Principles applied to Epidemiology:

1.Informed Consent: When individuals are to be the subject of any epidemiological studies, the purpose and general objectives of the study has to be explained to them keeping in mind their level of understanding. It needs to be ensured that privacy will be maintained.

In the context of developing countries, obtaining informed consent has been considered many times as difficult/impracticable/not meeting the purpose on various grounds such as

(a) Whether the subjects or patients are sufficiently knowledgeable or competent to understand the meaning of informed consent?

(b) Culturally, decision making will be done, not at the individual level but at the level of head of the family or village/community head.

However, there is no alternative to obtain an informed individual consent. What should be the contents of the informed consent also becomes a crucial issue. How much to disclose and the implications of nondisclosure are to be considered seriously.

In spite of obtaining informed individual consent, it is quite likely that the subjects/patients may not be fully aware and may not be aware of their rights. In this context, the role of investigator is crucial and he/she should remain vigilant and conscious of his/her obligations towards the subjects/patients, all through the course of the studies.

2. In most epidemiological research it would be necessary to have the consent of the community which can be done through the Village Leaders, the Panchayat etc.

3. In obtaining the consent of individuals or communities it is important to keep in mind that working through peer groups or through Panchayat etc., may mean that the individuals or community would feel reluctant to disagree and refuse to give consent because of societal pressures. This is something that has to be carefully avoided.

4. Particularly in country like India with the level of poverty that is prevalent it is easy to use inducements, especially financial inducements to get individuals and communities to consent. Such inducements are not permissible. However, it is necessary to provide for adequate compensation for loss of wages and travel/other expenses incurred for participating in the study.

5. All risks involved including the risk of loss of privacy must be explained to the participants in an epidemiological study.

6. The design of the study should ensure that the benefits of the study are maximised for the individuals and communities taking part in the study. This means that at the onset itself the investigators should design the way in which the results of the study are going to be communicated and also decide whether individuals identified at particular risk during the course of the studies would be informed. It may also be necessary in some instances to inform the concerned family members about the results. For example, as in AIDS, STD etc. It may not always be possible to communicate study results to individuals but research findings and advise should be publicised by appropriate available means. In countries like India it is important that the beneficial results of epidemiological studies are fed into the health system and necessary training modules should be developed as part of the epidemiological project.

7. All attempts should be made to minimise harm to the individuals and society at large. Special consideration for the cultural characteristics of the communities which are being studied is essential to prevent any disturbance to cultural sensitivities because of the investigation.

8. Maintaining confidentiality of epidemiological data is absolutely essential. A particular concern is the fact that some population based data may also have implications to issues like national security and these need to be carefully evaluated at the beginning.

9. In all situations where there is likely to be conflicts of interest it must be ensured that the interest of the individuals involved in the study are protected at all cost.

10. Scientific Objectivity should be maintained with honesty and impartiality, both in the design and conducting study and in presenting and interpreting findings. Selective withholding of data and similar practices are unethical.

11. Ethical Review Procedures:- In addition to the Research Review Procedures, Ethical Committee has authority and responsibility for review and approval of research proposals from ethical angle. Specific areas to be covered include:-

  • Plan for informed consent
  • Assess risks and anticipated benefits
  • Equitableness
  • Protecting vulnerable subjects.

In all Ethical Review Committees at least one or two individuals with an understanding of the principles of epidemiological ethics have to be included. Ethical Committees should be independent and comprise of epidimiologists, clinicians, statisticians, social scientist, philosopher, legal expert and representatives from voluntary groups. Members should be aware of local, social and cultural norms as this is the most important social control mechanism. Ethical Committee members should be kept informed as to how the ethical guidelines are actually being implemented. Regulatory mechanism can come from a core group of the technical monitoring committee which may refer issues of ethical concern to the ethical committee.

12. Distinction between research and programme evaluation: It is important to make a distinction between epidemiological research and programme evaluation. In order to evaluate the beneficial or other effects of various health related programmes which are initiated primarily by Governmental Agencies, Longitudinal epidemiological studies may be necessary. These studies are slightly different because they are not prospectively evaluating issues, but looking at the effects of a programme that is already initiated. It is ideal that whenever a programme is launched, the monitoring and evaluating mechanisms should clearly be planned at the very beginning so that there is no conflict at a later time.

Resource Material

1. International Guidelines for Ethical Review of Epidemiological Studies, CIOMS, Geneva, 1991.

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