APPLICATION OF EPIDEMIOLOGY IN HEALTH CARE DELIVERY

The ultimate goals of health care services are: to promote and protect health, to alleviate and minimize sufferings and disabilities and to regain health so as to lead socially useful and economically productive life. Preventive approach is the best approach to achieve these goals because preventive measures can be implemented with the joint efforts of health personnel and the people at large at the family and the community level. Epidemiologically the concept of preventive approach is broad based. There are three major levels of prevention i.e. primary, secondary, tertiary prevention. Each of these levels of prevention serves distinct purposes and involves specific interventions which are applied to entire population considering its physical, mental, social and spiritual domains.

1. Primordial Prevention: this includes prevention of the emergence or development of risk factors in countries or population groups in which they have not yet appeared. For e.g. many adult health problems (e.g. obesity, hypertension) have their origins in the childhood, because this is the time when lifestyles are formed (for e.g. smoking, eating patterns, physical exercise). In primordial prevention, efforts are directed towards discouraging children from adopting harmful lifestyles. The main interventi9n is through individual and mass education.

2. Primary Prevention: primary prevention can be defined as ―action taken prior to the onset of disease, which removes the possibility that the disease will ever occur.‖ Primary prevention is the first level prevention and is associated with the prepathogenesis phase or stage of susceptibility of the disease process when the epidemiological factors like: Agent-Host-Environment have not yet interacted to cause a disease. Primary prevention strategies during pre-pathogenesis phase of a disease are aimed to prevent the interaction of these epidemiological factors. If preventive measures are successful then the disease will not occur. There are two types of primary prevention:

a. General health promotion: health promotive factors include health education, wholesome nutritious diet, clean and safe environment to live, healthful life style, healthful behaviors and adequate resources. All these aspects are directly related to socioeconomic and cultural aspects of the family and community which must be improved. Health promotive measures encompass activities related to health education, environmental modification, nutritional interventions, life style and behavior changes, effective utilization of resources. These must be planned and executed effectively and efficiently.

b. Specific protection: specific protection includes those measures which are directed to intercept causative agents of a particular disease or group of diseases before these agents‘ effect people. These measures include immunization, use of specific nutrients, protection against accidents and environmental and occupational hazards , use of prophylactic and suppressive drugs, avoidance of allergens, protection from carcinogens, stimulation of proper personal

hygiene, control of quality safety of foods, cosmetics and drugs and genetic therapy and counseling.

The basis of primary prevention measures is to alter the host, agent and environment in such a way that the disease process does not initiate and does not occur. Much of the morbidity, mortality due to infectious diseases,

Non-infectious and chronic diseases have been averted and reduced due to primary preventive measures.

3. Secondary Prevention:

secondary prevention can be defined as ―action which halts the process of a disease at its incipient stage and prevents complications.‖ Secondary prevention is second level prevention and is associated with pathogenesis i.e. presymptomatic stage and symptomatic i.e. clinical stage of the pathogenesis phase of the disease process.

The objectives of secondary preventive measures are:-

Diagnose the disease at early stage.

Control the process of disease in man.

Prevent complication.

Restore health.

Prevent the spread of infections to others in the community.

Secondary prevention is more important and emphasized in some chronic and non-infectious diseases such as diabetes; caner, blood pressure etc. because there is limited knowledge of causes and primary preventive strategies. Secondary preventive measures include two types of strategies:

a. Early diagnosis and treatment: early diagnosis and treatment are the measures which control the disease process, prevent the spread of infection to others in case of communicable diseases, prevent complications and long term disabilities and restore health. Early diagnosis and treatment has been found the more effective mode of intervention in communicable diseases like tuberculosis, leprosy and STD. It helps in reducing the morbidity and mortality due to these infectious and non-infectious diseases. In case of acute communicable diseases, early diagnosis and treatment helps to shorten the period of communicability, thus limits the spread of infection and reduces mortality.

b. Disability limitations: disability interventions are applicable during the late pathogenesis period or clinical stage of the disease process. The objective of these interventions is to prevent

or delay the consequences of clinically advanced disease i.e. prevent impairment leading to disability and handicap. The sequence of events leading to disability and handicap is as follows: Impairment: any loss or abnormality of psychological, physiological, or anatomical structure or function‖, e.g. loss of foot, defective vision or mental retardation. Impairment can be visible or invisible; temporary or permanent; progressive or regressive. Further one impairment can lead to second impairment like leprosy damage of nerves lead to plantar ulcers. Disability: because of impairment the affected person may be unable to carry out certain activities considered normal for his age, sex, etc. this inability to carry out certain activities is termed as ―disability‖. A disability can be defined as ―any restriction or lack of ability to perform an activity in the manner or within the range considered normal for a human being‖ Handicap: it is a disadvantage for a given individual resulting from impairment or a disability that limits or prevents the fulfillment of a role that is normal (depending on age, sex and social and cultural factors) for that individual. Example: - Accident is disease.

Loss of foot impairment

Cannot walk is disability.

Unemployed is handicap (socialized).

Some of the nursing measures which may limit the impairment and are advisable in immobile patients are back-care, passive exercise; for diabetic patient include health teaching, exercise, skin care, psychological boosting.

4. Tertiary Prevention: tertiary prevention can be defined as ―all measures available to reduce or limit impairments and disabilities, minimize sufferings caused by the existing departures from good health and to promote the patient‘s adjustment to irremediable conditions‖ Tertiary prevention is the third level of prevention. It occurs late in the pathogenesis stage of disease process when irreversible changes either in anatomy or physiology or both have occurred. At this point the disease process has advanced its clinical stage and entered the disability stage. It is either because the primary and secondary preventive measures have not been effective or not known. Tertiary prevention helps to prevent disability through rehabilitative strategies. Rehabilitative stratigies are used to attain the highest possible level of functional ability. It involves coordinated efforts of medical personnel, sociologists, clinical psychologists, nurses etc. for training and retraining of and helping the person to function, lead a useful life as far as possible and restore a feeling of wellbeing.

Rehabilitation is with regard to restoration of:-

Bodily functions (medical rehabilitation).

Personal dignity and confidence (psychological rehabilitation).

Family and social relationship (social rehabilitation).

The capacity to earn livelihood (vocational rehabilitation).

To conclude the three levels of preventions are relative to various stages of natural history of disease. Mutually exclusive relationship exists among all the three levels of prevention.

HEALTH SURVEILLANCE

The surveillance means supervision or close watch especially on suspected person. Epidemiologically surveillance means close vigilance on occurrence and distribution of diseases and health related problems, population dynamics, community behavior and environmental processes resulting in increased risk of ill health in the community. It involves identification of missed and suspected cases and contacts, their confirmation by laboratory investigations; identifying source of infection and channel of transmission. This information‘s will help in planning and implementation of prevention and control programmers for various diseases in the community. Thus monitoring of the disease prevalence, its related risk factors and intervention of control programmers for the same are the important activities of surveillance.

The epidemiological surveillance can be done at the following levels:

I. Individual /family Surveillance: It includes surveillance of an infected person in a family as long as the individual is source of infection to others e.g. typhoid case and carriers.

II. Community /Local population Surveillance: It include surveillance of the whole community for early detection and prevention and control of a disease e.g. Malaria.

III. National Surveillance: It includes surveillance at the National level e.g. surveillance of small pox after its eradication.

IV. International Surveillance: It includes surveillance of some of the diseases which are listed by WHO e.g. Malaria, Influenza, Filarial, Polio etc. and are to be reported to WHO which then provides information to the countries in the world to take timely actions.

SURVELLIANCE PROCESS: Surveillance is a systematic process. The main steps involved are:-

1. Collection of relevant information about the diseases under surveillance: effectiveness of surveillance system depends upon identification of cases, collection of relevant information about disease, their recording and reporting. There are number of methods for collection of relevant information about the diseases under surveillance. It may be easier to find some diseases and may be difficult to identify some others. Because of this difficulty no single method can be adopted for surveillance of all diseases. The various methods of surveillance are as under:

a) Routine reporting of cases and deaths recorded at health centers, dispensaries and hospitals: All these institutions are required to maintain record of cases reported in their outpatient departments and clinics. Daily recording of cases in OPD of Health Centers includes month,

name, age, sex, address, diagnosis, date of onset and remarks. From this record daily, weekly, monthly and yearly reports of diseases occurred and reported at the centre are prepared. This kind of routine reporting can help in making assessment of frequency and distribution of diseases by age, sex, area and time. Such reports are sent to the district and state health authorities. The practice of recording of cases under the routine reporting system is called as passive surveillance.

b) Active surveillance: It means actively looking for those particular types of cases who have not been recorded under the routine system. Active surveillance is done by health workers and community people e.g. surveillance of Malaria or Tuberculosis cases.

c) Epidemiological investigations: Epidemiological investigations are usually done when there is occurrence of more than usual number of cases in a particular place during particular time period: when there is sudden outbreak of any disease and when a communicable disease which has never occurred before but it has occurred now. This will help in picking up cases and the associated causative factors. Thus epidemiological investigations provide important supplementary information which is not obtained by other surveillance methods.

d) Sentinel centers: sentinel centers are those hospitals, health centers, laboratories, special disease hospital etc. which are identified for collecting information for selected diseases. The information are collected, compiled and forwarded to higher authority for immediate action and for making future plans and policies. Sentinel survey can provide reliable information about selected diseases indicating the trend of disease prevalence in a particular area. Such information can call for immediate actions to control the disease and also timely remedial actions in future to prevent the occurrence of disease.

e) Special sample survey: Special sample survey of disease is an active and efficient method of surveillance. There are different methods of sample surveys but the survey by cluster sampling technique is recommended by the WHO. The target population, the sample size vary from disease to disease e.g. the target population for poliomyelitis is 5-9 years, for diarrhea 0-4 years, preceding the date of survey.

2. Compilation and analysis of data: Once the surveillance data is collected for a reporting period by whatever method, it needs to be compiled and analyzed to assess the frequency and distribution by person, place and time. The reporting period can be a week, a month and a year. This information can be presented in tables, spot maps, charts and graphs. This kind of presentation helps in determining the pattern of occurrence of disease and whether there is decrease or increase in the number of cases.

3. Reporting of data and providing feedback: Once the data is analyzed a report a report is to be prepared in the format prescribed by the authority. The report is sent regularly for each reporting period. The report should be complete. If there is nil information, it should be reported. If some information is missed or received late, it should be included in the next reporting period. If further investigations are done during the period and if any section is taken or going to be

taken, it needs to be reported. Feedback should be given to all the members of health team as to how the data are used which are collected by them and reported through regular meetings and as and when desired by anyone.

HEALTH INFORMATION

Health information system is an integral part of the national health system. The health information system can be defined as: ―a mechanism for the collection, processing, analysis and transmission of information required for organizing and operating health services and also for research and training‖

Objectives Of Health Information System:

To provide reliable, relevant, up-to-date, adequate, timely and reasonably complete information for health managers at all levels(i.e. centre, intermediate and local)

To share technical and scientific information by all health personnel participating in the health services of the country.

To provide at periodic intervals the data that will show the general performance of the health services.

To assist planners in studying their current functioning and trends in demand and workload.

Difference Between Data And Information: Data consist of discrete observations of events that carry little meaning when considered alone. Data as collected from operating health care systems are inadequate for planning. Data need to be transformed into information by reducing, summarizing, adjusting them for variations, such as age, sex composition of population so that comparisons over time and place are possible. Requirements To Be Satisfied By Health Information System: A W.H.O. Expert Committee identified the following requirements to be satisfied by the health information systems:

1. The system should be population based.

2. The system should avoid the unnecessary agglomeration of data.

3. The system should be problem-oriented.

4. The system should employ functional and operational terms(e.g. episodes of illness, treatment regimens, laboratory tests)

5. The system should express information briefly and imaginatively(e.g. tables, charts, percentages)

6. The system should make provision for the feed-back of data.

COMPONENTS OF A HEALTH INFORMATION SYSTEM:

A comprehensive health information system requires information and indicators on the following subjects:

1. Demography and vital events.

2. Environmental health statistics.

3. Health status: mortality, morbidity, disability and quality of life.

4. Health resources: facilities, beds, manpower.

5. Utilization and non-utilization of health services: attendance, admissions waiting lists.

6. Indices of outcome of medical care.

7. Financial statistics (cost, expenditure) related to the particular objective.

USES OF HEALTH INFORMATION:

The important uses to which health information may be applied are:-

1) To measure the health status of the people and to quantify their health problems and medical and health care needs.

2) For local, national and international comparisons of health status.

3) For planning administration and effective management of health services and programmers.

4) For assessing the attitudes and degree of satisfaction of the beneficiaries with the health system.

5) For research into particular problems of health and disease.

SOURCES OF HEALTH INFORMATION:

1. Census: the census is an important source of health information. It is take in most of the countries of the world at regular intervals, usually of 10 years. A census is defined by the United Nations as ―the total process of collecting, compiling and publishing demographic, economic and social data pertaining at a specified time or times to all persons in the country or delimited territory‖. Census is a massive undertaking to contact every member of the population in a given time and collect a variety of information. The first regular census in India was taken in 1881, and others took place at 10 year intervals. The supreme officer who directs guides and operates the census is the Census Commissioner for India.

2. Registration of Vital Events: registration of vital events (e.g. births and deaths) keeps a continuous check on demographic changes. If registration of vital events is complete and accurate, it can serve as a reliable source of health information. Much importance is therefore given to registration in certain countries. The United Nations defines a vital events registration system as including ―legal registration, statistical recording and reporting of the occurrence of, and the collection, compilation,presentation, analysis and distribution of statistics pertaining to vital events, i.e., live births, deaths, fetal deaths, marriages, divorces, adoptions, leg imitations, recognitions, annulments and legal separations‖. India has a long tradition of registration of births and deaths. In 1873, the Govt. of India had passed the Births, Deaths and Marriages Registration Act, but the act provided only for voluntary registration. However, the Registration system in India tended to be very unreliable, the data being grossly deficient in regard to accuracy, timeliness, completeness and coverage. This is because of illiteracy, ignorance, lack of concern and motivation. There are also other reasons such as lack of uniformity in the collection, compilation and transmission of data which is different for rural and urban areas, and multiple registration agencies (e.g. health agency, panchayat agency, police agency and revenue agency). The Central Births and Deaths Registration Act, 1969:- The Govt. of India promulgated the Central Births and Deaths Registration Act in 1969 in an effort to improve the civil registration system. The Act came to force on 1 April 1970. The Act provides for compulsory registration of births and deaths throughout the country and compilation of vital statistics in the states so as to ensure uniformity and comparability of data. The Act also fixes the responsibility for reporting births and deaths. While the public (e.g. parents, relatives) are to report events occurring in households, the heads of the hospitals, nursing homes, hotels, jails or dharamshalas are to report events occurring in such institutions to the concerning Registrar. The time event for registering the event of births is 14 days and that for the deaths is 7 days. In case of default a fine up to a fine up to Rs.50 can be imposed. Lay Reporting: Lay reporting is defined as the collection of information, its use, and its transmission to other levels of the health system by non-professional health workers like village health guides to record births and deaths in the community.

3. Sample Registration System (SRS): SRS was initiated in mid-1960‘s to provide reliable estimates of births and death rates at the national and state levels. The SRS is a dual record system, consisting of continuous enumeration of births and deaths by an enumerator and an independent survey every 6 months by an investigator-supervisor. This system is more reliable for information on birth and death rates, age specific fertility and mortality rates, infant and adult mortality etc.

4. Notification of Diseases: the primary purpose of notification is to effect prevention and control of the disease. Notification is also a valuable source of morbidity data i.e. the incidence and distribution of certain specified diseases which are modifiable. Lists of modifiable diseases vary from country to country and also within the same country between the states and between urban and rural areas. At the international level the diseases like cholera, plague, yellow fever, relapsing fever, polio, influenza, malaria, and rabies are modifiable to W.H.O. The limitations of

notification are: (a) it covers only a small part of the total sickness in the community (b) it suffers from under-reporting (c) many cases esp. atypical and sub clinical cases escape notification due to non recognition e.g. rubella, non-paralytic polio etc. In spite of the above limitations, notification provides valuable information about fluctuations in disease frequency and provides early warning about new occurrences or outbreaks of disease.

5. Hospital Records: in India where registration of vital events is defective and notification of infectious diseases is extremely inadequate, hospital data constitute a basic and primary source of information about diseases prevalent in the community. The main drawbacks of hospital data are:-

They provide information on only those patients who seek medical care. Mild cases may not attend hospital; sub clinical cases are always missed.

The admission policy may differ from hospital to hospital; therefore hospital statistics may be highly selective.

Population served by a hospital cannot be defined. There are no precise boundaries to the catchment area of the hospital.

In spite of above limitations, a lot of useful information about health care activities can be derived from hospital records. A study of hospital data provides information on the following aspects:

Geographic sources of patients

Age and sex distribution of different diseases and duration of hospital stay

Distribution of diagnosis

Association between different diseases

The period between disease and hospital admission

The distribution of patients acc. to different social and biological characteristics

The cost of hospital care

Such information is of great value in planning of health care services.

6. Disease Registers: a register requires that a permanent record be established, that the cases be followed up, and the basic statistical tabulations be prepared both on frequency and on survival. Morbidity registers exist only for certain diseases such as stroke, myocardial infarction, cancer, blindness, and congenital defects. Tuberculosis and leprosy are also registered in many countries where they are common. These registers are of valuable information as to the duration of illness, case fatality and survival. These registers provide follow-up of patients and provide a continuous

account at the frequency of disease in the community. The useful information can be obtained from registers on the natural course of disease, esp. chronic diseases. If the reporting system is effective the register can provide useful data on morbidity from the particular diseases, treatment given and disease-specific mortality.

7. Record Linkage: the term record linkage is used to describe the process of bringing together records relating to one individual (or to one family), the records originating in different times or places. The term medical record linkage implies the assembly and maintenance for each individual in a population, of a file of the more important records relating to his health. The events commonly recorded are birth, marriage, death, hospital admission and discharge. Other useful data might also be included such as sickness absence from work, prophylactic procedures, use of social services etc. the main problem with the record linkage is the volume of data that can accumulate. Therefore in practice record linkage has been applied only on a limited scale e.g. twin studies, measurement of morbidity, chronic disease epidemiology and family and genetic studies.

8. Epidemiological Survelliance: in many countries where particular diseases are endemic special control eradication programmers have been instituted for example National Disease Control Programmers against malaria, tuberculosis, leprosy etc. the surveillance programmers are set up to report on the occurrence of new cases and on efforts to control the diseases e.g. immunization is performed. These programmers have yielded considerable morbidity and mortality data for the specific diseases.

9. Other Health Service Records: these are hospital OPD‘s, primary health centers and sub centers, polyclinics, private practitioners, mother and child health centers, school health records, diabetic and hypertensive clinics etc. For e.g. records in MCH centers provide information about birth weight, height, arm circumference, immunization, disease specific mortality and morbidity. The drawback is that it relates only to a certain segment of the general population and the data generated by these records is mostly kept for administrative purposes rather than for monitoring.

10. Enviornmental Health Data: health statistics provide data on various aspects of air, water and noise pollution; harmful food additives; industrial toxicants; inadequate waste disposal and other aspects of combination of population explosion with increased production and consumption of material goods. Environmental data is helpful in the identification and quantification of factors causative of disease.

11. Health and Manpower Statistics: this information relates to the number of physicians (by age, sex, specialty and place of work), dentists, nurses, medical technicians etc. there records are maintained by The State Medical/Dental/Nursing Councils and the Directorates of Medical Education. The census also provides information about occupation. The Institute Of Applied Manpower Research attempts estimates of manpower, taking into account different sources of

data, mortality and out turn of qualified persons from different institutions. The Planning Commission also gives estimates of active doctors for different states.

12. Population Surveys: the term health surveys is used for surveys relating to any aspect of health- morbidity, mortality, nutritional status etc. when the mean variable to be studied is disease suffered by the people, the survey is referred as ―morbidity survey‖. The following types of surveys are included under health surveys:

Surveys for evaluating the health status of a population that is community diagnosis of problems of health and disease.

Surveys for investigations of factors affecting health and disease e.g. environment, occupation, income, circumstances associated with the onset of illness etc.

Surveys relating to administration of health services e.g. use of health services, expenditure on health. Evaluation of population health needs and unmet needs, evaluation of medical care.

Population surveys can be conducted in almost any setting. These may be cross-sectional or longitudinal; descriptive and analytical or both.

Classification of Health Surveys:

a) Health examination surveys: provide more valid information. This survey is carried out by teams consisting of doctors, technicians and interviewers. The main disadvantage of this type is it is expensive and cannot be carried out on the extensive scale. It also considers the provision of treatment to people found suffering from certain diseases.

b) The health interview: it measures subjective phenomena such as morbidity, disability, impairment, economic loss due to illness, expenditure on disease, beliefs and attitudes.

c) Health records survey: involves collection of data from health service records. It is the cheapest method of collecting data. The disadvantages of this method are that the estimates available from records are not population based; reliability is open to question and lack of uniform procedures in recording the data.

d) Questionnaire: it is simpler and cheaper and they may be sent. A certain level of skill and education is expected from respondents. There is usually high rate of non response. It is more time consuming also.

Other Routine Statistics Related To Health:

Demographic: in addition to routine census data, statistics on other demographic phenomena as population density, movement and education level.

Economic: consumption of consumer goods like tobacco, dietary fats, sales of drugs, employment and non-employment data.

Social security schemes: medical insurance schemes make it possible to study the occurrence of illnesses in the insured population.

. Non-Quantifiable Information: health planners require this information e.g. information on health policies, health legislation, public attitudes, programmed costs, procedures and technology. There should be proper storage, processing and dissemination of information.

EPDEMIOLOGY

Epidemiology is the study of the distribution and determinants of health-related states or events in specified populations, and the application of thisstudy to the control of health problems.

“Public health surveillance is the ongoing, systematic collection, analysis, interpretation, and dissemination of data about a health-related event for use in public health action to reduce morbidity and mortality and to improve health.”

GOALS OF SURVEILLANCE SYSTEM● Detect outbreaks● Detect public health threats● Detect infectious cases (case finding)● Monitor trends in a target population● Monitor exposed individuals for symptoms● Monitor treated individuals for complications● Direct public health interventions● Evaluate public health interventions● Generate hypotheses for further evaluation

Types of disease surveillance● Passive surveillance● Enhanced passive surveillance● Active surveillance

Sources of surveillance data● Mortality data– Death registry, medical examiner● Morbidity data– Legally reportable diseases, including cancer● Birth registry● Hospital discharge diagnoses(utilization data)● Special surveys (NHANES, NHIS, CHIS)

ROLE OF A NURSE IN EPIDEMIOLOGY