EPIDEMIOLOGY 2

Q1: DEFINATIONS OF MORTALITY RATES>

1. IMR: 42/1000 live birth2. Neonatal death: 28/1000 live birth (2/3 rd of infant mortality rate)3. Still birth rate: 21/1000 live birth (same as neonatal mortality rate)4. MMR= 194/ 100000live birth of childQ2: DEFINATION OF IMPAIRMENT, DISABILITY,HANDICAP ANS: Impairment: loss or abnormality of psychological, physiological, or anatomical structure or function Disability: any restriction or lack of ability to perform an activity in the manner or within the range considered normal. Handicap: disadvantage resulting from impairment or disability that limits or prevents the fulfillment of a role that is normal (depending on age, sex, social, and cultural factors).

Q3: WHAT IS GBD? AIMS, OBJECTIVES ANS: GBD is a measure of the amount of disease, disability, and death in the world today. It is a product of complex and interwoven demographic, economic, social, political, religious and environmental factors. It refers to the collective impact of disease on the world population.

Aims: To systematically incorporate information on non-fatal outcomes into the assessment of the health status (using a time-based measure of healthy years of life lost due either to premature mortality or to years lived with a disability, weighted by the severity of that disability) To ensure that all estimates and projections were derived on the basis of objective epidemiological and demographic methods, which were not influenced by advocates. To measure the burden of disease using a metric that could also be used to assess the cost-effectiveness of interventions. The metric chosen was the DALY The burden of disease can be viewed as the gap between current health status and an ideal situation in which everyone lives into old age free of disease and disability. Causes of the gap are premature mortality, disability and exposure to certain risk factors that contribute to illness.Objectives: a consistent and comprehensive assessment of disease and injury consequences an assessment of population health in terms of health losses by using common metric for mortality and morbidity outcomes.

Q: WHAT IS DALY? IMPORTANCE OF DALY.ANS: a unit for measuring the amount of health lost because of a particular disease or injury. It is calculated as the present value of future years of disability free life that are lost as the result of the premature deaths or causes of disability occurring in a particular year.Importance:

DALYs attempt to provide an appropriate, balanced attention to the effects of non-fatal as well as fatal diseases on overall health. In the absence of such assessments, conditions which cause decrements in function but not mortality tend to be neglected.DALYs help to inform debates on priorities for health service delivery, research and planning. For example, DALYs can be used to: Compare the health of one population with another and allow decision makers to focus on health systems with the worst performance Compare the health of the same population at different points in time Compare the health of subgroups within a population - to identify health inequalities

Q: WHAT IS BURDEN OF DISEASE? ANS: a general term used in public health and epidemiological literature to identify the cumulative effect of a broad range of harmful disease consequences on a community, including the health, social, and economic costs to the individual and to society.

Q: HOW RAPID CHANGES IN GLOBAL HEALTH PATTERNS.ANS: 1) Demographic transition increasing population size, substantial increase in the average age in most regions and falling death rates. 2) Cause of death transition fraction of deaths or years of life lost shifting from communicable, maternal, neonatal and nutritional to non-communicable diseases and injuries despite the HIV epidemic. 3) Disability transition steady shift to burden of disease from diseases that cause disability but not substantial mortality. 4) Risk transition shift from risks related to poverty to behavioral risks.

Q: WHAT ARE THE COMPONENETS OF PUBLIC HEALTH SUCCESS. ANS: Clean water supply Sanitary sewage disposal Food inspection Disease surveillance Maternal-child health Nutrition-free lunch/milk Housing regulations Worker safety, ages, hours

Q: WHAT ARE THE GOALS OF THE GLOBAL BURDEN OF DISEASE?ANS: Measure loss of health due to comprehensive set of disease injury and risk factor causes in a comparable way Decouple epidemiological assessment from advocacy Inject non-fatal health outcomes into health policy debate Use a common metric for burden of disease assessment using summary measure for population health and cost-effectiveness analysis

Q: NAME 10 LEADING CAUSES OF DEATH.Ans: 1. Ischemic heart disease. 2. Stroke 3. cancer of the trachea,lungs 4. alzihemers disease 5. copd 6. DM 7. lower respiratory tract infection 8. colorectal cancer 9. chronic kidney disease 10. other cardiovascular diseaseQ: WHAT ARE THE FACTS OF GLOBAL BUDEN OF DISEASE?ANS:

Q: WHAT ARE THE 20LEADING RISK FACTORS IN 2010.ANS:1. High blood glucose2. Tobacco smoking3. Alcohol4. Household air pollution5. Diet low in fruits6. High body mass index7. High fasting plasma glucose8. Childhood underweight9. Ambient particulate matter pollution10. Physical inactivity11. High sodium diet12. Diet low in nuts13. Iron deficiency14. Suboptimal breastfeeding15. High total cholesterol16. Diet low in vegetables17. Diet low in whole grains

Q: WHAT IS BIAS? WHAT ARE THE TYPES OF BIAS?ANS: Any trend in the collection, analysis, interpretation, publication or review of data that can lead to conclusions that are systematically different from the truth.

A process at any state of inference tending to produce results that depart systematically from the true values.

TYPES:1. Selection bias2. Confounding bias3. Information bias

Q: WHAT ARE THE DIFFERENCE BETWEEN CHANCE AND BIAS.ANS: Chance is caused by random errorBias is caused by systematic errorErrors from chance will cancel each other out in the long run (large sample size)Errors from bias will not cancel each other out whatever the sample sizeChance leads to imprecise resultsBias leads to inaccurate results

Q: WHAT IS SELECTION BIAS?GIVE EXAMPLE.ANS: Selective differences between comparison groups that impacts on relationship between exposure and outcomeUsually results from comparative groups not coming from the same study base and not being representative of the populations they come from

EXAMPLE: Case-control study: Controls have less potential for exposure than casesOutcome = brain tumour; exposure = overhead high voltage power linesCases chosen from province wide cancer registryControls chosen from rural areasSystematic differences between cases and controls.

Q: WHAT IS INFORMATION/MEASUREMENT/MISCLASSIFICATION BIAS? SOURCE OF INFORMATION BIAS.ANS: Method of gathering information is inappropriate and yields systematic errors in measurement of exposures or outcomes.Sources of information bias: Subject variationObserver variationDeficiency of toolsTechnical errors in measurement

Q: WHAT IS CONFOUNDING? GIVE EXAMPLE. HOW TO CONTROL CONFOUNDING.ANS: A third factor which is related to both exposure and outcome, and which accounts for some/all of the observed relationship between the two.

CONTROL:

IN STUDY DESIGN RESTRICTION of subjects according to potential confounders (i.e. simply dont include confounder in study) RANDOM ALLOCATION of subjects to study groups to attempt to even out unknown confounders MATCHING subjects on potential confounder thus assuring even distribution among study groups IN DATA ANALYSIS STRATIFIED ANALYSIS using the Mantel Haenszel method to adjust for confounders IMPLEMENT A MATCHED-DESIGN after you have collected data (frequency or group) RESTRICTION is still possible at the analysis stage but it means throwing away data MODEL FITTING using regression techniques

Q: WHAT IS CAUSE AND ASSOSIATION? ANS: Association (relationship): statistical dependence between two or more events, characteristics or other variables. The presence of a statistical association alone does not necessarily imply a causal relationship. Cause: an event, condition, characteristic (or a combination) which plays an important role / regular / predicable change in occurrence of the outcome (e.g. smoking and lung cancer) Causes may be genetic and / or environmental (e.g. many NCDs including: diabetes, cancers, COPD, etc) Causality (causation / cause-effect relationship): relating causes to the effects they produce.

Q: WHAT ARE THE TYPES OF CAUSE? GIVE EXAMPLE. ANS: 1. Both necessary and sufficient EXAMPLE: A gene mutation associated with Tay-Sachs is both necessary and sufficient for the development of the disease, since everyone with the mutation will eventually develop Tay-Sachs and no one without the mutation will ever have it. 2. Neither Necessary Nor SufficientGonorrheais neither necessary nor sufficient to causepelvic inflammatory disease, because you can have gonorrhea without ever developing PID and PID without ever having been infected with gonorrhea. Necessary But Not Sufficient A person must be infected withHIVbefore they can develop AIDS. HIV is therefore a necessary cause of AIDS; however, sinceevery person with HIV does not develop AIDS, it is not sufficient. Sufficient But Not NecessaryDecapitation is sufficient to cause death; however, people can die in many other ways.

Q: HILLS CRITERIA.1. ANS: Temporal relationship2. Strength of association3. Dose-response relationship4. Replication of findings5. Biologic plausibility6. Alternative explanations7. Cessation of exposure8. Consistency with other knowledge9. Specificity of the association

1. Temporal relationship Exposure to the factor must have occurred before the disease developed Length of interval between exposure and disease very important Easiest to establish in a cohort studies Asbestos and Lung cancer Asbestos Latent period Lung cancer (10-20 years)New study Asbestos Latent period Lung cancer (1-03 years)Latent period is not long enough for development of lung cancer if caused by exposure

Q: DIFFERENCE BETWEEN RANDOM AND SYSTEMIC ERROR. ANS: Random error cannot be controlled for because its source is not understood. Random errors are often introduced in little bits at each stage of data collection and processing

Q: WHAT ARE THE SOURCES OF ERROR. ANS: Burrough (1986) divides error sources into : 1. Obvious sources of error. 2. Errors resulting from natural variations or from original measurements. 3. Errors arising through processing. The third type is the least obviousQ: WHAT ARE THE FACTORS THAT INFLUENCE MEASUREMENT ERROR?ANS: Q: WHAT ARE THE CHARACTERESTICS OF MEASURES AND MANIPULATIONS.ANS: Q: WHAT IS RELIABILITY?ANS: Q: WHAT IS VALIDITY? KINDS OF VALIDITY.ANS: Validity: is the degree to which the data measure what they were intended to measure-that is , the result of a measurements corresponds to the true state of the phenomenon being measured. Another word for validity is accuracy.

Q: WHAT ARE THE THREATS OF INTERNAL VALIDITY? ANS: History Maturation Testing Instrumentation Statistical regression

Q: WHAT ARE THE THREATS OF EXTERNAL VALIDITY. ANS: Interaction of selection and treatment Interaction of setting and treatment Interaction of history and treatment

Q: WHAT IS INTERACTION? ANS: Definition when the magnitude of a measure of association (between exposure and disease) meaningfully differs according to the value of some third variable Synonyms Effect modification Effect-measure modification Heterogeneity of effect

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