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Dr. Bassam Hijawi Epidemiologist Director of Jordan Cancer Registry Director of Health Promotion

Dr. Bassam Hijawi Epidemiologist Director of Jordan Cancer Registry Director of Health Promotion. In Epidemiology. The most important tool for measuring the risk of occurrence of a particular event in a population during a given time period are :-. Rates Morbiditly Rats:

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Dr. Bassam Hijawi Epidemiologist Director of Jordan Cancer Registry Director of Health Promotion

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  1. Dr. Bassam HijawiEpidemiologist Director of Jordan Cancer RegistryDirector of Health Promotion

  2. In Epidemiology The most important tool for measuring the risk of occurrence of a particular event in a population during a given time period are :-

  3. Rates Morbiditly Rats: Measuring the occurrence (probability , risk) of disease (includes illness, injury, or disability). A term preferably avoided, used incidence rate or prevalence rate Mortality Rates: Measuring the occurrence of deaths. A term preferably a voided, many crude and specific death rates used. (indices of health ).

  4. Rates , may be : Crude Rates. Specific Rates. Standardized (adjusted ) Rates. • Example : • Population : 6,000 Men • 4,000 Women • 10,000 Total • Proportion : tell us what fraction of the population is affected . • Proportion of men = • = 0.60 = 60% • - Ratio M/F = • Ratio F/M =

  5. Example : • ( 40) new cancer lung cases reported during the yare 2004 from the previous population (30 among men and 10 among Women ). 6 cases died during the same year . (5 among men and 1 among women ) Rates : tell us how fast the disease is occurring in a population . • Lung Cancer Incidence Rate = • Female Lung cancer Incidence Rate = • Lung cancer death Rate =

  6. Measures of Disease Occurrence Morbidity Rates Routinely collected data on illness from different sources : • Incidence Rate: The number of new cases of a disease that occur during a specified period of time in a population at risk for developing a disease . IR per 1000 No. of new cases of a disease occurring in the population during a specified of time = _________________________________________________________________ x 1000 No. of persons at risk of developing the disease during that period of time

  7. The disease developed in a person who did not have the disease previously. • Transition from a non disease to diseased state. • Measure of risk in exposed population . • Denominator = number of people who are at risk for developing the disease (estimated mid year population ) • Any individual in the denominator, may (must have) to become counted in the numerator. (numerator included in the denominator). • Incidence for uterine cancer, the denominator must be women. Mean, men not at risk to develop uterine cancer. • Period of time must known, must specified for all individuals in the denominator. Incidence may be calculated in one week, one month, one year, 5 years.

  8. Pupulation at risk in a study of cervix carcinoma Defining pop. At risk: • Improve accuracy ( rate not diluted . • People who cannot contract the dis. are not included in the denominator. • Ex. • Occupational injuries occur among working people . • Brucellosis occur among people handling infected animals . (farms + slaughter houses 0-25 Y. All MEN AllWOMEN 25- 69 Y. 25- 69 Y. 70 + Y. Total Population All Women (Age groups Population At risk

  9. Cumulative Incidence : • Example : 482 women using oral contraceptive, followed for 3 years . • 27 of them developed Bacterurea. • C.I of Bacterurea among O.C users = • ( Assume all persons have been followed during the 3 years period ) • Incidence Density : • Due to loss of follow up (attrition ) for any reason, different individual in the denominator, may be observed for different length of time, person- years used in the denominator. • (Unequal Periods of observation ) • Valid under these conditions: • Risk of disease or death is constant . Throught the study period. • Rate of disease or death the same between those lost to follow up and those not. • Disease under study must be not rapidly fatal.

  10. 2 3 5 4 2.5 Example: 1000 persons followed , (some leave, some dropout some die, some migrate… )end by 800 Example : Total years at risk16.5 ID = 2 cases / 16.5 person years = 12.1 / 100 person – years observation ( Incidence Density )

  11. Attack Rats • It is incidence rate. • Usually expressed as percentage • Used for particular population . • Observed for limited period of time. • Used mostly in outbreaks/ epidemics.

  12. Secondary attack rate • Used in propagated spread . Number of new cases in group minus initial case (s). • = ______________________________________ x 100 Number of susceptible persons in group minus initial case (s) • During a specified time period . • Index case (s) excluded from both numerator and denominator .

  13. Specification of Numerator(Number of persons + Number of conditions) • More than one event can occur to the same person within stated time period . • This incidence rate tells us the number of events (colds) to be expected among the group of people in that year . • Incidence rate = Number of colds • PAR In one year period . • = Number of people who developed a cold • PAR In one year period. • This incidence rate tells us about the probability that any person will develop a cold in one year.

  14. Mortality Rates • Annual M.R. for all causes /1000 POP. • Annual M.R from all causes for children younger than 10 Y. / 1000 POP. • restriction on age • applied to Num. + Denominator specific Rate Age specific M.R Restriction on dis./ specific // Cause Cause Specific Death Rate (No. of deaths from lung cancer in one year ). Leading cause of death Restriction for ( specific age and specific Cause ) Ex. Annual M.R for leuk. For children < 10 Y.

  15. Case Fatality Rate Difference CDR + CFR * Measure of the severity of the dis. * Measure any benefits of a new therapy Therapy improve = CFR • Proportionate Mort. Rate. Means:What proportion of deaths attributed to Dis. X. ?

  16. Comparison of M.R, PMR, All causes H.D P.M.R = give us a quick look at the major causes of deaths, but can not tell us the risk of dying from a dis. We Need M R for that .

  17. Years of Potential Life LostYPLL Cause specific M.R 10th YPLL 6th In younger age Injuries, accidents, cancer… HIV Younger Involves a greater loss of future productive years than were it to occur at an older age.

  18. When M R is a good index of incidence ? Measure of dis. risk • Under 2 conditions : • CFR is • Duration of dis is short ( Survival ) rabies Cancer pancreas • Problems with Mortality Data • Death Certificate Problems • [ underlying cause of death ] • [ Immediate cause of death ] • ICD

  19. Morbidity IndicesPrevalence

  20. Special type of incidence, Prevalence

  21. Ex. Breast Cancer I.R. in Women by age • Distinction between • Distribution of dis. • Proportion of cases • I.R (risk of the dis.). Age

  22. Prevalence Rate ( P) • How many people have arthritis ? • Household Survey ? • Interviews , physical ex. • (I) + (P) difference We don’t take into account the duration of the dis. متى حدث Numerator mix . : not Measuring risk. Point Prevalence : (p) at a point in time Period Prevalence .

  23. Ex. Questions regarding asthma Do you currently have asthma. ? Point Prevalence . Have you had asthma during the last (n) years? Period Prevalence . Have you ever had asthma. ? عمرك اصبت بالأزمة Cumulative Incidence

  24. Mortality : Routinely collected data on deaths from different sources. • Crude Death Rate: • Specific Rates : A . Cause specific death rate: It means : • Risk of deaths from dis. (X). In POP. • Leading cause of deaths

  25. B. Age specific death rate : It means : • What proportion of death attributed to Dis. X. ? C. Proportionate mortality rate : D. Case Fatality Rate : / Ratio It means : • Severity of the Disease .

  26. Factors influencing observe Prevalence Rate Increased • Longer duration of dis. • Prolongation of life of patients without cure . • In new cases ( incidence ) • In – migration of cases. • Out –migration of healthy people . • In – migration of susceptible people. • Improved diagnostic facilities ( better reporting ) Decreased by • Shorter duration of dis. • Case – fatality rate from dis. • In new cases ( incidence ) • In – migration of healthy people • Out – migration of cases • Improved cure rate of cases

  27. Relation Between (I), (p)ex. Using chest x rays, 2000 persons are screened for T.B, 1000 ( upper income people) from x area, and 1000 (lower income people ) from Y area . Can we conclude that the risk of T.B, is high in X than Y area ?

  28. Descriptive Epidemiology • Study the distribution of disease within a population by person, place, and time. • Identify non-random variations in the distribution of disease to enable an investigator to generate testable hypotheses regarding etiology. - Who is getting the disease? - Where are the rats of disease highest and lowest? - When does disease occur commonly or rarely?

  29. Descriptive Epidemiology Describe patterns of disease: (or) distribution of dis. within a population by person place time. Person Who is getting the dis.? Age, sex, Ethnic status, Religion, Marital status, occupation, social class, Education, … others Place where are the rates of dis. Highest and lowest? Geographical distribution. Time when Does the dis. Occur commonly or rarely?

  30. Descriptive EpidemiologyPerson place timeWho here whenPerson:.1 Age:Most important variable.Distribution by age group Or disease frequency Explained by: Susceptibility Immunity Exposure Chronic diseases

  31. -Some dis. Occur exclusively in one particular age group.Ex. Ca.Prostate, chronic conditions by age.Ex.Aarthritis is, 10 times more common in 45 – 46 than < 45 years.Ex.Dental problems by age.Ex.Skin wrinkling by age skin elasticity

  32. Age specific death Rate Jordan - 1996all causes Total 80 Death 60 Male Rate/ 40 1000 Female 20 0-1 1-4 5-9 10-14 15-19 20-24 25-29 30-34 35-39 40-49 50-54 55-59 60-64 65-69 70-76 75-79 age groups

  33. DEATH RATE 50.0 40.0 Developed. 20.0 10.0 Rate/ 5.0 1000 1.0 Developing .05 <1 1-4 5-14 15-24 25-34 35-44 45-54 55 - 64 65-74 75+ Age groups (y.)

  34. %of pop. With limitation of activity - chronic dis. 60 50 48 40 30 20 10 20 20 - 44 45 - 64 65+ Age Groups (y.)

  35. 2. Gender: • Death Rates higher for Males than Females. • Sex Linked inheritance. • Difference in hormonal balance. • Environmental … Occupation. … exposure. … habit patterns. • Hereditary

  36. High Morbidity + Low mortality in F. May be due to: • F. seek medical care more freely and at early stage of dis. • Dis. Tend to have less lethal course in F.than M. • Expectation of life more in F. than M.

  37. Proportionate Mortality Ratio Jordan 1996

  38. 3. Ethnic group [Race] : • Whites ad non – whites. • Cancer Cervix in blacks. Breast in whites. Stomach in Japanese.

  39. 4. Social class: • Occupation • Education } Total • Area of residence } life • Income } style Reflect : Nutrition, crowding. Personal hygiene and Medical Care Utilization.

  40. Mortality R. by social class 70 - 72, U.k, Men aged 15 - 64 IMR by sex:

  41. Relationship between economic status and health care[ USA children, 6 - 11 years of age, grouped according to family income ] primary + permanent teeth Number of teeth Decayed Filled <3000 3-4.9 5-6.9 7-9.9 10-14.9 > 15000 < 3000 3-4.9 5-6.9 7-9.9 10-14.9 > 15000 Family Income (us $ ) economic status + health care USA children 6 – 11 y.

  42. 5. Occupation: * Spend 1/3 time working in different conditions affect health. * Exposure to: physical conditions: heat, cold, change atmospheric pressure, noise / Minining / construction / Diving ِ/Agriculture /injury and trauma. chemical : heavy metals (lead, mercury) , CO , So2 .. Biological : endemic dis. Occupational stress/jop: (hypertension, peptic ulcer, diabetes).

  43. Exposure to: • Silica Pul. Fibrosis • Asbestos mesothelioma, ca. Lung • Aniline dyes bladder cancer • chromate Lung cancer

  44. 6. Marital Status: for women (sexual exposure, pregnancy, childbearing, Lactation..) (Single, married, divorced) Cancer Cervix: > in married than single women. Cancer Breast: > in single than married women. Cancer Breast: > in early age at first pregnancy. (Protected by Lactation).

  45. 7.Family Variable: • Family Size. • Birth order. • Present of both parents, or parent. deprivation. • Maternal age. • Religion of parents. • Position of index person.

  46. 8. Others: Immunization. Habits. Personality traits: Type A: CHD. Type B: CHD. A B O System: - Type A risk of gastric cancer - Type O risk of duodenal ulcer - Sickle cell trait: risk of malaria. (plas. falciparum.)

  47. PLACE Freq. of dis. can be related to place of occurrence in terms of areas set off either by naturalbarriers as: mountains, rivers, deserts, and political boundaries. Or of certain dis. Due to particular env., climate,…. Temp., humidity., rainfall, water supply … etc.

  48. - E.g. Tropical diseases.- Endemic diseases.- Certain fungal dis.- Endemic goiter in (iodine def. areas).- Mottled dental enamel … fluoride content of drinking water.- Melanoma of skin … sunlight.- Burkitts lymphoma … endemic in equatorial Africa. (Epstein – Barr Virus.)

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