1. 1 Dr. Bassam Hijawi Epidemiologist Director of Jordan Cancer Registry Director of Health Promotion

2. 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. 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. 4 Rates, may be : Crude Rates. Crude Rates. Specific Rates. Standardized (adjusted ) Rates. Example 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 = = 3 : 2 6000 4000 6000 6000 + 4000 = 2 : 3 40006000

5. 5 Example 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 = X 1000 = 4 /1000 40 10,000 X 10,000 = 25 /10,000 104000 X 10,000 = 6 /10,000 610,000 X 100,000 = 60 /100,000 X 1000 = 0.6 /1000

6. 6 Measures of Disease Occurrence Morbidity Rates Routinely collected data on illness from different sources : 1. 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 = _________________________________________________________________ x 1000 No. of persons at risk of developing the disease during that period of time

7. 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. 8 Pupulation at risk in a study of cervix carcinoma Defining pop. At risk: 1. Improve accuracy ( rate not diluted. 2. People who cannot contract the dis. are not included in the denominator. 3. Ex. –Occupational injuries occur among working people. –Brucellosis occur among people handling infected animals. (farms + slaughter houses All WOMEN All MEN 0-25 Y. 25- 69 Y. 70 + Y. 25- 69 Y. Total PopulationPopulation At risk All Women (Age groups

9. 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: 1. Risk of disease or death is constant. Throught the study period. 2. Rate of disease or death the same between those lost to follow up and those not. 3. Disease under study must be not rapidly fatal. X 3 years = 5.6 person- years during three years. 27 482

10. 10 Example: 1000 persons followed, (some leave, some dropout some die, some migrate… )end by 800 1. 2 2. 3 3. 5 4. 4 5. 2.5 Example : Years followed Jan. July 94 93 92 91 90 Total years at risk 16.5 ID = 2 cases / 16.5 person years = 12.1 / 100 person – years observation ( Incidence Density )

11. 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. 12 Secondary attack rate Used in propagated spread. Number of new cases in group minus initial case (s). = ______________________________________ x 100 = ______________________________________ 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. 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 PAR In one year period. = Number of people who developed a cold PAR PAR In one year period. This incidence rate tells us about the probability that any person will develop a cold in one year.

14. 14 Mortality Rates Annual M.R. for all causes /1000 POP. Annual M.R. for all causes /1000 POP. Annual M.R from all causes for children younger than 10 Y. / 1000 POP. Annual M.R from all causes for children younger than 10 Y. / 1000 POP. restriction on age applied to Num. + Denominator x 1000 x 1000 Total No. of deaths from all causes in (Y.) C.D.R = No. of persons in the mid Y. POP. 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 specific Rate Restriction for ( specific age and specific Cause ) Ex. Annual M.R for leuk. For children < 10 Y.

15. 15 Case Fatality Rate Case Fatality Rate x 100 x 100 No. of deaths during a specified period of time after dis. onset or diag. CFR = No. of individuals with the specified dis. Difference CDR + CFR * Measure of the severity of the dis. * Measure any benefits of a new therapy Therapy improve = CFR Proportionate Mort. Rate. Proportionate Mort. Rate. x K x K No. of deaths from dis. X place / time P M R = P M R = Total Deaths Means: What proportion of deaths attributed to Dis. X. ?

16. 16 Comparison of M.R, PMR, All causes H.D Community B Community A 15/100030/1000M.R (all causes ) 20% 10 % P.M.R ( Heart dis.) 3/10003/1000M.R 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. 17 Years of Potential Life Lost YPLL Years of Potential Life Lost YPLL In younger age Injuries, accidents, cancer… HIVYounger Involves a greater loss of future productive years than were it to occur at an older age. Cause specific M.R 10 th YPLL6 th

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

19. 19 Morbidity Indices Prevalence x K x K No. of current cases ( new + old) of a dis. existing at a given point in time in an area. Point Prevalence = Rate Estimated POP. At risk at the same point in time in the same area. x K x K No. of cases ( new + old) of a dis. existing during a time interval. Period Prevalence = Rate Estimated mid – interval POP. At risk

20. 20 Special type of incidence, Prevalence DenominatorNumeratorTypeRate Total POP. at Risk New cases of Non- fatal Dis. I Morbidity R. Total POP. No. of Death from a dis. (or all causes) I Mortality R. No. of cases of that dis No. of Deaths from a dis. I Case- Fatality R. No. of persons autopsied No. of cases of a dis. P Disease Rate at Autopsy No. of Live Births No. of babies with a given abnormalities P Birth Defect Rate Total POP. No. of new cases and existing cases during a given time period P Period Prevalence Rate Total POP. at Risk for a limited period of observation No. of cases of dis. I Attack Rate

21. 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. 22 Prevalence Rate ( P) x K x K No. of cases of a dis. Present in the POP. at a specified time P = P = No. of persons in the Pop. at that specified time 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 متى حدث Numerator mix. : not Measuring risk. Point Prevalence : (p) at a point in time Period Prevalence.

23. 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. 24 Mortality : Routinely collected data on deaths from different sources. 1. Crude Death Rate: 2. Specific Rates : A. Cause specific death rate: A. Cause specific death rate: It means : Risk of deaths from dis. (X). In POP. Leading cause of deaths x K x K No. of deaths among residents in an area/year = Total POP. x K x K No. of deaths ( place – time ) from specific dis = Total POP.

25. 25 B. Age specific death rate : x K x K No. of deaths ( place – time) for specific age group from specific dis = Total POP. For the specific age group C. Proportionate mortality rate : x K x K No. of deaths from Dis x ( place – time ) = Total Deaths ( same place – time) It means : –What proportion of death attributed to Dis. X. ? D. Case Fatality Rate : / Ratio x K x K No. of Deaths from Dis x = No. of Cases from Dis x It means : –Severity of the Disease.

26. 26 Factors influencing observe Prevalence Rate Increased Longer duration of dis. Prolongation of life of patients without cure. In new cases ( incidence ) 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 In – migration of healthy people Out – migration of cases Improved cure rate of cases

27. 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. DurationY.(I) Per year P.R per 1000 POP. No. + ve x ray ScreenedPOP. 254100100 1000 ( x area) 3206060 1000 ( Y area Can we conclude that the risk of T.B, is high in X than Y area ?

28. 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. 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, 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. 30 Descriptive Epidemiology Personplacetime Who herewhen Person:.1 Age: Most important variable. Distribution by age group Or disease frequency Explained by: Susceptibility Immunity Exposure Chronic diseases

31. 31

32. 32 -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

33. 33 Age specific death Rate Jordan - 1996 all causes Total Total 80 80 Death 60 Male Rate/ 40 1000 Female 20 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 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

34. 34 DEATH RATE 50.0 50.0 40.0 Developed. 40.0 Developed. 20.0 20.0 10.0 10.0 Rate/ 5.0 1000 1.0 Developing.05.05 <1 1-4 5-14 15-24 25-34 35-44 45-54 55 - 64 65-74 75+ <1 1-4 5-14 15-24 25-34 35-44 45-54 55 - 64 65-74 75+ Age groups (y.)

35. 35 %of pop. With limitation of activity - chronic dis. 60 50 48 40302010 2020 - 44 45 - 6465+ Age Groups (y.)

36. 36 2. Gender: Death Rates higher for Males than Females. Sex Linked inheritance. Difference in hormonal balance. Environmental … Occupation. … exposure. … habit patterns. Hereditary

37. 37 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.

38. 38 M:F Ratio Cause of death 1.80 All causes 3.05Suicide 2.01 Heart Dis. 1.51 Malignant dis. 1.19 Cerebro – vas. – dis. 3.00 Chronic obst. Lung dis.

39. 39 Proportionate Mortality Ratio Jordan 1996 42% 1.Circulatory System Dis 13%2.Noplasms. 11%3.Accidants. 7% 4.Conditions in perinatal period 6% 5.Respir. System Dis. 4% 6.Cong. Deformities, chromosomal abnormality

40. 40 3. Ethnic group [Race] : - Whites ad non – whites. - Cancer Cervix in blacks. Breastin whites. Stomach in Japanese.

41. 41 4. Social class: -Occupation -Education}Total -Area of residence}life -Income}style Reflect : Nutrition, crowding. Personal hygiene and Medical Care Utilization.

42. 42 Mortality R. by social class 70 - 72, U.k, Men aged 15 - 64 IMR by sex:

43. 43 Number of teeth Decayed 15000 15000 Filled Family Income (us $ ) economic status + health care USA children 6 – 11 y. Relationship between economic status and health care [ USA children, 6 - 11 years of age, grouped according to family income ] primary + permanent teeth

44. 44 5. Occupation: * Spend 1/3 timeworking in different conditionsaffect 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).

45. 45 Exposure to: SilicaPul. Fibrosis Asbestosmesothelioma, ca. Lung Aniline dyesbladder cancer chromateLung cancer

46. 46 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).

47. 47 7.Family Variable: Family Size. Birth order. Present of both parents, or parent. deprivation. Maternal age. Religion of parents. Position of index person.

48. 48 8. Others: Immunization.Habits. Personality traits: Type A: CHD. Type B:CHD. Type B:CHD. A B O System: - Type Arisk of gastric cancer - Type Orisk of duodenal ulcer - Sickle cell trait:risk of malaria. (plas. falciparum.)

49. 49 PLACE Freq. of dis. can be related to place of occurrence in terms of areas set off either by natural barriers as: mountains, rivers, deserts, and political boundaries. Or of certain dis. Due to particular env., climate,…. Or of certain dis. Due to particular env., climate,…. Temp., humidity., rainfall, water supply … etc.

50. 50 - 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.)

51. 51 Political subdivisions: Reflect: … water supply, air pollution, vector control, medical care. Mapping of Env. Factors : Water supply, milk routes, school buses, oven, wind direction, provide a clue about mode of spread. Comparison:InternationalRegional. :National Urban Rural bedwin differences reflect(habit) and reflect (crowding, Social class)

52. 52.. Rural areas: disadvantages: - Illiteracy. - Lack of job opportunities. - Malnutrition. - Diseases. - Shortage of medical facilities and medical personnel. - Hazards of agricultural work. - Exposure to pesticides Urban areas: disadvantages - Urbanization problems - Modernization problems. … pollution … homicide ….. etc..

53. 53

54. 54 Diarrhea Mortality Rate / 1000 Population distributed by Governorates: Ref.UNICEF 1991< 5 y. Survey: Amman0.00 Balqa2.90 Zarqa0.61 Irbid0.00 Karak4.62 Mafraq0.60 Maan0.00 Jordan0.50

55. 55 Geographical areas of highest + Lowest incidence of selected cancer sites Ref.R. Doll 1982 Cancer siteincidenceincidenceratio BladderUSAJapan6:1 ColonUSANigeria10:1 EsophagusIRANNigeria300:1 LiverMozambEngland100:1 LungEnglandNigeria35:1 UterusUSAJapan30:1 PancreasN.ZIndia8:1 ProstateUSA(Black)Japan40:1 StomachJapanUganda25:1 OvaryDenmarkJapan6:1

56. 56 Time  Study of dis. Occur. By timebasic aspect of epidemiological analysis.  Occurrence is usually expressed onmonthly or annual basis.  Major kind of changes with time: 1. Secular trends: نزعات جيلية Long term Changes over a long period of time, years or decades. … occur both in infectious and non infections dis. تبدلات عبر امد طويل من الزمن

57. 57 60 60 40 40 20 stomach 20 stomach 0 30 40 50 60 70 80 90 years years Reflect: - changes in incidence - changes in survival - effect on age distribution Example: Infectious + Non - Infectious diseases Cancer death rate per 100,000 male population colon Pancreas

58. 58 2)Cyclic Changes: تغيرات فصلية Changes refers to recurrent alterations in the frequency of dis. Cycles, may be annual (seasonal) or other periodicity. e.g. - measles epidemic. - influenza (A, B ). - influenza (A, B ). - Diarrhea - Diarrhea - infectious + non infectious. - infectious + non infectious. No seasonal pattern in onset of cancer (in general) …. Exception (melanoma of upper extremities) Seasonal ….. Drowning, skiing injuries.

59. 59 (Cyclic Trends) Study of disease occurrence by time during the course of days/ weeks,months,seasons or years. Ex: R.Tr.Accidants, Measles Epidemic 1 II III 1 II III 80150 170 accident accident No No 1 a.m 8 a.m 1 pm 4 pm 12 pm 1 a.m 8 a.m 1 pm 4 pm 12 pm hours of the day

60. 60 Investigation of an epidemic 1. Verify Diagnosis: Do clinical, lab., epid. Studies autopsy. Do clinical, lab., epid. Studies autopsy. Establish criteria for labeling persons as cases (symptoms., lab. Or both) 2. Verify the existence of an epidemic: Compare current incidence with past levels of the disease. (epidemic curve, mapping) Compare current incidence with past levels of the disease. (epidemic curve, mapping)

61. 61 3) Describe the epidemic: (Person, Place, Time) Epidemic curve. Spot Map. Calculate Rates …(PAR)…by Age, sex, Occup., exposure to specific food 4) Formulate and test hypotheses: Identify type of epidemic; common source+propagated. Identify the possible source from which disease may have been contracted. Compare ill pop. (cases) with well pop. (control) with regard to exposure to the postulated source. Calculate R.R for exposed+non exposed persons. Carry out statistical test to determine probable source. Confirm epid. Findings by lab. Tests (samples of blood, feces, suspected food )

62. 62 5) Search for additional cases: (you have to locate unrecognized or unreproted cases) by: Contracting physicians, hospitals or any other health facilities in the area. Intensive investigation of a symptomatic persons or those with mild illness who may be contact of cases. 6) Analysis of data, interpreting of findings.

63. 63 7)Management of the epidemic: Prepare facilities. Treatment of cases. Prevention of spread Immediate control measures. Permanent control measures. 8) Report the investigation: include: Discussion of factors leading to the epidemic Evaluation of measures used for control Recommendations for prevention of similar episodes in the future. 9) Continued surveillance Keep the community under serve. To detect further rise in incidence and the effectiveness of control measures.

64. 64 SS.M TW. T. F 17% 16% 10% R. T. A s by day of the week

65. 65 3)Epidemic Pattern النمط الوبائي NoMeasles 1979 80 81 82 83 84 85 86 87 88 1979 80 81 82 83 84 85 86 87 88Years

66. 66 4) Seasonal pattern النمط الموسمي NoالاسهالDiarrhea 1986 1987 1988 Timeالزمن J F M A M J J A S O N D

67. 67 5) Short-term fluctuations: Found in epidemic of infectious dis. common source epidemic + Propagated or progressive epidemic Clusters by Time + Place : تعنقد او تجمع لمرض او احداث في الزمان والمكان

68. 68.changes in dis. Freq. With time are represented by

69. 69

70. 70 Propagated, progressive,contagious 300 200. initial rise is less abrupt.Cases steadily….. As vacc initial rise is less abrupt.Cases steadily….. As vacc Org. propagated in community. campaigns became effective Org. propagated in community. campaigns became effective 100 by Pass from person-person........ 0 sep nov dec jan feb mar apr may Month of year (small pox)

71. 71 اذا يختلف شكل المنحنى الوبائي بسبب 1. عدد القابلين للاصابة بالمرض: (H.Immunity) 2. فترة حضانة المرض: (MIP MIP) كمية المسبب للمرض عدوانية المسبب قابلية العائل للاصابة

72. 72 Propagated, progressive, contagious epidemic Most often of infectious origin Result from transmission of infectious agent from one susceptible host to another. Transmission continues until susceptible depleted. Examples. (HAV, Small pox).

73. 73 * Presence of several peaks separated in time but within the I.P. of IHV. * No. of susceptible is low, or insufficient contact (exposure between susceptible and infected cases.

74. 74