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FREQUENCY IN EPIDEMIOLOGY

FREQUENCY IN EPIDEMIOLOGY. FAJAR AWALIA YULIANTO. LAST SESSION. DOES ANYBODY STILL REMEMBER THE DEFINITION OF EPIDEMIOLOGY? DISTRIBUTION DETERMINANT POPULATION. distribution. MEASURE THE FREQUENCY IN A DISEASE THE PARAMETER OF THE FREQUENCY ARE: COUNTS RATIO PROPORTION RATE. COUNTS.

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FREQUENCY IN EPIDEMIOLOGY

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  1. FREQUENCY IN EPIDEMIOLOGY FAJAR AWALIA YULIANTO

  2. LAST SESSION • DOES ANYBODY STILL REMEMBER THE DEFINITION OF EPIDEMIOLOGY? • DISTRIBUTION • DETERMINANT • POPULATION

  3. distribution • MEASURE THE FREQUENCY IN A DISEASE • THE PARAMETER OF THE FREQUENCY ARE: • COUNTS • RATIO • PROPORTION • RATE

  4. COUNTS • THE SIMPLEST MEASURE IN EPIDEMIOLOGY • REFERS TO THE NUMBERS OF CASES OF A DISEASE OR OTHER HEALTH PHENOMENON BEING STUIDIED • e. g. NUMBER OF PERSONS WHICH BEEN NEWLY DIAGNOSED HAVING TUBERCULOSIS IS 245 THIS MONTH • USEFUL FOR ALLOCATION OF HEALTH RESOURCES • LIMITED USEFULLNESS FOR EPIDEMIOLOGIC PURPOSES WITHOUT KNOWING SIZE OF THE SOURCE POPULATION

  5. RATIO • THE QUOTIENT OF 2 NUMBERS (NUMERATOR AND DENOMINATOR) • A QUANTITY DIVIDE THE QUANTITY • NUMERATOR MIGHT BE DIFFERENCE FROM THE DENOMINATOR (NUMERATOR MIGHT NOT INCLUDED IN DENOMINATOR) • e. g. • SEX RATIO= PROPORTION OF MALES/PROPORTION OF FEMALES • ACREDITATION=STUDENT/TEACHER

  6. PROPORTION • TYPE OF RATIO, WITH THE NUMERATOR AS PART OF DENOMINATOR (NECESSARY!) • USUALLY MULTIPLIED BY 100, KNOWN AS PERCENTAGE • PROPORTION ALWAYS RANGES BETWEEN 0 AND 1 • e. g. 16 CASES OF DISEASE FROM 48 PEOPLE. THE PROPORTION OF THE CASE IS 30%

  7. RATE • TYPE OF RATIO THAT QUANTIFIES DYNAMIC PROCESS I. E. GROWTH AND ACCELERATION • FREQUENCY OF AN EVENT • RATE CONTAIN: • DISEASE FREQUENCY • UNIT SIZE IN POPULATION • TIME PERIOD DURING WHICH AN EVENT OCCURS • RATE = (NUMERATOR/DENOMINATOR)X F • NUMERATOR: SUM OF INDIVIDUAL EXPERIENCED IN AN EVENT • DENOMINATOR: SUM OF POPULATION AT RISK • F: CONSTANTA

  8. remember • IN EPIDEMIOLOGY, WE HAVE TO DEFINE THE: • DISEASE • POPULATION • TIMEFRAME

  9. DISEASE • ABNORMAL AMONG THE NORMALS • DIAGNOSED FROM: • SYMPTOMS • SIGNS • MEDICAL HISTORY • TEST RESULT

  10. POPULATION • GROUP OF PEOPLE WITH THE SAME PURPOSES, LIMITED BY TIME AND PLACE • POPULATION AT RISK IS THE MAIN DENOMINATOR FOR DISEASE FREQUENCY IN EPIDEMIOLOGY (NOT THE POPULATION!) • CLASSIFICATION: • CLOSED POPULATION: SUBJECT ENTER AT THE SAME TIME AND THERE ARE VERY FEW LOSSES TO FOLLOW UP • OPEN POPULATION: SUBJECTS ENTER AT ANY TIME AND THERE ARE MANY LOSSES TO FOLLOW UP

  11. TIMEFRAME • POINT (SNAPSHOT) • PERIOD (FOLLOWED)

  12. BASIC MEASURE OF DISEASE FREQUENCY • POINT PREVALENCE • PERIOD PREVALENCE • INCIDENCE PROPORTION • INCIDENCE RATE

  13. PREVALENCE

  14. POINT PREVALENCE • PROPORTION OF THE POPULATION AT RISK WHO HAVE THE DISEASE AT A PARTICULAR MOMENT (SNAPSHOT)

  15. PERIOD PREVALENCE • PROPORTION OF THE POPULATION AT RISK WHO HAVE THE DISEASE WITHIN A CERTAIN PERIOD (VIDEOCAMERA) • POPULATION AT RISK IN PERIOD PREVALENCE IS (PARstart+PARend)/2

  16. INCIDENCE

  17. INCIDENCE PROPORTION (CUMULATIVE INCIDENT) • REFLECTS THE ABSOLUTE RISK FOR DISEASE WITHIN A GIVEN POPULATION • IP= N NEW CASES/N DISEASE FREE AT THE START OF FOLLOW UP • PEOPLE WHO HAVE THE DISEASE IS NOT INCLUDED IN DENOMINATOR

  18. INCIDENCE RATE (INCIDENSE DENSITY,HAZARD RATE, PERSON TIME RATE, DISEASE INTENSITY • THE INCIDENCE RATE MEASURES THE PACE AT WHICH NEW CASE OCCUR IN A POPULATION • IR=N NEW CASES/SUM OF DISEASE-FREE TIME OF EACH INDIVIDUAL • EACH PERSON OBSERVED UNTIL DIAGNOSIS OF DISEASE, END OF STUDY, LOSS TO FOLLOW UP

  19. HOMEWORK ASSIGNMENT (FREQUENCY EPIDEMIOLOGY) • PLEASE LOG IN TO: • http://vimeo.com/46161438 AND MAKE YOUR SUMMARY OF THER ANIMATION • TRUE OR FALSE. EXPLAIN THE ANSWER • WE CAN MEASURE THE INCIDENCE IN HOSTPITAL • PREVALENCE IS THE EXAMPLE OF RATIO • INCIDENCE IS THE EXAMPLE OF RATE

  20. ALHAMDULILLAH

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