Rate, ratio, proportion
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This document discusses various tools used to measure health indicators, including rates, ratios, and proportions. It provides definitions and examples of different types of rates that are used as mortality and morbidity indicators, such as crude death rate, specific death rates, infant mortality rate, and prevalence. These rates are calculated using a numerator (e.g. number of deaths) and denominator (e.g. population size), and provide information about the health status and needs of a population. Measuring these indicators helps health planners to assess health care needs, allocate resources, and evaluate programs.
Rate, ratio, proportion
- 2. • It Signifies speed or the frequency of occurrence per unit time. • The numerator is a part of the denominator. • Eg. Notification rate of new sputum smear +ve cases = New ss +ve / 100,000 population • Cure rate :No. of cases cured x100 No. Of cases under Trt.
- 3. RATIO : • Relation of size between two random quantities. • The numerator is not a component of denominator. • e.g. Sex ratio, doctor-population ratio, child- women ratio.
- 4. PROPORTION • Is a ratio which indicates the relation in magnitude of a part of the whole. • Numerator is always included in denominator. • Usually expressed as %ge. • Measurement of the size of a part out of the whole, usually the whole taken as 100. If the fraction is too small, the base can be 1000 or any 10x.
- 8. Characteristics of an indicator An ideal indicator should be ØValid –measures what supposed to measure ØPrecise/reliable –same results if used by different individuals in similar circumstances. ØSensitive- reflect small changes in health status. ØSpecific- only in the situation concerned. ØFeasible- ability to obtain data needed. ØRelevant- Contribute to the phenomenon of interest.
- 11. MORTALITY INDICATORS CRUDE DEATH RATE- No of deaths during the year 1000 Mid year population • Decrease in CDR provides a good tool for assessing the overall health improvement in a population. • They lack the comparability for communities or national or international level b/c they differ by age, sex, race etc.
- 12. SPECIFIC DEATH RATES • Cause or disease specific- TB, cancer, accident -Computed for total population -Calculated per 100,000 -Makes easier for comparison bet. diff. causes • Related to specific groups- Age, sex, both No of deaths in specified age group 1000 Mid yr. population of same age group -Can help us to identify particular groups or groups at risk for preventable action.
- 13. • STILL BIRTH RATE= Fetal deaths weighing over 500g. 1000 Total live +still births over 500g. at birth • PERINATAL MORTALITY RATE= Late fetal +Early neonatal deaths 1000 Live births in same year -gives good indication of the extent of pregnancy wastage, quality & quantity of maternity care available to mother &newborn. • -reflects the results of maternity care.
- 14. NEONATAL MORTALITY RATE • No. of deaths of children under 28 days of age in a yr. 1000 Total live births in the same year -Measures the intensity with which endo- genous factors (e.g. LBW, Birth injuries) affect infant life. -High NMR with endogenous causes suggest to improve antenatal & postnatal services to expectant mothers.
- 15. POSTNEONATAL MORTALITY RATE • No. of deaths of children between 28 days & 1 yr. of age in a given yr. 1000 Total no. of live births in the same yr. - Dominated by exogenous causes. • INFANT MORTALITY RATE No. of deaths of children less than 1000 1 yr. age in a year No. of live births in the same yr. -Most sensitive indicator of health status & SE conditions of the population.
- 16. CHILD DEATH RATE • No. of deaths of children aged 1-4 yrs. during a given year 1000 Total no. of children aged 1-4 yrs. at the middle of year -It is the more refined indicator of the social situation in a country. - If more, it reflects the inadequate MCH services, insufficient nutrition, low immuniza- tion coverage &adverse env. exposure etc.
- 17. UNDER -5 MORTALITY RATE • No. of deaths of children less than 5 yrs. of age in a given year 1000 No. of live births in the same yr. - UNICEF considers it as the best single indicator of social development&wellbeing. MATERNAL MORTALITY RATE Total no. of maternal deaths in an area during a given yr. 1000 Total no. of live births in same area & yr. -Fine measure of quality of maternity service.
- 18. SEX SPECIFIC DEATH RATE • MALE DEATH RATE = Male deaths in a year 1000 Mid year population of males - For comparison. AGE-SEX SPECIFIC DEATH RATE • Death rate of women in reproductive age gr. = Female deaths in age gr. 15-49 1000 Female population of age gr. 15-49
- 19. CASE FATALITY RATE • Total no. of deaths due to a particular disease 100 Total no. of cases due to same disease -Time interval is not specified. -Represents the killing power of a disease. -Used in acute infectious disease. -Closely related to virulence. -Important while investigating an epidemic.
- 20. PROPORTIONAL MORTALITY RATE • Expresses the no. of deaths due to a particular cause (or in a specified age group) per 100 or 1000 total deaths. • a) Proportional mortality from specific disease • b) Under 5 proportional mortality rate • c) Proportional mortality rate for aged 50 years or above • Useful indicators within any population group of the relative importance of specific disease or dis. group as a cause of death.
- 21. SURVIVAL RATE • Total no. of patients alive after a period * 100 Total no. of patients diagnosed or treated -Can be used for assessment of standards of therapy. STANDARDISED DEATH RATES - for the purpose of comparison between different populations. 1) Direct standardization 2) Indirect standardization- a) Standardized mortality ratio (SMR)- observed deaths * 100 expected deaths a) By index rates b) Life table –age adjusted summary of current all- causes mortality.
- 23. INCIDENCE • No. of new cases of specific disease during a specified time interval * 1000 Population at risk during that period • Attack rate • Secondary attack rate – Restricted to acute diseases. – Is a health status indicator. Useful for taking steps for prevention & treatment.
- 25. Incidence may change genuinely (increase or decrease) with the following factors: • Introduction of a new risk factor (e.g., contraceptive and increase in Thromboembolism, food additives and cancer); • Changing habits. • Changing virulence of causative organisms. • Changing potency of treatment or intervention programmes. • Selective migration of susceptible persons to an endemic area, which increase the incidence of the disease.
- 26. PREVALENCE • Refers to all current cases ( old & new) existing at a given point or period of time in a given population. • Prevalence = All current cases existing at a given point or period of time * 100 Population at risk • May be -Point prevalence -Period prevalence • Uses -1)Helps to estimate the magnitude of disease & identify high risk population. 2)Useful for administrative & planning purposes.
- 27. These rates are typically obtained from cross –sectional studies; occasionally, they are based on registersof specific disease. Prevalencedepends on two main factors: - previous incidence ,and - Duration or chronicity of disease. When both incidence and during of a specific disease are relatively stable, Prevalence(P) = incidence (I) X duration (D)
- 28. Prevalence may change over time in response to: • Changes in incidence, • Changes in disease duration and chronicity (e.g., some disease may become shorter in duration or more acute because of high recovery rate or high case fatality rate), • Intervention (preventive) programmes, • Selective attrition (e.g., selective migration of cases,or of susceptible or immune persons ), and • Changing classification of what constitutes an “active ” case and whether an “ arrested”case is counted or not.
- 29. Results of Screening for diabetes on incidence rate 5 died 5 migrated 5 recovered 25 cases 40 cases 960 free 20 cases 940 free 1000 women Screening 1 January 1 January 2012 31 December 2012 Incident cases during 2012 Prevalent cases on 31 December Attrition
- 30. Duration of illness • 1)Days of illness per exposed person • 2)Days per illness per ill per person • 3)Days of illness per spell Other morbidity indicators • Notification rates • Attendance rates at OPDs, health centre etc. • Admission, readmission & discharge rates
- 31. DISABILITY RATES • Event type indicators - -No. of days of restricted activity -Bed disability days -Work loss days within a specified period. • Person type indicators- -Limitation of mobility -Limitation of activity • Health adjusted life expectancy (HALE) • Disability adjusted life year (DALY)
- 32. • HALE (Health-Adjusted life expectancy) – The equivalent number of years in full health that a newborn can expect to live based on current rates of ill-health and mortality. • QALY (Quality adjusted life years) – measure of disease burden both the quality and quantity of life lived. It is used in assessing the value for money of a medical intervention. • DFLE (Disability free life expectancy) – Av. No. of years an individual is expected to live free of disability. • DALY (Disability adjusted life years) –measure of overall disease burden, expressed as a no. of years lost due to ill-health, disability or early death.
- 33. FERTILITY INDICATORS • Crude birth rate • Fertility rates- General fertility rate Age specific fertility rate Total fertility rate • Reproduction rate- Gross reproduction rate Net reproduction rate • Sex ratio at birth • Pregnancy rate • Abortion rate
- 34. NUTRITIONAL STATUS INDICATORS • Anthropometric measurements of preschool children e.g. weight, height, mid- arm circumference • Heights (sometimes weights) of children at school entry • Prevalence of low birth weight (<2.5 kg.)
- 35. HEALTH CARE DELIVERY INDICATORS • Doctor population ratio • Doctor –nurse ratio • Population – bed ratio • Population per Health / sub centre • Population per T.B.A. -These reflect the equity of distribution of health resources in diff. parts of country & of the provision of health care.
- 36. UTILIZATION RATES • Utilization of services – or actual coverage- is expressed as the proportion of people in need of a service who actually receive it in a given period. • E.g.Proportion of infants fully immunized. Pregnant women who receive ANCs. %ge of population using various methods of family planning Bed occupancy rate Average length of stay
- 37. INDICATORS OF SOCIAL & MENTAL HEALTH • Suicide, homicide & other violence &crime • Road traffic accidents • Juvenile delinquency • Alcohol & drug abuse, smoking • Obesity • Family violence, battered baby & battered wife syndromes
- 38. ENVIRONMENTAL INDICATORS Reflect the quality of physical & biological env. in which diseases occur & people live. These indicators are relating to • Pollution of air & water • Radiation, Noise • Solid wastes • Exposure to toxic sub.s in food & drink Most useful- proportion of population having assess to safe water & sanitation facilities.
- 39. SOCIO-ECONOMIC INDICATORS • Rate of population increase • Per capita GNP • Level of unemployment • Dependency ratio • Literacy rates (esp. Female literacy rate) • Family size • Housing, the no. of living room • Per capita calorie availability
- 41. INDICATORS OF QUALITY OF LIFE • PQLI- Most important & composite health indicator. • It includes -Infant mortality -Life expectancy at age one -Literacy
- 42. OTHER INDICATORS • Social indicators- Population, Family formation, Learning & educational services, Earning activities, Social security & welfare services etc. • Basic needs indicators- used by ILO Calorie consumption, assess to water, life expectancy, deaths due to disease, illiteracy, doctors & nurses per population, rooms per person, GNP per capita
- 44. Social & economic indicators related to health - Rate of population increase - GNP or GDP -Income distribution -Work conditions - Adult literacy rate -Housing -Food availability Indicators for the provision of health care - Availability -accessibility -Utilization -Quality of care
- 45. Health status indicators • LBW • Nutritional status & psychosocial dev. of children • IMR ,Child mortality rate( 1-4 yrs.) • Life expectancy at birth , MMR • Disease specific mortality • Morbidity- incidence, prevalence • Disability prevalence
- 46. USES OF EPIDEMIOLOGY • To study historically the rise and fall of disease in the population – history of diseases • Community diagnosis – identification and quantification of health problems in a community in terms of mortality and morbidity rates and ratios, and identification of their correlates for the purpose of defining those individuals or groups at risk or those in need of health care. • Planning and evaluation – Planning is essential for rational allocation of limited resources. Evaluation is to know whether the measures undertaken are effective or not in reducing the frequency of disease or health problems.
- 47. • Evaluation of individual’s risks and chances – degree of risk in a population. Eg. Risk of lung ca in smokers and nonsmokers. • To identify syndromes • Completing the natural history of disease – entire spectrum of the disease • Searching for causes and risk factors – to identify causes and risk factors for a disease • To forecast future disease trends