Mortality Indicators and Morbidity Indicators Dr. MUSTAQUE AHMED MBBS,MD(COMM MEDICINE),FELLOWSHIP

Objective of the class Enumerate various mortality indicators Describe some important mortality indicators. To describe the morbidity measurement To understand the incidence and prevalence Uses of morbidity data.

Mortality is a term which means “death” or describes death and related issues MORTALITY RATES 1. CRUDE DEATH RATE 2. SPECIFIC DEATH RATE 3. CASE FATALITY RATE 4. PROPORTIONAL MORTALITY RATE 5. SURVIVAL RATE 6. ADJUSTED (OR) STANDARDIZED RATES

CRUDE RATE 1. Crude Death Rate(CDR)- Annual number of deaths per 1000 mid year population.

SDR TB = NO OF DEATHS FROM TB IN YEAR X 1000 Specific Death Rates used especially when we have to throw light on etiology Specific to a cause eg: specific deaths due to tuberculosis ,,,HIV/AIDS SDR TB = NO OF DEATHS FROM TB IN YEAR X 1000 MID YEAR POPULATION

PROPORTIONAL MORTALITY RATE 1.PMR expresses the no. Of deaths due to a particular cause per 100 total deaths. Note : PMR is computed usually for a communicable diseases & for specific disease of major public health importance ex:cancer,CAD

Case Fatality Rate CFR = TOTAL NO.OF DEATHS DUE TO DISEASE X 100 Represents Killing power of a disease (how fatal a diseases can be ) It is a ratio of deaths to cases Used For acute cases. Expressed in percent. Cannot be used for chronic diseases CFR = TOTAL NO.OF DEATHS DUE TO DISEASE X 100 NO OF CASES DUE TO SAME DISEASE

Survival rate Expressed in percent. Method of describing prognosis in certain disease conditions Can be used as a yard stick for the assessment of standards of therapy Specially useful in cancer studies Expressed in percent. total no. of patients alive after 5 years = ─────────────────────× 100 total no. of patients diagnosed or treated

Adjusted or standardized rates To compare the death rates of two populations with different age- composition Most common method of adjustment are Direct standardization Indirect standardization For standardizing we need to have a standard population whose age and sex composition is known. Standard population is defined as one for which the numbers in each age & sex groups are known. National population is usually taken as standard population Direct standardization is used whenever stable stratum-specific rates are available Indirect standardization is used when stratum-specific rates are unavailable or unstable because of small numbers

Direct standardization A standard population is chosen where the numbers of each age and sex group are known. Apply to the standard population, the age-specific rates of the population whose crude death rate is to be adjusted For each age group, an expected no. of deaths in the standard population is obtained These are added together for all the age groups, to give the total expected deaths

Specific death rates/1000 by age for a city X Expected deaths and standardized death rate

Indirect standardization The specific death rates of the standard population are applied to the respective age groups of the populations of the areas to be compared Standardized mortality rate is standardized for age

Measurement of Morbidity It is defined as any departure, subjective or objective, form a state of physiological well being It is known by different names like illness, sickness. Morbidity could be measured in terms of - persons who were ill ------------------ (frequency) - illnesses that these person experienced ---------(severity) - Duration of these illness-----------------------------(duration) Disease frequency is measured by incidence and prevalence Duration of illness is measured by the disability rate Severity is measured by the case fatality rate

Morbidity rates for assessment of ill-health Incidence and prevalence. Notification rates. Attendance rates at OP depts. Admission, readmission & discharge rates Duration of stay in hospital. Spells of sickness or absence from work or school.

INCIDENCE Def: Number of NEW cases occurring in a defined population during a specified period of time. An incidence rate includes three important elements: 1. a numerator -- the number of new cases 2. a denominator -- the population at risk 3. time -- the period during which the cases occurred. no. of new cases of specific disease during a given time period INCIDENCE = X 1000 population at risk during that period

Special incidence rates Attack rate- it is used only when population is exposed to risk for a limited period of time such as during an epidemic No. of new cases of a specified disease during a specified time interval ─────────────────────--------------─ × 100 Total population at risk during the same interval Reflects the extent of epidemic. Expressed in percent. Secondary attack rate- No. of exposed persons developing the disease within the range of the incubation period ────────────────-----------------------------------─ ×100 Total no. of exposed contacts Useful in epidemiology of communicable diseases.

PREVALENCE All current cases (NEW+ OLD) existing at a given point or period of time in a given population. Obtained from cross-sectional studies. Prevalence is two types: point prevalence period prevalence

Factors influencing prevalence Increased by: Decreased by: - longer duration - shorter duration - prolongation of life - high case-fatality - increase in new cases - decrease in new cases - out-migration of healthy - in-migration of healthy I I Baseline Prevalence Pot Prevalence=IncidenceXDuration Discuss using TB

Calculation of Incidence and prevalence

Relationship between incidence and prevalence Prevalence(P) = incidence(I)×mean duration(D) The longer the duration of the disease, greater is its prevalence If the disease is acute, then prevalence will be low compared with the incidence

Uses of prevalence Uses of incidence To estimate the magnitude of health / disease problems in the community. Useful for administrative and planning purposes e.g. hospital beds, manpower needs. Uses of incidence control of disease For research into etiology and pathogenesis, distribution of diseases. Efficacy of preventive and therapeutic measures Uses of morbidity data Describe the extent and nature of the disease load in the community.