3: Morbidity & Mortality Flashcards
Count
Simplest and most frequently used quantitative measure. Refers to number of cases of a disease or other health phenomenon being studied. Significant for rare diseases or symptom presentations.
Ratio
value obtained by dividing one quantity by another. Includes proportions, rates, and percentages. x/y, where x and y are independent factors
Proportion
States a count relative to the size of the group. x is contained in y. typically expressed as a percentage. can demonstrate the magnitude of a problem
Rate
A ratio that consists of a numerator and denominator in which time forms part of the denominator. Contains disease frequency, unit size of population, and time period during which an event occurs.
Prevalence
Number of existing cases of a disease or health condition in a population at some designated time. Provides an indication of the extent of a health problem.
Uses of Prevalence
- Describing the burden of a health problem in a population.
- Estimating the frequency of an exposure.
- Determining allocation of health resources such as facilities and personnel.
- DOES NOT GIVE RISK!!
Point Prevalence
ill at point in time/total # in group at point in time
Point Prevalence
ill at point in time/total # in group at point in time
Period Prevalence
ill during time period/average population during time period
Incidence
Number of new cases of a disease that occur in a group during a certain time period
Incidence Rate (Cumulative Incidence)
Describes the rate of development of a disease in a group over a certain time period.
Uses of Incidence Rate
- Help in research on etiology
- Estimate risk of developing a disease
- Estimate effects of exposure to a hypothesized factor of interst
Incidence Rate
new cases over time period/total population at risk over time period
Attack Rate (AR)
Alternative form of incidence rate. used for disease observed in a population for a short time period, usually infectious. Not a true rate because time dimension often uncertain. Can be used to find source of attack. AR= ill/ill+well x 100 (during a time period)
Attack Rate (AR)
Alternative form of incidence rate. used for disease observed in a population for a short time period, usually infectious. Not a true rate because time dimension often uncertain. Can be used to find source of attack. AR= ill/ill+well x 100 (during a time period)
Incidence Density
Incidence measure used when members of a population or study group are under observation for different lengths of time. Incidence Density=new cases during time period/total person-time of observation.
Interrelationship between Prevalence and Incidence
Prevalence is proportional to incidence rate x duration of disease
Interrelationship between Prevalence and Incidence
Prevalence is proportional to incidence rate x duration of disease
Crude Birth Rate
Used to project population changes; affected by number and age composition of women of childbearing age. Crude Birth Rate=live births/population size x 1,000
General Fertility Rate
Used for comparisons of fertility among age racial and socioeconomic groups. General Fertility Rate=live births/#women 15-44yrs x 1,000
Infant Mortality Rate
Used for international comparisons; high rate indicates unmet health needs and poor environmental conditions. Infant mortality=infant (0-365 days) deaths/live births x 1,000
Infant Mortality Rate
Used for international comparisons; high rate indicates unmet health needs and poor environmental conditions. Infant mortality=infant (0-365 days) deaths/live births x 1,000
Infant Mortality Rate
Used for international comparisons; high rate indicates unmet health needs and poor environmental conditions. Infant mortality=infant (0-365 days) deaths/live births x 1,000
Fetal Death Rate
Used to estimate the risk of death of the fetus associated with the stages of gestation. Fetal Death Rate=fetal deaths >20 weeks gestation/live births + fetal deaths >20 weeks gestation x 1,000
Fetal Death Rate
Used to estimate the risk of death of the fetus associated with the stages of gestation. Fetal Death Rate=fetal deaths >20 weeks gestation/live births + fetal deaths >20 weeks gestation x 1,000
Late Fetal Death Rate
fetal deaths >28 weeks gestation/live births + fetal deaths >28 weeks gestation x 1,000
Fetal Death Ratio
Measure of fetal loss relative tot he number of live births. Fetal Death Ratio=fetal deaths >20 weeks gestation/live births x 1,000
Fetal Death Ratio
Measure of fetal loss relative tot he number of live births. Fetal Death Ratio=fetal deaths >20 weeks gestation/live births x 1,000
Neonatal Mortality Rate
Reflects events happening after birth, primarily congenital malformations, prematurity, and low birth weight. Neonatal Mortality Rate= infant deaths
Postneonatal Mortality Rate
Reflects environmental events, control of infectious diseases, and improvement in nutrition. infant deaths (28-365 days)/live births - neonatal deaths x 1,000
Postneonatal Mortality Rate
Reflects environmental events, control of infectious diseases, and improvement in nutrition. infant deaths (28-365 days)/live births - neonatal deaths x 1,000
Perinatal Mortality Rate
Reflects environmental events that occur during pregnancy and after birth; it combines mortality during the prenatal and postnatal periods. late fetal deaths + infant deaths
Perinatal Mortality Rate
Reflects environmental events that occur during pregnancy and after birth; it combines mortality during the prenatal and postnatal periods. late fetal deaths + infant deaths
Perinatal Mortality Ratio
late fetal deaths + infant deaths
Maternal Mortality Rate
Reflects health care access and socioeconomic factors; it includes maternal deaths resulting from causes associated with pregnancy and puerperium (during and after childbirth). maternal deaths/ live births x 100,000
Crude Rates
observed differences in crude rates may be the result of systematic factors (i.e. sex, or age distributions) within the population rather than true variation in rates. Corrected by constructing specific and adjusted rates.
Specific Rates
Refer to a particular subgroup of the population defined in terms of race, age, sex, or single cause of death or illness. Much better indicators of risk than crude rates.
Cause-Specific Rate
mortality or frequency of given disease/population size x 100,000
Cause-Specific Rate
mortality or frequency of given disease/population size x 100,000
Proportional Mortality Ratio (PMR)
Indicates relative importance of a specific cause of death; NOT a measure of the risk of dying of a particular cause. mortality due to specific cause/mortality due to all causes x 100
Age-Specific Rate (Ri)
common factor for rate adjustment is age. cases in age group/total in age group x 100,000
Age-Specific Rate (Ri)
common factor for rate adjustment is age. cases in age group/total in age group x 100,000
Adjusted Rates
Summary measures of the rate of morbidity and mortality in a population. Direct and Indirect Methods.
Direct Method
Application of an observed rate of disease in a population to a standard population. Specific rates in a population needs to be known. Rates can be standardized using year 2000 data as the standard. Provides a way to compare rates from one year to another.
Indirect Method
Age-specific death rates of the population for standardization are unknown or unstable. construct a SMR
Standardized Mortality Ratio (SMR)
observed deaths/expected deaths x 100
SMR=1.0
observed mortality is not unusual
SMR=2.0
death rate in study population is two times greater than expected.
