# prevalence

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## rate

[rāt]the speed or frequency with which an event or circumstance occurs per unit of time, population, or other standard of comparison.

**adjusted rate**a fictitious summary rate statistically adjusted to remove the effect of a variable, such as age or sex, to permit unbiased comparison between groups having different compositions with respect to these variables. See also crude rate and specific rate.

**attack rate**in the analysis of acute outbreaks of disease, the proportion of persons who are exposed to the disease during the outbreak who do become ill.

**basal metabolic rate**an expression of the rate at which oxygen is utilized in a fasting subject at complete rest as a percentage of a value established as normal for such a subject. Abbreviated BMR.

**birth rate**the number of live births in a geographic area in a defined period, usually one year, relative to some specified population. For the crude birth rate, it is the average total population or the midyear population in the area during the period. Specific birth rates for subsets of the population may also be calculated, for example, an age-specific birth rate is limited to the population of females of a defined age range.

**case fatality rate**the number of deaths due to a specific disease as compared to the total number of cases of the disease.

**crude rate**one giving the total number of events occurring in an entire population over a period of time, without reference to any of the individuals or subgroups within the population. See also adjusted rate and specific rate.

**death rate**the number of deaths in a certain period of time divided by the total of a given population. The

*crude death rate*is the ratio of the number of deaths in a geographic area in one year divided by the average population in the area during the year. The

*age-specific death rate*is the ratio of the number of deaths occurring in a specified age group to the average population of that group. The

*cause-specific death rate*is the ratio of the number of deaths due to a specified cause to the average total population. Called also mortality rate.

**DEF rate**an expression of dental caries experienced in primary teeth, calculated by adding number of those requiring filling (

*D*), decayed teeth requiring extraction (

*E*), and those that have already been successfully filled (

*F*); missing primary teeth are not included in the calculation.

**DMF rate**an expression of the condition of the permanent teeth based on the number of teeth decayed, missing (or indicated for removal), and filled or bearing restorations. It is calculated by adding the number of carious permanent teeth requiring filling (

*D*), carious ones requiring extraction (

*Mr*), ones previously extracted because of caries (

*Mp*), and permanent teeth (

*F*).

**dose rate**the amount of any therapeutic agent administered per unit of time.

**erythrocyte sedimentation rate**(ESR) see erythrocyte sedimentation rate.

**fatality rate**the death rate in a specific group of persons simultaneously affected by some event or circumstances, such as a natural disaster.

**fertility rate**a measure of fertility in a defined population over a specified period of time, usually one year; particularly the general fertility rate, but also including more specific rates such as those for females of a given parity or a particular age range or that describing the completed rate for females who have finished childbearing.

**fetal death rate**the ratio of the number of fetal deaths in one year to the total number of both live births and fetal deaths in that year.

**five-year survival rate**an expression of the number of survivors with no trace of a given disease five years after each has been diagnosed or treated for the disease.

**flow rate**flow (def. 2).

**forced expiratory flow rate**forced expiratory flow.

**general fertility rate**the most widely used measure of fertility; the number of live births in a geographic area in a year per 1000 women of childbearing age, which is usually defined as age 15 to 44 years.

**glomerular filtration rate**an expression of the quantity of glomerular filtrate formed each minute in the nephrons of both kidneys, calculated by measuring the clearance of specific substances, e.g., inulin or creatinine.

**growth rate**an expression of the increase in size of an organic object per unit of time.

**heart rate**the number of contractions of the cardiac ventricles per unit of time (usually per minute).

**incidence rate**the risk of developing a particular disease during a given period of time; the numerator of the rate is the number of new cases during the specified time period and the denominator is the population at risk during the period. Compare prevalence r.

**infant mortality rate**the ratio of the number of deaths in one year of children less than one year of age to the number of live births in that year.

**intrinsic rate**in cardiac pacing terminology, the heart rate unaided by an artificial pacemaker, expressed in beats per minute (bpm). See also cycle length.

**maternal mortality rate**a rate in which the numerator is the number of maternal deaths ascribed to puerperal causes in one year; the number of live births in that year is often used as the denominator, although to make a true rate the denominator should be the number of pregnancies (live births plus fetal deaths). Called also puerperal mortality rate.

**maximal expiratory flow rate**(MEFR) maximal expiratory flow.

**maximal midexpiratory flow rate**(MMFR) maximal midexpiratory flow.

**mendelian rate**an expression of the numerical relations of the occurrence of distinctly contrasted mendelian characteristics in succeeding generations of hybrid offspring.

**metabolic rate**an expression of the amount of oxygen consumed by the body cells.

**mortality rate**death rate.

**neonatal mortality rate**the ratio of the number of deaths in one year of children less than 28 days of age to the number of live births in that year.

**paced rate**in cardiac pacing terminology, the rate of pulses of an artificial pacemaker, expressed as pulses per minute (ppm). See also cycle length.

**perinatal mortality rate**the ratio of the number of the sum of fetal deaths after 28 or more weeks of gestation (stillbirths) and deaths of infants less than 7 days of age in one time period and population to the sum of the number of live births and fetal deaths after 28 or more weeks of gestation (stillbirths) in that same time period and population.

**postneonatal mortality rate**the ratio of the number of deaths in a given year of children between the 28th day of life and the first birthday relative to the difference between the number of the live births and neonatal deaths in that year; the denominator is sometimes simplified, less correctly, to the number of live births. The ratio is sometimes approximated as the difference between the infant mortality rate and the neonatal mortality rate.

**prevalence rate**the number of people in a population who have a disease at a given time; the numerator is the number of existing cases of disease at a specified time and the denominator is the total population. Time may be a point or a defined interval, and is traditionally the former if unspecified. Compare incidence r.

**puerperal mortality rate**maternal mortality r.

**pulse rate**the rate of the pulse, measured as number of pulsations in an artery per unit of time; normally between 60 and 80 per minute in an adult.

**respiration rate**the number of inhalations and exhalations per unit of time, usually measured by observation of chest movements and averaging 16 to 20 per minute in an adult.

**sedimentation rate**the rate at which a sediment is deposited in a given volume of solution, especially when subjected to the action of a centrifuge; see also erythrocyte sedimentation rate.

**slew rate**in cardiac pacing, the rate, expressed in units of mV/msec, at which an R wave reaches peak amplitude; it represents the maximum rate of change of amplifier output voltage.

**specific rate**a rate that applies to a specific demographic subgroup, e.g., individuals of a specific age, sex, or race, giving the total number of events in relation only to that subgroup. See also adjusted rate and crude rate.

**stillbirth rate**fetal death rate.

## prev·a·lence

(prev'ă-lĕns),*Do not confuse this word with incidence.*

The number of cases of a disease existing in a given population at a specific period of time (

*period prevalence*) or at a particular moment in time (*point prevalence*).## prevalence

/prev·a·lence/ (prev´ah-lins) the number of cases of a specific disease present in a given population at a certain time.## prevalence

(prĕv′ə-ləns)*n.*

**1.**The condition of being prevalent.

**2.**

*Medicine*The total number of cases of a disease in a given population at a specific time.

## prevalence

[prev′ələns]

Etymology: L,

*praevalentia,*a powerful force(in epidemiology) the number of all new and old cases of a disease or occurrences of an event during a particular period. Prevalence is expressed as a ratio in which the number of events is the numerator and the population at risk is the denominator. See also rate.

*prevalent,**adj.*## prevalence

Epidemiology(1) The number of people with a specific condition or attribute at a specified time divided by the total number of people in the population.

(2) The number or proportion of cases, events or conditions in a given population.

Statistics

A term defined in the context of a 4-cell diagnostic matrix (2 X 2 table) as the amount of people with a disease, X, relative to a population.

Veterinary medicine

(1) A clinical estimate of the probability that an animal has a given disease, based on current knowledge (e.g., by history of physical exam) before diagnostic testing.

(2) As defined in a population, the probability at a specific point in time that an animal randomly selected from a group will have a particular condition, which is equivalent to the proportion of individuals in the group that have the disease. Group prevalence is calculated by dividing the number of individuals in a group that have a disease by the total number of individuals in the group at risk of the disease. Prevalence is a good measure of the amount of a chronic, low-mortality disease in a population, but is not of the amount of short duration or high-fatality disease. Prevalence is often established by cross-sectional surveys.

## prevalence

Epidemiology**1.**The number of Pts with a specific condition at a specified time divided by the total number of people in the population.

**2.**The number or proportion of cases, events or conditions in a given population at a given time. See Disease prevalence, Period prevalence. Cf Incidence Pharmacology The proportion of positives among the agents tested. See Two-by-two table.

## prev·a·lence

(prev'ă-lĕns)The number of cases of a disease existing in a given population at a specific period of time (i.e., period prevalence) or at a particular moment in time (i.e., point prevalence).

## prevalence

The number of people suffering from a particular disease at any one time in a defined population. Prevalence is usually expressed as a rate per 100,000 of the population. Compare INCIDENCE.## prevalence

The number of people with a disease or condition in a given population at a specific time, either a point in time (

**point****prevalence**) or over a period of time (**period prevalence**).*Example*: the prevalence of keratoconus in Olmsted County, Minnesota on the third of December 1982 was 54.5 per 100 000 population.*See*incidence.## prev·a·lence

(prev'ă-lĕns)Number of cases of a disease existing in a given population at a specific period of time or at a particular moment in time.

## prevalence

the total number of cases of a specific disease in existence in a given population at a certain time, i.e. prevalence. See also cross-sectional study.

**instantaneous prevalence**

the prevalence at a particular moment. Called also spot prevalence.

**period prevalence**

the number of cases of a disease which occur during a specified period, e.g. annual, lifetime, as a percentage of the total or average total number of animals at risk during the same period.

**point prevalence**

as for period prevalence (above) except that the assessment is made at a specific point in time rather than over a period, a rather impractical exercise.

**prevalence rate**

the number of patients who have the disease at a particular time, divided by the population at risk of having the disease at that time.

**spot prevalence**

see instantaneous prevalence (above).

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