Health and disease Flashcards
What is the equation for incidence rate of a disease
Incidence rate = events / (people X time)
What are the units for incidence rate of a disease
Number of events, per person, per year
What is the incidence rate of a disease
It is the new events of a particular disease
What is prevalence of a disease
It is a measure of the existing cases of a disease.
What is the equation relating prevalence to incidence of a disease
Prevalence = incidence rate X length of disease
What is the incidence rate ratio
It compares the incidence rate of disease between two groups which can be useful in identifying the aetiology of a disease or the efficacy of a treatment.
What is the incidence rate ratio equation
Incidence rate ratio = observed rate in exposed group / observed rate in unexposed group. 1 = no difference between the two groups
What is a confounding factor
Is a type of systematic variation that independently act on both the exposure and the outcome of a disease
What is the standardised mortality ratio and what is it useful for
It is a ratio of mortality rate where age and sex confounding factors are removed, by comparing the observed / to the expected of the same age and sex bracket. The figure is usually multiplied by 100, where 100 represents parity between the two groups
What is doctor foster
A hospital guide for potential patients
What three things should be considered when making a target
Appropriateness of measure
Suitability of target level
Consequential effects
What is a census
A measure of the population through the simultaneous recording of demographic data by the government of a particular time, to a group of persons who live in a particular geography
Characteristics of a census
Run by government, defined area, simultaneous, universal, regular intervals
What does a census reveal
The population size, structure and characteristics
What are the 3 factors that affect the population size
Births, deaths, migration
What is the crude birth rate CBR and when is it used
Number of live births per 1000, to describe the impact of births on population size as compared to migration and deaths
What is the general fertility rate GFR
Number of live births per 1000 of the female population in the 15-44 year bracket. Used to compare fertility rates of women in different populations
What is the advantage of the general fertility rate over the crude fertility rate
The GFR only applies to the section of the population capable of giving birth
What is the total period fertility rate TPFR?
It is the sum of the fertility rate of women at each year of their fertile age.
What is the advantage of the TPFR
The TPFR averages the fertility rate over a lifetime, without being influenced by the number of women in each age group. Providing a value of the hypothetical number of children a woman would have. It is not influenced by the number of people at each age range. For example, excess hold people, with a lower overall birth rate, would skew the GFR
What is fecundity
The physical ability to reproduce
What is fertility
The realisation of the potential to reproduce
What are conceptions
The total number of births, miscarriages and abortions
What birth records are compulsory
Birth notification within 36 hours of birth, birth registration within 42 days
What are the compulsory ways to record death
Death certification by the doctor, death registration within 5 days by the realtime usually
What is the crude death rate
Number of deaths per 1000 of population
What is Age Specific Death Rate ASDR
Number of deaths per 1000 within a given age range
Why record death rates
Analyse patterns in death rates, deliver services, identify health problems, effects on the population
What is a sample
A representative group of a larger population
What is a sampling frame
A method to help you select a sample
What is the p value
The probability that an observation is true, given that the null hypothesis is also true.
What is the significance of a p-value less than 0.05 and what are the limitations
The result gives sufficient evidence to reject the null hypothesis, we are confident that the observation did not happen by chance.
However, this does not allow us to accept the alternative hypothesis.
Statistical significance depends on sample size, it is arbitrary and may not be clinically significant.
What is random variation
A number of samples can all vary in their nature, by the random effects of selecting the sample. Therefore they all have different individual qualities, but come from one central quality in the popualtion which is true and needs to be discovered
What is a confidence interval
The range within which you are (normally 95%) sure that the true popualtion value lies
How do you determine the 95% confidence interval using error factors
Upper limit = observed value X error factor
Lower limit = observed value / error factor
What is the error factor equation for a rate of standardised mortality ratio
Error factor = exponential (2 X ^^^[1/no of cases])
What is the error factor equation for a rate ratio?
Error factor = exponential (2 X ^^^[1/population A + 1/population B])
What is a cohort study
A study that identifies a group of people free of an outcome and follows them over time to see how their different exposures affect the outcome
What are the advantages of a cohort study
Can be done retrospectively as well as prospectively (concurrent).
Can look at risk factors that cannot be controlled experimentally, for ethical reasons, eg. Alcohol during pregnancy
You can obtain more detailed information especially in prospective studies as more exposures can be included.
You can study confounding issues
You can investigate causation, especially if there is a strong dose affect with the risk factor
What are person years in a cohort study
The amount of years that a person actively participated and was followed up in a study. Person years = number of people X length of study
