C14 - Non-communicable Diseases Flashcards
What’s a NCD?
A non-communicable disease which cannot be transmitted from person to person.
They’re often long term or life lasting and progress slowly (chronic)
What are the four main types of non-communicable disease?
Cardiovascular disease
Cancer
Diabetes
Chronic respiratory diseases
What’s a risk factor?
A variable associated with an increased risk of disease.
What are the types of risk factor?
Hereditary- certain ethnicities show increased risk in type 2 diabetes.
Behaviour - smoking increases risk of lung cancer.
Other conditions - high blood pressure increases the risk of stroke.
What can be used to assess the strength of association between variables?
Statistical analysis
What are the various statistical tests?
Pairs t-test
Unpaired t-test
Spearman’a ranked correlation
Pearson’s correlation
Chi-squared test
Mann-Whitney U test
ANOVA test
What’s a t-test?
A statistical test requiring large sets of data (+25) including continuous variables and normal distribution.
It tests if the means of 2 sets of data are significantly different.
The t-test enables you to see whether two samples are different when you have data that are continuous and normally distributed.
The test allows you to compare the means and standard deviations of the two groups to see whether there is a statistically significant difference between them.
For example, you could test the heights of the members of two different biology classes.
What’s an unpaid t-test?
When the variables are separate from each other
E.g. Size of the leaf on the north and south side of a tree
What’s a paired t-test?
When the variables are related (or in pairs)
E.g. Width and length of a leaf
What is Spearman’s ranked correlation test?
A statistical test used to identify if one variable changes as another does.
It is used for data that DOES NOT have a normal distribution of data.
Results show a positive or negative correlation as well as strength of correlation.
E.g. Does biodiversity change as you get further from the path.
The Spearman’s rank correlation coefficient tests the relationship between two variables in a dataset; for example, is a person’s weight related to their height?
If there is a statistically significant relationship, you can reject the null hypothesis, which may be that there is no link between the two variables.
What’s Pearson’s correlation a.k.a the correlation coefficient test?
A statistical test to identify if one variable changes as another does.
It is used for data that DOES have a normal distribution of data.
Results show a positive or negative correlation as well as strength of correlation.
The Pearson correlation coefficient is used to measure the strength of a linear association between two variables, where the value r = 1 means a perfect positive correlation and the value r = -1 means a perfect negataive correlation.
What’s the chi-squared test?
A statistical test used to identify if the observed relationship is significantly different from the expected relationship.
E.g. Genetic frequencies and heterozygotes.
The chi-squared test is used with categorical data to see whether any difference in frequencies between your sets of results is due to chance. For example, a ladybird lays a clutch of eggs. You expect that all of the clutch will hatch, but only three-quarters of them do.
In a chi-squared test, you draw a table of your observed frequencies and your predicted frequencies and calculate the chi-squared value. You compare this to the critical value to see whether the difference between them is likely to have occurred by chance.
If your calculated value is bigger than the critical value, you reject your null hypothesis.
What’s the Mann-Whitney U test?
A statistical test similar to the t-test.
It is used when comparing ordinal data (i.e. data that can be ranked or has some sort of rating scale) that are not normally distributed.
Measurements must be categorical – for instance, yes or no – and independent of each other (e.g. a single person cannot be represented twice). For example, the Mann–Whitney U-test could be used to test the effectiveness of an antihistamine tablet compared to a spray in a group of people with hay fever.
To do this, you would split the group in half, then give each half a different treatment and ask each person how effective they thought it was. The test could be used to see whether there is a difference in the perceived efficacy of the two treatments.
What is epidemiology?
The study and analysis of patterns, causes and effects of health and disease conditions in defined populations.
It identifies the risk factors for disease and targets for preventive healthcare.
What’s a causal relation?
When one factor causes the other.
Correlation doesn’t imply causation however, if causal, there must be a correlation.
What are the 3 groups/types of risk factors?
Conditions
Behaviour
Hereditary
E.g. Stroke:
Conditions - increased age, diabetes, high blood pressure or cholesterol etc.
Behaviour - physical inactivity, excess alcohol or salt intake etc.
Hereditary - Sickle cell disease
What is a tumour?
A mass of abnormal cells which constantly develops and expands in size.
What are the 2 types of tumour?
Benign and Malignant
What is a benign tumour?
A tumour formed when cells divide too many times and tend to be slow growing and are located within a specific tissue.
They don’t break off and spread so aren’t normally life threatening but can cause damage if pressing on vessels or nerves.
They can be removed by surgery and don’t normally return e.g. moles and renal adenomas.
What is a malignant tumour?
A tumour which usually grows rapidly. Some cells can break off the primary tumour and spread to neighbouring tissues via lymph system or blood plasma (described as a metastatic tumour now classified as cancer)
When the primary tumour becomes metastatic and spreads to another location, this new tumour is called a secondary tumour.
