Flashcards in L31. Clinical Trials in CVD Deck (10):

1

## What are clinical trials?

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Longitudinal Studies

Assess whether an INTERVENTION changes the incidence of an outcome

Must always include a CONTROL group

They are GOLD STANDARD for evidence of causality

2

## What are the key outcomes of clinical trials?

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RELATIVE:

Relative Risks

Hazard Ratios

ABSOLUTE:

Absolute risk/rate reduction

Number needed to treat

3

## What is a major method to reduce confounding?

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Randomisation of subjects into each arm of the trial

Can also match by confounders

4

## What is blinding? What does it deal with?

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Blinding is a non-awareness of intervention allocation at multiple levels (subjects, assessors and examiners) for single or double blinding

This is to reduce information bias

5

## What is intention-to-treat analysis? What does it deal with?

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Treating every subject regardless of what they ended up doing (Eg. switching drugs or dying or dropping out of the study) were initially assigned to

Minimises selection bias and gives a conservative estimate of the results

6

## What is a hazard?

###
A rate that is continuously updated

Gives the instantaneous rate of incidence that gives exactly when events occur

Eg. Hazard for outcome is 10/1000 in one week then 15/990 in the next week

7

## What is the hazard Ratio?

###
A specific type of Relative Risk

It is a ratio of Hazard of intervention: Hazard Control

It gives the probability of an outcome in intervention group at any given point in time

8

## What is survival analysis?

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Is a measure of the outcomes and their time of occurance giving a "time to event" measurement

Eg. Survival curves

9

## What is the number needed to treat analysis?

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The number of people needed to undergo the intervention in order to stop the outcome occurring in just one person.

Marks the EFFICIENCY of the intervention

NNT = 1 / absolute risk or rate raduction

10