Clinical Trials of Treatments For Heart Disease Flashcards
Define intervention
allocation of participants to treatment or control group (untreated,standard therapy,placebo)
What is an intervention study?
experiment where an intervention is
administered to evaluate its efficacy + safety by observing/measuring how participants respond
aka experimental study/clinical trial RCT
Define random allocation/randomisation
individuals allocated randomly to each treatment/control group + assignment of patients to group is independent of allocation of other patients
Why random allocation?
Avoids allocation bias
What’s the difference in health outcomes between
intervention + control groups is attributed to?
Intervention
What’s the placebo effect?
cure/alleviation of symptoms after an intervention which patient believes to be effective against the ailment but completely
neutral (sugar pill), effects based on
person’s own self-healing
capacity, which’s triggered by belief that they’re receiving active medication
Why do blinding in intervention studies?
Prior expectations of trial participant or observer may influence results
Diff between double vs single blind?
double: neither patient + observers / researchers know which group
patient allocated
single: either patient
or observers don’t know which group patient allocated
What’s parallel group?
Who’s eligible to participate in trial must be clearly defined, treatment + control groups only take 1 treatment then assess outcome (n)
What’s cross-over study?
Treatment + control swap then assess outcome
Describe eg of contingency table
Treatment vs placebo death YES/NO to find if no association
(placebo/total)xYES death
equal to
(treatment/total)xYES death
What are the features of Chi squared test?
Test compares O+E
(under Ho) counts between groups
• 2 categorical variables
• Each variable has 2 or more levels
• Data tabulated in contingency table as counts of individuals by level of each variable
• Validity: 80% expected frequencies > 5 and all > 1
• Gives P-value
