Population Study Flashcards
What is confidence interval?
→‘estimates’ or ‘means of something of interest’ is defined by the 95%
confidence interval
What does a narrow confidence interval mean?
→ precise estimate
What is 95% reference range?
→A measure of the spread of the continuous numerical data only
What is 95% confidence interval?
→A measure of the precision of a sample estimate (95% probability
that interval contains the true population value for any parameter of
interest)
What is the formula for reference range?
→Mean +/- 2 Standard Deviations
What is the formula of confidence interval?
→Mean +/- 2 Standard Errors
What are the phases of clinical trials?
→Preclinical →Phase 1- 20-80, safety study →Phase 2 100-300, side effects and effectiveness →Phase 3 1000-3000 people →Phase 4- long term side effects
What are the objectives of Phase 1 study?
→To assess a safe & tolerated dose
- To see if pharmacokinetics differ much from animal
to man - To detect any predictable toxicity
What demographic is excluded from Phase 1 studies?
→women of child bearing age
→children
What is the inclusion criteria for Phase 1 study?
→Uniformity of subjects: age, sex,
nutritional status
Which group of people are involved in Phase 2 drugs?
→20 – 200 patients with relevant disease
What are the objectives of Phase 2?
→Therapeutic benefits & ADRs evaluated
→Establish a dose range to be used in late phase
→Single blind [Only patient knows] comparison with standard drug
→6 months to 2 years [ 35% success rate]
Who performs Phase 3?
→Clinicians in the hospital
What is the target population in Phase 3?
→250 – 1000 patients
What are the objectives of Phase 3?
→Vigilant recording of all adverse drug reactions
→ Rigorous statistical evaluation of all clinical data
→up to 5 years [25% success]
Describe Phase 4
→No fixed duration / patient population
→Starts immediately after marketing
→Report all Adverse reactions
What are the objectives of Phase 4?
→rare ADRs
→ Drug interactions
→Also new uses for drugs
Who are the participating parties in clinical trials?
→Patient / Healthy volunteer
→Clinical Pharmacologist, Clinical
Investigator & team: [Qualified and
competent]
→ Institution where trials are held :
[Approval required]
→Research Ethics Committee (REC) or
Institutional Ethical Committee
→Sponsor
→Regulatory Authorities:
What are the roles of the Sponsor in clinical trials?
→Pays for all expenses;
→ Appoints competent investigators,
→Ships all drugs for the trial,
→ Files all papers to legal / regulatory authorities,
Describe cohort studies
→A group of subjects followed over time
→Purpose: defining the incidence and investigating potential causes of a
condition (incidence)
→Can be prospective – investigator chooses a sample group and measures
characteristics in each subject over a period of time that might predict
outcomes
→Can be retrospective – same as prospective, except all data collection and
follow-up has happened in the past; only possible if adequate data is
available
What are the strengths of experimental studies?
→Can demonstrate causality
What are the types of interventions?
→behavioural
→drug
→device
Compare parallel and crossover designs
→Parallel: simple treatment versus placebo
→Crossover: Comparison of treatment and placebo made in each subject
→Allows each subject to be a control such that treatments can be assessed in each subject (advantage)
→Period effects, carry-over effects, sequence effects all need to be considered (disadvantage)
→Longer duration and more complex stats (disadvantage)
→Smaller study sample required for power (advantage)
Describe the timeline of a trial
→• 1) recruitment (adverts)
• 2)Screening (inclusion/exclusion criteria)
• 3) Informed Consent after patient information sheet
• 4)Randomisation/blinding
• 5) Protocol visits step by step procedures (deviations have to be communicated to sponsor and ethics research committee)
• 6) Reports of adverse events
• 7) Store investigatory product
• 8)Subject compensation
• 9) Electronic data collection
• 10) Study closure
Describe informed consent
→Voluntary
• Explained in simple nontechnical language
• Translated in the native language of the subject
• Comprehensive information regarding the trials
• Benefit of new therapy over existing ones
• Alternative treatments available
• All possible adverse reactions
• Freedom to withdraw from the trial
What is a confounder?
→Associated with the exposure of interest
→Independently associated with the risk of developing the outcome
What can confounding lead to?
→under- or over-estimation of a real association between Exposure and Outcome
→Produce a spurious positive or negative association between Exposure and Outcome
What can be calculated from the results of a cohort study?
→Risk ratio or relative risk (RR)
What can be interpreted in RR>1?
→increased risk in exposed group compared to unexposed group
