Week 8 Lecture: Clinical Trials (both the lecture slides & part two recording) Flashcards
What is a clinical trial, as defined why the WHO?
‘any research study that prospectively assigns human participants or groups of humans to one or more health-related interventions to evaluate the effects on health outcomes’.
What are prospective studies in health research?
a study or clinical trial in which participants are identified and then followed forward in time.
What are examples of health-related interventions?
- experimental drugs
- cells and other biological products
- vaccines
- medical devices
- surgical and other medical treatments and procedures
- psychotherapeutic and behavioural therapies
- health service changes
- preventive care strategies and
- educational interventions.
- diagnostic and screening tests
What are some examples of outcome markers? (how to measure progress in a field)
- Drugs – mortality or markers of recovery
- Vaccines – protection from disease
- Medical devices – lower rate of revision surgery over time or
better function. - Health Service Changes – higher rates of satisfaction or reduced
waiting times. - Preventive care strategies – reduced injury or disease rates
- Diagnostic and screening tests – sensitivity and specificity
What are the benefits of clinical trials?
Methodology is rigorous and the results are generally trusted.
Clinical trials offer patients access to medications and services that are not yet available in the open market. This is particularly important for difficult-to-treat patients.
Provide an overview of the history of clinical trials
562 BC King Nebuchadnezzar of Babylon conducted the first documented clinical trial / scientific research used to inform public health: (this part is just for interest, don’t have to memorise) he compared the health of those who ate meat/alcohol (c`ontrol as this was the diet by law) and legumes/water (outlaws were vegetarian) - then realised that the vegetarian diets yielded healthier people (so he changed the law to allow people to be legally vegetarian)
1747: Dr James Lind Britain - cured scurvy through lemons
1863 Austin Flint - first placebo controlled trial (used herbal remedy as the placebo for rheumatism)
1940s Philip Hart - first double blind controlled trial - patulin for common cold (2 placebo, 2 patulin groups, double blinding)
1946 Bradford Hill - first randomised controlled trial - Streptomycin in pulmonary tuberculosis by MRC of the UK; introduced randomised allocation order (random sampling numbers) and also allocation concealment.
Outline the Salk vaccine clinical trials (case study)
Context: to find polio vaccine
In 1935, John Kolmer (trialled the live vaccine) and Maurice Brodie (trialled a formaldehyde-killed vaccine) failed clinical trials.
In 1952, Jonas Salk conducted a clinical trial of his polio vaccine (‘killed’) - sequentially.
Phase I - on a small group of adults and children
Phase II - 4000 primary school children
Phase III - 1.8 million people - 1.2 nothing, 440000 vaccine, 210000 placebo.
Was effective against various forms of polio -> licensed -> cases fell.
Phase IV - post-release monitoring + safety
Outline the Salk vaccine case of post-licensing safety
In 1955 mass vaccination commenced but reports of patients contracting paralytic polio about a week after being vaccinated with Salk polio vaccine. Discovered that two laboratories had not killed the virus adequately. 250 cases of polio had occurred. After this all vaccine lots were tested before release.
List 10 hallmarks of a competent clinical trial
- A clear statement of the aims of the investigation with stated hypotheses.
- Methods include strategies to minimize bias
- Personnel are led by experienced trialist
- Good Governance – competence/safety
- An appropriate outcome measure or endpoint (One primary ‘endpoint’ or multiple primary endpoints? Direct ‘clinical’ endpoints or indirect ‘surrogate’ endpoints?)
- Involvement of a statistician/methodologist
- Stopping rules
- Adequately powered
- A priori analysis plan
- Realistic recruitment rates based on evidence.
What should a good aim contain?
(Aim should include Population, Intervention, Comparison, Outcome)
List five types of bias in clinical trials
- Selection bias
- Performance bias
- Detection bias
- Attrition bias
- Reporting bias
What is selection bias? What is a strategy to prevent it?
What it is: the introduction of systematic differences between baseline characteristics of the groups that are being compared.
Strategy: Randomization prevents selection bias in the way it allocates interventions to participants ensuring the highest likelihood of equivalence between groups.
What is detection bias? What is a strategy to prevent it?
Detection bias refers to systematic differences between groups in how outcomes are determined.
Strategy: Blinding of outcome assessors can reduce the risk that knowledge of the intervention rather than the intervention will affect the measure.
e.g. Postoperative pain measurement (0-10) might be sensitive to suggestion – “are you sure?”
What is performance bias? What is a strategy to prevent it?
Performance bias refers to systematic differences between the care or exposure that each group experiences.
Strategy: Blinding of the participant and personnel ensures that the compared groups receive a similar amount of attention, treatment and investigations. This can be very difficult in surgical trials but has been done. Single, double, triple, quadruple blinded
What is attrition bias? What is a strategy to prevent it?
Attrition bias refers to systematic differences between groups in withdrawals from a study.
Strategy: Intention to treat analysis. Because anything that happens after randomisation can affect the participant,it is important that all patients are analysed in the groups to which they were allocated.
What is reporting bias? What is a strategy to prevent it?
Reporting bias refers to systematic differences between between reported and unreported findings.
Statistically significant differences between intervention groups are more likely to be reported than non-significant differences.
Strategy: Trial Registries have been designed to ensure that data is not buried AFTER the trial is completed.
What does good governance mean? What are three phases of good governance?
Good governance means that the trial is optimized for successful completion and protection of the participants.
Phases:
- Well developed idea and argument.
- Ethics approvals
- Facilities budget, insurance, legislative compliance and
contracts.
List factors to consider as part of governance, related to accountability and risk management
- Finance – study budget (site fees, HREC and RGO approvals,
study visit costs, participant reimbursements) - Insurances
- Legislation
- Intellectual property
- Contracts/ Agreements
- Monitoring protocol amendments/ serious adverse events
- Protocol deviations
- Regular Reporting