Clinical trials
Clinical trials
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Randomised-control trials (RCTs) are the bedrock of evidence-based medicine. They are the only way to conduct causal inference with confidence. This is because by prospectively allocating participants or clusters to treatment arms at random, the effects of idiosyncratic differences between the groups within each arm tend to equilibrate, allowing for accurate and reliable estimation of the effect of the treatments only. However, it is important that trials are designed and reported rigourously to minimise risk of bias and maximise generalisability to allow others to extrapolate results into clinical practice in different settings.
Treatment allocation in randomised-control trials
Treatment allocation in randomised-control trials
Across medicine and surgery, most RCTs allocate individual patients to treatment arms. However, in ophthalmology there is the option of treating one or two eyes per patient, complicating allocation. It is important that treatment allocation is consistent (controlled) in order to ensure that each intervention group is similar, facilitating fair comparisons.
We conducted a meta-research study (TAO-RCT) of all eye-related RCTs published over a 12-month period to explore the frequency of uncontrolled treatment allocation as well as how often treatment allocation is unclearly reported. 15% of the RCTs exhibited uncontrolled allocation, and the allocation pattern was unclear in 19% of RCTs.
To improve reporting and maximise the clarity and fairness of ophthalmological RCTs, we suggest that researchers use a simple nomenclature system as described in our article in Eye.
Endpoints in inherited retinal disease
Endpoints in inherited retinal disease
Inherited retinal diseases are the most frequent cause of irreversible blindness in working-age adults in the UK, and developing effective treatments has been an important research priority in recent years. Design of randomised-control trials to validate new treatments requires definition of endpoints which are how benefits to vision are measured. There are a plethora of conventional clinical endpoints and emerging anatomical, physiological, and functional biomarkers that may be selected.
In our review in Gene Therapy, we explore this wide range of proven and potential endpoints, and explore their strengths and weaknesses in the context of the diverse phenotypes caused by inherited retinal disease. There is no single endpoint that should be used in all trials, and investigators must instead carefully consider the natural history and visual function of the population in question, as well as the possible clinical benefits of effective treatment.
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