Choosing the right outcome is key to a clinical trial. Sometimes a #CompositeOutcome
- an outcome that combines more than one dimension into a single measure - is felt to be most appropriate. These can be useful but can be fraught with difficulty 1/8
#MethodologyMonday
One of the primary reasons for using a composite outcome is trial efficiency - you can get more events quickly compared to the individual components thus increasing precision and efficiency in sample size calculations 2/8
jamanetwork.com/journals/jama/…
However, the validity of a composite relies on consistency of the individual components -see Montori et al 3/8

bmj.com/content/330/74…
Montori et al also stress the need for both elements to be important to patients & suggest a set of questions to help with the interpretation of composite outcomes 4/8
Composite endpoints can be problematic & very difficult to interpret if the different components actually have different levels of importance to clinicians/patients 5/8
This is exacerbated if the events in the component of greater importance is small compared to the number of events in the components of lesser importance 6/8
bmj.com/content/334/75…
To accommodate for the situation where there is a hierarchy in the composite components, the “win ratio” method was developed by Pocock as a method to deal with it. 7/8
pubmed.ncbi.nlm.nih.gov/21900289/
As such care needs to be taken before deciding whether to use a composite and, if so, which one. A neat summary of the pros & cons is outlined in this paper by Sue Ross 8/8
sciencedirect.com/science/articl…

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More from @MarionKCampbell

Feb 6
Given the complexity of delivering clinical trials, they are a fertile ground to gain from #interdisciplinary thinking. For example, the field of trial #recruitment has already gained enormously from insights from other disciplinary approaches 1/7
#MethodologyMonday
A recent paper highlighted the use of #StatedPreference methods in this space. It showed aspects of trial design can affect recruitment 2/7

bmcmedresmethodol.biomedcentral.com/articles/10.11…
#StatedPreference methods eg discrete choice experiments are more commonly used by health economists to value and quantify aspects of health care but can be used to determine preference priorities in any domain 3/7

link.springer.com/article/10.216…
Read 7 tweets
Jan 9
It’s good to start a new year getting the basics right. It’s the same with methods; important not to slip into using common errors.The recent Xmas BMJ paper which showed the most common stats/methods errors is a great place to start 1/7
#MethodologyMonday

bmj.com/content/379/bm…
The BMJ stats editors highlighted the top 12 most common stats errors they come across. They are summarised in a neat infographic 2/7
All are important,but a couple particularly resonate. One is “dichotomania” (the term coined by Stephen Senn for this) where a perfectly good continuous measure eg blood pressure or weight is then arbitrarily dichotomised into two categories - good/bad; high/low etc 3/7
Read 7 tweets
Dec 12, 2022
Following the paper noted this week to have just added capital “T”s to a graph to depict standard errors 😱🤯, a short note on the importance of accurate data visualisation in any research report … 1/8
#MethodologyMonday
This was the tweet & thread which highlighted T-gate. There are lots of other issues with that paper, but data visualisation is a core element 2/8
The paper had attempted to use a #DynamitePlot (sometimes known as a Plunger Plot) to display the data. Even without adding T’s there are major issues with dynamite plots and frankly most statisticians would like them consigned to history! 3/8
Read 8 tweets
Nov 28, 2022
We are all being rightly encouraged to be #efficient in our trial design & conduct. Efficiency comes primarily through design choices … whether classic or more modern efficient designs … a few reflections below 1/7
#MethodologyMonday
A #crossover design can be highly efficient. Each person acts as their own control removing large element of variation, making the design more powerful. The outcome needs to be short term however & the intervention can’t have a long-standing effect 2/7
bmj.com/content/316/71… Image
This is particularly the case when a cluster design is also in play. A #ClusterCrossover design can majorly reduce the sample size requirements compared with a std cluster design. A good primer on this was published by @karlahemming and colleagues 3/7
bmj.com/content/371/bm… ImageImage
Read 7 tweets

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