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http://www.virology.ws/2018/01/17/trial-by-error-professor-crawleys-bogus-buzzfeed-claims/
Trial By Error: Professor Crawley’s Bogus BuzzFeed Claims
17 JANUARY 2018
By David Tuller, DrPH
Tom Chivers’ terrific article on the Lightning Process and Professor Esther Crawley’s SMILE trial in the Archives of Disease in Childhood has received a lot of attention and comment. I wanted to respond to the short sections in which Professor Crawley seeks to justify her methodological choices. Here are the relevant passages:
In the highest-quality medical trials, subjects are “blinded” – they don’t know whether they’re getting the treatment that’s being tested, or what it’s being tested against. It helps stop the results being biased in favour of the treatment. If you can’t blind the trial, said [Professor Jonathan] Edwards, then it’s important to ensure that you measure something that can’t be affected by patients’ perceptions. “You can have an unblinded trial and measure everyone’s blood sodium concentration at the end,” he said. “They can’t do anything to their sodium concentration, so it doesn’t matter if they know whether they’re getting the treatment or not.
“And the other way around is fine: If you blind everything so they patients don’t know if they’ve had the treatment, then you can use a subjective measure. But you can’t have an unblinded trial and a subjective outcome.” But the SMILE trial was unblinded, and Edwards also pointed out that the primary outcome that was measured was changed from an objective measure, school attendance, to a questionnaire. Edwards said such self-reported measures are often prone to bias, as subjects give the answers they think they are expected to give. For that reason, he believes, the trial is “useless”.
In response, Crawley said “all the outcomes were collected as planned, but children didn’t like our recommended primary outcome, school attendance, so we used disability.” She added that the primary outcome measure change was made, and reported, before results were collected.