Aug. 25 (UPI) -- Food and Drug Commissioner Stephen Hahn said criticism about his interpretation of the benefits of using convalescent plasma to treat coronavirus patients is "entirely justified."
He offered some clarity on his remarks late Monday, one day after he, along with President Donald Trump, announced the FDA's emergency use authorization for plasma to be used in treatments for COVID-19.
"I have been criticized for remarks I made Sunday night about the benefits of convalescent plasma. The criticism is entirely justified. What I should have said better is that the data show a relative risk reduction not an absolute risk reduction," Hahn tweeted.
During Sunday's announcement, Hahn and Health and Human Services Secretary Alex Azar touted what they said was the plasma's success at treating patients. They repeated one statistic in particular -- that there was a 35% increase in survival with patients under 80 who were not on artificial respiration.
"Many of you know I was a cancer doctor before I became FDA commissioner. And a 35% improvement in survival is a pretty substantial clinical benefit. What that means in -- and if the data continue to pan out -- 100 people who are sick with COVID-19, 35 would have been saved because of the admission of plasma," Hahn said.
That figure was not born out in the Mayo Clinic data released Aug. 12 and cited by the FDA. The observational study was not peer-reviewed, nor did it compare figures to a control group.
As part of the study, the Mayo Clinic compared the seven-day mortality rates of people given higher levels of antibodies in plasma treatment (8.9%) versus those given lower levels of antibodies (13.7%).
With the relative risk reduction doctors observed a 35% reduction in the number of people who died with the higher levels of plasma treatment versus those with the lower levels of plasma treatment.
So instead of 35 people out of 100 surviving because they received plasma treatment, the Mayo Clinic data actually shows 5 people out of 100 surviving because of the higher levels of plasma treatment.
Peter Lurie, a former FDA official and president of the Center for Science in the Public Interest, said Sunday's announcement was more "hype than hope" and warned the emergency authorization could draw people away from clinical trials. He praised Hahn for admitting "his mistake when he overstated the benefits of convalescent plasma for COVID-19."
"But it was part of a press conference that relied on exaggeration, non-randomized trials, cherry-picked data and subset analyses."
Hahn said in his Monday night tweet that the FDA was not under political pressure to authorize the emergency use of convalescent plasma.
"The decision was based on significant data from the Mayo Clinic and other reliable sources, plus a century of experience with convalescent plasma," he tweeted.
"We at FDA do not permit politics to enter into our scientific decisions. This happens to be a political season but FDA will remain data driven. On behalf of FDA's 18,000 career employees, I want to reassure the American public about this commitment."
According to a global tracker by Johns Hopkins University, there have been 5.8 million confirmed cases of COVID-19 in the United States and more than 178,000 deaths.