The FDA itself did not do the kind of meta-analysis that produced the journal report, Wolfe said, but the evidence that the products caused harm should have been evident by the year 2000, he said.
"In the eight countries where there are clinical trials, if they had been aware of the cumulative picture, they would not have allowed the trials to go forward," he said.
The FDA "does not concur that a prior meta-analysis would have modified our assessment or resulted in stopping all studies in 2000," said Karen Riley, a spokeswoman for the agency.
"We discussed the safety of these products at several public meetings and workshops," Riley said. "Because of safety concerns, there are no ongoing studies of hemoglobin-based blood products in the United States and no approved products."
The FDA will hold a workshop on the issue on Tuesday and Wednesday. Wolfe said he will attend but will not be allowed to speak because of the meeting format.
A workable artificial blood product is still desirable, Wolfe said, and several products that are not based on hemoglobin are in the early stages of development. Careful animal experiments with those products are needed before human trials can be considered, he said.
"We are not opposed to moving forward, but it needs to be done carefully now that we know what we know," Wolfe said.
The FDA has known for months that the report was being prepared, just as it had information on the possible hazards of the hemoglobin-based products years ago, Wolfe added. "The inevitable conclusion of the paper is that an agency that had more active data before we did should have done something," he said.
Hemoglobin-based blood substitutes are currently approved for use in two countries, South Africa and Russia, noted Dean A. Fergusson, a senior scientist at the Ottawa Health Research Institute in Canada. The new report may well affect those approvals, said Fergusson, who co-authored a journal commentary on the study.
A safe blood substitute would always be useful in emergency treatment, Fergusson said, but the risk-benefit ratio of such a product would have to be established before its general use.
"Blood right now, in America and Europe, is pretty darn safe," he said.
Current alternatives to blood transfusion are described by the American Cancer Society.
SOURCES: Sidney Wolfe, M.D., director, health research group, Public Citizen, Washington, D.C.; Charles Natanson, M.D., head, anesthesia section, National Institutes of Health Clinical Center, Bethesda, Md.; Dean A. Fergusson, Ph.D., senior scientist, Ottawa Health Research Institute, Ontario, Canada; Karen Riley, spokeswoman, U.S. Food and Drug Administration, Rockville, Md.; April, 28, 2006, online Journal of the American Medical Association