Innovative study design
The ADAPTABLE study used an innovative low-cost design, which involved direct communication with the patients themselves.
Using the National Patient-Centered Clinical Research Network (PCORnet), a group of 40 U.S. centers committed to compiling data in a common format, invitations to enroll in the study were sent to eligible patients identified from medical records. Consent and randomization took place on the patient web portal.
Participants then purchased aspirin at the assigned dose themselves, and all follow-up was done virtually or on the phone, with outcomes ascertained remotely (from patient reports, electronic medical records, and insurance claims) without adjudication.
“This is a pretty neat way to do clinical research, enabling us to conduct a 15,000-patient trial on a very tight budget,” Dr. Jones commented.
He estimated that the trial cost around $18 to $19 million. “No industry funder would have sponsored such a study of aspirin, and a typical trial with this many patients conducted in the traditional way would have cost at least 5 or 10 times more,” he said.
“This is the first time this type of study has been done in the U.S. on such a large scale, and it opens up this method for future research.”
He explained that this design, communicating directly with patients, somewhat limits the questions that can be addressed. “As aspirin is purchased over the counter by patients themselves, this is a question that lent itself to be answered in this way.”
Another innovative design feature was the inclusion of “patient partners,” with one patient nominated by each center to be part of the organization of the trial. “This helped keep the research relevant to what patients care about.
They also helped with the recruitment strategy and communication with participants. I think this is something we need to continue and prioritize in clinical research going forward,” Dr. Jones noted.
‘Pioneering’ trial
Discussants of the study at the ACC presentation congratulated the investigators on conducting such an innovative trial.
Donald Lloyd-Jones, MD, chair of preventive medicine at Northwestern University, Chicago, said, “This is really a pioneering large pragmatic trial, and we’re going to need to see more of these over the next few years. The most important legacy from this trial for me is that you did it, and that you showed us many of the promises and some of the pitfalls of these large pragmatic designs.”
Akshay Desai, MD, associate professor of medicine, Harvard Medical School, Boston, added: “This was an innovative approach to answering an important question for daily clinical practice.”
On the results of the study, Dr. Lloyd-Jones said, “Maybe the outcomes were not too surprising, and I certainly endorse your cautious status quo statement about patients staying on the dose that they are on.”
But he suggested that the bleeding safety outcomes were perhaps a little unexpected, being a little lower in the lower-dose group, and he asked whether there was a sensitivity analysis looking at bleeding on a per protocol basis. Dr. Jones answered that this was planned.
Dr. Desai also raised questions about the “unusual bleeding endpoint,” noting that the rates of bleeding were far lower than would be expected, compared with other clinical trials.
Dr. Jones replied that the bleeding endpoint with blood product transfusion was chosen to allow the researchers to accurately identify these events in claims codes. He said the endpoint probably mirrored the GUSTO (Global Use of Strategies to Open Occluded Coronary Arteries) severe bleeding classification.
In an editorial accompanying the publication of ADAPTABLE, Colin Baigent, FMedSci, says the study provides proof of principle that large pragmatic randomized trials can be conducted in the United States.
But Dr. Baigent, who is professor of epidemiology and director of the Medical Research Council Population Health Research Unit at the University of Oxford (England), says that the high degree of switching between dosages that occurred during the trial gives rise to some uncertainty about the results.
“Because switching was not likely to have been at random, bias arising from this degree of crossover could have obscured a true difference in efficacy or safety (or both), and moreover it is also not possible to conclude that the lack of any significant difference between the two dose groups implies equivalence of the effects of the doses,” he writes.
He suggests that a pilot study may have identified a preference for the 81-mg dose and allowed methods to facilitate equipoise, such as a run-in period with both doses, and only patients adhering being considered for randomization.
But Dr. Baigent concludes that the ADAPTABLE trial is a “major achievement” in that it paves the way for low-cost randomized trials in the United States, which should allow many more clinical questions to be answered.
The trial was supported by an award from the Patient-Centred Outcomes Research Institute. Dr. Schuyler Jones reports consultant fees/honoraria from Bayer Healthcare and Janssen and research grants from Boehringer Ingelheim, Bristol Myers Squibb, and the Patient-Centered Outcomes Research Institute. Dr. Baigent reports grants from Boehringer Ingelheim, Medical Research Council, British Heart Foundation, and National Institute of Health Research, outside the submitted work.
A version of this article first appeared on Medscape.com.