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MI trial participants show lower risk profile than general population with MI
Among patients with MI, participants in clinical trials have lower risk profiles and better prognoses compared with nonparticipants, according to new findings.
“Efforts to improve trial participation are needed to enhance generalizability of results,” Jacob A. Udell, MD, MPH, and colleagues wrote in a research letter to JAMA. “Nesting trials within existing registries may help meet this goal.”
Udell, from Women’s College Hospital, University of Toronto, and colleagues evaluated 190,476 patients with MI between July 2008 and March 2011 at 609 centers participating in the National Cardiovascular Data Registry’s Acute Coronary Treatment and Intervention Outcomes Network Registry-Get With the Guidelines (ACTION-GWTG).
They excluded patients with missing or incomplete data on trial participation (n=472) or eligibility (n=48,869) and found no clinically relevant differences between those excluded from the analysis vs. those included.
The remaining patients were stratified by whether they participated in a trial (n=4,008), were eligible to participate but did not (n=93,274) or were ineligible to participate (n=43,853). Eligibility criteria from three antiplatelet therapy trials conducted during the study period were used. Exclusion criteria included age younger than 18 years, systolic BP >180 mm Hg, stage V kidney disease or dialysis-dependent renal failure, cardiogenic shock, major bleeding within 24 hours of presentation, international normalized ratio >1.5, hemoglobin <10 g/dL or use of fibrinolytic therapy.
Udell and colleagues found that compared with nonparticipants, trial participants were younger, had less previous CVD, had lower predicted risk for mortality, had shorter hospital stays and received more frequent treatment with evidence-based therapy.
Compared with trial participants, in-hospital mortality was more likely in eligible nonparticipants (adjusted OR=1.63; 95% CI, 1.11-2.41) and ineligible nonparticipants (adjusted OR=1.91; 95% CI, 1.29-2.83), the researchers found.
They found the same to be true for a composite of in-hospital death or recurrent MI (eligible nonparticipants, adjusted OR=1.41; 95% CI, 1.05-1.89; ineligible nonparticipants, adjusted OR=1.6; 95% CI, 1.19-2.16) and for cardiogenic shock (eligible nonparticipants, adjusted OR=1.52; 95% CI, 1.15-2.01; ineligible nonparticipants, adjusted OR=1.41; 95% CI, 1.06-1.87).
There was no difference in in-hospital major bleeding between trial participants and eligible nonparticipants, but ineligible nonparticipants had an elevated risk compared with participants (adjusted OR=1.19; 95% CI, 1.01-1.39), according to the researchers. They also found no difference between the groups in risk for in-hospital congestive HF.
“We know that clinical trials can be tremendously expensive and a huge burden on our health care system,” Udell said in a press release. “Our study shows participants often reflect a small portion of the typical patients we see in offices and hospitals, and we are missing a large number of potentially eligible patients who are right at our fingertips.”
Disclosure: The research was supported by the American College of Cardiology Foundation’s National Cardiovascular Data Registry. ACTION-GWTG is funded in part by Bristol-Myers Squibb and Sanofi. See the full study for a list of the researchers’ relevant financial disclosures.