Although adherence to guideline-based care remains paradoxically lower in those MI patients at higher risk of mortality and most likely to benefit from treatment, care is improving for eligible patients within all risk categories, and the gaps between low- and high-risk groups seem to be narrowing, based on a study in the Oct. 17 issue of the Journal of the American College of Cardiology.
“For individuals conducting (or reading) comparative effectiveness research, the risk-treatment paradox is an important source of confounding to be cognizant of when drawing conclusions about treatment effects on the basis of associations between treatment exposure and outcomes,” wrote Finlay A. McAlister, MD, from the division of general internal medicine and the Patient Health Outcomes Research Institute, University of Alberta in Edmonton, Alberta, in an accompanying editorial.
The goals of this analysis, according to the study authors, were to determine: 1) whether guideline-based care during hospitalization for MI varied as a function of patients' baseline risk; and 2) whether temporal improvements in guideline adherence occurred in all risk groups.
Apurva A. Motivala, MD, of the Montefiore Medical Center/Albert Einstein College of Medicine, Bronx, N.Y., and colleagues included a total of 112,848 patients with MI who were enrolled at 279 hospitals participating in Get with the Guidelines-Coronary Artery Disease (GWTG–CAD) between August 2000 and December 2008. They developed and validated an in-hospital mortality model (C-statistic: 0.75) to stratify patients into risk tertiles: low (0 percent to 3 percent), intermediate (3 percent to 6.5 percent) and high (more than 6.5 percent).
The researchers found that high-risk patients were significantly less likely to receive aspirin, beta-blockers, ACE inhibitors/ARBs, statins, diabetic treatment, smoking cessation advice or cardiac rehabilitation referral at discharge compared with those at lower risk.
However, the use of guideline-recommended therapies increased significantly in all risk groups per year (low-risk odds ratio: 1.33; intermediate-risk odds ratio: 1.30; and high-risk odds ratio: 1.30). Also, there was a narrowing in the guideline adherence gap between low- and high-risk patients over time.
“Our findings have broad implications, both to the practicing clinician taking care of these patients as well as to healthcare policy makers,” Motivala et al concluded. “[T]he existence of the risk-treatment paradox must be kept in mind when practitioners feel the reluctance to initiate/continue therapies to patients presenting with an MI. Whenever possible, objective data should be used to carefully weigh risks and benefits before withholding evidence-based therapies in these patients.
"For policymakers, it is noteworthy that hospitals participating in quality improvement projects such as the GWTG have been shown to have superior acute cardiac care and secondary prevention measures performance that is sustained over time, compared with hospitals not participating in this program.”
Thus, McAlister wrote that other factors “must be driving the persistence of the risk-treatment paradox in MI. As clinicians, we tend to be risk-averse, and errors of omission (e.g., not prescribing a preventive therapy) are easier to accept than errors of commission (e.g., prescribing a medication that then causes an adverse effect in a patient), especially in patients whom we perceive to have a poor prognosis.”
He added that it is “not surprising” that an analysis of Medicare data revealed that utilization of cardiac catheterization in elderly patients with acute MI was more closely correlated with markers of potential harm (i.e., patients' bleeding risk and number of comorbidities) than with potential to benefit (i.e., patients' baseline risk). “This problem is compounded by the fact that as clinicians we underestimate the potential benefits and overestimate the risks of preventive therapies for cardiovascular conditions, especially in older or sicker patients,” McAlister wrote.
“[A]lthough the rising tide of quality appears to be attenuating the risk-treatment paradox in acute MI,” he concluded, “there are multiple other areas in cardiology (and other fields of medicine) in which gaps in care are still sufficiently large that the risk-treatment paradox remains an important issue for clinicians and purveyors/consumers of comparative effectiveness research. It is premature to declare the end