Many areas in medicine have received a lot of attention regarding their quality of care in terms of provider and facility performance. These include how sites and providers maintain proper hemoglobin A1c levels, as well as how they reduce cath lab complications and heart failure readmissions. However, data regarding the performance of anticoagulation management is scarce.
Warfarin is the most widely used oral anticoagulant drug globally, with more than 30 million prescriptions written for it in the U.S. in 2004 (Arch Intern Med 2007;167:1414-1419).
While patients might research the physicians and hospitals to whom they will entrust their coronary stenting or bypass surgery, they rarely do so with those who will manage their warfarin therapy, says Adam J. Rose, MD, a general internist at the Center for Health Quality, Outcomes and Economic Research at the Bedford VA Medical Center in Bedford, Mass.
"The lifetime rate of serious complications for oral anticoagulation therapy is higher than for most commonly performed surgeries. Yet, ways to optimize anticoagulation outcomes requires more research," he says.
In fact, none of the approximately two dozen core measures and menu requirements for Stage 1 meaningful use of health IT involves anticoagulation control, Rose says. "This topic—performance measures associated with anticoagulation control—has not appeared on anyone's radar. If someone said that a particular surgical procedure had a high risk of morbidity, everyone would be rushing to measure it."
Defining quality of care
The problem with warfarin is not the problem of compliance per se, says Howard Herrmann, MD, director of interventional cardiology and the cardiac cath labs at the University of Pennsylvania Medical Center in Philadelphia. "The problem is that even when it is taken the way it's prescribed, the therapeutic effect varies, based on diet, the frequency with which adjustments are made based on blood tests and the frequency with which blood tests are obtained."
All patients, no matter how carefully and compliant they are with taking the drug, will inevitably have some highs and lows to their therapeutic level of anticoagulation. "Even in carefully controlled clinical trials, only about two-thirds of patients at any one time fall within expected therapeutic range," Herrmann says.
Connolly et al performed a post hoc analysis of the ACTIVE W trial (526 centers in 29 countries) to explore the variation in INR control, as measured by time in therapeutic range (TTR) (Circulation 2008;118;2029-2037). Although centers were encouraged to achieve a TTR greater than 60 percent, researchers found a wide variation, between 44 to 78 percent, with one-third of centers below the median TTR of 65 percent. Centers below the median TTR had worse outcomes (stroke, MI, vascular death or major bleed) than centers above the median TTR.
"The finding of a threshold below which oral anticoagulation benefits are diminished, or do not occur, points to a potentially useful program for improved quality of anticoagulation: Routine measurement of the center TTR for patients with atrial fibrillation and then corrective action if the TTR is less than 65 percent," Connolly et al concluded.
Rose agrees with Connolly et al that anticoagulation control is the best measurement of quality of care. "It's easy to abstract, calculate and understand; it varies among providers or sites of care; improvement is possible; and there is strong evidence linking it to important outcomes, such as stroke, venous thromboembolism and major hemorrhage," Rose says.
The problem with using TTR as a quality indicator is the absence of a risk adjustment model, which "can ensure that sites are being compared regarding quality of care rather than regarding merely differences in case mix," Rose and colleagues wrote (Circ Cardiovasc Qual Outcomes 2011;4:22-29).
The risk-adjusted model consists of many variables likely to affect TTR, including demographics, area-level poverty, driving distance to care, physical health conditions, mental health conditions, number of medications and number of hospitalizations. Researchers found difficult case mixes equally among the best- and worst-performing sites. They concluded, "Without risk-adjusted TTR, sites could claim that their poor performance was solely because of their case mix." The real culprit is low-quality anticoagulation control, Rose says.
In benchmarking for warfarin therapy, the "quality