Study Quantifies Impact of Guideline Adherence on Mortality Following AMI

Alan Go, MD

A new study of more than 25,000 patients with previous acute myocardial infarction (AMI) is revealing just how impactful adherence to secondary prevention guidelines can be for reducing mortality.

Using a set of guidelines established by the from the American Heart Association (AHA) and American College of Cardiology (ACC) as a standard, investigators found adherence to each additional guideline lowered risk of death by 8% to 11% while strict adherence to all guidelines decreased the risk by as much as 43%.

“Our findings show that following all the recommended treatments after a heart attack is critical to long-term health and wellness,” said Alan Go, MD, a cardiologist and research scientist with Kaiser Permanente Northern California, in a statement. “Doctors and patients must work to ensure every single evidence-based recommendation is followed. Following 'most' of the recommended treatments is not enough."

With little research available that quantifies the impact of cumulative adherence to evidence-based guideline recommendations for patients with previous AMI, investigators sought to demonstrate the impact of adherence to guidelines. To do so, investigators examined adherence to guideline-recommended medical therapy, optimal risk factor control, recommended lifestyle interventions at days 30 and 90 after AMI and the associations of cumulative and individual guideline adherence with all-cause mortality.

For the purpose of the analysis, investigators used the 2014 AHA/ACC Guideline for the Management of Patients With Non—ST-Elevation Acute Coronary Syndromes. Individuals included in the study were identified through Kaiser Permanente’s database from 2008-2014, which 4.4 million patients—33,526 of which had been hospitalized with AMI.

To be included in the present study, patients needed to be 18 years of age or older, have index hospitalization records, have 12 months of membership prior to the index date, and have at least 12 months of prior drug coverage. Additional inclusion criteria were survival to 30 or 90 days post-discharge.

In total, 25,788 individuals were included in the 30-day group and 24,200 were eligible for the 90-day group. Most patients (64%) were men, the mean age of the study population was 68 years, and the median follow-up was approximately 2.8 years after index AMI. Investigators noted the index AMI was their first in the Kaiser Permanente system for more than 90% of patients.

Cox proportional hazard models were used to evaluate associations—investigators also noted the use of propensity score and subgroup analyses by age group, sex, chronic kidney disease status, and diabetes mellitus status. Individuals were classified based on their guideline adherence and survival to 30 or 90 days. Groups established by Go and colleagues for the analysis were defined 0—2, 3, 4, 5, or all 6 guidelines at 30 days and 0–3, 4, 5, 6, or all 7 guidelines at 90 days.

Adherence to medical treatment was defined as adherence to prescriptions for β-blockers, renin-angiotensin-aldosterone system inhibitors, lipid medications, and antiplatelet medications. Risk factor control included a blood pressure less than 140/90 mmHg and LDL-C less than 100 mg/dL—the latter was only assessed in the 90-day group.

Of note, very few patients were categorized into the lowest group of guideline adherence with just 5% adhering to 2 or fewer guidelines and 10% adhering to 3 or fewer in the 30- and 90-day analyses. In comparison, 35% and 34% adhered to 5 or 6 guidelines at 30 days and 31% and 23% adhered to 6 or 7 guidelines in the 90-day analyses.

Notable levels of patient adherence to individual components of guidelines included 67% taking prescribed non-aspirin antiplatelet drugs to 88% taking high cholesterol medications at 30 days.

Results of the analysis indicated greater guideline adherence was independently associated with lower mortality for meeting 7 (HR 0.57, 95% CI, 0.49—0.66) and for those meeting 6 guidelines (HR 0.69, 95% CI, 0.61–0.78) compared to those meeting 3 or fewer guidelines at 90 days. Investigators pointed out similar results were observed in 30-day models and that in both models, significantly lower mortality per adherence to each additional guideline.

This study, “Cumulative Adherence to Secondary Prevention Guidelines and Mortality After Acute Myocardial Infarction,” was published in the Journal of the American Heart Association.