Quality of care and outcomes among patients with acute myocardial infarction by level of kidney function at admission: report from the get with the guidelines coronary artery disease program

Abstract

Background: Many patients admitted for acute myocardial infarction (AMI) have chronic renal insufficiency. We studied the impact of chronic renal insufficiency on mortality and quality of inpatient care for AMI from the American Heart Association's Get With The Guidelines-Coronary Artery Disease Program.

Hypothesis: We hypothesized that mortality and quality of inpatient care would not vary with renal function.

Methods: We examined in-hospital AMI performance measures by renal function based on glomerular filtration rate (GFR). Severity of renal insufficiency was categorized as normal (GFR ≥ 90 mL/min/1.73 m(2)), mild (GFR 60-90 mL/min/1.73 m(2)), moderate (GFR 30-60 mL/min/1.73 m(2)), severe (GFR 15-30 mL/min/1.73 m(2)), and kidney failure (GFR ≤ 15 mL/min/1.73 m(2) or dialysis). A total of 21721 patients from 291 sites were studied, with most data collected in 2008 to 2009. Multivariable regression analysis after adjusting for patient characteristics was performed and generalized estimating equations were used to account for within-hospital clustering. In-hospital mortality and quality of inpatient care were assessed.

Results: Renal insufficiency was present in 82.0 percent of AMI patients. The adjusted odds ratio vs normal renal function for mortality increased with worsening renal function: 1.45 for mild renal insufficiency (95% confidence interval [CI]: 1.03-2.05, P = 0.03); 3.36 for moderate renal insufficiency (95% CI: 2.31-4.89, P < 0.0001); 5.43 for severe renal insufficiency (95% CI: 3.70-7.95, P < 0.0001); and 6.35 for kidney failure (95% CI: 4.48-9.01, P < 0.0001). Patients with renal insufficiency received less inpatient and discharge guideline-recommended therapy for AMI.

Conclusions: Among AMI patients, mortality and guideline-recommended inpatient therapy correlated inversely with renal function. Adjusted mortality was equally poor among patients with severe renal dysfunction and on dialysis.

Figure 1

Unadjusted rates of in‐hospital mortality (A) increased with worsening kidney function. Adjusted odds ratio (B) compared with normal kidney function after multivariable adjustment. Variables in the model: age, female sex, Caucasian race, body mass index, insurance (Medicare, Medicaid, other, none), AF, COPD, diabetes, hyperlipidemia, hypertension, PVD, MI, CVA/TIA, heart failure, ischemic etiology of heart failure, smoking, SBP at admission, heart rate at admission. Hospital characteristics: region (Northeast, West, Midwest, South), bed size, academic institution. Horizontal line represents normal as reference (OR: 1.0). P‐values for mild vs. normal is 0.03 and <0.001 for all other comparisons. Abbreviations: AA, aldosterone antagonist; ACEI/ARB, angiotensin‐converting enzyme inhibitor/angiotensin II receptor blocker; AF, atrial fibrillation; ASA, aspirin; BB, β‐blocker; CI, confidence interval; COPD, chronic obstructive pulmonary disease; CVA, cerebrovascular accident; D2B, door‐to‐balloon time; D/C, discharge; LVSD, left ventricular systolic dysfunction; MI, myocardial infarction; OR, odds ratio; PVD, peripheral vascular disease; rec, recommendation; SBP, systolic blood pressure; TIA, transient ischemic attack.

Figure 2

(A) Observed rates of quality of care measures per renal function group. (B) Adjusted odds ratios of deliver of quality of care measures relative to normal renal function. Horizontal line represents normal as reference (OR: 1.0). Abbreviations: AA, aldosterone antagonist; ACEI/ARB, angiotensin‐converting enzyme inhibitor/angiotensin II receptor blocker; ASA, aspirin; BB, β‐blocker; D2B, door‐to‐balloon time; D/C, discharge; LDL, low‐density lipoprotein cholesterol; LVSD, left ventricular systolic dysfunction; QOC, quality of care; rec, recommendation; SBP; systolic blood pressure.