One-year health status outcomes of unstable angina versus myocardial infarction: a prospective, observational cohort study of ACS survivors

Abstract

Background: Unstable angina (UA) patients have lower mortality and reinfarction risks than ST-elevation (STEMI) or non-ST elevation myocardial infarction (NSTEMI) patients and, accordingly, receive less aggressive treatment. Little is known, however, about the health status outcomes (angina, physical function, and quality of life) of UA versus MI patients among survivors of an ACS hospitalization.

Methods: In a cohort of 1,192 consecutively enrolled ACS survivors from two Kansas City hospitals, we evaluated the associations between ACS presentation (UA, NSTEMI, and STEMI) and one-year health status (angina, physical functioning and quality of life), one-year cardiac rehospitalization rates, and two-year mortality outcomes, using multivariable regression modeling.

Results: After multivariable adjustment for demographic, hospital, co-morbidity, baseline health status, and treatment characteristics, UA patients had a greater prevalence of angina at 1 year than STEMI patients (adjusted relative risk [RR] = 1.42; 95% CI [1.06, 1.90]) and similar rates as NSTEMI patients (adjusted RR = 1.1; 95% CI [0.85, 1.42]). In addition, UA patients fared no better than MI patients in Short Form-12 physical component scores (UA vs. STEMI score difference -0.05 points; 95% CI [-2.41, 2.3]; UA vs. NSTEMI score difference -1.91 points; 95% CI [-4.01, 0.18]) or Seattle Angina Questionnaire quality of life scores (UA vs. STEMI score difference -1.39 points; 95% CI [-5.63, 2.85]; UA vs. NSTEMI score difference -0.24 points 95% CI [-4.01, 3.54]). Finally, UA patients had similar rehospitalization rates as MI patients (UA vs. STEMI adjusted hazard ratio [HR] = 1.31; 95% CI [0.86, 1.99]; UA vs. NSTEMI adjusted HR = 1.03; 95% CI [0.73, 1.47]), despite better 2-year survival (UA vs. STEMI adjusted HR = 0.51; 95% confidence interval (CI) [0.28, 0.95]; UA vs. NSTEMI adjusted HR = 0.40; 95% CI [0.24, 0.65]).

Conclusion: Although UA patients have better survival rates, they have similar or worse one-year health status outcomes and cardiac rehospitalization rates as compared with MI patients. Clinicians should be aware of the adverse health status outcome risks for UA patients and consider close monitoring for the opportunity to improve their health status and minimize the need for subsequent rehospitalization.

Figure 1

Flowchart of screened and enrolled patients in the INFORM registry.

Figure 2

(a) Unadjusted Kaplan-Meier survival curves of two-year mortality by ACS presentation (b) Unadjusted and sequential adjustment of two-year mortality by ACS presentation (Model 1 = unadjusted comparison; Model 2 = adjustment for demographic variables (age, race, sex, insurance status); Model 3 = adjustment for demographic and hospital site variables (Mid-America Heart Institute or Truman Medical Center); Model 4 = adjustment for demographic, site, and clinical variables (prior angina, prior myocardial infarction, prior percutaneous coronary intervention, prior coronary artery bypass graft, congestive heart failure, hypertension, diabetes, hyperlipidemia, cerebrovascular accident/transient ischemic attack, renal failure, anemia and tobacco use); Model 6 = adjustment for demographic, site, clinical, and treatment (revascularization [percutaneous coronary intervention, coronary artery bypass graft, thrombolysis] and discharge medications [angiotensin converting enzyme inhibitors, lipid lowering agents, beta-blockers, calcium channel blockers, nitrates, and aspirin]) variables)

Figure 3

(a) Unadjusted Kaplan-Meier survival curves of one-year cardiac rehospitalization by ACS presentation (b) Unadjusted and sequential adjustment of one-year cardiac rehospitalization by ACS presentation (Model 1 = unadjusted comparison; Model 2 = adjustment for demographic variables (age, race, sex, insurance status); Model 3 = adjustment for demographic and hospital site variables (Mid-America Heart Institute or Truman Medical Center); Model 4 = adjustment for demographic, site, and clinical variables (prior angina, prior myocardial infarction, prior percutaneous coronary intervention, prior coronary artery bypass graft, congestive heart failure, hypertension, diabetes, hyperlipidemia, cerebrovascular accident/transient ischemic attack, renal failure, anemia and tobacco use); Model 6 = adjustment for demographic, site, clinical, and treatment (revascularization [percutaneous coronary intervention, coronary artery bypass graft, thrombolysis] and discharge medications [angiotensin converting enzyme inhibitors, lipid lowering agents, beta-blockers, calcium channel blockers, nitrates, and aspirin]) variables)

Figure 4

(a) Unadjusted and sequential adjustment of one-year angina by ACS presentation (b) Unadjusted and sequential adjustment of one-year physical functioning by ACS presentation (c) Unadjusted and sequential adjustment of one-year quality of life by ACS presentation (Model 1 = unadjusted comparison; Model 2 = adjustment for demographic variables (age, race, sex, insurance status); Model 3 = adjustment for demographic and hospital site variables (Mid-America Heart Institute or Truman Medical Center); Model 4 = adjustment for demographic, site, and clinical variables (prior angina, prior myocardial infarction, prior percutaneous coronary intervention, prior coronary artery bypass graft, congestive heart failure, hypertension, diabetes, hyperlipidemia, cerebrovascular accident/transient ischemic attack, renal failure, anemia and tobacco use); Model 5 = adjustment for demographic, site, clinical, and baseline health status variables (SF-12 physical component score and SAQ quality of life score models only); Model 6 = adjustment for demographic, site, clinical, baseline health status (SF-12 physical component score and SAQ quality of life score models only), and treatment (revascularization [percutaneous coronary intervention, coronary artery bypass graft, thrombolysis] and discharge medications [angiotensin converting enzyme inhibitors, lipid lowering agents, beta-blockers, calcium channel blockers, nitrates, and aspirin]) variables)