Discordance between level of risk and intensity of evidence-based treatment in patients with acute coronary syndromes

Abstract

Objectives: To examine the relation between treatment intensity and level of risk in routine hospital care of patients with acute coronary syndromes (ACS), and to identify independent predictors of use or omission for each of eight evidence-based treatments.

Design: Retrospective cohort study of patients fulfilling case definition for ACS in whom absolute risk of adverse outcomes was quantified (as low, moderate, or high risk) using formal prediction rules, and for whom treatment eligibility was determined using expert-agreed criteria.

Participants and setting: 3912 consecutive or randomly selected patients admitted to 21 hospitals in Queensland, Australia between 1 August 2001 and 31 December 2005.

Results: The proportions of eligible patients receiving treatment varied inversely with risk level in regard to reperfusion therapies of fibrinolytic therapy or primary angioplasty (low risk, 88.3%; moderate risk, 61.9%; high risk, 18.2%; P < 0.001), heparin (91.4%; 83.7%; 72.8%; P < 0.001) and early invasive intervention (33.6%; 24.0%; 18.5%; P < 0.001). Significantly more low- and moderate- than high-risk patients received beta-blockers (87.0%; 88.5%; 79.1%; P < 0.001), lipid-lowering agents (87.3%; 84.8%; 65.8%; P < 0.001), and referral to cardiac rehabilitation (51.8%; 46.0%; 34.4%; P < 0.001) at discharge. The most frequent independent predictors of treatment omission in all patients included increasing age (5 of 8 treatments), previous ACS or atrial tachyarrhythmias (4 of 8), and past history of cerebrovascular accident or congestive heart failure (3 of 8).

Conclusion: In routine care of ACS, eligible patients at high risk receive treatment less frequently than those at low and moderate risk. Reforms in professional education, routine use of risk stratification tools, guideline recommendations tailored to population-specific reductions in absolute risk, and better hospital networking with standardised triage and referral procedures for invasive procedures may help reduce selection bias in the delivery of indicated care.