Underuse of an invasive strategy for patients with diabetes with acute coronary syndrome: a nationwide study

BACKGROUND: Guidelines recommend an early invasive strategy for patients with diabetes with acute coronary syndromes (ACS). We investigated if patients with diabetes with ACS are offered coronary angiography (CAG) and revascularisation to the same extent as patients without diabetes. METHODS AND RESULTS: The study is a nationwide cohort study linking Danish national registries containing information on healthcare. The study population comprises all patients hospitalised with first-time ACS in Denmark during 2005–2007 (N=24 952). Diabetes was defined as claiming of a prescription for insulin and/or oral hypoglycaemic agents within 6 months prior to the ACS event. Diabetes was present in 2813 (11%) patients. Compared with patients without diabetes, patients with diabetes were older (mean 69 vs 67 years, p<0.0001), less often males (60% vs 64%, p=0.0001) and had more comorbidity. Fewer patients with diabetes underwent CAG: cumulative incidence 64% vs 74% for patients without diabetes, HR=0.72 (95% CI 0.69 to 0.76, p<0.0001); adjusted for age, sex, previous revascularisation and comorbidity HR=0.78 (95% CI 0.74 to 0.82, p<0.0001). More patients with diabetes had CAG showing two-vessel or three-vessel disease (53% vs 38%, p<0.0001). However, revascularisation after CAG revealing multivessel disease was less likely in patients with diabetes (multivariable adjusted HR=0.76, 95% CI 0.68 to 0.85, p<0.0001). CONCLUSIONS: In this nationwide cohort of patients with incident ACS, patients with diabetes were found to be less aggressively managed by an invasive treatment strategy. The factors underlying the decision to defer an invasive strategy in patients with diabetes are unclear and merit further investigation.