B SMYTH1, S KOTWAL1,2, M GALLAGHER1,3, M JARDINE1,3
1The George Institute for Global Health, Sydney, NSW; 2Prince of Wales Hospital, Sydney, NSW; 3Concord Repatriation and General Hospital, Sydney, NSW
Aim: To model the impact of different definitions of cardiovascular composites in a cohort of Australian dialysis patients.
Background: The negative outcomes of high-profile trials testing interventions targeting endovascular disease in people with End Stage Kidney Disease (ESKD) have generated speculation about the makeup of cardiovascular composite endpoints. .
Methods: We linked the Australian and New Zealand Dialysis and Transplant registry, the NSW hospitalisation database and the death registry for patients undergoing dialysis between 1 July 2000 and 31 July 2010 in NSW. We used ICD10-AM codes to define composite outcomes of death plus endovascular disease (acute myocardial infarction (AMI), cerebrovascular accident (CVA), coronary revascularisation, cerebral revascularisation) or death plus heart failure. Survival from initiation of the cohort to first event was examined by Kaplan-Meier analysis.
Results: Of 8424 patients identified with 33766 years of follow up, 45.6% experienced at least one nonfatal event (14.0% endovascular only, 15.9% heart failure only and 15.6% both) while 44.2% of the total cohort died. The endovascular composite rate was 17.9 (17.4-18.4)/100 patient-years, which reduced to 16.9 (16.4-17.4)/100 patient years when revascularisation events were excluded. Median event-free survival from cohort inception was 3.7 (3.6-3.9) and 4.0 (3.8-4.1) years respectively. The heart failure-mortality composite rate was 17.9 (17.4-18.5)/100 patient-years (median survival of 3.8 (3.7-4.0) years). The combined composite of AMI, stroke, heart failure and mortality was 22.1 (21.5-22.7)/100 patient-years with median event-free survival of 3.1 (2.9-3.2) years.
Conclusions: Heart failure and endovascular events are common although mortality is the single most frequent event in a fatal/non-fatal composite. The addition of revascularisation to the endovascular composite has a marginal impact on event rates.