BackgroundMost patients managed in primary care have more than one condition. Multimorbidity presents challenges for the patient and the clinician, not only in terms of the process of care, but also in terms of management and risk assessment.AimTo examine the effect of the presence of chronic kidney disease and diabetes on mortality and morbidity among patients with established cardiovascular disease.Design of studyRetrospective cohort study.SettingRandom selection of 35 general practices in the west of Ireland.MethodA practice-based sample of 1609 patients with established cardiovascular disease was generated in 2000-2001 and followed for 5 years. The primary endpoint was death from any cause and the secondary endpoint was a cardiovascular composite endpoint that included death from a cardiovascular cause or any of the following cardiovascular events: myocardial infarction, heart failure, peripheral vascular disease, or stroke.ResultsRisk of death from any cause was significantly increased in patients with increased multimorbidity (P<0.001), as was the risk of the cardiovascular composite endpoint (P<0.001). Patients with cardiovascular disease and diabetes had a similar survival pattern to those with cardiovascular disease and chronic kidney disease, but experienced more cardiovascular events.ConclusionLevel of multimorbidity is an independent predictor of prognosis among patients with established cardiovascular disease. In such patients, the presence of chronic kidney disease carries a similar mortality risk to diabetes. Multimorbidity may be a useful factor in prioritising management of patients in the community with significant cardiovascular risk.