Chronic kidney disease and mortality and morbidity among patients with established cardiovascular disease: a West of Ireland community-based cohort study

Background. The importance of chronic kidney disease as an independent risk factor for morbidity and mortality in patients with cardiovascular disease in the community is not widely recognized. Methods. A retrospective cohort study based in the West of Ireland followed a randomized practice-based sample of patients with cardiovascular disease. A database of 1609 patients with established cardiovascular disease was established in 2000. This was generated from a randomized sample of 35 general practices in the West of Ireland. The primary endpoint was a cardiovascular composite endpoint, which included death from a cardiovascular cause or any of the cardiovascular events of myocardial infarction (MI), heart failure, peripheral vascular disease and stroke. The secondary endpoint was death from any cause. Results. Of the original community-based cohort of 1609 patients with cardiovascular disease, 1272 (79%) had one or more serum creatinine measurements during the study period and 31 (1.9%) patients were lost to follow-up. Median follow-up was 2.90 years (SD 1.47) and the risk of the cardiovascular composite endpoint (total of 219 events) was significantly increased in those patients with reduced estimated glomerular filtration rate (GFR) [log rank (Mantel-Cox) 26.74, P < 0.001] as was the risk of death from any cause (total of 214 deaths) [Log Rank (Mantel-Cox) 56.97, P < 0.001]. On the basis of the proportional hazards model, while adjusting for other significant covariates, reduced estimated GFR was associated with a significant increase in risk of the primary and secondary outcomes (P < 0.01). For every 10 ml decrement in estimated GFR there was a corresponding 20% increase in hazard of the cardiovascular composite endpoint and a 33% increase in hazard of death from any cause. Conclusions. Estimated GFR appears to discriminate prognosis between patients with established cardiovascular disease. These results emphasise the importance of recognising chronic kidney disease as a significant risk factor in patients with cardiovascular disease in the community.