[THE LANCET] Severe chronic kidney disease patients have higher coronary risk than diabetics. Time for a new coronary heart disease equivalent?

Image: CC/PD. Enlarged kidney (drawing). 

Primer: Coronary heart disease (CHD) “equivalent”, a term used to describe some trait or factor that results in a 10-year risk of coronary death/myocardial infarction (MI) of >20%, currently includes diabetes, abdominal aortic aneurysm, peripheral artery disease and carotid artery disease per ATP III guidelines. Panels have suggested the chronic kidney disease (CKD) should be included as a CHD equivalent because of the increased risk of coronary events in these patients. However what needs to be assessed is if this increased risk of events is of similar magnitude when compared to current CHD equivalents.

This [retrospective] study: Data were obtained from the Alberta Kidney Disease Network (AKDN). Authors examined 1.3 million individuals who were admitted to the hospital for MI for a period of 2 years and assessed diagnoses of CKD by the Chronic Kidney Disease Epidemiological Collaboration GFR calculation. Predictably, those who had the highest unadjusted rate of MI were those with prior MI. While the authors note a statistically significant lower rate of MI in patients with diabetes (without CKD) vs. CKD (without diabetes) (5.4 per 1000 person-years, vs 6.9 per 1000 person-years), this association disappears after adjusting for age, sex and comorbidities. This suggests that much of the risk in CKD patients is due to other chronic risks found in CAD patients.

However, stage 3 or 4 CKD + severe proteinuria without diabetes resulted in rates similar or higher to diabetes (see study appendix). In addition, unadjusted mortality rates after MI in CKD patients were higher than those with a history of MI or diabetes (3.6 vs. 2.7 vs. 1.9 per 1000 person-years, respectively). This may be due to the decreased likelihood of CKD patients undergoing revascularization procedures after presenting with a MI, a fact which has been previously demonstrated.

In sum: CKD alone does not seem to be a CHD equivalent based on comparison with diabetes and subsequent risk of MI. However, if we make the criteria more stringent – that is stage 3 or 4 CKD + severe proteinuria – there may be a case for classifying it as a CHD equivalent. This subgroup had similar or higher rates of MI vs. diabetes, suggesting CKD. Mortality rates (unadjusted) in CKD patients with MI remain higher than in those with prior MI or diabetes, suggesting primary prevention, namely lipid control, may be of benefit in CKD patients. The large study size and comparative nature of this study are strengths that may make it valuable for future clinical decision making.  

Click to read the full study, just published in The Lancet.

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