Long-term impact of cardiorenal syndromes on major outcomes based on their chronology: a comprehensive French nationwide cohort study.

Background: Cardiorenal syndromes (CRSs) are reputed to result in worse prognosis than isolated heart failure (HF) and chronic kidney disease (CKD). Whether it is true for all major outcomes over the long-term regardless of CRS chronology (simultaneous, cardiorenal and renocardiac CRS) is unknown.

Methods: The 5-year adjusted risk of major outcomes was assessed in this nationwide retrospective cohort study in all 385 687 with either CKD or HF (out of 5 123 193 patients who were admitted in a French hospital in 2012).

Results: Overall, 84.0% patients had HF and 8.9% had CKD (they had similar age, sex ratio, diabetes and hypertension prevalence), while 7.1% had CRS (cardiorenal: 44.6%, renocardiac: 14.5%, simultaneous CRS: 40.8%).The incidence of major outcomes was 57.3%, 53.0%, 79.2% for death; 18.8%, 10.9%, 27.5% for cardiovascular death; 52.6%, 34.7%, 64.3% for HF; 6.2%, 5.5%, 5.6% for myocardial infarction (MI); 6.1%, 5.8%, 5.3% for ischaemic stroke; and 23.1%, 4.8%, 16.1% for end-stage kidney disease (ESKD) for isolated CKD, isolated HF and CRS, respectively.As compared with isolated CKD or HF, the risk of death, cardiovascular death and HF was markedly increased in CRS, the worse phenotype being cardiorenal CRS, while the increased risk of MI and ischaemic stroke associated with CRS subtypes was statistically but not clinically significant. As compared with isolated CKD, the risk of ESKD was similar for cardiorenal CRS only and marginally increased for renocardiac and simultaneous CRS. We could not find a synergy between HF and CKD on major clinical outcomes in the whole population (n = 5 123 193 patients).

Conclusions: The additional impact of CRS versus isolated HF or CKD on long-term kidney and cardiovascular risk is highly heterogenous, depending of the event considered and CRS chronology. No synergy between HF and CKD could be demonstrated.