Cardiovascular morbidity and long term mortality associated with in hospital small increases of serum creatinine.

BACKGROUND: The cardiovascular risk associated with an increase in serum creatinine below the acute kidney injury (AKI) threshold, during hospitalization, has not been studied in depth. We assessed patients' features and outcomes associated with these changes.

METHODS: Retrospective cohort study of 12,493 consecutive patients admitted to hospital throughout 12 months. We investigated the patients who had a small creatinine increase (SISCr) between 1.2 and <1.5 times the admission value, and tested the association of creatinine changes with the prevalence of cardiovascular disease (CVD). In a follow-up study, we assessed the all-cause mortality and its relationship with SISCr.

RESULTS: Among patients with two or more creatinine measurements, 14.9% showed a SISCr. Older age, female gender and higher estimated glomerular filtration rate (eGFR) at admission were characteristics of these patients. The prevalence of CVD was 14.6% in patients with SISCr vs. 10.7% in those with stable creatinine (p < 0.001). SISCr was detected in 36, 26.6 and 18.9% of chronic heart failure (CHF), chronic ischemic heart disease (CIHD) and acute myocardial infarction (AMI) patients, respectively. The follow-up was 26.7 ± 10.6 months with 770 all-cause deaths. Serum creatinine increase above 20% was associated with a significant higher mortality compared to changes below 20%, adjusted hazard (HR) ratio 1.577 (p < 0.001). A higher risk was found associated with creatinine increases >1.5 times the baseline: HR 1.704 (p < 0.001).

CONCLUSIONS: In hospitalized patients, increases in serum creatinine below the AKI threshold are associated with CHF, CIHD and long-term mortality.