Acute kidney injury referred to the nephrologist: A single centre experience in a tertiary care hospital

Aim Acute kidney injury (AKI) shows an increasing incidence, accounting for a remarkable proportion of nephrology team in-hospital activity. The aim was to describe main features and outcomes of AKI observed in patients admitted to a tertiary care hospital. Methods We conducted a retrospective analysis in all consecutive AKI patients referred for nephrology consultation (November 2018-February 2020) focusing on the factors associated with in-hospital mortality within 90 days and kidney function recovery (KFR) upon discharge. Demographic, clinical and laboratory data, as well as main features of AKI episodes, were collected from medical records of the entire hospital stay. AKI was defined according to KDIGO Clinical Practice Guideline. Results Among 1145 patients referred for nephrology consultation, 559 were evaluated for AKI (598 episodes). Pre-existing CKD was present in 54.7% of patients. In 69.2% of cases AKI was evaluated within 48 h from its onset. Most of the episodes (66.6%) were classified as KDIGO Stage 3. In-hospital mortality within 90 days since admission was 43.3%. Multivariate Cox regression analysis showed a higher mortality risk for advancing age (HR 1.02/unit, 95% CI 1.01-1.03) and oliguria (HR 1.91, 95% CI 1.45-2.52), while a higher eGFR (HR 0.72/unit, 95% CI 0.54-0.95) and KFR within 7 days (HR 0.62, 95% CI 0.41-0.94) were associated to a lower mortality. KFR was observed in 96.4% of survivors. In patients with partial KFR, the loss of eGFR was -29.2 +/- 17.9 ml/min. KFR incidence rate was 6.79 per 100-person days (95% CI 6.72-6.87) in survivors and 2.30 (95% CI 2.25-2.35) in non-survivors. Conclusion AKI-related nephrology activity accounts for most of the nephrologist workload as consultant. Referred AKI episodes are frequently severe and superimposed on CKD, carrying a relatively high mortality in a patient population developing AKI outside ICU. Early KFR appears strongly associated with a favourable impact upon in-hospital survival.