Abstract
Background and Aims
The current diagnostic criteria for acute kidney injury (AKI) predict the need for dialysis and early mortality, but are less useful to predict long-term outcomes. Acute kidney disease (AKD) defines patients with AKI or subacute loss of kidney function lasting for more than 7 days, which should predict better subsequent chronic kidney disease (CKD). The aim of this study was to investigate the risk factors and prognosis of AKD and to compare different types of acute/subacute renal impairment among Chinese inpatients.
Method
From a cohort of 450,000 patients consecutive admitted from June 1, 2012, to March 31, 2018 to five district hospitals, complete data were available from 71,041 inpatients. AKI and AKD were diagnosed based on the Acute Disease Quality Initiative Criteria 2017.
Based on this diagnostic criterion of AKI and AKD, patients were classified as having (1) AKI Recover, if Scr back to baseline value within 7 days (renal impairment duration of less than 7 days or rapid recovery within 7 days), and (2) AKD with AKI, if a condition in which stage 1 or greater AKI was present ≥ 7 days after an AKI initiating event (continuous AKI progressing to AKD), (3) AKD without AKI, if Scr levels increased slowly but lasted more than 7 days (subacute AKD without meeting the AKI criterion).
Results
Of 71,041 inpatients, 16,098 (22.66%) patients developed AKI or AKD. 5,895 (8.30%) AKI patients recovered within 7 days (AKI Recover), 5,623 (7.91%) were followed by AKD and 4,580 (6.44%) patients developed AKD without AKI. Thus, AKI and AKD are frequent complications in Chinese inpatients (Fig 1).
Compared to AKI recover or AKD without AKI, patients with AKI followed by AKD had higher hospital mortality (16.59% vs. 3.82% vs. 2.12%, P<0.05) and more de novo CKD (8.95% vs. 7.29% vs. 5.48%, P<0.05). Mortality was proportional to stages of AKI and AKD (P for trend <0.05), while AKI followed by AKD was associated with a higher risk of long-term mortality (hazard ratio (HR) 4.51, 4.32-4.71, P<0.05) as compared to AKD without AKI (HR 2.25, 2.13-2.39, P<0.05) and AKI Recover (HR 1.18, 1.09-1.26, P<0.05).
The AKI criterion yielded a higher risk for overall survival and a lower risk for de novo CKD than the AKD criterion, indicating that both criteria imply persistent kidney damage but that a rapid decline in excretory kidney function implies higher mortality risks while a persistent decline may rather result in de novo CKD (Fig 2). Meanwhile, these associations between different kidney injury criteria and outcomes had good generalizability and were constant across different genders, surgeries, and comorbidities (Fig 2). The AKD criterion was robustly associated with overall survival (area under the receiver operating characteristic curve (AUROC) 0.71) and de novo CKD (AUROC 0.71), while AKI criterion showed a relatively lower ability to fitting risk of overall survival (AUROC 0.65, P<0.05) and CKD (AUROC 0.63, P<0.05). Moreover, combining AKI and AKD was strongly associated with long-term mortality (AUROC 0.725) and de novo CKD (AUROC 0.72) compared to each single criterion of AKI or AKD (Fig 3).
Conclusion
(1) Adding AKD as a definition for renal failure lasting >7 days up to 90 days is of clinical importance in addition to the existing definitions for AKI and CKD. (2) These findings suggest research activities and clinical practice should also focus on AKD, which is far more accurate to predict subsequent de novo CKD.
Evolution of chronic renal impairment and long-term mortality after de novo acute kidney injury in the critically ill; a Swedish multi-centre cohort study
