Abstract
Abnormal measurements of kidney function or structure may be identified that do not meet criteria for acute kidney injury (AKI) or chronic kidney disease (CKD) but nonetheless may require medical attention. The Kidney Disease: Improving Global Outcomes Clinical Practice Guideline for AKI proposed criteria for the definition of acute kidney diseases and disorders (AKD), which include AKI; however, the incidence and prognosis of AKD without AKI remain unknown. To characterize the incidence and outcomes of AKD without AKI, with or without CKD. Retrospective cohort study including all adult residents in a universal health care system in Alberta, Canada, without end-stage kidney disease (ESKD) and with at least 1 serum creatinine measurement between January 1 and December 31, 2008, in a community or hospital setting. Data analysis took place in 2018. The Kidney Disease: Improving Global Outcomes guideline definitions for CKD, AKI, and AKD based on serum creatinine, estimated glomerular filtration rate, and albuminuria criteria were applied to estimate the proportion of patients with CKD, AKI, and AKD without AKI, and combinations of the conditions. Patients were followed up for up to 8 years (study end date, June 31, 2016) to characterize their risks of mortality, development of new CKD, progression of preexisting CKD, and ESKD. Among 1 109 099 Alberta residents included in the cohort, the mean (SD) age was 52.3 (17.6) years, and 43.0% were male. Findings showed that AKD without AKI was common (3.8 individuals without preexisting CKD and 0.6 with preexisting CKD per 100 population tested). In Cox proportional hazards and competing risks models over a median (interquartile range) of 6.0 (5.7-6.3) years of follow-up, AKD without AKI (compared with no kidney disease) was associated with higher risks of developing new CKD (37.4% vs 7.4%%; adjusted sub-hazard ratio [sHR], 3.17; 95% CI, 3.10-3.23), progression of preexisting CKD (49.5% vs 34.6%; adjusted sHR, 1.38; 95% CI, 1.33-1.44), ESKD (0.6% vs 0.1%; adjusted sHR, 8.56; 95% CI, 7.32-10.01), and death (25.8% vs 7.3%; adjusted hazard ratio, 1.42; 95% CI, 1.39-1.45). Criteria for AKD identified many patients who did not meet the criteria for CKD or AKI but had overall modestly increased risks of incident and progressive CKD, ESKD, and death. The clinical importance of AKD remains to be determined.
Highlights
Kidney function is assessed routinely in clinical practice to detect acute kidney injury (AKI) and chronic kidney disease (CKD); AKI is defined as decline in kidney function over 1 week or less, while CKD is defined as alteration of kidney function and structure for more than 3 months.[1,2,3,4] alterations in kidney function or structure are frequently detected in acute and chronic illness that do not meet the criteria for CKD or AKI but may require medical attention
We identified CKD, AKI, acute kidney diseases and disorders (AKD) without AKI, and combinations of these states based on all serum creatinine (sCr), estimated glomerular filtration rate (eGFR), and albuminuria determinations over the 3 months before and after the index date based on the algorithm provided in the Kidney Disease: Improving Global Outcomes (KDIGO) Clinical Practice Guideline for AKI3 and criteria described by the Acute Disease Quality Initiative consensus statement.[5]
The number of patients with CKD, AKI, and AKD identified by applying each component of the KDIGO criteria is shown in Table 1, with further details of the frequency of each criterion for AKD in eFigure 3 in the Supplement
Summary
Kidney function is assessed routinely in clinical practice to detect acute kidney injury (AKI) and chronic kidney disease (CKD); AKI is defined as decline in kidney function over 1 week or less, while CKD is defined as alteration of kidney function and structure for more than 3 months.[1,2,3,4] alterations in kidney function or structure are frequently detected in acute and chronic illness that do not meet the criteria for CKD or AKI but may require medical attention. The 2012 Kidney Disease: Improving Global Outcomes (KDIGO) Clinical Practice Guideline for AKI proposed an operational definition for acute kidney diseases and disorders (AKD) as alterations in kidney function or structure for less than 3 months, which includes AKI (eTable 1 in the Supplement).[3]. Identification of AKD, in addition to AKI and CKD, could enable creation of standardized diagnostic algorithms for prompt recognition and appropriate clinical evaluation of these disorders and facilitate comprehensive research, surveillance, and public health initiatives for kidney diseases. The purpose of this study was to characterize the frequency and prognosis of AKD without AKI across a geographic region with universal access to health care and clinical laboratory testing that included serum creatinine (sCr) and albuminuria measurements from all adult residents of the province of Alberta, Canada. We sought to compare the frequency of identification of AKD without AKI with that of CKD, AKI, and combinations of these conditions, as well as to compare the prognosis of these groups for the risks of development or progression of CKD or end-stage kidney disease (ESKD) and risk of death
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