Outpatient nephrology referral rates after acute kidney injury

Abstract

AKI associates with an increased risk for the development and progression of CKD and mortality. Processes of care after an episode of AKI are not well described. Here, we examined the likelihood of nephrology referral among survivors of AKI at risk for subsequent decline in kidney function in a US Department of Veterans Affairs database. We identified 3929 survivors of AKI hospitalized between January 2003 and December 2008 who had an estimated GFR (eGFR) <60 ml/min per 1.73 m(2) 30 days after peak injury. We analyzed time to referral considering improvement in kidney function (eGFR ≥60 ml/min per 1.73 m(2)), dialysis initiation, and death as competing risks over a 12-month surveillance period. Median age was 73 years (interquartile range, 62-79 years) and the prevalence of preadmission kidney dysfunction (baseline eGFR <60 ml/min per 1.73 m(2)) was 60%. Overall mortality during the surveillance period was 22%. The cumulative incidence of nephrology referral before dying, initiating dialysis, or experiencing an improvement in kidney function was 8.5% (95% confidence interval, 7.6-9.4). Severity of AKI did not affect referral rates. These data demonstrate that a minority of at-risk survivors are referred for nephrology care after an episode of AKI. Determining how to best identify survivors of AKI who are at highest risk for complications and progression of CKD could facilitate early nephrology-based interventions.

Figure 1.

Study population flowchart. *Patients can have more than one exclusion criterion.

Figure 2.

Cumulative incidences of nephrology referral, dialysis initiation, improvement in kidney function, and death analyzed as competing risks. This figure summarizes the cumulative incidences of the prespecified outcomes as competing risks during the 12-month surveillance period (30–395 days following peak injury). Beginning at 30 days after peak injury, the cumulative incidences of first improving kidney function to an eGFR >60 ml/min per 1.73 m², dying, being referred to nephrology, or receiving dialysis were 44.0% (95% CI, 42.4–45.5), 11.5% (95% CI, 10.5–12.5), 8.5% (95% CI, 7.6–9.4), and 0.2% (95% CI, 0.1–0.4), respectively.