Referral patterns and outcomes in noncritically ill patients with hospital-acquired acute kidney injury

Abstract

Background and objectives: Despite modern treatment, the case fatality rate of hospital-acquired acute kidney injury (HA-AKI) is still high. We retrospectively described the prevalence and the outcome of HA-AKI without nephrology referral (nrHA-AKI) and late referred HA-AKI patients to nephrologists (lrHA-AKI) compared with early referral patients (erHA-AKI) with respect to renal function recovery, renal replacement therapy (RRT) requirement, and in-hospital mortality of HA-AKI.

Design, setting, participants, & measurements: Noncritically ill patients admitted to the tertiary care academic center of Lausanne, Switzerland, between 2004 and 2008 in the medical and surgical services were included. Acute kidney injury was defined using the Acute Kidney Injury Network (AKIN) classification.

Results: During 5 years, 4296 patients (4.12% of admissions) experienced 4727 episodes of HA-AKI during their hospital stay. The mean ± SD age of the patients was 61 ± 15 years with a 55% male predominance. There were 958 patients with nrHA-AKI (22.3%) and 2504 patients with lrHA-AKI (58.3%). RRT was required in 31% of the patients with lrHA-AKI compared with 24% of the patients with erHA-AKI. In the multiple risk factor analysis, compared with erHA-AKI, nrHA-AKI and lrHA-AKI were significantly associated with worse renal outcome and higher in-hospital mortality.

Conclusions: These data suggest that HA-AKI is frequent and the patients with nrHA-AKI or lrHA-AKI are at increased risk for in-hospital morbidity and mortality.

Figure 1.

Patients included and excluded in the analysis. SCr, serum creatinine; HA-AKI, hospital-acquired acute kidney injury; nrHA-AKI, patients with HA-AKI with no referral to the nephrologist; lrHA-AKI, late-referred HA-AKI patients; erHA-AKI, early-referred patients with HA-AKI.

Figure 2.

(A) Percentage of emergent renal replacement therapy (RRT) (hemodialysis [HD]) for non-intensive care unit (ICU) patients (i.e., medicine and surgery wards) in hospital-acquired acute kidney injury (HA-AKI) patients according to their status. The x-axis shows the percentage of nrHA-AKI and early-referred (erHA-AKI) patients who received emergency RRT. The y-axis reflects the percentage of patients studied. (B) Percentage of patients with HA-AKI requiring RRT (HD or peritoneal dialysis) at the time of hospital discharge. The x-axis shows the percentage of nrHA-AKI and erHA-AKI patients who required RRT at hospital discharge. The y-axis reflects the percentage of patients studied.

Figure 3.

Outcome of renal function determined by SCr level evolution in each patient group in medicine and surgery wards with HA-AKI at hospital discharge. For details, see Methods. , percentage of patients with complete recovery (>75% ΔSCr); , percentage of patients with partial recovery (25% to 75% ΔSCr); ■, percentage of patients with no recovery (<25% ΔSCr). P = 0.001. nrHA-AKI, hospital-acquired acute kidney injury; without nephrology referral; lrHA-AKI, late-referred HA-AKI; erHA-AKI, early-referred HA-AKI.

Figure 4.

Timing to nephrology referral. Mean time in days ± SD before the patients with hospital-acquired acute kidney disease (HA-AKI) was referred to the nephrologist. ■, late-referred (lrHA-AKI) patients to the nephrologist (>5 days after SCr increase as defined according the Acute Kidney Injury Network [AKIN] criteria) hospitalized in the medicine and surgery wards; [GRAPHIC], early-referred (erHA-AKI) patients to the nephrologist (≤5 days after SCr increase as defined) hospitalized in the medicine and surgery wards.

Figure 5.

Length of hospital stays for patients with hospital-acquired acute kidney injury (HA-AKI). Mean times in days ± SD for hospital stay for patients with HA-AKI in the medicine and surgery wards with or without RRT (HD). *P = 0.002, patients without any HA-AKI during hospital stay compared with HA-AKI patient groups (nrHA-AKI, lrHA-AKI, and erHA-AKI). nrHA-AKI, HA-AKI without nephrology referral; lrHA-AKI, late-referred HA-AKI; erHA-AKI, early-referred HA-AKI.

Figure 6.

Kaplan–Meier curves for survival (in-hospital) by referral class during the first 20 days of hospitalization. Patients discharged alive were censored. Log-rank statistic, P < 0.001. erHA-AKI, early-referred hospital-acquired acute kidney injury; nrHA-AKI, hospital-acquired acute kidney injury without nephrology referral; lrHA-AKI, late-referred HA-AKI.