Part Ⅰ An Early Warning System For The Differential Diagnosis Of In-Hospital Acute Kidney Injury For Better Patient Outcome: Study Of A Quality Improvement Initiative

Abstract

Background

Acute kidney injury (AKI) is a syndrome with heterogeneous causes and mechanisms. An early warning system (EWS) for AKI was created to reduce the incidence and improve outcomes. However, the benefits of AKI-EWS remain debatable.

Methods

We launched a project to design and create AKI-EWS for inpatients in our institute. The incidence of AKI and its outcome before and after the implementation of AKI-EWS were collected for analysis.

Results

We enlisted a stakeholder map before creating AKI-EWS. We then started an action plan for this initiative. The diagnosis was automatic and based on the definition of Kidney Disease: Improving Global Outcomes (KDIGO). The differential diagnosis of causes of AKI was also automatic. Users are to adjust the threshold of detection. After the implementation of this AKI-EWS, the incidence of AKI fell. The proportion of AKI > 4% was reduced significantly (47.7% and 41.6%, p = 0.010) in patients with serum creatinine measured. The proportion of AKI > 0.9% also dropped significantly (51.67% and 35.94%, p = 0.024) in all inpatients. Trends in AKI outcomes also showed improvement. The loading of consultations with nephrologists decreased by 15.5%.

Conclusions

Through well-designed AKI-EWS, the incidence of AKI dropped, showing improved outcomes. The factors affecting benefits from AKI-EWS included high-risk identification (individual threshold detection), timely and automatic diagnosis, real-time alerting on electronic health information systems, fast self-diagnosing of the cause of AKI, and coverage of all inpatients.

Keywords

early warning system (EWS); acute kidney injury (AKI); electronic health information systems (EHIS); inpatient; diagnosis; outcome; Cistanche's effects.

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1. Introduction

Acute kidney injury (AKI) is characterized by a rise in the serum creatinine level or a declined urine output within days. Patients with AKI have a variety of clinical presentations. The outcome varies, including full recovery, acute kidney disease (AKD), chronic kidney disease (CKD), CKD G5CKD G5, or dialysis and mortality. In a large meta-analysis of 110 studies on AKI (429,535 patients) according to the Kidney Disease: Improving Global Outcomes (KDIGO) definition, the mortality increased to 23% [1]. For hospitalized AKI patients, those discharged have a higher risk of death, rehospitalization, and progressive CKD and CKD G5 [2]. Currently, no global standard is available for the prevention, recognition, treatment, and follow-up of AKI because of the vast differences in care delivery. Recently, a quality improvement projection for AKI (“zero preventable deaths by 2025”) by the International Society of Nephrology’s 0 by 25 initiative (a human rights case for nephrology) was reported [3]. It was aimed to establish awareness and reduce variations in care delivery for AKI. Early diagnosis of AKI is necessary for timely intervention to improve outcomes. Early nephrologist involvement in hospital-acquired AKI suggested patient benefit [4]. Therefore, early recognition to raise awareness is our first step.

Prompt diagnosis of AKI is important. First, AKI is not associated with specific symptoms and signs. Second, the diagnosis of AKI relies on laboratory measurements (serum creatinine) and urine amount. Usually, missing checkups or serum creatinine measurements, or collection of urine delays the diagnosis of AKI. Third, the diagnostic criteria are based on different diagnostic criteria, KDIGO definition and staging system [5,6], RIFLE criteria (risk, injury, failure, loss of kidney function, and end-stage kidney disease) [7], and Acute Kidney Injury Network (AKIN) and others [8–10]. The KDIGO guidelines [5,6] define AKI as presenting one of the following conditions: an increase in serum creatinine by ≥0.3 mg/dL within 48 h; an increase in serum creatinine to ≥1.5 times baseline, which is known or presumed to have occurred within the prior seven days; a urine volume of <0.5 mL/kg/h for six hours. In clinical practice, clinicians usually used a staging system of AKI from the KDIGO criteria to evaluate the severity of AKI. It is suggested by the KDIGO guidelines to tailor management to the AKI stage. Staged-based management of AKI can improve the response to therapy according to the different severity of AKI [6]. In stage 1 AKI, the clinician should perform a noninvasive diagnostic workup and also consider an invasive diagnostic workup. In stage 2 AKI, the clinician should check for changes in drug dosing and consider renal replacement therapy and ICU admission. Finally, in stage 3 AKI, clinicians should avoid subclavian catheters if possible. Even though the current consensus is that the KDIGO definition of AKI is most favored, memorizing the criteria of KDIGO for AKI is not easy. The complicated criteria of AKI impair the awareness of AKI. Therefore, an automatic early warning system (EWS) for AKI is helpful. However, not all applications of EWS for AKI benefit the AKI outcome because of differences in the data collection system, i.e., with or without intervention [11].

In this study, we created a quality improvement (QI) project to improve the diagnosis and outcome of AKI. QI can improve the quality of processes to improve performance. QI programs are critical because they improve patient outcomes, and the efficiency of staff, and reduce waste due to failed processes. This QI focused on the analysis of the current status of AKI in our institute, the creation of EWS, interventions of AKI, and feedback for this system. In addition to creating an EWS for AKI, we were also interested in the effect of this notification on AKI incidence and outcome in our institute. We also sought to identify the key point that determined a better outcome of AKI after the implantation of AKI-EWS.

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2. Material and Methods

Patients and Intervention (EWS)

In this study, we present the whole process of the EWS of AKI. All inpatients enrolled were >20 years old except patients who underwent dialysis. This system has been in working condition since September 2018. The content management system was later created in September 2019. In March 2020, EWS was created in the Electronic Health Information Systems (EHIS) and opened to all users. This EWS will screen all adult inpatients (including all hospital settings except outpatients, such as an ordinary ward, intensive care unit, emergent room, and delivery room) every midnight based on the serum creatinine-based diagnosis of AKI. Every morning, users of EHIS can see the automatic diagnosis of AKI and differential diagnosis of causes for AKI.

As for the baseline serum creatinine value, we set the baseline value as follows: the lowest value within 2 days, the lowest value within 7 days, or the latest value within 6 months. First, the EWS screened the serum creatinine value that had been obtained in the last 2 days, and the latest value had to be higher by 0.3 mg/dL than the baseline serum creatinine value based on the KDIGO guidelines. If the value of serum creatinine was not obtained in the last 2 days, EWS screened the serum creatinine value that had been obtained in the last 7 days, and the latest serum creatinine value had to be 50% higher than the baseline serum creatinine value (using the lowest value as the baseline). Finally, if the required value had not been obtained in the last 7 days, but had been obtained in the last 6 months, the latest value had to be 50% higher than the baseline value (using the latest value within 6 months as the baseline).

Definition of AKI and Outcome Measures

We adopted the KDIGO definition of AKI [7,12]. Once diagnosed as AKI, we evaluated the outcome of AKI as AKD, CKD, and CKD G5 (dialysis-dependent). The term “AKD” defined by KDIGO [4,13] is defined as showing kidney damage for <3 months (structural criteria), with AKI or GFR < 60 mL/min per 1.732 m2 for <3 months or decreased in GFR by ≥35% or increased in serum creatinine by >50% for <3 months (functional criteria). CKD is defined as showing elevated serum levels of creatinine or GFR < 60 mL/min per 1.732 m2 for >3 months (functional criteria) or other evidence of kidney damage, with a presence >3 months (structural criteria) [5]. Those with dialysis dependence 3 months after AKI diagnosis were defined as CKD G5.

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We collected data on AKI incidence from September 2018 to January 2021. The trend line of daily incidence was separated in March 2020 (on board of EWS over EHIS). We defined daily AKI incidence rates (%) according to two definitions: case numbers of AKI/inpatients with data of serum creatinine (Definition 1) and case numbers of AKI/all inpatients with or without data of serum creatinine (Definition 2).

Endpoints

For daily monitoring of AKI incidence, we plotted the data in terms of a trend line, together with the equation and the coefficient of determination. We presented the mean incidence of AKI before and after EWS. As the daily incidence of AKI was not distributed normally, we also compared the different proportions of AKI incidence before and after EWS to assess the benefits of AKI-EWS. For outcome analyses (including full recovery, AKD, CKD, CKD G5, and mortality), we collected patients with AKI from September 2018 to November 2020. We also recorded the case numbers of consultations of nephrologists before and after the AKI-EWS for the analysis of clinical loading of nephrology

Statistical Analysis

Data are expressed as means, standard deviations, or percentages. Differences between incidence rates of AKI before and after notification were evaluated by Student’s t-test. A linear regression model was plotted for trend lines to visualize the trend of AKI incidence and the outcomes before and after EWS. A statistically significant difference was set at p < 0.05. All analyses were performed with the SPSS statistical software, version 12.0 (SPSS Inc., Chicago, IL, USA). All methods were carried out by human research guidelines and regulations of TCVGH (Institutional Review Board number: CW 17045A).

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References

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Ming-Ju Wu 1,2 , Shih-Che Huang 3,4, Cheng-Hsu Chen 1,2,5 , Ching-Yao Cheng 6,7 and Shang-Feng Tsai 1,2,5,8

1 Division of Nephrology, Department of Internal Medicine, Taichung Veterans General Hospital, Taichung 407, Taiwan; wmj530@gmail.com (M.-J.W.); cschen@vghtc.gov.tw (C.-H.C.)

2 Department of Post-Baccalaureate Medicine, College of Medicine, National Chung Hsing University, Taichung 402, Taiwan

3 Division of Clinical Information, Center of Quality Management, Taichung Veterans General Hospital, Taichung 407, Taiwan; cucu0214@gmail.com

4 Department of Emergency Medicine, Taichung Veterans General Hospital, Taichung 407, Taiwan

5 Department of Life Science, Tunghai University, Taichung 407, Taiwan

6 Department of Pharmacy, Taichung Veterans General Hospital, Taichung 407, Taiwan; chingyao@vghtc.gov.tw

7 School of Pharmacy, China Medical University, Taichung 404, Taiwan

8 School of Medicine, National Yang-Ming University, Taipei 112, Taiwan