Body Composition, Kidney Size, and Medication Dosing in Acute Kidney Injury: Follow-Up at 90 Days and 12 Months

Body Composition, Kidney Size, and Medication Dosing in Patients With Acute Kidney Injury: A Telephone-Based Follow-Up Study at 90 Days and 12 Months

Acute Kidney Injury (AKI) is a common and serious condition affecting up to 12% of hospitalized patients, with increasing severity linked to higher mortality. Despite early detection via automated warning systems, clinical outcomes such as hospital length of stay, dialysis need, and death remain suboptimal. This non-interventional study evaluates modifiable factors influencing AKI outcomes by integrating four key components: body composition, kidney size, medication dosing, and patient-reported outcomes. Body composition is assessed using non-invasive bioimpedance spectroscopy to evaluate fluid status, muscle mass, and fat mass. Kidney size and structure are assessed via point-of-care ultrasound to detect underlying chronic kidney disease or obstructive causes. A standardized national medication plan is used to review drug dosing, interactions, and potential errors, supported by nephrology and pharmacy expertise. Additionally, patients are contacted by telephone at 90 and 365 days post-diagnosis to assess awareness of AKI, perceived severity, health literacy, and current kidney function (via blood tests and medication review). The study evaluates whether early, multidimensional assessment is associated with improved patient understanding, care coordination, and long-term outcomes. Findings may inform future strategies to enhance AKI management, reduce complications, and improve patient-centered care.

Study Overview

• Status: Completed
• Conditions: Acute Kidney Injury

Detailed Description

Acute kidney injury (AKI) is a common and serious condition affecting up to 12% of hospitalized patients, with mortality increasing significantly with severity. Despite the implementation of automated AKI alert systems, clinical outcomes such as hospital length of stay, dialysis need, and death remain suboptimal. This non-interventional, single-center study aims to improve understanding of modifiable factors influencing AKI outcomes by integrating four key components: body composition, kidney size, medication dosing, and patient-reported outcomes.

The primary objective is to assess the prevalence of fluid imbalance, structural kidney abnormalities, and medication errors in patients with AKI Stage 3. It is hypothesized that most patients with AKI are not in a state of euvolemia (i.e., they have either fluid overload or dehydration), that pre-existing chronic kidney disease is detectable via abnormal kidney sonography, and that a significant proportion of patients have medication dosing errors, including inappropriate, contraindicated, or nephrotoxic drugs.

Secondary objectives include evaluating patient awareness of AKI diagnosis, assessing whether patients receive follow-up kidney function monitoring within 90 days after hospital discharge, and identifying gaps in post-discharge care. It is hypothesized that fewer than 100% of patients are aware of their AKI diagnosis, and that a substantial proportion do not undergo follow-up kidney function testing within 90 days.

The study population includes adult patients (≥18 years) with a confirmed diagnosis of AKI Stage 3, defined by an increase in serum creatinine ≥3-fold from baseline or ≥4 mg/dL with an acute rise of ≥0.5 mg/dL, or oliguria (<0.5 mL/kg/h for >6 hours). Patients are identified via the hospital's automated AKI alert system and approached by the nephrology consultative service during hospitalization. Inclusion requires informed consent; exclusion criteria include participation in another clinical trial within the past 4 weeks or a life expectancy of less than 28 days, as judged by the treating physician.

A total of approximately 120 patients are planned for inclusion, with the expectation that around 100 will be available for follow-up at 90 and 365 days post-discharge. Data collection includes electronic health records (Nephro7, SAP) for vital signs, laboratory values, diagnoses, and medication lists. Additional assessments include:

• Body composition analysis using non-invasive bioimpedance spectroscopy (50 frequencies, 5-1000 kHz) to measure total body water, extracellular water, muscle mass, and fat mass. Overhydration (>1000 mL) is a primary outcome.
• Point-of-care ultrasound of the kidneys to assess kidney length (<10 cm), parenchymal thickness (<10 mm), and signs of chronic kidney disease or obstruction. Findings are correlated with estimated glomerular filtration rate (eGFR <45 mL/min).
• Medication review using the national standardized medication plan (Bundesmedikationsplan), supplemented by a joint evaluation by a nephrologist and clinical pharmacist to identify dosing errors, contraindications, or nephrotoxic drugs.

Patients are contacted by telephone at 90 and 365 days after AKI diagnosis to assess:

• Awareness of the AKI diagnosis (Yes/No),
• Perceived severity of the event (Likert scale: 1-5),
• Health literacy regarding AKI (Likert scale: 1-5),
• Whether kidney function (serum creatinine, urea, potassium) was rechecked by their primary care provider within 90 days.

All data are anonymized and stored securely on hospital servers. The study is non-interventional; no changes to standard care are made. The only interventions are the assessments and follow-up calls. The study is ethically approved and conducted in accordance with GDPR and local regulations.

The anticipated benefits include improved patient safety through early detection of fluid imbalance, kidney structural changes, and medication errors. The follow-up calls may prompt overdue kidney function checks by primary care providers. Risks are minimal: potential anxiety from the phone call is mitigated by trained staff and clear communication. The study is considered medically justified as it enhances care quality beyond routine practice.

Data collection concludes with the final follow-up call at 365 days post-AKI alert. Results will inform strategies to improve AKI management, patient education, and post-discharge monitoring, ultimately reducing complications and improving long-term outcomes.

• Study Type: Observational
• Enrollment (Actual): 154

Contacts and Locations

Study Locations

• Germany
  • Braunschweig, Germany
    • Academic Teaching Hospital Braunschweig

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

In-house patients of the academic teaching hospital Braunschweig

Description

Inclusion Criteria:

• Age: Adult patients (≥18 years)
• Diagnosis: Confirmed diagnosis of Acute Kidney Injury (AKI) Stage 3, defined by one of the following: Increase in serum creatinine ≥3-fold from baseline, Serum creatinine ≥4 mg/dL with an acute rise of ≥0.5 mg/dL, Oliguria (<0.5 mL/kg/h for >6 hours)
• Informed Consent: Willingness to provide written informed consent for participation in the study

Exclusion Criteria:

• Participation in another clinical trial: Participation in any other interventional or observational clinical study within the last 4 weeks prior to study enrollment
• Short life expectancy: Clinically assessed life expectancy of less than 28 days by the treating physician
• Inability to consent: Cognitive or language barriers that prevent informed consent or participation in telephone follow-up
• Terminal illness: Active, untreated, or progressive terminal illness (e.g., advanced cancer with no curative intent)
• Inability to follow up: Unavailability of contact information or inability to be reached by telephone at 90 and 365 days post-discharge

Study Plan

How is the study designed?

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort
AKI Stage 3; Patients (≥18 years) with stage 3 acute kidney injury (AKI) as defined by the following criteria: a ≥3-fold increase in serum creatinine from baseline, a serum creatinine level ≥4 mg/dL with an acute rise of ≥0.5 mg/dL, or oliguria (<0.5 mL/kg/h for >6 hours). Patients were identified via the institutional AKI alert system and confirmed by a nephrologist.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Proportion of Participants Surviving at 90 Days	Defined as alive at 90 days post-inclusion. Assessed via telephone follow-up and medical record review.	90 days after study inclusion
Proportion of Participants Surviving at 365 Days	Defined as alive at 365 days post-inclusion. Assessed via telephone follow-up and medical record review.	365 days after study inclusion

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Proportion of Participants Aware of AKI Diagnosis	Assessed via structured telephone interview: "Do you know you had acute kidney injury during your hospital stay?" (Yes/No).	90 days after study inclusion
Perceived Severity of AKI (Likert Scale)	Assessed using a 5-point Likert scale: 1 = not severe, 2 = slightly severe, 3 = moderately severe, 4 = severely severe, 5 = very severely severe.	90 days after study inclusion
Proportion of Participants with Follow-Up Kidney Function Testing within 90 Days	Defined as serum creatinine, urea, and potassium measured by the primary care provider within 90 days of study inclusion. Confirmed via patient report and primary care medical record review.	90 days after study inclusion

Collaborators and Investigators

• Sponsor: Hannover Medical School
• Collaborators: Academic Teaching Hospital Braunschweig
• Investigators: Principal Investigator: Jan T Kielstein, MD, Academic Teaching Hospital Braunschweig

Study record dates

Study Major Dates

• Study Start (Actual): August 1, 2021
• Primary Completion (Actual): September 1, 2022
• Study Completion (Actual): September 1, 2022

Study Registration Dates

• First Submitted: July 28, 2026
• First Submitted That Met QC Criteria: August 3, 2026
• First Posted (Actual): August 4, 2026

Study Record Updates

• Last Update Posted (Actual): August 4, 2026
• Last Update Submitted That Met QC Criteria: August 3, 2026
• Last Verified: July 1, 2026

More Information

Terms related to this study

• Keywords: AKI detection system
• Additional Relevant MeSH Terms: Urogenital Diseases; Male Urogenital Diseases; Kidney Diseases; Urologic Diseases; Female Urogenital Diseases; Female Urogenital Diseases and Pregnancy Complications; Renal Insufficiency; Acute Kidney Injury
• Other Study ID Numbers: B3 D2 AKI - Study

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: Individual-level data (IPD) will not be shared due to ethical and legal constraints. All data collected in this study are anonymized and stored in compliance with the General Data Protection Regulation (GDPR). The study involves sensitive health information, and sharing raw individual data would pose a risk of re-identification, even after anonymization. Furthermore, the study is non-interventional and does not include a data-sharing agreement with external partners. Therefore, IPD will remain confidential and accessible only to the study team at Academic Teaching Hospital Braunschweig. Aggregate results will be published in peer-reviewed journals, but individual-level data will not be made publicly available.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No