This study evaluates the clinical performance of a non-invasive digital diagnostic test (KF4+, developed and manufactured by Gisens Biotech) for the measurement of urea and potassium in capillary blood in patients with end-stage renal disease (ESRD) undergoing dialysis. Measurements obtained using the KF4+ test in capillary blood are compared with hospital laboratory reference methods performed on venous blood samples. The study also assesses the feasibility of determining dialysis efficiency, expressed as Kt/V, using non-invasive samples. The objective is to determine agreement, correlation, and clinical comparability between methods, and to evaluate the use of capillary blood as an alternative to venous sampling in routine dialysis monitoring.
The adequacy of dialysis treatment is traditionally assessed by measuring serum urea and calculating Kt/V, which requires venous blood sampling and laboratory infrastructure. This observational diagnostic study evaluates the use of a portable, bioelectronic point-of-care test (KF4+, Gisens Biotech) for measuring urea and potassium in capillary blood as a non-invasive alternative. KF4+ test is a disposable cartridge based on electrochemical detection of analytes inside. Adult patients with end-stage renal disease undergoing chronic hemodialysis from Hospital Interzonal General de Agudos "General San Martín" are enrolled. Capillary blood samples are collected before and after dialysis sessions and analyzed using the KF4+ digital test. Venous blood samples collected at the same time points are analyzed using standard hospital laboratory reference methods with the autoanalyzer Wiener Lab CMD 800i. Method comparison analyses are performed to evaluate agreement and correlation between capillary and venous measurements. Dialysis efficiency is assessed by calculating Kt/V using urea values obtained from capillary blood and comparing these results with Kt/V calculated from venous blood measurements. The study is conducted at a single hospital center and follows a paired, comparative, observational design. KF4+ results were not used for clinical decision-making.
Study Type
OBSERVATIONAL
Enrollment
55
This is an observational clinical study. The KF4+ is a portable and digital test used to measure urea and potassium concentrations in capillary blood samples. Results are compared with hospital laboratory reference methods performed on venous blood. The KF4+ test is used for measurement only and does not influence clinical management or dialysis prescription.
Hospital Interzonal General de Agudos General San Martín La Plata, Argentina
La Plata, Buenos Aires, Argentina
Agreement and correlation of urea concentrations measured in capillary blood using the KF4+ digital test and in venous blood using the reference laboratory method.
Urea concentrations measured using the KF4+ digital test in capillary blood will be compared with urea concentrations measured using the reference laboratory method in venous blood samples. Agreement between the two methods will be assessed using Bland-Altman analysis, including Bland-Altman plots. Correlation between the two methods will be assessed using Spearman correlation analysis and linear regression. All analyses will be based on paired capillary and venous blood measurements.
Time frame: Immediately before and immediately after a routine dialysis session.
Agreement and correlation of potassium concentrations measured in capillary blood using the KF4+ digital test and in venous blood using the reference laboratory method
Potassium concentrations measured using the KF4+ digital test in capillary blood will be compared with potassium concentrations measured using the reference laboratory method in venous blood samples. Agreement between the two methods will be assessed using Bland-Altman analysis, including Bland-Altman plots. Correlation between the two methods will be assessed using Spearman correlation analysis and linear regression. All analyses will be based on paired capillary and venous blood measurements.
Time frame: Immediately before a routine dialysis session.
Agreement between Kt/V calculated from capillary blood urea and Kt/V calculated from venous blood urea.
Agreement between Kt/V calculated using urea concentrations measured in capillary blood with the KF4+ test and Kt/V calculated using urea concentrations measured in venous blood using the reference laboratory method. Agreement between the two methods will be assessed using paired statistical tests. Kt/V will be calculated using the single pool Kt/V equation as indicated by KDIGO 2024 clinical guideline.
Time frame: Kt/V is calculated immediately after a routine dialysis session using urea levels measured immediately before and immediately after the dialysis session.
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