Single-Capillary Dual Point-of-Care Testing to Support Cardio-Renal Diagnostic Decision-Making in Ambulatory Care

Integrated interpretation of renal function and natriuretic peptides is essential in ambulatory cardio-renal care. This study evaluated whether a single-capillary dual point-of-care testing (POCT) strategy combining creatinine/eGFR and NT-proBNP could support real-time, integrated clinical decision-making during a single consultation.

In this exploratory, single-center, real-world study that was designed as a feasibility study focusing on workflow integration and clinical usability, capillary creatinine/eGFR and NT-proBNP were evaluated using a single-fingerstick dual-POCT workflow in two exploratory clinical subgroups recruited according to their respective clinical indications. Analytical agreement was assessed using Passing-Bablok regression (slope, intercept, and 95% confidence intervals) and Bland-Altman analysis. Agreement at guideline-based clinical thresholds (eGFR ≤60 mL/min/1.73m²; NT-proBNP ≥125 ng/L) was evaluated using Cohen's kappa. Workflow feasibility and time-to-result were also documented.

Forty-three patients underwent creatinine/eGFR testing, and a separate subgroup of 22 patients underwent NT-proBNP testing, reflecting different clinical indications and real-world recruitment during this exploratory feasibility study. Passing-Bablok regression showed good agreement with slopes close to unity and no significant systematic bias. Bland-Altman analysis demonstrated clinically acceptable limits of agreement. Diagnostic agreement at clinical thresholds was substantial for eGFR (κ=0.71) and perfect for NT-proBNP (κ=1.00), with no clinically relevant misclassification. Dual biomarker results were available within approximately 15 minutes, enabling same-visit clinical decisions.

A single-capillary dual-biomarker POCT workflow enables rapid and reliable cardio-renal assessment within one ambulatory visit. Its primary value lies in integrated, threshold-based clinical interpretation enabled by the simultaneous availability of complementary biomarkers, rather than analytical comparison alone.