MO193: Capillary Point-Of-Care Creatinine Testing in Kidney Disease Patients

Abstract

Abstract BACKGROUND AND AIMS Creatinine measurement is part of daily nephrological practice to estimate the glomerular filtration rate (eGFR). Creatinine is usually measured in plasma or in serum by the Jaffe method or enzymatic reactions [1]. New point-of-care testing (POCT) devices have been developed to allow rapid creatinine quantification from venous, arterial or capillary samples [2, 3]. Importantly, capillary sampling and quantification could enable autonomous patient-performed creatinine measurements at home. This method has so far not been extensively tested in chronic kidney disease (CKD), kidney transplanted (TPL) and haemodialysis [HD]-dependent patients. The 2-fold aim of this study was to assess the adequacy and patient acceptance of capillary creatinine POCT in the aforementioned different kidney disease patients’ groups. METHOD Consecutive eligible patients followed at the nephrology outpatient unit of the Bern University Hospital were included. In each patient, creatinine was both measured by Nova Max® Creatinine in three different capillary measurements (index test) and from venous sampling by the central hospital laboratory (enzymatic reference test). In HD patients, analyses were performed before and after a HD session. Intra-essay variation and correlation between the index and the reference test were calculated. In order to explore patients’ acceptance and perception of autonomous capillary creatinine measurement at home, subjects were asked to fill a standardized survey. RESULTS A total of 128 patients were included: 33 CKD, 68 TPM and 27 HD. Capillary POCT creatinine ranged from 55–604 umol/L, 50–458 umol/L and 133–872 umol/L for CKD, TPL and HD patients, respectively. Intra-assay variation was 23 umol/L (IQR: 10.5–47.5 umol/L), corresponding to 12% (IQR: 7–21%) variation. Correlation between capillary and plasma creatinine was high at r2 = 0.89, 0.76 and 0.72 for CKD, TPL and HD patients, respectively. Within the latter group, correlation was considerably higher after dialysis (r2 = 0.83) compared to before dialysis (r2 = 0.55). Overall, 54 patients (42%) filled the questionnaire; 97% considered POCT creatinine an easy test to perform and 94% considered it an implementable test at home. Over three quarters of the sample (77%) associated such intervention with improvement for patient care. Patients were particularly sensitive to the potential time saving and capacity to monitor their creatinine levels swiftly. CONCLUSION Autonomous capillary POCT creatinine measurement is an adequate, relevant and implementable test in specific subgroups of kidney disease patients. Correlation with plasma creatinine is high for CKD and TPL patients, while there are important inter-assay variations in HD patients. This test has economical, ecological and logistic implications that warrant further evaluation. The next step in evaluating this test would require an investigation of its reproducibility and clinical impact over time.