Serum Creatinine and Tacrolimus Assessment With VAMS Finger-Prick Microsampling: A Diagnostic Test Study

Scuderi, Carla E., Parker, Suzanne L., Jacks, Margaret, John, George T., McWhinney, Brett, Ungerer, Jacobus, Mallett, Andrew J., Healy, Helen G., Roberts, Jason A., and Staatz, Christine E. (2023) Serum Creatinine and Tacrolimus Assessment With VAMS Finger-Prick Microsampling: A Diagnostic Test Study. Kidney Medicine, 5 (4). 100610.

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Rationale & Objective: Kidney transplant recipients require frequent venipunctures. Microsampling methods that use a finger-prick draw of capillary blood, like volumetric absorptive microsamplers (VAMS), have the potential to reduce the pain, inconvenience, and volume of blood loss associated with venipuncture. This study aimed to provide diagnostic accuracy using VAMS for measurement of tacrolimus and creatinine compared to gold standard venous blood in adult kidney transplant recipients.

Study Design: Diagnostic test study. Prospective blood samples for measurement of tacrolimus and creatinine were collected using Mitra VAMS and venipuncture immediately before and 2 hours after tacrolimus dosing.

Setting & Participants: A convenience sample of 40 adult kidney transplant participants in the outpatient setting.

Tests Compared: Method comparison was assessed by Passing-Bablok regression and Bland-Altman analysis. The predictive performance of VAMS measurement compared to venipuncture was also assessed through estimation of the median prediction error and median absolute percentage prediction error.

Results: A total of 74 tacrolimus samples and 70 creatinine samples were analyzed from 40 participants. Passing-Bablok regression showed a systematic difference between VAMS and venipuncture when measuring tacrolimus and creatinine with a slope of 1.08 (95% CI, 1.03-1.13) and a slope of 0.65 (95% CI, 0.6-0.7), respectively. These values were then corrected for the systematic difference. When used for Bland-Altman analysis, corrected values of tacrolimus and creatinine showed a bias of -0.1 μg/L and 0.04 mg/dL, respectively. Tacrolimus (corrected) and creatinine (corrected) microsampling values when compared to corresponding venipuncture values met median prediction error and median absolute percentage prediction error predefined acceptability limits of <15%.

Limitations: This study was conducted in a controlled environment using a trained nurse to collect VAMS samples.

Conclusions: In this study, VAMS was used to reliably measured tacrolimus and creatinine. This represents a clear opportunity for more frequent and less invasive sampling for patients.

Item ID: 78335
Item Type: Article (Research - C1)
ISSN: 2590-0595
Keywords: Creatinine, kidney transplant, tacrolimus, therapeutic drug monitoring, volumetric absorptive microsampling
Copyright Information: © 2023 The Authors. Published by Elsevier Inc. on behalf of the National Kidney Foundation, Inc. This is an open access article under the CC BY-NC-ND license (
Funders: National Health and Medical Research Council (NHMRC)
Projects and Grants: NHMRC APP1142757, NHMRC APP2007007, NHMRC APP2009736, NHMRC APP1142757
Date Deposited: 10 Oct 2023 01:28
FoR Codes: 32 BIOMEDICAL AND CLINICAL SCIENCES > 3202 Clinical sciences > 320214 Nephrology and urology @ 100%
SEO Codes: 20 HEALTH > 2001 Clinical health > 200199 Clinical health not elsewhere classified @ 100%
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