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. 2023 Feb 4;5(4):100610.
doi: 10.1016/j.xkme.2023.100610. eCollection 2023 Apr.

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

Carla E Scuderi  1   2 , Suzanne L Parker  3 , Margaret Jacks  1 , George T John  1 , Brett McWhinney  4 , Jacobus Ungerer  4   5 , Andrew J Mallett  6   5   7   8 , Helen G Healy  1   6 , Jason A Roberts  3   9   10   11 , Christine E Staatz  2
Affiliations

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

Carla E Scuderi et al. Kidney Med. .

Abstract

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.

Keywords: Creatinine; kidney transplant; tacrolimus; therapeutic drug monitoring; volumetric absorptive microsampling.

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Figures

None
Graphical abstract
Figure 1
Figure 1
Passing-Bablock regression fit between venous blood (VB) and microsamples (VAMS) for tacrolimus (A) and creatinine (B). Description of sample comparison: VAMS Tacro = tacrolimus blood concentration estimate based on VAMS collection VB Tacro = tacrolimus blood concentration measurement based on venepucture sampling VAMS Creatinine = creatinine plasma concentration estimate based on VAMS collection VB Creatinine = creatinine plasma concentration measurment based on venepucture sampling Creat, creatinine; Tacro, tacrolimus; VAMS, volumetric absorptive microsamples; VB, venous blood sample.
Figure 2
Figure 2
Bland-Altman analysis of venous blood (VB) and microsamples (VAMS) for tacrolimus (A) and creatinine (B).
See this image and copyright information in PMC

References

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