Background/Purpose:  A key factor in the success of gout management is the long-term lowering of serum uric acid (sUA) levels below predetermined targets (5 or 6 mg/dL). Monitoring of uricemia in gout patients is therefore important, especially during drug titration, and is presently done in the laboratory on serum samples obtained after venous puncture. An accurate sUA meter that would allow rapid testing by the health care professionals and self-measurement of uric acid by the gouty patient should improve patient monitoring and management of gout. This study aimed to assess the reliability of immediate uricemia measurement in capillary blood samples obtained from fingertip puncture using the HumaSens-plus point-of-care meter compared with that of a standard laboratory assay.

Methods:  Finger-prick blood sUA levels were measured from 238 consenting diabetic patients using the commercially available HumaSens-plus sUA meter (European Conformity marked and approved for EU market use only). Each patient also had a venous sample taken and prepared as Li-Heparin plasma for analysis in the biochemistry laboratory using a uricase automated colorimetric assay. Since the sUA meter has a dynamic range of 3–20 mg/dL, a subject’s capillary reading was excluded from statistical analysis when the meter read LO or HI, indicating that the subject’s sUA value was lower than or higher than the calibrated range. Statistical analysis included calculation of the Pearson’s correlation coefficient (PCC) between the 2 measured values and Bland-Altman graphic representations of means and differences between the 2 measurement results. A total of 206 paired measurements were calculated to be necessary for calculation of a PCC of 80% with a precision of 0.10 and an alpha risk of 0.05%.

Results: Eighteen capillary samples were marked LO by the meter: 15 were confirmed by standard biochemistry to be below 3 mg/dL, and 3 were above (3.2, 3.4, and 7.1 mg/dL). Two capillary samples were read HI and were measured at 5.1 and 3.6 mg/dL by biochemistry. In the remaining 218 samples, PCC was 0.92, and Bland-Altman curve showed acceptable agreement all over the tested values, with the following limits of agreement: [-1.1 mg/dL; 1.39 mg/dL]. On average, plasma measurements were 1.03-fold higher than capillary measurements. Accuracy was 92.7% at the 20% margin. Predictive value was 77.1% for a capillary measurement found to be above the target (6 mg/dL) by biochemistry measurement. For capillary measurement found to be below the target by biochemistry measurement, predictive value was 92.7%.

Conclusion:  HumaSens meters were easy to use, and these preliminary results showed that the meters give results that are reasonably comparable to those of the laboratory assay; as a result, they may be useful in the clinic and in epidemiologic studies. Further studies are underway to better understand discrepancies between the two techniques by looking at drug intakes and other biochemical and hematologic parameters measured in these patients, as well as by comparing results of both techniques to liquid chromatography-mass spectrometry reference measurements.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/accuracy-of-humasens-plus-point-of-care-uric-acid-meter-using-capillary-blood-obtained-by-fingertip-puncture/