THE NOVAMAXCREAT POINT OF CARE DEVICE AND TEST STRIPS CAN WITHSTAND HEAT

Introduction:

Point-of-care (POC) kidney function testing will play an increasingly important role in the early identification of acute kidney injury (AKI) and chronic kidney disease (CKD) and optimisation of CKD management in targeted populations. In these (often tropical) settings, POC testing may be the only accessible tool. Patient and healthcare confidence in the reliability of POC devices, is therefore vital to promote engagement. 

The aims of this study were to assess whether accuracy and precision of serum creatinine (SCr) were affected at higher temperatures over longer time periods using the NovaMaxCreat test strips and device (Nova Biomedical, Waltham, MA, USA).

Methods:

We performed a longitudinal cohort study, using sera from participants recruited in the RAPID study (ISRCTN 31697115). 

Thawed sera, maintained at 4-degrees Celsius, were tested using NovaMaxCreat test strips kept at room temperature (RT) or 35 degrees Celsius (35-D) to mimic tropical environments. SCr (mmol/L) was measured in duplicate for each participant serum at both temperatures after 30 minute (manufacturer recommendation), 1, 2, 4 and 6-hour intervals.

Baseline characteristics were recorded as counts and percentages. Data were parametric. Mean bias ± standard deviation (SD) and coefficient of variation (CV) were assessed at each time interval and temperature. Repeated measures ANOVA and paired t-tests assessed any differences between temperatures and over time.

Results:

Sera from 10 participants (mean age 55.8 ± 20.2 years; 60% female) were studied. 

Compared to the reference test (RT-SCr at 30-minutes), mean SCr bias for RT tests, were: 1-h = 6.63 ± 14.0, 2-h = -9.11 ± 14.1, 4-h = -10.3 ± 14.6 and 6-h = -2.87 ± 16.9 mmol/L. There were no significant differences between time intervals at room temperature. 

For 35-D tests, mean SCr bias was: 30-min = -8.49 ± 10.4, 1-h = -2.52 ± 14.8, 2-h = 4.64 ± 13.0, 4-h = 4.77 ± 21.0 and 6-h = 8.40 ± 14.6 mmol/L. There was no significant difference between time intervals at 35 degrees. There was also no significant difference between RT and 35-D at each time interval. 

There was no significant difference in precision across time or between temperature (Table 1).

Conclusions:

We report no significant difference in accuracy or precision of SCr concentration using the NovaMaxCreat device over time or at a higher temperature. This provides confidence in the reliability and validity of SCr results in warmer conditions for AKI identification, CKD diagnosis and optimisation of CKD management. 

Limitations include using sera and the small sample size. Further evaluation using a larger cohort and assessing other factors such as humidity and the handling of test strips is still recommended.

I have no potential conflict of interest to disclose.

I did not use generative AI and AI-assisted technologies in the writing process.