Assessment of a glycated hemoglobin point-of-care analyzer (A1CNow+) in comparison with an immunoturbidimetric method: a diagnostic accuracy study

CONTEXT AND OBJECTIVE: To monitor glycemic control in diabetic patients, regular measurement of glycated hemoglobin (HbA1c) is recommended, but this can be difficult in remote places without access to laboratories. Portable point-of-care testing devices can prove a useful alternative. Our study aimed to assess the performance of one of them: A1CNow+, from Bayer. DESIGN AND SETTING: Cross-sectional accuracy study conducted at a university hospital in Brazil. METHODS: We made three successive measurements of capillary HbA1c using the A1CNow+ in 55 diabetic volunteers, while the same measurement was made on venous blood using the hospital reference method (Vitros 5,1 FS). We used the Bland-Altman graphical method to assess the A1CNow+ in relation to the Vitros 5,1 FS method. We also evaluated clinical usefulness by calculating the sensitivity and specificity of A1CNow+ for detecting patients with HbA1c lower than 7%, which is the usual limit for good glycemic control. RESULTS: The coefficient of variation between repeat testing for the A1CNow+ was 3.6%. The mean difference between A1CNow+ and Vitros 5,1 FS was +0.67% (95% confidence interval, CI: +0.52 to +0.81). The agreement limits of our Bland-Altman graph were -0.45 (95% CI: -0.71 to -0.19) and +1.82 (95% CI: +1.52 to +2.05). The sensitivity and specificity in relation to the 7% limit were respectively 100% and 67.7%. CONCLUSIONS: Although the A1CNow+ had good sensitivity, its accuracy was insufficient for use as a replacement for laboratory measurements of HbA1c, for glycemic control monitoring in diabetic patients.

研究背景与目的：为监测糖尿病患者的血糖控制情况，临床推荐定期检测糖化血红蛋白（glycated hemoglobin, HbA1c），但在无实验室检测条件的偏远地区，该检测操作往往难以开展。便携式床旁检测设备可作为有效的替代方案。本研究旨在评估拜耳（Bayer）旗下A1CNow+设备的检测性能。
研究设计与研究场景：本研究为在巴西某大学医院开展的横断面准确性研究。
研究方法：我们对55名糖尿病志愿者采用A1CNow+连续三次检测毛细血管血糖化血红蛋白，同时采用医院参考方法Vitros 5,1 FS检测静脉血糖化血红蛋白。我们使用Bland-Altman图示法，以Vitros 5,1 FS为参照方法，评估A1CNow+的检测性能；此外，通过计算A1CNow+检测HbA1c低于7%（临床公认的良好血糖控制阈值）的灵敏度与特异度，评估其临床应用价值。
研究结果：A1CNow+的重复检测变异系数为3.6%。A1CNow+与Vitros 5,1 FS的平均检测差值为+0.67%（95%置信区间（confidence interval, CI）：+0.52~+0.81）；Bland-Altman图显示的一致性界限分别为-0.45（95%置信区间（CI）：-0.71~-0.19）与+1.82（95%置信区间（CI）：+1.52~+2.05）。以7%为阈值时，A1CNow+的灵敏度与特异度分别为100%与67.7%。
研究结论：尽管A1CNow+具备良好的灵敏度，但其检测准确度不足以替代实验室糖化血红蛋白检测，用于糖尿病患者的血糖控制监测。