Comparison of longitudinal point‐of‐care and high‐performance liquid chromatography HbA_1c measurements in a multi‐centre trial

Abstract

Aims Point-of-care HbA1c is routine in clinical practice. Comparison of point-of-care HbA1c against laboratory measurements across sites and over time is warranted. Methods One hundred and twenty-one young persons with Type 1 diabetes from four centres provided 450 paired samples collected over 10 months for point-of-care HbA1c and central laboratory-based high-performance liquid chromatography (HPLC) HbA1c determinations. Change in HbA1c over time was assessed by difference from initial to final HbA1c and by growth modelling with annualized slope calculation. Change in HbA1c was categorized as improved (decrease of ≥ 0.5% or negative slope), no change (± 0.4% of initial HbA1c or slope = 0) or worsened (increase of ≥ 0.5% or positive slope). Results The 450 paired samples (median of four pairs/patient) were highly correlated (r = 0.97, P < 0.0001), as were time-specific and site-specific pairs (r = 0.94 to 0.98, P < 0.0001). Initial-to-final point-of-care HbA1c and HPLC HbA1c changes were 0.3 ± 1.1% (range −2.7 to 4.1) and 0.4 ± 1.2% (–3.9 to 4.5), respectively, with 21% of patients (n = 26) discordant for change categories. ΔHbA1c by point-of-care HbA1c vs. HPLC HbA1c differed across the HbA1c range and by ≥ 0.5% absolute difference in ΔHbA1c in 14 (54%) of the 26 patients discordant for HbA1c change categories. Mean annual HbA1c slope was 0.4 ± 1.5% (−5.4 to 4.8) for point-of-care HbA1c and 0.4 ± 1.6% (−6.9 to 5.2) for HPLC HbA1c, with 18% (n = 22 pairs) discordant for change categories. Conclusions Assessment of absolute HbA1c change may not be different for point-of-care HbA1c compared with HPLC HbA1c; however, misclassification of patients by discrete cut-off values may occur with point-of-care HbA1c compared with HPLC HbA1c determinations.

Socioeconomic status and glycemic control in adult patients with type 2 diabetes: a mediation analysis

“… 86 Finally, although the point-of-care A1CNow+ device has been shown to have good measurement properties, 42 87 results should be replicated by testing HbA 1c level from blood samples using gold standard laboratory testing (high-performance liquid chromatography). 88 …”

The development of a clinically relevant sleep modification protocol for youth with Type 1 diabetes.

“…Continuous glucose monitors (CGMs) were used to assess glucose levels and variability as these devices are recognized for capturing short-term, day-to-day fluctuations in glycemic control. We used the iPro-2 Professional CGM (Medtronics, Minneapolis, MN), which is a U.S. Food and Drug Administration–approved blinded device, validated for use with children under 18 to track glucose levels every 5 min (Agus, Alexander, Wolfsdorf, 2010; Al-Ansary et al, 2011; Alleyn et al, 2011). Retrospective CGM recordings have the benefit of not influencing diabetes management during clinical trials (Muchmore, Sharp, & Vaughn, 2011).…”

Response to Alleyn et al. Comparison of longitudinal point‐of‐care and high‐performance liquid chromatography HbA1c measurements in a multi‐centre trial

“…We read with interest the paper by Alleyn et al. [1] and, whilst supporting the view that standardization of HbA 1c estimation is required for research purposes, believe this would also be of benefit in clinical practice. In keeping with other studies, the authors set < 5.5 mmol/mol (0.5%) HbA 1c as their cut‐off for an acceptable difference when comparing anaytical methods.…”