Comparison of longitudinal point-of-care and high-performance liquid chromatography HbA1c measurements in a multi-centre trial

Diabet Med. 2011 Dec;28(12):1525-9. doi: 10.1111/j.1464-5491.2011.03404.x.

Abstract

Aims: Point-of-care HbA(1c) is routine in clinical practice. Comparison of point-of-care HbA(1c) 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 HbA(1c) and central laboratory-based high-performance liquid chromatography (HPLC) HbA(1c) determinations. Change in HbA(1c) over time was assessed by difference from initial to final HbA(1c) and by growth modelling with annualized slope calculation. Change in HbA(1c) was categorized as improved (decrease of ≥ 0.5% or negative slope), no change (± 0.4% of initial HbA(1c) 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 HbA(1c) and HPLC HbA(1c) 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. ΔHbA(1c) by point-of-care HbA(1c) vs. HPLC HbA(1c) differed across the HbA(1c) range and by ≥ 0.5% absolute difference in ΔHbA(1c) in 14 (54%) of the 26 patients discordant for HbA(1c) change categories. Mean annual HbA(1c) slope was 0.4 ± 1.5% (-5.4 to 4.8) for point-of-care HbA(1c) and 0.4 ± 1.6% (-6.9 to 5.2) for HPLC HbA(1c), with 18% (n = 22 pairs) discordant for change categories.

Conclusions: Assessment of absolute HbA(1c) change may not be different for point-of-care HbA(1c) compared with HPLC HbA(1c); however, misclassification of patients by discrete cut-off values may occur with point-of-care HbA(1c) compared with HPLC HbA(1c) determinations.

Publication types

  • Comparative Study
  • Multicenter Study
  • Research Support, N.I.H., Extramural
  • Research Support, N.I.H., Intramural
  • Research Support, Non-U.S. Gov't
  • Validation Study

MeSH terms

  • Adolescent
  • Biomarkers / blood
  • Blood Glucose / metabolism*
  • Child
  • Chromatography, High Pressure Liquid*
  • Community Health Services
  • Cross-Sectional Studies
  • Diabetes Mellitus, Type 1 / blood*
  • Diabetes Mellitus, Type 1 / epidemiology
  • Female
  • Glycated Hemoglobin A / metabolism*
  • Humans
  • Longitudinal Studies
  • Male
  • Pilot Projects
  • Point-of-Care Systems*
  • Reference Values
  • Reproducibility of Results

Substances

  • Biomarkers
  • Blood Glucose
  • Glycated Hemoglobin A