Critical appraisal and meta-analysis of biological variation studies on glycosylated albumin, glucose and HbA(1c)

OBJECTIVES: Numerous biological variation (BV) studies have been performed over the years, but the quality of these studies vary. The objectives of this study were to perform a systematic review and critical appraisal of BV studies on glycosylated albumin and to deliver updated BV estimates for glucose and HbA(1c), including recently published high-quality studies such as the European Biological Variation study (EuBIVAS). METHODS: Systematic literature searches were performed to identify BV studies. Nine publications not included in a previous review were identified; four for glycosylated albumin, three for glucose, and three for HbA(1c). Relevant studies were appraised by the Biological Variation Data Critical Appraisal Checklist (BIVAC). Global BV estimates were derived by meta-analysis of BIVAC-compliant studies in healthy subjects with similar study design. RESULTS: One study received BIVAC grade A, 2B, and 6C. In most cases, the C-grade was associated with deficiencies in statistical analysis. BV estimates for glycosylated albumin were: CV(I)=1.4% (1.2–2.1) and CV(G)=5.7% (4.7–10.6), whereas estimates for HbA(1c), CV(I)=1.2% (0.3–2.5), CV(G)=5.4% (3.3–7.3), and glucose, CV(I)=5.0% (4.1–12.0), CV(G)=8.1% (2.7–10.8) did not differ from previously published global estimates. CONCLUSIONS: The critical appraisal and rating of BV studies according to their methodological quality, followed by a meta-analysis, generate robust, and reliable BV estimates. This study delivers updated and evidence-based BV estimates for glycosylated albumin, glucose and HbA(1c).