Evaluation of two methods to measure hemoglobin concentration among women with genetic hemoglobin disorders in Cambodia: a method-comparison study.

Background: Genetic hemoglobin (Hb) E variants are common in Cambodia and result in an altered and unstable Hb molecule. We evaluated two methods to measure Hb concentration among individuals with and without Hb variants using a hemoglobinometer (HemoCue) and a hematology analyzer (Sysmex XT-1800i).

Methods: We determined the bias and concordance between the methods among 420 Cambodian women (18-45 y).

Results: Bias and concordance appeared similar between methods among women with no Hb disorders (n=195, bias=2.5, ρc=0.68), women with Hb E variants (n=133, bias=2.5, ρc=0.78), and women with other Hb variants (n=92, bias=2.7, ρc=0.73). The overall bias was 2.6g/l, resulting in a difference in anemia prevalence of 11.5% (41% using HemoCue and 29.5% using Sysmex, p<0.001). Based on visual interpretation of the concordance plots, the HemoCue device appears to underestimate Hb concentrations at lower Hb concentrations and to overestimate Hb concentrations at higher Hb concentrations (in comparison to the Sysmex analyzer).

Conclusions: Bias and concordance were similar across groups, suggesting the two methods of Hb measurement were comparable. We caution field staff, researchers and policy makers in the interpretation of data and the impact that bias between methods can have on anemia prevalence rates.