title: Indirect viscosimetric method is less accurate than ektacytometry for the measurement of red blood cell deformability.
abstract: The aim of this study was to test the accuracy of viscosimetric method to estimate the red blood cell (RBC) deformability properties. Thirty-three subjects were enrolled in this study: 6 healthy subjects (AA), 11 patients with sickle cell-hemoglobin C disease (SC) and 16 patients with sickle cell anemia (SS). Two methods were used to assess RBC deformability: 1) indirect viscosimetric method and 2) ektacytometry. The indirect viscosimetric method was based on the Dintenfass equation where blood viscosity, plasma viscosity and hematocrit are measured and used to calculate an index of RBC rigidity (Tk index). The RBC deformability/rigidity of the three groups was compared using the two methods. Tk index was not different between SS and SC patients and the two groups had higher values than AA group. When ektacytometry was used, RBC deformability was lower in SS and SC groups compared to the AA group and SS and SC patients were different. Although the two measures of RBC deformability were correlated, the association was not very high. Bland and Altman analysis demonstrated a 3.25 bias suggesting a slight difference between the two methods. In addition, the limit of agreement represented 28% (>15%) of the mean values of RBC deformability, showing no interchangeability between the two methods. In conclusion, measuring RBC deformability by indirect viscosimetry is less accurate than by ektacytometry, which is considered the gold standard.
authors.affiliation: UMR Inserm 665, Pointe-à-Pitre, Université des Antilles et de la Guyane, Pointe-à-Pitre, Guadeloupe, France.
authors.forename: Jens
authors.initials: J
authors.lastname: Vent-Schmidt
authors.affiliation: UMR Inserm 665, Pointe-à-Pitre, Université des Antilles et de la Guyane, Pointe-à-Pitre, Guadeloupe, France Laboratoire ACTES (EA 3596), Département de Physiologie, Université des Antilles et de la Guyane, Pointe-à-Pitre, Guadeloupe, France Laboratory of Excellence GR-Ex «The red cell: from genesis to death», PRES Sorbonne Paris Cité, Paris, France.
authors.forename: Xavier
authors.initials: X
authors.lastname: Waltz
authors.affiliation: Université Paris 13, Laboratoire «Réponses Cellulaires et Fonctionnelles à L'hypoxie» Bobigny, France Laboratory of Excellence GR-Ex «The red cell: from genesis to death», PRES Sorbonne Paris Cité, Paris, France.
authors.forename: Aurélien
authors.initials: A
authors.lastname: Pichon
authors.affiliation: UMR Inserm 665, Pointe-à-Pitre, Université des Antilles et de la Guyane, Pointe-à-Pitre, Guadeloupe, France Laboratory of Excellence GR-Ex «The red cell: from genesis to death», PRES Sorbonne Paris Cité, Paris, France.
authors.forename: Marie-Dominique
authors.initials: MD
authors.lastname: Hardy-Dessources
authors.affiliation: UMR Inserm 665, Pointe-à-Pitre, Université des Antilles et de la Guyane, Pointe-à-Pitre, Guadeloupe, France Laboratory of Excellence GR-Ex «The red cell: from genesis to death», PRES Sorbonne Paris Cité, Paris, France.
authors.forename: Marc
authors.initials: M
authors.lastname: Romana
authors.affiliation: UMR Inserm 665, Pointe-à-Pitre, Université des Antilles et de la Guyane, Pointe-à-Pitre, Guadeloupe, France Laboratoire ACTES (EA 3596), Département de Physiologie, Université des Antilles et de la Guyane, Pointe-à-Pitre, Guadeloupe, France Laboratory of Excellence GR-Ex «The red cell: from genesis to death», PRES Sorbonne Paris Cité, Paris, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Connes
mesh_terms: D000755:Anemia, Sickle Cell / Q000097:blood*; D001809:Blood Viscosity; D004907:Erythrocyte Deformability; D004912:Erythrocytes / Q000378:metabolism*; D005260:Female; D006801:Humans; D008297:Male
keywords: Ektacytometry; blood viscosity; methodology; red blood cell deformability