The impacts of super obesity versus morbid obesity on red blood cell aggregation and deformability among patients qualified for bariatric surgery.

The aim of this study was to evaluate the effects of the obesity degree on red blood cell aggregation and deformability. We studied 56 obese patients before weight loss surgery who were divided into two groups: morbid obesity and super obesity. The aggregation and deformability of RBCs were evaluated using a Laser-assisted Optical Rotational Cell Analyzer (Mechatronics, the Netherlands). The following parameters specific to the aggregation process were estimated: aggregation index (AI), aggregation half-time (t1/2) and threshold shear rate (γthr). RBC deformability was expressed as erythrocyte elongation (EI), which was measured at 18.49 Pa and 30.2 Pa shear stresses. Super obese patients presented significantly higher AI (P < 0.05) and γthr (P < 0.05) and significantly lower t1/2 (P < 0.05) compared with morbidly obese individuals. Multivariate analyses showed that fibrinogen (β 0.46, P < 0.01 and β 0.98, P < 0.01) and hematocrit (β 0.38, P < 0.05 and β 1.01, P < 0.01) independently predicted the AI in morbidly obese and super obese patients. Fibrinogen (β -0.4, P < 0.05 and β -0.91, P < 0.05) and hematocrit (β -0.38, P < 0.05 and β -1.11, P < 0.01) were also independent predictors of the t1/2 in both obese groups. The triglyceride level (β 0.32, P < 0.05) was an independent predictor of the t1/2 in the morbidly obese group. No differences in EI were observed between obese subjects. Multivariate analyses showed that the triglyceride level independently predicted EI at 18.49 Pa (β -0.42, P < 0.05 and β -0.53, P < 0.05) and 30.2 Pa (β -0.44, P < 0.01 and β -0.49, P < 0.05) in both obese groups. This study indicated that the obesity degree of patients who qualify for bariatric surgery affects RBC aggregation properties, but it does not indicate the reasons for this difference. Further studies are needed to determine factors associated with hyperaggregation in super obesity.