Comparison of Two Methods of Capillary Sampling in Blood Pre-Donation Anemia Screening in Brazil.

Abstract

The laboratory tests most used by blood banks to diagnose anemia are the hemoglobin (Hb) and microhematocrit (Hct) tests, measured from capillary samples. To analyze the two capillary screening methods for pre-donation anemia by comparing their agreement in diagnosing anemia. A cross-sectional study in a population of 15,521 blood donation candidates for whom information was available on Hb and Hct, performed from capillary blood samples. Hb was determined using the HemoCue® test and Hct by the centrifugation method. The Kappa coefficient was calculated to assess the agreement between the methods. Pearson's correlation tests and gender-adjusted linear regression were used to assess the change in the response variable (Hb) as a function of the explanatory variable (Hct). The majority of the study population were men (70.4%), aged between 18 and 44 years (72.1%), who declared themselves white or mixed skin color (85.6%), and had undergone at least 11 years of complete education (72.4%). The Kappa coefficient found was 92.7 and 99.2 for women and men, respectively. Pearson's correlation showed a correlation coefficient of 0.98 and the linear regression graph showed an adequate relationship between the tests with R2 = 0.97. Comparing the Hb and Hct capillary tests, it was found that Hct can be safely used to screen for anemia in pre-blood donation.