Validation of the Accuracy of Self-Reported ABO Blood Types in the Japan Nurses’ Health Study

Background: The associations between ABO blood type and risk of diseases including cancer have been reportedfrom epidemiological studies. Self-reporting is one of the most widely used methods of collecting the ABO blood typeinformation. Verifying the accuracy of self-reporting is important to consider measurement errors. We aimed to conductvalidation of self-reported ABO blood types in the Japan Nurses’ Health Study (JNHS), which is a large prospectivecohort study. Methods: The concordance rate between self-reported and serologically or genetically inferred ABOblood groups was investigated for a subsample of 41 subjects from the Gunma Nurses’ Health Study, which was a pilotcohort study that preceded the JNHS. The presence of antibodies to A or B antigens in serum (serological test) andallele types of the ABO gene (genotyping test) were determined by using frozen blood samples that were preservedfor approximately 7 years. ABO blood types were determined from these tests and compared with self-reported data.Results: All of the nurses reported that their ABO blood groups were concordant with those determined by a serologicaland/or genotyping test. Self-reported ABO blood types of 35 of 38 (92.1%) participants were consistent with the resultsfrom serological typing, while the answers of three participants were not. In these three participants, ABO genotypesthat were inferred from genotyping of three single nucleotide polymorphisms in ABO loci perfectly matched with theirself-reported ABO types, and all of these were O-type. Conclusions: Japanese health professionals report their bloodtype with a high degree of accuracy. Special attention should be paid to the O-type group in serological analysis ofblood samples that have been preserved for several years in longitudinal studies.