Despite the significance of red blood cell (RBC) alloimmunization, the lack of standardized registries in the US has prevented the completion of large studies. Data from 3·5 years of the Recipient Epidemiology and Donor Evaluation Study-III (REDS-III) recipient database, containing information from 12 hospitals, were studied. A RBC alloantibody responder had an antibody identified at any point during the study, and a non-responder had a negative antibody screen at least 15 days post-RBC transfusion. Demographics, blood type, ICD9/10 codes, and other potential correlates were evaluated. Of 319 177 (2·07%) screened patients, 6597 had a total of 8892 clinically significant RBC alloantibodies identified, with 75% being in the Rh or Kell families. Alloimmunization was more common in females (2·38%) than males (1·68%), and in RhD negative (2·82%) than RhD positive (1·94%) patients. Age, sex, RhD status and race were associated with being a responder, and certain diagnoses (including sickle cell disease or trait, systemic lupus erythematosus, rheumatoid arthritis and myelodysplastic syndrome) were more common among responders than non-responders. Data collected in this multi-centre recipient database provide the largest RBC alloimmunized patient cohort studied in the US, with previously known demographic and disease associations of responder status confirmed, and new associations identified.

Introduction Blood transfusion is one of the most common medical procedures during hospitalization in the United States. To understand the benefits of transfusion while mitigating potential risks, a multicenter database containing detailed information on transfusion incidence and recipient outcomes would facilitate research. Methods The Recipient Epidemiology and Donor Evaluation Study-III (REDS-III) program has developed a comprehensive transfusion recipient database utilizing data from hospital electronic health records at 12 participating hospitals in four geographic regions. Transfused inpatient and outpatient data from January 1, 2013 until December 31, 2014 included patient age, sex, ethnicity, primary diagnosis, type of blood product provided, issue location, pre- and post-transfusion hemoglobin, and hospital outcomes. Transfusion incidence per encounter was calculated by blood product and various patient characteristics. Results During the two-year study period, 80,362 (12.5%) inpatient encounters involved transfusion. Among inpatients, the most commonly transfused blood products were red cells (10.9% of encounters), followed by platelets (3.2%), and plasma (2.9%). Among transfused patients, the median number of red-cell units was one, pre-transfusion hemoglobin was 7.6 g/dL, and hemoglobin increment/unit was 1.4 g/dL. Encounter mortality increased with patient age, number of units transfused, and the use of platelet or plasma products. The most common reported transfusion reaction was febrile non-hemolytic. Conclusion The REDS-III recipient database contains comprehensive data regarding transfusion use and patient outcomes. This report describes an evaluation of the first two years of a planned four-year linked blood donor-component-recipient database which represents a critical new resource for transfusion medicine researchers.

; for the NHLBI Recipient Epidemiology and Donor Evaluation Study-III (REDS-III) Group IMPORTANCE Evidence regarding associations of blood donor sex with mortality among red blood cell transfusion recipients is conflicting. OBJECTIVE To study associations of donor sex and prior pregnancy with mortality of transfusion recipients. DESIGN, SETTING, AND PARTICIPANTS Data from 3 retrospective cohorts of transfusion recipients (the Kaiser Permanente Northern California [KPNC] and Recipient Epidemiology and Donor Evaluation Study-III [REDS-III] databases of data from January 2013 to December 2016 and the Scandinavian Donations and Transfusions [SCANDAT] database with data from January 2003 to December 2012) were analyzed. Final dates of follow-up were December 31, 2016, for the KPNC and REDS-III cohorts and December 31, 2012, for the SCANDAT cohort. Stratified Cox regression models were used to estimate associations between donor exposure groups with risk of mortality, adjusting for the number of red blood cell unit transfusions. EXPOSURES The number of transfused red blood cell units from female donors, previously pregnant donors, and sex-discordant donors (male donor and female recipient or female donor and male recipient). MAIN OUTCOMES AND MEASURES In-hospital mortality. RESULTS The study population included 34 662 patients (mean age, 69 years; 18 652 [54%] women) from the KPNC cohort, 93 724 patients (mean age, 61 years; 48 348 [52%] women) from the REDS-III cohort, and 918 996 patients (mean age, 72 years; 522 239 [57%] women) from the SCANDAT cohort. The median number of red blood cell transfusions per patient was 3 in the KPNC cohort, 2 in the REDS-III cohort, and 3 in the SCANDAT cohort. The percentage of transfusions from previously pregnant or parous donors was 9% in the KPNC cohort, 18% in the REDS-III cohort, and 25% in the SCANDAT cohort. The percentage of transfusions in the 3 cohorts from female donors ranged from 39% to 43%, from previously pregnant or parous donors ranged from 9% to 25%, and from sex-discordant donors ranged from 44% to 50%. There were 3217 in-hospital deaths in the KPNC cohort, 8519 in the REDS-III cohort, and 198 537 in the SCANDAT cohort. There were no statistically significant associations between any of the 3 donor exposures and in-hospital mortality in the 3 cohorts. Hazard ratios for in-hospital mortality per transfused unit from female donors were 0.99 (95% CI, 0.96-1.03) for the KPNC cohort, 1.00 (95% CI, 0.99-1.01) for the REDS-III cohort, and 1.00 (95% CI, 0.99-1.00) for the SCANDAT cohort. For units from previously pregnant or parous female donors, hazard ratios were 1.00 (95% CI, 1.00-1.01) for the KPNC cohort, 1.01 (95% CI, 0.98-1.03) for the REDS-III cohort, and 1.00 (95% CI, 1.00-1.01) for the SCANDAT cohort. For units from sex-discordant transfusions, hazard ratios were 1.02 (95% CI, 0.99-1.05) for the KPNC cohort, 0.99 (95% CI, 0.98-1.00) for the REDS-III cohort, and 1.00 (95% CI, 0.99-1.00) for the SCANDAT cohort. CONCLUSIONS AND RELEVANCE Among red blood cell transf...

BACKGROUND: Recent publications have reported conflicting findings regarding associations of blood donor demographics and mortality of transfused patients. We hypothesized that the analysis of additional donor characteristics and consideration of alternative outcomes might provide insight into these disparate results. STUDY DESIGN AND METHODS:We analyzed data from a retrospective cohort of transfused patients from the Recipient Epidemiology and Donor Evaluation Study-III (REDS-III). We used stratified Cox regression models to estimate associations between blood donor characteristics and hospital mortality and posttransfusion length of stay among patients transfused red blood cell (RBC) units. Donor characteristics evaluated included age, body mass index, hemoglobin levels, and smoking status. The statistical analyses were adjusted for recipient factors, including total number of transfusions. RESULTS:We studied 93,726 patients in 130,381 hospitalizations during which 428,461 RBC units were transfused. There were no associations between blood donor characteristics and hospital mortality. Receipt of RBC units from donors less than 20 years of age was associated with a shorter hospital length of stay (hazard ratio for discharge per transfused unit, 1.03; 95% confidence interval, 1.02-1.04; p < 0.001) but not for other donor characteristics. CONCLUSION:We found no evidence of associations between blood donor factors and in-hospital mortality. Our finding of shorter hospital length of stay in patients transfused RBCs from younger donors is intriguing but requires confirmation. Future collaborations are needed to develop a framework of appropriate methodologic approaches to be used in linked analyses across large cohorts.

Previous observational studies suggest associations between red blood cell (RBC) transfusion and risk for arterial or venous thrombosis. We determined the association between thrombosis and RBC transfusion in hospitalized patients using the Recipient Database from the National Heart Lung and Blood Institute (NHLBI) Recipient Epidemiology and Donor Evaluation Study-III. A thrombotic event was a hospitalization with an arterial or venous thrombosis ICD-9 code and administration of a therapeutic anticoagulant or antiplatelet agent. Patients with history of thrombosis or a thrombosis within 24 hours of admission were excluded. A proportional hazards regression model with time-dependent covariates was calculated. Estimates were adjusted for age, sex, hospital, smoking, medical comorbidities, and surgical procedures. Of 657 412 inpatient admissions, 67 176 (10.2%) received at least one RBC transfusion. Two percent (12927) of patients experienced a thrombosis. Of these, 2587 developed thrombosis after RBC transfusion. In unadjusted analyses, RBC transfusion was associated with an increased thrombosis risk [HR = 1.3 (95% CI 1.23-1.36)]. After adjustment for surgical procedures, age, sex, hospital, and comorbidities, no association between RBC transfusion on risk of venous and arterial thrombosis was found [HR 1.0 (95% CI: 0.96-1.05)]. Thus, RBC transfusion does not appear to be an important risk factor for thrombosis in most hospitalized patients.

Nutritional guidance for the adolescent athlete engaged in demanding training schedules is mostly based on adult recommendations (1) . The young athlete's ultimate aim is to maintain levels of carbohydrate required by the body during prolonged intensive training as this is a key factor in performance and exercise capacity. Although paediatric exercise science literature is revealing increasing differentiations in exercise physiology between the child and adult athlete, there remains little child-specific evidence regarding the regulatory mechanisms of carbohydrates during exercise (2) . The aim of this study was to examine whether carbohydrate (CHO) of different glycaemic index (GI) would enhance performance in adolescent swimmers when used as the carbohydrate supplementation indicator in a pre-exercise meal. Eleven adolescent swimmers (mean (SD) age: 12.9 (SD 1.24) completed two trials, separated by 14 d, in a random crossover design. Each consumed a low GI (pasta) or high GI (potato) evening meal (2.5 g CHO/kg body mass) 90 min prior to initial exercise followed by 50 m and 400 m front crawl time trials. Dietary intake was also controlled from lunchtime onwards on each trial day. No statistically significant differences were observed in performance times in the low GI trial v. high GI trial in either 50 m [mean (SD) low v. high GI 50 m: 32.87 (SD 1.92) v. 32.83 (SD 1.26) or 400 m (mean (SD) low v. high GI 400 m: 327.11 (SD 14.55) v. 323.95 (SD 15.0)] (P > 0.05). The results of this study indicate that there was no significant improvement in either sprint or endurance performance times, despite a greater dependence on CHO with this mode of exercise, following CHO supplementation of different GI. Due to ethical limitations, it was not possible to obtain blood samples or expired gas samples from the adolescent subjects, at any point during this study. This would have enabled the measurement and observation of certain metabolic responses and subsequent substrate utilisation to the high GI and low GI meals, and their influences in relation to exercise performance. The unique fuel-use profile and blood-lactate concentration of a child athlete during submaximal exercise has mostly been attributed to their increased oxidative and decreased glycolytic ability compared with adults. However, this view has recently been challenged by some eminent researchers (3) . It is clear that further research is required to investigate any potential performance benefits to the adolescent athlete, using the GI as the CHO supplementation indicator in a pre-exercise meal.