This study furnishes evidence that both confirms and refutes a long-standing maxim that a one-unit transfusion of red blood cells should yield a posttransfusion hemoglobin increment of 1 g/dL.

Background: Red blood cell (RBC) transfusion effectiveness varies due to donor, component, and recipient factors. Prior studies identified characteristics associated with variation in hemoglobin increments following transfusion. We extended these observations, examining donor genetic and non-genetic factors affecting transfusion effectiveness.Methods: This is a multicenter retrospective study of 46,705 patients, and 102,043 evaluable RBC transfusions from 2013-2016 across 12 hospitals. Transfusion effectiveness was defined as hemoglobin, bilirubin, or creatinine increments following single RBC unit transfusion. Models incorporated a subset of donors with data on single nucleotide polymorphisms associated with osmotic and oxidative hemolysis in vitro. Mixed modelling accounting for repeated transfusion episodes identified predictors of transfusion effectiveness.Results: Blood donor (sex, Rh status, fingerstick hemoglobin, smoking), component (storage duration, gamma irradiation, leukoreduction, apheresis collection, storage solution), and recipient (sex, body mass index, race, age) characteristics were associated with hemoglobin and bilirubin but not creatinine increments following RBC transfusions. Increased storage duration was associated with increased bilirubin and decreased hemoglobin increments, suggestive of in vivo hemolysis following transfusion. Donor G6PD-deficiency and polymorphisms in SEC14L4, HBA2, and MYO9B genes were associated with decreased hemoglobin increments. Donor G6PD-

BACKGROUND Recent publications have reported conflicting results regarding the role of blood donor tobacco use on hemoglobin (Hb) levels in patients after red blood cell (RBC) transfusion. We examined associations and interactions between donor, component, and recipient factors to better understand the impact of donor smoking on transfusion outcomes. STUDY DESIGN AND METHODS We linked blood donor and component manufacturing data, including self‐reported cigarette smoking, with a cohort of patients transfused RBCs between 2013 and 2016. Using multivariable regression, we examined Hb increments and subsequent transfusion requirements after single‐unit RBC transfusion episodes, adjusting for donor, component, and recipient factors. RESULTS We linked data on 4038 transfusion recipients who received one or more single‐unit RBC transfusions (n = 5086 units) to donor demographic and component manufacturing characteristics. Among RBC units from smokers (n = 326), Hb increments were reduced after transfusion of gamma‐irradiated units (0.76 g/dL; p = 0.033) but not unirradiated units (1.04 g/dL; p = 0.54) compared to those from nonsmokers (1.01 g/dL; n = 4760). In parallel with changes in Hb levels, donor smoking was associated with the receipt of additional RBC transfusions for irradiated (odds ratio [OR], 2.49; p = 0.01) but not unirradiated RBC units (OR, 1.10; p = 0.52). CONCLUSION Donor smoking was associated with reduced Hb increments and the need for additional transfusions in recipients of gamma‐irradiated RBC units. Additional research is needed to better understand interactions between donor, component, and recipient factors on efficacy measures of RBC transfusion.

This cohort study examines rehospitalization factors, hospitalization and mortality, discharge disposition, and the changes in these variables over time among all adult patients in the Kaiser Permanente Northern California health system.

Objectives To determine the associations between a care coordination intervention (the Transitions Program) targeted to patients after hospital discharge and 30 day readmission and mortality in a large, integrated healthcare system. Design Observational study. Setting 21 hospitals operated by Kaiser Permanente Northern California. Participants 1 539 285 eligible index hospital admissions corresponding to 739 040 unique patients from June 2010 to December 2018. 411 507 patients were discharged post-implementation of the Transitions Program; 80 424 (19.5%) of these patients were at medium or high predicted risk and were assigned to receive the intervention after discharge. Intervention Patients admitted to hospital were automatically assigned to be followed by the Transitions Program in the 30 days post-discharge if their predicted risk of 30 day readmission or mortality was greater than 25% on the basis of electronic health record data. Main outcome measures Non-elective hospital readmissions and all cause mortality in the 30 days after hospital discharge. Results Difference-in-differences estimates indicated that the intervention was associated with significantly reduced odds of 30 day non-elective readmission (adjusted odds ratio 0.91, 95% confidence interval 0.89 to 0.93; absolute risk reduction 95% confidence interval −2.5%, −3.1% to −2.0%) but not with the odds of 30 day post-discharge mortality (1.00, 0.95 to 1.04). Based on the regression discontinuity estimate, the association with readmission was of similar magnitude (absolute risk reduction −2.7%, −3.2% to −2.2%) among patients at medium risk near the risk threshold used for enrollment. However, the regression discontinuity estimate of the association with post-discharge mortality (−0.7% −1.4% to −0.0%) was significant and suggested benefit in this subgroup of patients. Conclusions In an integrated health system, the implementation of a comprehensive readmissions prevention intervention was associated with a reduction in 30 day readmission rates. Moreover, there was no association with 30 day post-discharge mortality, except among medium risk patients, where some evidence for benefit was found. Altogether, the study provides evidence to suggest the effectiveness of readmission prevention interventions in community settings, but further research might be required to confirm the findings beyond this setting.