Long-Term Outcomes Among Patients Discharged From the Hospital With Moderate Anemia: A Retrospective Cohort Study

Abstract

Background: Randomized clinical trial findings support decreased red blood cell (RBC) transfusion and short-term tolerance of in-hospital anemia. However, long-term outcomes related to changes in transfusion practice have not been described.

Objective: To describe the prevalence of anemia at and after hospital discharge and associated morbidity and mortality events.

Design: Retrospective cohort study.

Setting: Integrated health care delivery system with 21 hospitals serving 4 million members.

Participants: 445 371 surviving adults who had 801 261 hospitalizations between January 2010 and December 2014.

Measurements: Hemoglobin levels and RBC transfusion, rehospitalization, and mortality events within 6 months of hospital discharge. Generalized estimating equations were used to examine trends over time, accounting for correlated observations and patient-level covariates.

Results: From 2010 to 2014, the prevalence of moderate anemia (hemoglobin levels between 7 and 10 g/dL) at hospital discharge increased from 20% to 25% (P < 0.001) and RBC transfusion declined by 28% (39.8 to 28.5 RBC units per 1000 patients; P < 0.001). The proportion of patients whose moderate anemia had resolved within 6 months of hospital discharge decreased from 42% to 34% (P < 0.001), and RBC transfusion and rehospitalization within 6 months of hospital discharge decreased from 19% to 17% and 37% to 33%, respectively (P < 0.001 for both). During this period, the adjusted 6-month mortality rate decreased from 16.1% to 15.6% (P = 0.004) in patients with moderate anemia, in parallel with that of all others.

Limitation: Possible unmeasured confounding.

Conclusion: Anemia after hospitalization increased in parallel with decreased RBC transfusion. This increase was not accompanied by a rise in subsequent RBC use, rehospitalization, or mortality within 6 months of hospital discharge. Longitudinal analyses support the safety of practice recommendations to limit RBC transfusion and tolerate anemia during and after hospitalization.

Primary funding source: National Heart, Lung, and Blood Institute.

Figure.. Use of RBCs among inpatients and outpatients across 21 KPNC facilities, by month and year.

The number of RBC units transfused per 1000 adults was stable from 2008 through 2010 (39.8 units; P = 0.55 by linear regression) and decreased each year thereafter to 28.5 RBC units transfused per 1000 patients through 2015, representing a 28% relative decline from 2010 (P < 0.001). KPNC = Kaiser Permanente Northern California; RBC = red blood cell.