Abstract
Patients with cancer or other diagnoses associated with chronic anemia often receive red blood cell (RBC) transfusion as outpatients for symptoms including fatigue. To determine the effect of RBC transfusion on functional status and quality of life (QoL), we measured 6-minute walk test distance and fatigue-related QoL scores before and after RBC transfusion in outpatients.
Methods
The Red Cells in Outpatients Transfusion Outcomes (RETRO) study was a prospective, observational study of subjects before and after RBC transfusion. Patients were recruited through hospital outpatient infusion units at 4 sites. To account for potential confounding effects of chemotherapy, patients were classified into 2 groups based on cancer treatment (CT) within 4 weeks before or after the study transfusion (CT group) or not (No CT group). Inclusion criteria were age ≥ 50, ambulatory, and chronic anemia with at least one prior RBC within 6 months. Exclusion criteria included active bleed and recent myocardial infarction. Walk test distance, QoL (FACIT-Fatigue Scale), and hemoglobin (Hgb) were measured before and at 5-10 days post-transfusion. Extra RBC transfusions given as part of clinical care and interim Emergency Department (ED) or hospital admissions during the study were recorded. Unadjusted results are expressed as median, interquartile range (IQR) and p values assigned using signed rank test. Regression analyses of change in walk test distance and change in QoL score were performed using backwards elimination to identify significant clinical variables. Minimum clinically important change in walk test distance was 20 meters (m) and in QoL score was 3 points based on literature review.
Results
A total of 221 patients with at least one benign or malignant hematology/oncology diagnosis enrolled and 200 (138 CT, 62 No CT) completed both pre- and post-transfusion walk tests. Mean subject age was 66 and 1 RBC (73%) or 2 RBC (27%) were transfused during the study transfusion episode; 18% received 1-3 additional RBC between walk tests. On average, walk test distance and QoL scores were higher after transfusion. In the No CT group, unadjusted median change in walk test distance was 30 m (IQR 0 to 50; p<0.001). In the CT group, median change in walk test was 16 m (IQR -11 to 45; p<0.001). Median change in QoL score pre- to post-transfusion in the no CT group was 4.0 points (IQR 0 to 11; p<0.001) and 2.5 points (IQR -3 to 7.5; p<0.003) in the CT group.
In the regression model of change in walk test distance with RBC, no recent cancer treatment, absence of interim ED visits or hospitalizations, post-transfusion Hgb ≥8 g/dL, and total RBC dose predicted larger increases in walk distance (p<0.05) (Table). Patients with no recent CT had an estimated adjusted change in walk test distance of 24.2 m greater on average than CT patients. Grouped by post-transfusion Hgb, the mean change in walk test distance between patients with post-transfusion Hgb ≥8 and <8 g/dL was 31 m. The total number of RBC transfused between walk tests also predicted greater improvement in walk performance (estimated adjusted mean difference in walk test distance 17.9 m per RBC unit).
In the regression model of QoL, baseline Hgb, and Karnofsky score were associated with change in fatigue-related QoL in addition to no CT and lack of interim events (p<0.05). Patients with higher baseline Hgb had larger increase in QoL score (adjusted mean difference 3.8 scale points per g/dL Hgb).
The following variables were not significantly associated with change in either primary outcome with transfusion: age, sex, body mass index, number of previous RBC transfusions, and change in Hgb at 1 week.
Conclusions
RBC transfusion in outpatients improves walk test performance and fatigue-related QoL. Patients who maintained Hgb 8 g/dL or greater at one week post RBC showed clinically important (>20 m) increases in mean walk test distance. Patients with higher baseline Hgb levels showed relatively larger improvement in QoL scores. For both outcomes, improvement with RBC was most apparent in clinically stable patients not on chemotherapy. The finding that increased RBC dose between walk tests predicted greater increase in walk distance suggests that more RBC transfusion may further improve functional status in some patients. Studies that measure patient-related outcomes, including functional status and QoL, are essential in deciding which oncology patients will benefit the most from RBC transfusion.
Carson: Terumo: Research Funding.
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