Use of n-of-1 (single patient) trials to assess the effect of age of transfused blood on health-related quality of life in transfusion-dependent patients
Department of Medicine, Division of Hematology, Western University, London Health Sciences Centre, London, Ontario; Department of Epidemiology & Biostatistics, Western University, London Health Sciences Centre, London, Ontario; Division of Dermatology, Department of Medicine, University of Calgary, Calgary, Alberta, Canada
BACKGROUND The impact of age of red blood cells on health-related quality of life (HRQL) in patients who require chronic transfusions is not known. We assessed this using n-of-1 trials in patient populations where large randomized trials have not been done to date. STUDY DESIGN AND METHODS Chronically transfusion-dependent adult patients were randomly assigned over time to four fresh (<7 days of storage) and four standard-issue (up to 42 days of storage) blood transfusions in prospective double-blinded multicrossover studies (n-of-1 trials). HRQL questionnaires were completed before and at 24 hours after each transfusion. Hemoglobin (Hb) levels were measured before each subsequent transfusion.
RESULTS Twenty transfusion-dependent patients were enrolled, of whom nine (five myelodysplastic syndromes, two myelofibrosis, one beta-thalassemia major, one Diamond-Blackfan anemia) completed at least six transfusions. Mean ages of fresh and standard-issue blood transfused were 4.0 and 23.2 days, respectively. There were no significant differences in the effect of standard and fresh blood on follow-up Hb levels or the eight HRQL dimensions assessed in all analyses. CONCLUSIONS In chronically transfused patients, there were no significant differences in HRQL or Hb levels between fresh versus standard blood. While larger trials are needed, these results support current practices in hospital blood transfusion laboratories using a first-in, first-out model of blood utilization for these transfusion-dependent patients. Use of n-of-1 trials to determine the benefits of transfusions in single patients appears to be feasible.
