Sanne de Bruin

58 Chapter 3 Study design During two focus group meetings with clinical experts on transfusion practices themes were identified and used to compile the questionnaire. The questionnaire was piloted with physicians working in different countries within Europe and Northern America. In this survey, the use of different blood products including red blood cells (RBCs), platelet concentrates and plasma products in different subpopulations (e.g. trauma, obstetric, etc.) was explored. The survey included a maximum of 50 questions divided into 3 subsections: respondents’ demographics (7 questions), transfusion practice in the massively bleeding patient (7-10 questions) and transfusion practices in the non-mas- sively bleeding patient (33 questions, see Additional file 1 for static version). Massive bleeding was defined as having one or more of the following conditions: 1) a systolic blood pressure <90mmHg with bleeding + non-responsiveness to resuscitation therapy, 2) any case where a massive transfusion protocol (MTP) was initiated or 3) the admin- istration of ≥4 blood products within 2 hours. In non-massively bleeding patients, hemoglobin (Hb), platelet count and fibrinogen level thresholds were investigated for RBC transfusion, platelet transfusion and fibrin- ogen administration, respectively. The use of tranexamic acid (TXA) was examined in different subpopulations (i.e. trauma patients, obstetrics, gastroenterology). Statistical analysis Only completed surveys were included for analysis. A questionnaire was defined as complete when the respondents went through all question. Since, not all questions were applicable for all respondents, some questions were allowed to leave open. Continuous data were assessed for distribution: normally distributed variables were described by mean (standard deviations) and non-parametric data by median [first quartiles- third quartile]. 10 th and 90 th percentiles were estimated by the largest obser- vation less than or equal to Q3 + 1.5 x the interquartile range and the lowest observation or higher than Q1 – 1.5 x interquartile range, respectively. Normal distributed variables were analyzed using Students t-test and analysis of vari- ance (ANOVA). Non-parametric data were analyzed with MannWhitney U-test or Krus- kal-Wallis. The Dunn test with Bonferroni correction was used to assess the differences in applied transfusion thresholds between different subpopulations. Categorical vari- ables were tested using the Chi-squared test with Yates correction for continuity and were described by frequencies and percentages. Data was analyzed using R statistics