All of the data were collected as a part of the routine evaluation, follow-up and management of b-thalassemia major and transfusion-dependent b-thalassemia intermedia patients.The study was conducted using data recorded in WebThal®.WebThal is a software which was developed in the year 2000 within a project among five Italian thalassemia centers, based on the Torino center experience, with the aim of optimizing the clinical management of the disease. WebThal is a computerized clinical record for all thalassemic patients attended at each specialized center. 115 The research on WebThal was conducted on 6 th November 2018.We extracted data from WebThal to an Excel spreadsheet.For each patient we recorded the following information in the database: date of birth, gender, diagnosis, first transfusion date, date of blood samplings collection, age at each blood test, Hb level, Hb type (pretransfusion, posttransfusion or check), splenectomy status, date of splenectomy, number or blood units transfused at each transfusional event, cumulative blood units pure red cells content expressed in ml infused at each transfusion, iron input expressed in mg for each transfusional event, blood units hematocrit, blood unit preparation type and transfusion interval.Splenectomy status was indicated as "yes" if the patient had undergone splenectomy.Splenectomy status and date of splenectomy was reported in the database at each transfusional event.Hb type was defined as "pretransfusion", "posttransfusional" or "check".Pretransfusion Hb was the Hb value measured on the day of the transfusional event, before starting transfusion therapy.Posttransfusional Hb was either measured or calculated at the end of the transfusional event.Hemoglobin labeled as "check" was a hemoglobin value measured during the intertransfusion period, either during blood tests performed in other clinical contests or during weekly blood count checks in patients receiving chelation therapy with deferiprone.Patients may transfuse all the blood units planned on the basis of their transfusion requirement either on one day or on two consecutive days. In this latter case, pretransfusion Hb level was measured both on the first day and on the second day of the transfusional event: however, inter-transfusion interval (expressed in days) was the same reported for the first day of transfusion.Therefore, we labeled pretransfusion Hb level of the second day as "check".