The WAA apheresis registry contains data on more than 140,000 apheresis procedures conducted in 12 different countries. The aim is to give an update of indications, type and number of procedures and adverse events (AEs). MATERIAL AND METHODS: The WAA-registry is used for registration of apheresis procedures and is free of charge. The responsible person for a center can apply at the site www.waa-registry.org RESULTS: Data includes reported AEs from 2012 and various procedures and diagnoses during the years 2018-2022; the latter in total from 27 centers registered a total of 9500 patients (41% women) that began therapeutic apheresis (TA) during the period. A total of 58,355 apheresis procedures were performed. The mean age was 50 years (range 0-94). The most common apheresis procedure was stem cell collection for which multiple myeloma was the most frequent diagnosis (51%). Donor cell collection was done in 14% and plasma exchange (PEX) in 28% of patients; In relation to all performed procedures PEX, using a centrifuge (35%) and LDL-apheresis (20%) were the most common. The main indication for PEX was TTP (17%). Peripheral veins were used in 56% as the vascular access. The preferred anticoagulant was ACD. AEs occurred in 2.7% of all procedures and were mostly mild (1%) and moderate 1.5% (needed supportive medication) and, only rarely, severe (0.15%). CONCLUSION: The data showed a wide range of indications and variability in apheresis procedures with low AE frequency.

4 Internal Hematological Klinik Fakultni Nemocnice Hradec Králové Czech Republic

Academic Teaching Hospital Braunschweig Medical Clinic 5 Nephrology Rheumatology Blood Purification Germany

Apheresis Center University Hospital Orebro Sweden

Apheresis Department Institute of Hematology and Blood Transfusion Prague Czech Republic

AZ Delta Roeselare Belgium

Blood Centre University Hospital Ostrava Ostrava Czech Republic

Bone Marrow Transplant and Apheresis Apheresis and Cell Therapies Unit Concord Repatriation General Hospital Concord NSW Australia

Clinical Department of Transfusion Medicine and Transplantation Biology University Hospital Centre Zagreb Croatia

Dep of Immunology and Transfusion Medicine Akershus University Hospital Lorenskog Norway

Department Haematology University Hospital Ankara Turkey

Department of Clinical Immunology and Transfusion Medicine and Department of Biochemical and Clinical Sciences Linköping University Linköping Sweden

Department of Clinical Microbiology Division of Clinical Immunology Umeå University Umeå Sweden

Department of Nephrology University Hospital Uppsala Sweden

Nephrocare Rostock GmbH Rostock Germany

Public Health and Clinical Medicine Umeå University Umeå Sweden

South African National Blood Service Johannesburg South Africa

St Anna Kinderspital University Hospital Vienna Austria

The Institute for the Diagnosis and Therapy of Atherosclerosis and Fat Metabolism Disorders Athos Vienna Austria

Therapeutic apheresis unit Vilnius university hospital Santariskiu clinics Vilnius Lithuania

Unit of Transfusion medicine of Sanquin Blood Supply Sanquin Blood Supply Foundation in Amsterdam the Netherlands

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