Therapeutic apheresis in Sweden: update of epidemiology and adverse events

Abstract

The indications of apheresis have changed over time due to results from various studies as well as the innovation of new techniques and ideas. To get an overview of the indications used for apheresis by colleagues elsewhere, data from registries are valuable. In addition, registries can be used for detection of severe adverse events as well as extent of adverse events in various types of treatment. To have a basis for statistical calculations, apheresis units need to be very large or centralisation of data needs to be performed. Data from more than 20 000 procedures show that in about 4.3% of occasions adverse events and other problems will develop. Interruption of the procedure was done in 1%, most frequently a plasma exchange. Technical problems can be expected more frequent when performing LDL apheresis and immunoadsorption. Severe adverse events needing medication or interruption of the treatment, such as hypotension and arrhythmia, will develop in about 1% of the procedures. Such an episode occurs more often in patients with TTP/HUS and Guillain-Barré syndrome than in hypercholesterolemia, hyperviscosity syndrome or septic shock/MODS. The non-severe adverse events have increased over time. The results will provide focus in analyses for the reduction of such adverse events.

Introduction

Annual survey of therapeutic apheresis (TA) has been conducted in depth in Sweden since 1995 and an annual report is distributed. Thirty-five centres have been involved in reporting of therapeutic apheresis and 15 in reporting adverse events. Over the years seven centres have reported cessation of TA. Four centres have not participated regularly, and their average reported activity has been used to calculate the coverage. The data of TA are estimated to cover >90% of all procedures performed in Sweden. The treatment has been concentrated to larger hospitals over the time period. TA is performed mainly in Transfusion centres and Dialysis wards representing about 50% and 35% of all procedures, respectively. The data have been useful to estimate the extent of apheresis activities and the resources allocated. The nurses do the data collection and processing. The identity of the patient is not revealed. The data has been sent to the centre of the Registry by copies of a questionnaire [1].

This report is the updated Swedish registry including data from 2001. Statistical analyses were performed with Spearman correlation test for trends and Chi2 analyses for group comparisons. Odds ratio (OR) and confidence interval (CI) and a significance level of p<0.05 was used.

The TA and plasma exchange (PE) procedures have decreased over the years (p<0.017). The shift in technique from filtration to centrifugation in plasma exchange is continuing (p=0.001). In 2001 centrifugation devices were used in more than 80% of the procedures. The use of plasma modulation (PM) techniques have remained at about the same level for the last three years after an initial increase of both LDL-apheresis and immune adsorption using protein A columns. The use of extracorporeal phototherapy (ECP) shows an overall increase over time (p=0.007). There has been no change in haematopoietic progenitor cell (HPC) collection. Table 1 shows the development.

The changes over time with regard to indications for PE or PM are shown in Table 2. There is an overall decrease in the number of patients referred (p<0.001). There has been a gradual decrease in the number of patients treated for Guillain-Barrés syndrome (r−0.99, p<0.001), transplant rejection (−0.86, p<0.015), septic shock (r−0.77, p<0.042), TTP/HUS (p<0.026) and Wegener’s granulomatosis (p=0.023). The number of patients treated for the other diseases remain fairly stable. Hyperviscosity syndromes due to monoclonal components remain the largest group of patients.

Indications for the collection of haematopoietic stem cells are also collected in the registry (Table 3). There is a small increase of patients (p=0.036) with a significant rise in those with multiple myeloma (p<0.001) while the usage has virtually stopped in the treatment of breast cancer (p<0.001) after that studies showed the lack of benefit. The use of allogeneic donors for the collection of HPC has increased (p<0.004).

Information about the use of extracorporeal phototherapy (ECP) has also been collected more in depth since 1995. In the last 5 years there has been a shift towards treatment in the connection with bone marrow and organ transplantation. 33% of all treatments up through 2001 have been performed for GVHD and 25% of additional treatments for rejection processes. T-cell lymphomas and cutaneous T-cell malignancies account for 25% of all procedures. A completed controlled study of diabetes mellitus account for 7% and a number of systemic inflammatory diseases for the remaining 9% of treatments performed.