Safety of laboratory analyzers for infection testing - results of the market surveillance by the BfArM until End 2007.

The European Directive 98/79/EC on in vitro diagnostic medical devices (IVD) stipulates the marketing and post market surveillance of IVD in the European Economic Area. In cases of issues and field corrective actions, the manufacturers have to inform the responsible Competent Authorities (CA). In Germany, the Federal Institute for Drugs and Medical Devices (BfArM) is the responsible CA for most IVD, with a small subset of IVD for immune hematological and infectiological testing as well as tissue typing as specified in Annex II of the Directive, being within the responsibility of the Paul-Ehrlich-Institute (PEI). In this study, all issues regarding laboratory analyzers for infection testing and their consumables, but not reagents, kits and general culture media, reported to the BfArM between begin 1999 and end of 2007 were analyzed in respect to the sources of report, the underlying product failure and the performed corrective actions. Within the observation period a total of 1471 reports for IVD were received of which 73 related to the IVD for infection testing were included in our study. Reports were predominantly received from manufacturers (56) and competent authorities (15). Affected products were most frequently those for immunological analysis (42) whereas those based on culturing techniques (17) and molecular biological techniques (14) played only minor roles. In all these groups, laboratory analyzers (55) were more frequently affected than their consumables (18). Investigations of the manufacturers were able to identify the underlying root causes of product failures in 62 cases (84.9%). In 2 cases (2.7%) the root cause remained unclear and in 9 cases (12.3%) a product failure was excluded or a user error was the underlying cause. Product failures in laboratory analyzers were most frequently caused by software errors (31) and constructional faults (8) whereas the predominant cause of product failure in consumables were errors in production and quality control (8). Manufacturers issued corrective measures in 66 cases (90.4%) from which 49 and 17 were related to laboratory analyzers and their consumables, respectively. Based on the underlying root causes of product failures these were predominantly customer information (48), recalls (40), software-updates (30) and design changes (9) in the product group of laboratory analyzers as well as customer information (16), recalls (12) and modifications of production and quality management (11) in the group of consumables. The results and experiences obtained since 1999 suggest that the system for post marketing surveillance of IVD is an established tool to ensure product safety, even though the current system can be further enhanced.

Safety of reagents for infection testing: results of the market surveillance by the Federal Institute for Drugs and Medicinal Devices until end 2006.

The European Directive 98/79/EC on in vitro diagnostic medical devices (IVD) stipulates the marketing and post market surveillance of IVD in the European Economic Area. In cases of issues and field corrective actions, the manufacturers have to inform the responsible Competent Authorities (CA). In Germany, the Federal Institute for Drugs and Medical Devices (BfArM) is the responsible CA for most IVD, with a small subset of IVD for immune hematological and infection testing as well as tissue typing as specified in Annex II of the Directive, being within the responsibility of the Paul-Ehrlich-Institute (PEI). In this study, all issues regarding reagents for infection testing, but not laboratory analyzers, reported to the BfArM between begin 1999 and end of 2006 were analyzed in respect to the source of report, the underlying product defects, and the performed corrective actions. Within the observation period a total of 888 reports on IVD were received of which 90 related to the IVD for infection testing included in our study. Reports were predominantly received from manufacturers (55) and Competent Authorities (29). Affected products were most frequently those for serological analysis (42) and culturing techniques (36), whereas molecular biological tests played only a minor role (12). Investigations of the manufacturers were able to identify the underlying root causes of product failures in 68 cases (75.6%). In 16 cases (17.8%) the root cause remained unclear and in 6 cases (6.6%) a product failure was excluded or a user error was the underlying cause. Most frequently product failures were caused by material defects (25), production errors (11), microbial contamination (6), and labelling errors (5). Manufacturers issued corrective measures in 73 cases (81.1%). Based on the underlying root causes of product failures, these were predominantly (multiple entries) customer information (71), recall (58), modifications in production or quality management (50), modifications of the raw materials (17), and modifications of the instructions for use (12). The results and experience obtained since 1999 suggest that the system for post marketing surveillance of IVD is an established tool to ensure product safety even though the current system can be further optimised.

Theoretical modelling of plasma protein adsorption/desorption processes onto solid surfaces.

Experimental data from particle electrophoretic measurements of polymer particles have been used for modelling competitive protein adsorption. It could be demonstrated that protein adsorption onto a solid surface is a two-step process: firstly fast reversible adsorption and, secondly, irreversible coupling at the adsorption centres dependent on contact time. The extent of protein competition is influenced by a characteristic time-dependence of the adsorption process. Analysis of the experimental findings results in two models whose corresponding systems of kinetic equations were solved. Both suggested models are based upon relatively simple mechanisms: (a) the parallel reaction; and (b) the exchange reaction. It has been shown that in our experiments a classical exchange process for describing competitive protein adsorption can be very probably supposed.