Statistical control of the production of blood components by control charts of attribute to improve quality characteristics and to comply with current specifications.

Statistical process control (SPC) is closely related to good quality control practices in the manufacturing process. One of the primary goals is to detect unnatural patterns, allowing the production service to control the conformity of the blood components produced. Despite being recommended by national and international standards, its exercise is not uniform, and sometimes the methodology used is misinterpreted as SPC. When the input data has a Gaussian distribution, control charts for variables are proposed. However, when the data distribution is not normal, control charts for attributes are suggested. This article presents and discusses four statistical procedures for the control of attributes using p-, np-, u-, and c-charts. An empirical demonstration shows these models are reliable for in routine use in the Blood Establishment quality control, as also suggests the use when the control charts for variables are inapplicable.

Statistical methods to the control of the production of blood components: principles and control charts for variables.

General quality control good practices require the control of the production of blood components using statistical techniques, such as mandatory by the European Commission Directives and the American Association of Blood Banks standards. Sometimes, the control procedure is exclusively in favor of the compliance verification with specifications per individual component or to compute the number of defective parts usually on a monthly basis. However, this is a critical restriction to detect unnatural patterns such as to guarantee that the production has a non-significance chance to manufacturing nonconforming components. Therefore, a crucial issue in Blood Establishments is the application of a reliable statistical process control methodology to assure products reliable and consistent to specifications. Statistical principles and control charts for variables are reviewed, discussed and recommended, based on current good practices. The empirical data demonstrate the consistency of these models on blood establishment routine. A flowchart to select the type of control chart is suggested.

Sampling methods to the statistical control of the production of blood components.

The control of blood components specifications is a requirement generalized in Europe by the European Commission Directives and in the US by the AABB standards. The use of a statistical process control methodology is recommended in the related literature, including the EDQM guideline. The control reliability is dependent of the sampling. However, a correct sampling methodology seems not to be systematically applied. Commonly, the sampling is intended to comply uniquely with the 1% specification to the produced blood components. Nevertheless, on a purely statistical viewpoint, this model could be argued not to be related to a consistent sampling technique. This could be a severe limitation to detect abnormal patterns and to assure that the production has a non-significant probability of producing nonconforming components. This article discusses what is happening in blood establishments. Three statistical methodologies are proposed: simple random sampling, sampling based on the proportion of a finite population, and sampling based on the inspection level. The empirical results demonstrate that these models are practicable in blood establishments contributing to the robustness of sampling and related statistical process control decisions for the purpose they are suggested for.

Highlights of PBTI Coimbra Conference on PRT of Plasma & Current Opinions on Pathogen Reduction Treatment of Blood Components.

Two experts from Octapharma and from Cerus addressed, in very concise ways, the concerns about non-viral inactivated FFP and how they managed to obtain highest standard of safety margin for pathogen reduction treatment [PRT] of plasma. The session was moderated by Portuguese Institute of Blood and Transplantation (PIBT) consultant advisor [Jerard Seghatchian] with long standing familiarity and international recognition in PR technologies for plasma, platelets and WB/red cells. The focus of conference was mainly on the criteria of acceptability of PRT-FFP; added values of having diversity in choice without fears of liability, as both of PRT technologies provide an excellent safeguard margins, for more than a decade of usage. In most European countries, it is believed that patients' safety come first followed by the safe usage initiatives, in particular using locally available products. Portugal is finally going forward with the implementation PRT plasma using its own FFP for their clinical use. The round table Q&A session focused on the impacts of the additional processing, which is still continuously improving, on the residual/emerging pathogen infectivity; eliminating the clinical impacts of donors viable leukocytes; the degree of altered product potency in particular cold activation of FVII; and loss of endothelial permeability factors during fluid storage of plasma. Both speakers highlighted their product safety and clinical efficacy using both routine in vitro, including the modern proteomic tests to establish the relevant changes in various parameters and in the overall clinical outcomes. The advancements in pharmacovigilance and hemovigilance, regulatory aspects and cost effectiveness were also highlighted. A local speaker [from the PIBT] described the state of the art of local processing issues and overall required standards used both during validation and the intercept process scale up, which is going ahead smoothly to providing the highest safety standards PRT-intercept plasma locally, in production now. Overall this was an excellent conference, open to transfusion medicine specialists and other health care professionals, for feedback and quality awareness, of providing diversity in choice, to local clinicians, who demand the best for the ultimate patient requirements. This is achieved in a period where both cost effectiveness and affordability matter, so is the clinical outcome, which ultimately counts. There was an atmosphere of non-competitive collaboration and sharing knowledge and working togetherness, even between two manufacturer representatives, which made the conference most joyful event. This was the opportunity to the scientific update and sharing "the once upon a time" impossible task of going for PRT-plasmas in Portugal, making it a reality in their local setting, in real time using Portuguese plasmas. This is in fact the timely news in the period of austerity, to provide a pre launching session for reporting the state of the arts of Portugal achievements to staff, academician, laboratory experts and clinician alike.

The role of uncertainty regarding the results of screening immunoassays in blood establishments.

The risk of uncertain results in infectious agents' tests is recognized in blood establishments, being particularly evident during the blood donor selection. The current risk-based approaches require risk assessment and "risk-based thinking". Accordingly, the blood establishment should consider the effect of uncertainty in all the technical decisions taken in a screening laboratory. Since the post-transfusion safety is one of the blood establishments' goals, the risk of post-transfusion infection should be evaluated and actions taken to decrease the chance of blood donations validation use false negative results. This article reviews and discusses the sources of uncertainty of infectious agents' reported results in blood establishments. It describes a set of sources of uncertainty that should be considered in screening immunoassay's decisions. The infectious agents' uncertainty concern is critical for reporting reliable results.

Quality management in European screening laboratories in blood establishments: A view of current approaches and trends.

The screening laboratory has a critical role in the post-transfusion safety. The success of its targets and efficiency depends on the management system used. Even though the European Union directive 2002/98/EC requires a quality management system in blood establishments, its requirements for screening laboratories are generic. Complementary approaches are needed to implement a quality management system focused on screening laboratories. This article briefly discusses the current good manufacturing practices and good laboratory practices, as well as the trends in quality management system standards. ISO 9001 is widely accepted in some European Union blood establishments as the quality management standard, however this is not synonymous of its successful application. The ISO "risk-based thinking" is interrelated with the quality risk-management process of the EuBIS "Standards and criteria for the inspection of blood establishments". ISO 15189 should be the next step on the quality assurance of a screening laboratory, since it is focused on medical laboratory. To standardize the quality management systems in blood establishments' screening laboratories, new national and European claims focused on technical requirements following ISO 15189 is needed.

Scheme for the selection of measurement uncertainty models in blood establishments' screening immunoassays.

Blood establishments routinely perform screening immunoassays to assess safety of the blood components. As with any other screening test, results have an inherent uncertainty. In blood establishments the major concern is the chance of false negatives, due to its possible impact on patients' health. This article briefly reviews GUM and diagnostic accuracy models for screening immunoassays, recommending a scheme to support the screening laboratories' staffs on the selection of a model considering the intended use of the screening results (i.e., post-transfusion safety). The discussion is grounded on a "risk-based thinking", risk being considered from the blood donor selection to the screening immunoassays. A combination of GUM and diagnostic accuracy models to evaluate measurement uncertainty in blood establishments is recommended.

Memory complaints in healthy young and elderly adults: reliability of memory reporting.

The relationship between memory complaints and objective memory performance remains poorly understood, particularly in young and middle aged people. We studied the relationship between reports of memory complaints and objective memory performance, and the possibility of differentiating good and poor reporters across the lifespan based on concordance between reported abilities and objectively assessed performance. This cross-sectional study enrolled 292 healthy individuals, aged 18 to 87 years, able to perform common activities of daily living and without neurological or psychiatric conditions or systemic diseases likely to interfere with cognition. No correlation between memory complaints, as assessed by the Subjective Memory Complaints scale (SMC) score and the objective memory performance, evaluated by the long-delay free recall (LDFR) score of the California Verbal Learning Test (CVLT), was found, even when grouping the participants by decade. The SMC score was influenced by the presence of depressive symptoms. Participants who were more educated, female and younger tended to have a higher CVLT-LDFR score. Younger subjects were more likely to have good memory performance and report few memory complaints than older subjects. In conclusion, there are differences in the reliability of memory reporting across the lifespan, younger subjects being more likely to correctly report good memory than older subjects.

An overview of unresolved inherent problems associated with red cell transfusion and potential use of artificial oxygen carriers and ECO-RBC: current status/future trends.

This manuscript deals with why we need alternatives to liquid stored RBC highlighting some of the unresolved inherent problems related to red cell storage lesion and their potential impacts on the clinical outcomes and transfusion complications. The promise of several potential alternatives to red cell transfusions such as: Perfluorocarbon; Modified Hb-based oxygen carriers and newer design of Hb-based oxygen carriers are reviewed. It is noteworthy to say that since the first introduction of these oxygen carriers, almost five decades ago, the only successful drive has been to prepare safer and more convenient oxygen carriers, for enhancing the quality of life of recipients and their usage, either as substitutes to red cell transfusion or even as the bridge, remains patchy. Moreover, as new products with better characteristics become available the older products from the competitors are withdrawn. Finally, the current progress on universal RBC, known as ECO-cells is highlighted and, in the future perspectives, some of the current efforts in making the red cells transfusion safer and more efficacious are briefly addressed.

Pathogen-reduction systems for blood components: the current position and future trends.

The current multi-layered interventional approaches to blood safety have dramatically reduced the risk of viral contamination of blood components. Nowadays most of the residual transfusion transmitted infections (TTI) occur as the result of the interval between the time the donor is infected and the moment at which tests are capable of detecting the agent, the so called "window period" which has been considerably reduced by the increased sensitivity of nucleic acid testing (NAT). However, the residual risk of bacterial contamination and the unexpected appearance of some other emerging pathogens, almost every five years, are still of major concern to the public, politicians, regulatory agencies and place immense pressures on the organisations responsible for the provision of safe blood and its components. In view of these bleak scenarios, the use of human blood as a raw biological source is inherently unsafe, and screening/testing alone cannot exclude all the potential human pathogens; hence we need to put in place some sort of safer alternatives and/or additional preventative safety measures. Recently, several substitutes (alternatives) to virtual blood components have been developed and tried. Moreover, various mechanical methods such as cell washing and leukofiltration have been implemented as additional preventative safety measures but with limited success in abrogating the risk of transfusion transmitted cell-associated agents. The most promising approaches, so far, are methods that target pathogen nucleic acids (Methylene blue; Psolaren and Riboflavin UV light treatment). These procedures have undergone considerable in vitro studies to ensure their extremely high safety margins in terms of toxicity to the cells or to the recipients. In essence, while the technology of targeting nucleic acid to stop viral proliferation is common to the above three strategies, in practice these procedures differ in terms of operational, physicochemical and biological characteristics; including the potential impacts of their metabolites and photo-adducts; their effects on the spectrum of pathogens affected and the log reductions in culture infective studies. Accordingly, any strategy that involves addition of an extraneous agent or physicochemical manipulation of blood must balance the benefits of pathogen reduction against the loss or alteration to the cells and plasma functional integrity, short and long term toxicity to the cells and to the recipients, as well as the risk to the personnel involved and the community at large. Moreover, it must be noted that each method will have a different profile of adverse reactions and may differ in terms of the risk to particularly vulnerable groups of patients, requiring in depth clinical trials, while taking into consideration the cost benefit of the final process. Newer diagnostic procedures must be in place to establish the storage stability of products that have undergone pathogen inactivation, in particular tests reflecting the release of platelet-derived cytokines, cellular apoptosis or microvesiculation and their role in immunosupressiveness. This overview aims to provide an update on the continual improvements in blood component safety, in particular using methods that target pathogen nucleic acid. Emphasis is placed on methylene blue light treatment (MBLT) and Intercept or Mirasol PRT systems for platelets and plasma. The status of pathogen reduction of whole blood and red cells is also highlighted, though the progress in this area has been virtually stopped after the finding of antibody development in the clinical trial.

The combined effect of platelet storage media and intercept pathogen reduction technology on platelet activation/activability and cellular apoptosis/necrosis: Lisbon-RBS experience.

Platelets are known to undergo shape change, activation, a release reaction and apoptosis/necrosis during processing and storage, all of which are collectively known as the platelet storage lesion. Any additional processing may have some deleterious impact on platelet activability and functional integrity, which need to be investigated. This preliminary investigation was undertaken to establish the combined effects of standard platelet storage media and the intercept pathogen reduction technology on platelet activation and activability during 7 day storage, using buffy-coat derived platelets in standard storage media containing 35% plasma (N=24). P-selectin (CD62p) expression, a classical marker of platelet activation, and phosphatidylserine (PS) exposure on the platelet surface membrane, a hallmark of cellular necrosis/apoptosis, were both measured by flow cytometry. The results reveal significant increases in activation, from an average of 22.7% on day 1 before treatment to 31.6% on day 2 after treatment and 58.7% at the end of storage. Concomitantly, the basal expression of PS was slightly increased from 1.9% to 2.8% at day 2 after treatment and 7.3% at the end of storage. However, the functional reserve of platelets during storage, which reflects their capability to undergo activation and the release reaction when platelets were challenged with either calcium ionophore or thrombin, was relatively well maintained. These preliminary data confirm the earlier data on the use of intercept, and for the first time, based on the assessment of platelet functional integrity, suggest that platelet functional reserve is relatively well maintained, with little change in the formation of apoptotic cells.

What's happening: an overview of potential adverse reactions associated with apheresis technology.

The current status of potential adverse reactions associated with the use of apheresis technology is reviewed, focussing on three main areas: adverse events related to component collection, progenitor cells collection and therapeutic apheresis. Based on available information it is believed that apheresis technologies are safe and increasingly used in transfusion medicine, including in auto-transfusion and different types of therapy. Occasionally, however, for various donor/patient and operational reasons, mild or moderate adverse reactions do occur. The majority of these reactions are related to vascular access and anticoagulants used, which can be mostly eliminated with calcium/magnesium administration. The reactions associated with therapeutic apheresis are more frequent (6.75%) than the multi-components and stem cell collections. Most of these reactions are generally mild and only 0.89% has been classified as severe. A national registry of donor adverse reactions as well as a planned haemovigilance system may prove helpful in identifying the potential causes which might be associated with either to donor/donation and/or with a particular technology or procedure.

Update on leucodepletion, HLA and platelet serology at Lisbon Regional Blood Centre.

The characteristic performance of some leucodepletion processes at the Lisbon Regional Blood Centre is presented. The current position on HLA and platelet serology is briefly described.

Blood cell apoptosis/necrosis: some clinical and laboratory aspects.

Exposure of phosphatidyl-serine on blood cell membrane surface and microvesiculation as the hallmarks of apoptosis/necrosis were investigated. The effect of leukofiltration on the retention/generation of microvesicules, leukocyte subsets and major biological response modifiers were evaluated in a like study. It is concluded that apoptotic cells potentially contribute to transfusion reactions in donor/recipient-specific ways.