Risk assessment and cost-effectiveness/utility analysis

Integration of PKPD relationships into benefit-risk analysis

AIM

Despite the continuous endeavour to achieve high standards in medical care through effectiveness measures, a quantitative framework for the assessment of the benefit-risk balance of new medicines is lacking prior to regulatory approval. The aim of this short review is to summarise the approaches currently available for benefit-risk assessment. In addition, we propose the use of pharmacokinetic-pharmacodynamic (PKPD) modelling as the pharmacological basis for evidence synthesis and evaluation of novel therapeutic agents.

METHODS

A comprehensive literature search has been performed using MESH terms in PubMed, in which articles describing benefit-risk assessment and modelling and simulation were identified. In parallel, a critical review of multi-criteria decision analysis (MCDA) is presented as a tool for characterising a drug's safety and efficacy profile.

RESULTS

A definition of benefits and risks has been proposed by the European Medicines Agency (EMA), in which qualitative and quantitative elements are included. However, in spite of the value of MCDA as a quantitative method, decisions about benefit-risk balance continue to rely on subjective expert opinion. By contrast, a model-informed approach offers the opportunity for a more comprehensive evaluation of benefit-risk balance before extensive evidence is generated in clinical practice.

CONCLUSIONS

Benefit-risk balance should be an integral part of the risk management plan and as such considered before marketing authorisation. Modelling and simulation can be incorporated into MCDA to support the evidence synthesis as well evidence generation taking into account the underlying correlations between favourable and unfavourable effects. In addition, it represents a valuable tool for the optimization of protocol design in effectiveness trials.

Human immunodeficiency virus prevalence, incidence, and residual transmission risk in first-time and repeat blood donations in Zimbabwe: implications on blood safety

BACKGROUND

National Blood Service Zimbabwe human immunodeficiency virus (HIV) risk management strategy includes screening and discarding of first-time donations, which are collected in blood packs without an anticoagulant (dry pack). To evaluate the impact of discarding first-time donations on blood safety the HIV prevalence, incidence, and residual risk in first-time and repeat donations (wet packs) were compared.

STUDY DESIGN AND METHODS

Donor data from 2002 to 2010 were retrieved from a centralized national electronic donor database and retrospectively analyzed. Chi-square test was used to compare HIV prevalence with relative risk (RR), and the RR point estimates and 95% confidence interval (CI) are reported. Trend analysis was done using Cochran-Armitage trend test. HIV residual risk estimates were determined using published residual risk estimation models.

RESULTS

Over the 9 years the overall HIV prevalence estimates are 1.29% (n = 116,058) and 0.42% (n = 434,695) for first-time and repeat donations, respectively. The overall RR was 3.1 (95% CI, 2.9-3.3; p < 0.0001). The overall mean residual transmission risk of HIV window phase donations in first-time was 1:7384 (range, 1:11,308-1:5356) and in repeat donors it was 1:5496 (range, 1:9943-1:3347).

CONCLUSION

The significantly high HIV prevalence estimates recorded in first-time over repeat donations is indicative of the effectiveness of the HIV risk management strategy. However, comparable residual transmission risk estimates in first-time and repeat donors point to the need to further review the risk management strategies. Given the potential wastage of valuable resources, future studies should focus on the cost-effectiveness and utility of screening and discarding first-time donations.

External financial aid to blood transfusion services in sub-Saharan Africa: a need for reflection

Jean-Pierre Allain and colleagues argue that, while unintended, the foreign aid provided for blood transfusion services in sub-Saharan Africa has resulted in serious negative outcomes, which requires reflection and rethinking.

[Pathogen reduction of blood components: from financial issues to possible long-term consequences]

Pathogen inactivation of blood products represents a global and major paradigm shift in transfusion medicine. In the next near future, it is likely that most blood products will be inactivated by various physicochemical approaches. The concept of blood safety will be challenged as well as transfusion medicine practice, notably for donor selection or biological qualification. In this context, it seems mandatory to develop analytical economic approaches by assessing costs-benefits ratio of blood transfusion as well as to set up cohorts of patients based on hemovigilance networks allowing rigorous scientific analysis of the benefits and the risks of blood transfusion at short- and long-term.

Advances in transfusion medicine in the first decade of the 21st century: Advances in miniaturized technologies

Several miniaturized high throughput technologies have been developed in the last decade, primarily to study genomic structures and gene expression patterns under various conditions. At the same time, the microarrays, biosensors, integrated microfluidic lab-on-a-chip devices, next generation sequencing or digital PCR are gradually finding their diagnostic applications, although their suitability for specialised diagnostic fields has still to be assessed. In this review we discuss the potential applications of the new technologies to blood testing.

Detection of blood-transmissible agents: can screening be miniaturized?

Transfusion safety relating to blood-transmissible agents is a major public health concern, particularly when faced with the continuing emergence of new infectious agents. These include new viruses appearing alongside other known reemerging viruses (West Nile virus, Chikungunya) as well as new strains of bacteria and parasites (Plasmodium falciparum, Trypanosoma cruzi) and finally pathologic prion protein (variant Creutzfeldt-Jakob disease). Genomic mutations of known viruses (hepatitis B virus, hepatitis C virus, human immunodeficiency virus) can also be at the origin of variants susceptible to escaping detection by diagnostic tests. New technologies that would allow the simultaneous detection of several blood-transmissible agents are now needed for the development and improvement of screening strategies. DNA microarrays have been developed for use in immunohematology laboratories for blood group genotyping. Their application in the detection of infectious agents, however, has been hindered by additional technological hurdles. For instance, the variability among and within genomes of interest complicate target amplification and multiplex analysis. Advances in biosensor technologies based on alternative detection strategies have offered new perspectives on pathogen detection; however, whether they are adaptable to diagnostic applications testing biologic fluids is under debate. Elsewhere, current nanotechnologies now offer new tools to improve the sample preparation, target capture, and detection steps. Second-generation devices combining micro- and nanotechnologies have brought us one step closer to the potential development of innovative and multiplexed approaches applicable to the screening of blood for transmissible agents.

Health economics of blood transfusion safety--focus on sub-Saharan Africa

BACKGROUND AND OBJECTIVES

Health economics provides a standardised methodology for valid comparisons of interventions in different fields of health care. This review discusses the health economic evaluations of strategies to enhance blood product safety in sub-Saharan Africa.

METHODS

We reviewed health economic methodology with special reference to cost-effectiveness analysis. We searched the literature for cost-effectiveness in blood product safety in sub-Saharan Africa.

RESULT

HIV-antibody screening in different settings in sub-Saharan Africa showed health gains and saved costs. Except for adding HIV-p24 screening, adding other tests such as nucleic acid amplification testing (NAT) to HIV-antibody screening displayed incremental cost-effectiveness ratios greater than the WHO/World Bank specified threshold for cost-effectiveness. The addition of HIV-p24 in combination with HCV antibody/antigen screening and multiplex (HBV, HCV and HIV) NAT in pools of 24 may also be cost-effective options for Ghana.

CONCLUSIONS

From a health economic viewpoint, HIV-antibody screening should always be implemented in sub-Saharan Africa. The addition of HIV-p24 antigen screening, in combination with HCV antibody/antigen screening and multiplex (HBV, HCV and HIV) NAT in pools of 24 may be feasible options for Ghana. Suggestions for future health economic evaluations of blood transfusion safety interventions in sub-Saharan Africa are: mis-transfusion, laboratory quality and donor management.

Transfusion-transmitted hepatitis B virus infection

Hepatitis B virus (HBV) remains a major risk of transfusion-transmitted infection due to the pre-seroconversion window period (WP), infection with immunovariant viruses, and with occult carriage of HBV infection (OBI). Reduction of HBV residual risk depends upon developing more sensitive HBV surface antigen (HBsAg) tests, adopting anti-HBc screening when appropriate, and implementing HBV nucleic acid testing (NAT), either in minipools or more efficiently in individual samples. HBV NAT combines the ability to significantly reduce the window period and to detect occult HBV carriage substantiating decades of clinical observation that HBsAg-negative/anti-HBc-positive blood could transmit HBV. Clinical observations suggest limited transmission rate of occult HBV compared to WP. Low transmission rate might be related to low viral load observed in OBIs or to the presence of mutants associated with occult carriage. OBIs carrying detectable anti-HBs ( approximately 50%) are essentially not infectious by transfusion. However, recent data suggest that the neutralizing capacity of low anti-HBs may be inefficient when overcome by exposure to high viral load. Anti-HBc blood units without detectable anti-HBs appear moderately infectious except in immunocompromised recipients. Immunodeficient elderly and patients receiving immunosuppressive treatments may be susceptible to infection with lower infectious dose even in the presence of anti-HBs. The immune status of blood recipients should be taken into consideration when investigating "post-transfusion" HBV infection. Pre-transfusion testing and post-transfusion long-term follow-up of recipients, and molecular analysis of the virus infecting both donor and recipient are critical to definitively incriminate transfusion in the transmission of HBV.