Cost‐effectiveness of screening for HLA‐B*1502 prior to initiation of carbamazepine in epilepsy patients of Asian ancestry in the United States

Cost-effectiveness analysis of HLA-B*15:02 screening before treatment of epilepsy in Indonesia

INTRODUCTION

Adverse skin reactions due to drugs such as Stevens Johnson Syndrome (SJS) and Toxic Epidermal Necrolysis (TEN) occur in 3% of people receiving anti epileptic drugs (AED). Although SJS/TEN has a low incidence, the mortality and morbidity rates are high. Indonesia has not adopted HLA-B*1502 screening prior to administration of carbamazepine (CBZ), although previous studies found a relationship between HLA-B*1502 and SJS/TEN.

METHODS

A hybrid decision tree and Markov model was developed to evaluate three strategies for treating newly diagnosed focal epilepsy: CBZ direct therapy, levetiracetam (LEV) direct therapy, and therapy based on HLA-B*15:02 test results. From a societal perspective, base case and sensitivity analyses were carried out over a lifetime.

RESULTS

Direct administration of CBZ appears to have a slightly lower average cost than the HLA-B*15:02 allele screening strategy. The increase in quality-adjusted life year (QALY) in HLA-B*15:02 screening before treatment related to the cost difference reached 0.519 with an incremental cost-effectiveness ratio (ICER) of around USD 984 per unit of QALY acquisition. Direct treatment of LEV increased treatment costs by almost USD 2000 on average compared to the standard CBZ strategy. The increase in QALY is 0.834 in direct levetiracetam treatment, with an ICER of around USD 2230 for each QALY processing.

CONCLUSION

Calculation of the cost-effectiveness of lifetime epilepsy therapy in this study found that the initial screening strategy with the HLA-B*15:02 test was the most cost-effective.

Update on HLA-B*15:02 allele associated with adverse drug reactions

HLA alleles, part of the major histocompatibility complex, are strongly associated with adverse drug reactions (ADRs). This review focuses on HLA-B*15:02 and explores its association with ADRs in various ethnic populations and with different drugs, aiming to provide insights into the safe clinical use of drugs and minimize the occurrence of ADRs. Furthermore, the review explores the potential mechanisms by which HLA-B*15:02 may be associated with ADRs, aiming to gain new insights into drug modification and identification of haptens. In addition, it analyzes the frequency of the HLA-B*15:02, genotyping methods, cost-effectiveness and treatment measures for adverse reactions, thereby providing a theoretical basis for formulating clinical treatment plans.

Integrating real-world data in cost-effectiveness analysis of universal HLA-B*15:02 screening in Malaysia

AIMS

Despite the availability of newer antiseizure medications, carbamazepine (CBZ) remains the gold standard. However, patients of Asian ancestry are susceptible to CBZ-related severe cutaneous adverse reactions. Universal HLA-B*15:02 screening is a promising intervention to address this. With the increasing recognition of integrating real-world evidence in economic evaluations, the cost-effectiveness of universal HLA-B*15:02 screening was assessed using available real-world data in Malaysia.

METHODS

A hybrid model of a decision tree and Markov model was developed to evaluate 3 strategies for treating newly diagnosed epilepsy among adults: (i) CBZ initiation without HLA-B*15:02 screening (current practice); (ii) universal HLA-B*15:02 screening prior to CBZ initiation; and (iii) alternative prescribing without HLA-B*15:02 screening. The model was populated with real-world inputs derived from the Malaysian population. From a societal perspective, base-case analysis and sensitivity analyses estimated the costs and outcomes over a lifetime. Incremental cost-effectiveness ratios were calculated.

RESULTS

In the base-cases analysis, universal HLA-B*15:02 screening yielded the lowest total costs and the highest total quality-adjusted life years (QALYs) gained. Compared with current practice, universal screening was less costly by USD100 and more effective by QALYs increase of 0.1306, while alternative prescribing resulted in 0.1383 QALYs loss at additional costs of USD332. The highest seizure remission rate (56%) was estimated for universal HLA-B*15:02 screening vs. current practice (54%) and alternative prescribing (48%).

CONCLUSION

Our study suggests that universal HLA-B*15:02 screening is a cost-effective intervention in Malaysia. With the demonstrated value of real-world evidence in economic evaluations, more relevant standardization efforts should be emphasized to better inform decision-making.

Epilepsy genetics: a practical guide for adult neurologists

An understanding of epilepsy genetics is important for adult neurologists, as making a genetic diagnosis gives clinical benefit. In this review, we describe the key features of different groups of genetic epilepsies. We describe the common available genetic tests for epilepsy, and how to interpret them.

Treatment-Resistant Schizophrenia, Clozapine Resistance, Genetic Associations, and Implications for Precision Psychiatry: A Scoping Review

Treatment-resistant schizophrenia (TRS) is often associated with severe burden of disease, poor quality of life and functional impairment. Clozapine is the gold standard for the treatment of TRS, although it is also known to cause significant side effects in some patients. In view of the burgeoning interest in the role of genetic factors in precision psychiatry, we conducted a scoping review to narratively summarize the current genetic factors associated with TRS, clozapine resistance and side effects to clozapine treatment. We searched PubMed from inception to December 2022 and included 104 relevant studies in this review. Extant evidence comprised associations between TRS and clozapine resistance with genetic factors related to mainly dopaminergic and serotoninergic neurotransmitter systems, specifically, TRS and rs4680, rs4818 within COMT, and rs1799978 within DRD2; clozapine resistance and DRD3 polymorphisms, CYP1A2 polymorphisms; weight gain with LEP and SNAP-25 genes; and agranulocytosis risk with HLA-related polymorphisms. Future studies, including replication in larger multi-site samples, are still needed to elucidate putative risk genes and the interactions between different genes and their correlations with relevant clinical factors such as psychopathology, psychosocial functioning, cognition and progressive changes with treatment over time in TRS and clozapine resistance.

Cost Effectiveness of Pharmacogenetic Testing for Drugs with Clinical Pharmacogenetics Implementation Consortium (CPIC) Guidelines: A Systematic Review

The objective of this study was to evaluate the evidence on cost-effectiveness of pharmacogenetic (PGx)-guided treatment for drugs with Clinical Pharmacogenetics Implementation Consortium (CPIC) guidelines. A systematic review was conducted using multiple biomedical literature databases from inception to June 2021. Full articles comparing PGx-guided with nonguided treatment were included for data extraction. Quality of Health Economic Studies (QHES) was used to assess robustness of each study (0-100). Data are reported using descriptive statistics. Of 108 studies evaluating 39 drugs, 77 (71%) showed PGx testing was cost-effective (CE) (N = 48) or cost-saving (CS) (N = 29); 21 (20%) were not CE; 10 (9%) were uncertain. Clopidogrel had the most articles (N = 23), of which 22 demonstrated CE or CS, followed by warfarin (N = 16), of which 7 demonstrated CE or CS. Of 26 studies evaluating human leukocyte antigen (HLA) testing for abacavir (N = 8), allopurinol (N = 10), or carbamazepine/phenytoin (N = 8), 15 demonstrated CE or CS. Nine of 11 antidepressant articles demonstrated CE or CS. The median QHES score reflected high-quality studies (91; range 48-100). Most studies evaluating cost-effectiveness favored PGx testing. Limited data exist on cost-effectiveness of preemptive and multigene testing across disease states.

Gene panel to guide antiseizure medication prescribing: Does the cost justify the benefits?

Pharmacogenomics hold the potential to identify variants associated with adverse drug reactions and treatment efficacy of anti-seizure medications. A model-based cost-utility analysis by Gordon and colleagues showed that genetically-guided therapy costs more, yielded higher quality-adjusted life years outcomes, and was considered to be cost-effective compared to usual care. The study provided preliminary evidence on the value of pharmacogenetic testing in patients with drug-resistant epilepsy. However, data input for the model was based on assumptions that need to be empirically tested. Further, there are many other factors that may affect the cost-effectiveness of pharmacogenetic testing that need to be considered, including the model of service delivery, its implementation in complex clinical service, whether clinicians will modify treatment decisions based on pharmacogenetic information, and the fidelity with which recommendation on testing is adhered to in the real-world. The cost-effectiveness analysis should be repeated when more robust data on the effectiveness of pharmacogenetics are available and conducted alongside a budget impact analysis, incorporating the direct health care resources required to implement widespread testing and potential subsequent changes in treatment.

Practical Implementation of Genetics: New Concepts in Immunogenomics to Predict, Prevent, and Diagnose Drug Hypersensitivity

Delayed drug hypersensitivities are CD8⁺ T cell-mediated reactions associated with up to 50% mortality. Human leukocyte antigen (HLA) alleles are known to predispose disease and are specific to drug, reaction, and patient ethnicity. Pretreatment screening is recommended for a handful of the strongest associations to identify and prevent drug use in high-risk patients. However, an incomplete predictive value implicates other HLA-imposed risk factors, and low carriage of many identified HLA-risk alleles combined with the high cost of sequence-based typing has limited economic viability for similar recommendation of screening across drugs and health care systems. For mitigation, an expanding armory of low-cost polymerase chain reaction-based screens is being developed, and HLA-imposed risk factors are being discovered. These include (1) polymorphic variants of metabolic and endoplasmic reticulum aminopeptidase enzymes toward multiallelic screening with increased predictivity; (2) regulation by immune checkpoint inhibitors, enabling detolerized animal models of human disease; and (3) immunodominant T cell receptors (TCR) on clonally expanded CD8⁺ T cells. For the latter, HLA risk-restricted TCR provides immunogenomic strategies and samples from a single patient to identify novel HLA-risk associations in underserved minority populations, tissue-relevant effector biomarkers toward earlier diagnosis and treatment, and HLA-TCR-presented immunogenic structures to aid future drug development.

A systematic review of the methodological quality of economic evaluations in genetic screening and testing for monogenic disorders

PURPOSE

Understanding the value of genetic screening and testing for monogenic disorders requires high-quality, methodologically robust economic evaluations. This systematic review sought to assess the methodological quality among such studies and examined opportunities for improvement.

METHODS

We searched PubMed, Cochrane, Embase, and Web of Science for economic evaluations of genetic screening/testing (2013-2019). Methodological rigor and adherence to best practices were systematically assessed using the British Medical Journal checklist.

RESULTS

Across the 47 identified studies, there were substantial variations in modeling approaches, reporting detail, and sophistication. Models ranged from simple decision trees to individual-level microsimulations that compared between 2 and >20 alternative interventions. Many studies failed to report sufficient detail to enable replication or did not justify modeling assumptions, especially for costing methods and utility values. Meta-analyses, systematic reviews, or calibration were rarely used to derive parameter estimates. Nearly all studies conducted some sensitivity analysis, and more sophisticated studies implemented probabilistic sensitivity/uncertainty analysis, threshold analysis, and value of information analysis.

CONCLUSION

We describe a heterogeneous body of work and present recommendations and exemplar studies across the methodological domains of (1) perspective, scope, and parameter selection; (2) use of uncertainty/sensitivity analyses; and (3) reporting transparency for improvement in the economic evaluation of genetic screening/testing.

Genotyping HLA alleles to predict the development of Severe cutaneous adverse drug reactions (SCARs): state-of-the-art

Introduction: Pharmacogenomics has great potential in reducing drug-induced severe cutaneous adverse drug reactions (SCARs). Pharmacogenomic studies have revealed an association between HLA genes and SCARs including acute generalized exanthematous pustulosis (AGEP), drug reaction with eosinophilia and systemic symptoms (DRESS), Stevens-Johnson syndrome (SJS), and toxic epidermal necrolysis (TEN).Areas covered: Pharmacogenomics-guided therapy could prevent severe drug hypersensitivity reactions. The US Food and Drug Administration (FDA), Clinical Pharmacogenetics Implementation Consortium (CPIC), and Dutch Pharmacogenetics Working Group (DPWG) provided guidelines in the translation of clinically relevant and evidence-based SCARs pharmacogenomics research into clinical practice. In this review, we intended to summarize the significant HLA alleles associated with SCARs induced by different drugs in different populations. We also summarize the SCARs associated with genetic and non-genetic factors and the cost-effectiveness of screening tests.Expert opinion: The effectiveness of HLA screening on a wider scale in clinical practice requires significant resources, including state-of-the-art laboratory; multidisciplinary team approach and health care provider education and engagement; clinical decision support alert system via electronic medical record (EMR); laboratory standards and quality assurance; evidence of cost-effectiveness; and cost of pharmacogenomics tests and reimbursement.

Severe cutaneous adverse reaction associated with antiseizure medications: Diagnosis, management, and prevention

Severe cutaneous adverse reactions (SCARs) are potentially life-threatening, with considerable morbidity and mortality. They are nonimmediate hypersensitivity reactions that occur in specifically predisposed patients with delayed T-cell-mediated hypersensitivity reaction. Antiseizure medications (ASMs) are among the drugs that can induce SCAR. Increased awareness of SCAR among clinicians treating patients with ASMs is critically important for early recognition of symptoms, prompt identification and removal of the causal drug, and early intervention to reduce SCAR-related acute and long-term morbidity and mortality. The diagnosis, management, and prevention of Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), and drug reaction with eosinophilia and systemic symptoms (DRESS) are reviewed, along with the current understanding of the pathomechanisms and role of genetics in SCAR development. Supportive care and immunomodulating treatments for SCAR are discussed.

Current role of carbamazepine and oxcarbazepine in the management of epilepsy

Epilepsy is one of the most common neurological disorders, affecting approximately 50 million people worldwide. Despite a dramatic increase in treatment options over the past 30 years, it still ranks fourth in the world's disease burden. There are now close to 30 antiepileptic drugs (AEDs), with more than two thirds introduced to the market after carbamazepine (CBZ) and one third after its derivative, oxcarbazepine (OXC). Following the introduction of these newer AEDs, the role of CBZ and OXC in the therapeutic armamentarium for seizure control and effective epilepsy management needs to be reviewed. The main guidelines list both CBZ and OXC as first-line options or second-line alternatives for the treatment of focal-onset epilepsy and primary generalized tonic-clonic seizures. While evidence suggests that overall AEDs have similar efficacy, some newer AEDs may be better tolerated than CBZ. In line with this, there have been changes in treatment patterns, with many variations across different countries. However, CBZ remains among the two or three most prescribed drugs for focal epilepsy in many countries, and is widely used across Europe, Africa, South America, and Asia, where it represents a good compromise between cost, availability, and effectiveness. OXC is among the first-choice options for the initial treatment of focal-onset seizures in several countries, including the US and China, where the oral suspension is commonly prescribed. This review provides guidance on the optimal use of these two drugs in clinical practice, including in children, the elderly, and in pregnancy.

Challenges and Opportunities in Implementing Pharmacogenetic Testing in Clinical Settings

The clinical implementation of pharmacogenetic biomarkers continues to grow as new genetic variants associated with drug outcomes are discovered and validated. The number of drug labels that contain pharmacogenetic information also continues to expand. Published, peer-reviewed clinical practice guidelines have also been developed to support the implementation of pharmacogenetic tests. Incorporating pharmacogenetic information into health care benefits patients as well as clinicians by improving drug safety and reducing empiricism in drug selection. Barriers to the implementation of pharmacogenetic testing remain. This review explores current pharmacogenetic implementation initiatives with a focus on the challenges of pharmacogenetic implementation and potential opportunities to overcome these challenges.