An assessment of the impact of pharmacogenomics on health disparities: a systematic literature review

Implementation of clinical pharmacogenetic testing in medically underserved patients: a narrative review

As an emerging health technology, pharmacogenetic (PGx) testing has the capacity to improve medication therapy. However, implementation in medically underserved populations (MUPs) remains limited, which has the potential to increase healthcare disparities. While there is no single accepted definition for MUPs, demographic, socioeconomic, cultural, and geographic factors can lead to reduced access to healthcare, which contributes to disparate health outcomes in these populations. In the case of PGx testing, as MUPs have an increased risk of adverse drug events, have lower numbers of healthcare encounters, and are prescribed more medications which can be guided by PGx testing, additional benefits from PGx testing may occur in MUPs. Study of the acceptability and perceptions of PGx testing in MUPs, as reported in literature, provides support for the development of successful PGx testing implementations. Additionally, a few limited pilot PGx testing implementations in MUPs have assessed feasibility. However, further studies establishing the feasibility and effectiveness of PGx testing implementations in MUPs will enable more widespread PGx testing in those who are medically underserved. Thus, this narrative review explores the impact of medical underservice on health, PGx testing's potential impact on MUPs, and the research and early clinical implementations of PGx in MUPs.

Prevalence of CYP2C19*2 and CYP2C19*3 Allelic Variants and Clopidogrel Use in Patients with Cardiovascular Disease in Trinidad & Tobago

INTRODUCTION

Trinidad & Tobago has the highest prevalence of cardiovascular disease (CVD) in the Caribbean and clopidogrel is a ubiquitously used treatment. Yet, the extent of genetically mediated clopidogrel resistance is unknown. To determine this, we investigated whether the association between CYP2C19*2 and CYP2C19*3 genetic variants and clopidogrel resistance holds, and calculated the frequencies of these in the Trinidadian CVD population.

METHODS

Demographic data, clinical data, and a saliva sample were collected under informed consent from 22 patients with CVD on dual anti-platelet therapy whose biochemical resistance to clopidogrel is known, and a further 162 patients accessing the main public CVD clinic in Trinidad and who are either currently being treated or are likely to be treated with clopidogrel. A polymerase chain reaction (PCR) and restriction enzyme digestion procedure was used to genotype each patient for the CYP2C19*2 and CYP2C19*3 allelic variants. Genotype was compared to known clopidogrel resistance in the 22 patients, and to disease status and clopidogrel usage in the larger cohort.

RESULTS

CYP2C19*2 genotype was concordant with clopidogrel resistance. CYP2C19*2 was detected in 61.1% (99/162) of patients and CYP2C19*3 was undetected. Clopidogrel was the most prescribed antiplatelet therapy (42%). A total of 120 people presented with coronary artery disease (CAD) and 52.5% of these (n = 63/120) are currently prescribed clopidogrel. 63.5% (40/63) of patients with CAD who are prescribed clopidogrel carry the CYP2C19*2 allele; ten homozygous and 30 heterozygous. Indian patients comprised 65% of the cohort and were four times more likely to carry the CYP2C19*2 allele than African patients.

CONCLUSIONS

A large proportion of Trinidadian patients with CVD who are prescribed or may be prescribed clopidogrel carry genetic variants associated with clopidogrel resistance. These results emphasize the clinical need for further investigation into whether CYP2C19*2 genotype should guide clopidogrel use for the cardiovascular disease population in Trinidad & Tobago. A slide deck is available for this article.

Mining local exome and HLA data to characterize pharmacogenetic variants in Saudi Arabia

Pharmacogenomics (PGx) is a promising field of precision medicine where efficacy of drugs is maximized while side effects are minimized for individual patients. Knowledge of the frequency of PGx-relevant variants (pharmacovariants) in the local population is a pre-requisite to informed policy making. Unfortunately, such knowledge is largely lacking from the Middle East. Here, we describe the use of a large clinical exome database (n = 13,473) and HLA haplotypes (n = 64,737) from Saudi Arabia, one of the largest countries in the Middle East, along with previously published data from the local population to ascertain allele frequencies of known pharmacovariants. In addition, we queried another exome database (n = 816) of well-phenotyped research subjects from Saudi Arabia to discover novel candidate variants in known PGx genes (pharmacogenes). Although our results show that only 26% (63/242) of class 1A/1B PharmGKB variants were identified, we estimate that 99.57% of the local population have at least one such variant. This translates to a minimum estimated impact of 9% of medications dispensed by our medical center annually. We also highlight the contribution of rare variants where 71% of the pharmacogenes devoid of common pharmacovariants had at least one potentially deleterious rare variant. Thus, we show that approaches that go beyond the use of commercial PGx kits that have been optimized for other populations should be implemented to ensure universal and equitable access of all members of the local population to personalized prescription practices.

A systematic review finds a lack of consensus in methodological approaches in health inequality/inequity focused reviews

OBJECTIVES

To critically review and analyze evidence synthesis articles using health inequality/inequity guidance to support their review.

STUDY DESIGN AND SETTING

A comprehensive, systematic search of six social science databases (1990 to May 2022) and grey literature sources was undertaken. A narrative approach to synthesis was adopted, describing and categorizing the characteristics of included articles. A comparison of the existing methodological guides was also conducted, discussing the similarities and differences between them.

RESULTS

From 205 identified reviews published between 2008 and 2022, 62 (30%) focusing on health inequality/inequity, met the criteria. The reviews were diverse in terms of methodology, populations, intervention level, and clinical areas. Only 19 (31%) reviews discussed the definition of inequality/inequity. Two methodological guides were identified: (i) the PROGRESS/Plus framework and (ii) the Preferred Reporting Items for Systematic Reviews and Meta-Analyses-Equity checklist.

CONCLUSION

A critique on the methodological guides reaffirms a lack of clarity or guidance on how health inequality/inequity should be considered. The PROGRESS/Plus framework narrowly focuses on dimensions of health inequality/inequity but rarely considers the pathways and interactions of these dimensions and their effect on outcomes. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses-Equity checklist on the other hand provides guidance on report. A conceptual framework is needed to show the pathways and interactions of dimensions of health inequality/inequity.

Exploring perceptions, knowledge, and attitudes regarding pharmacogenetic testing in the medically underserved

Introduction: Pharmacogenetic testing may hold promise in addressing health disparities, as medically underserved patients appear to be prescribed medications with pharmacogenetic guidelines at higher rates. While routine clinical implementation of testing in medically underserved populations has not yet been achieved, using patient perspectives to inform implementation should increase the likelihood of success. The aim of this study was to assess the perceptions, knowledge, and attitudes regarding pharmacogenetic testing in medically underserved patients. Methods: We developed a survey instrument to assess respondent views on pharmacogenetic testing. The survey instrument was developed through a process of literature review, expert input, iterative pilot testing, and final refinement. The survey instrument was fielded to US adults with an estimated household income of $42,000 per year or less. Results: During the survey instrument development, 59 pilot testers provided 133 comments which lead to 38 revisions to the survey instrument. The nationwide survey resulted in 1,060 respondents, of which half (49.8%) reported having no health insurance or being on Medicaid. Most patients (78.9%) had not previously heard of pharmacogenetic testing. After being provided an explanation of pharmacogenetic testing, 60.5% were very or moderately interested in receiving testing if there were no cost and 75.8% of respondents agreed or strongly agreed that pharmacogenetic testing should be available to help with medication selection regardless of cost. Respondents shared that their greatest concern with pharmacogenetic testing was that the test would cost them money, which was expressed by over half (52.7%). This was followed by concerns that the results could reveal a risk for a disease, could affect health insurance, and would not improve care. Discussion: Our results indicate a strong interest in pharmacogenetic testing and identify key perceptions, attitudes, concerns, and potential barriers that can be addressed as pharmacogenetic testing is clinically implemented in medically underserved patient populations.

Cardio oncology: Digital innovations, precision medicine and health equity

The rapid emergence of cardio-oncology has resulted in a rapid growth of cardio-oncology programs, dedicated professional societies sections and committees, and multiple collaborative networks that emerged to amplify the access to care in this new subspecialty. However, most existing data, position statements and guidelines are limited by the lack of availability of large clinical trials to support these recommendations. Furthermore, there are significant challenges regarding proper access to cardio-oncology care and treatment, particularly in marginalized and minority populations. The emergence and evolution of personalized medicine, artificial intelligence (AI), and machine learning in medicine and in cardio-oncology provides an opportunity for a more targeted, personalized approach to cardiovascular complications of cancer treatment. The proper implementation of these new modalities may facilitate a more equitable approach to adequate and universal access to cardio-oncology care, improve health related outcomes, and enable health care systems to eliminate the digital divide. This article reviews and analyzes the current status on these important issues.

The pursuit of health equity in digital transformation, health informatics, and the cardiovascular learning healthcare system

African Americans have a higher rate of cardiovascular morbidity and mortality and a lower rate of specialty consultation and treatment than Caucasians. These disparities also exist in the care and treatment of chemotherapy-related cardiovascular complications. African Americans suffer from cardiotoxicity at a higher rate than Caucasians and are underrepresented in clinical trials aimed at preventing cardiovascular injury associated with cancer therapies. To eliminate racial and ethnic disparities in the prevention of cardiotoxicity, an interdisciplinary and innovative approach will be required. Diverse forms of digital transformation leveraging health informatics have the potential to contribute to health equity if they are implemented carefully and thoughtfully in collaboration with minority communities. A learning healthcare system can serve as a model for developing, deploying, and disseminating interventions to minimize health inequities and maximize beneficial impact.

Ethnic Diversity and Warfarin Pharmacogenomics

Warfarin has remained the most commonly prescribed vitamin K oral anticoagulant worldwide since its approval in 1954. Dosing challenges including having a narrow therapeutic window and a wide interpatient variability in dosing requirements have contributed to making it the most studied drug in terms of genotype-phenotype relationships. However, most of these studies have been conducted in Whites or Asians which means the current pharmacogenomics evidence-base does not reflect ethnic diversity. Due to differences in minor allele frequencies of key genetic variants, studies conducted in Whites/Asians may not be applicable to underrepresented populations such as Blacks, Hispanics/Latinos, American Indians/Alaska Natives and Native Hawaiians/other Pacific Islanders. This may exacerbate health inequalities when Whites/Asians have better anticoagulation profiles due to the existence of validated pharmacogenomic dosing algorithms which fail to perform similarly in the underrepresented populations. To examine the extent to which individual races/ethnicities are represented in the existing body of pharmacogenomic evidence, we review evidence pertaining to published pharmacogenomic dosing algorithms, including clinical utility studies, cost-effectiveness studies and clinical implementation guidelines that have been published in the warfarin field.

Health equality, race and pharmacogenomics

Pharmacogenomics is increasingly moving into mainstream clinical practice. Careful consideration must be paid to inclusion of diverse populations in research, translation and implementation, in the historical and social context of population stratification, to ensure that this leads to improvements in healthcare for all rather than increased health disparities. This review takes a broad and critical approach to the current role of diversity in pharmacogenomics and addresses potential pitfalls in order to raise awareness for prescribers. It also emphasizes evidence gaps and suggests approaches that may minimize negative consequences and promote health equality.

Applicability of Pharmacogenomically Guided Medication Treatment during Hospitalization of At-Risk Minority Patients

Known disparities exist in the availability of pharmacogenomic information for minority populations, amplifying uncertainty around clinical utility for these groups. We conducted a multi-site inpatient pharmacogenomic implementation program among self-identified African-Americans (AA; n = 135) with numerous rehospitalizations (n = 341) from 2017 to 2020 (NIH-funded ACCOuNT project/clinicaltrials.gov#NCT03225820). We evaluated the point-of-care availability of patient pharmacogenomic results to healthcare providers via an electronic clinical decision support tool. Among newly added medications during hospitalizations and at discharge, we examined the most frequently utilized medications with associated pharmacogenomic results. The population was predominantly female (61%) with a mean age of 53 years (range 19-86). On average, six medications were newly prescribed during each individual hospital admission. For 48% of all hospitalizations, clinical pharmacogenomic information was applicable to at least one newly prescribed medication. Most results indicated genomic favorability, although nearly 29% of newly prescribed medications indicated increased genomic caution (increase in toxicity risk/suboptimal response). More than one of every five medications prescribed to AA patients at hospital discharge were associated with cautionary pharmacogenomic results (most commonly pantoprazole/suboptimal antacid effect). Notably, high-risk pharmacogenomic results (genomic contraindication) were exceedingly rare. We conclude that the applicability of pharmacogenomic information during hospitalizations for vulnerable populations at-risk for experiencing health disparities is substantial and warrants continued prospective investigation.

Pharmacogenomics: A road ahead for precision medicine in psychiatry

Psychiatric genomics is providing insights into the nature of psychiatric conditions that in time should identify new drug targets and improve patient care. Less attention has been paid to psychiatric pharmacogenomics research, despite its potential to deliver more rapid change in clinical practice and patient outcomes. The pharmacogenomics of treatment response encapsulates both pharmacokinetic ("what the body does to a drug") and pharmacodynamic ("what the drug does to the body") effects. Despite early optimism and substantial research in both these areas, they have to date made little impact on clinical management in psychiatry. A number of bottlenecks have hampered progress, including a lack of large-scale replication studies, inconsistencies in defining valid treatment outcomes across experiments, a failure to routinely incorporate adverse drug reactions and serum metabolite monitoring in study designs, and inadequate investment in the longitudinal data collections required to demonstrate clinical utility. Nonetheless, advances in genomics and health informatics present distinct opportunities for psychiatric pharmacogenomics to enter a new and productive phase of research discovery and translation.

Economic Impact of the Application of a Precision Medicine Model (5SPM) on Psychotic Patients

BACKGROUND

Schizophrenia is a severe mental disorder that often manifests within the first three decades of life. Its prognosis is uncertain and may result in a prolonged treatment that could extend throughout the entire lifespan of the patient. Antipsychotic drugs are characterized by a high interindividual variability when considering therapeutic effect and emergence of adverse effects. Such interindividual variability is thought to be associated primarily with pharmacokinetic matters.

OBJECTIVE

The objective of this study was to evaluate the economic impact of the application of the 5-Step Precision Medicine model (5SPM), an approach based on the pharmacogenetic analysis of the primary genes involved in the metabolism of the therapy for each patient, restructuring treatment as necessary.

PATIENTS AND METHODS

One hundred eighty-eight psychiatry patients were analysed for single nucleotide polymorphisms on genes CYP1A2, CYP2B6, CYP2C9, CYP2C19, CYP2D6, CYP3A5 and ABCB1. Information on patients' diagnosis, pharmacotherapy, and hospitalizations was collected.

RESULTS

We achieved a cost-benefit ratio of 3.31-3.59 with a reduction of direct cost (hospitalizations plus pharmacotherapy) with a reduction of total cost in 67% of the patients who underwent the clinical intervention.

CONCLUSION

A rational Precision Medicine-based approach to psychiatric patients could result in a reduction on number of drugs required to control exacerbations, and the underlying pathologies, reducing the risk of adverse effects and improving adherence to treatment, leading to a potential decrease in direct costs. This methodology has been shown to be cost-dominant and, being based on a pharmacogenetic analysis, it has a lifelong nature, as the data obtained can be applied to other medical disciplines.

Case Report: Pharmacogenetics Applied to Precision Psychiatry Could Explain the Outcome of a Patient With a New CYP2D6 Genotype

Precision medicine applied to psychiatry provides new insight into the promising field of precision psychiatry. Psychotic disorders are heterogeneous, complex, chronic, and severe mental disorders. Not only does the prognosis and the course of the disease vary among patients suffering from psychotic disorders, but the treatment response varies as well. Although antipsychotic drugs are the cornerstone of the treatment of schizophrenia, many patients only partially respond to these drugs. Furthermore, patients often experience adverse events which can lead to poor treatment adherence. Interindividual variability in drug response could be related to age, gender, ethnicity, lifestyle factors, pharmacological interactions, obesity, and genetics, all of which influence the process of drug metabolism. Commonly prescribed antipsychotics are metabolized by cytochrome P450 (CYP450) enzymes, and CYP450 genes are highly polymorphic. Pharmacogenetic testing is increasingly being used to predict a patient's drug response and could help to find the most appropriate therapy for an individual patient. In this report, we describe a psychotic patient who did not receive adequate clinical follow-up and subsequently presented adverse events, which could be explained by his pharmacogenetic profile and the drug interactions resulting from the polypharmacy prescribed.

Why African Americans say "No": A Study of Pharmacogenomic Research Participation

Objective

To identify reasons for nonparticipation by African Americans in cardiovascular pharmacogenomic research.

Design

Prospective, open-ended, qualitative survey.

Setting

Research staff approached patients eligible for the Discovery Project of The African American Cardiovascular pharmacogenomics CONsorTium in the inpatient or outpatient setting at four different institutions during September and October 2018.

Participants

Potential Discovery Project participants self-identified as African American, aged >18 years, were on one of five cardiovascular drugs of interest, and declined enrollment in the Discovery Project.

Main Outcome Measures

Reasons for nonparticipation.

Methods

After declining participation in the Discovery Project, patients were asked, "What are your reasons for not participating?" We analyzed their responses using a directed content analytic approach. Ultimately, responses were coded into one of nine categories and analyzed using descriptive statistics.

Results

Of the 194 people approached for the Discovery Project during an eight-week period, 82 declined participation and provided information for this study. The most common reason for refusal was concern about the amount of blood drawn (19.5%). The next most common reasons for refusal to participate included concerns about genetic testing (14.6%) and mistrust of research (12.2%). Across study sites, significantly more patients enrolled in the inpatient than outpatient setting (P<.001). Significantly more women and younger individuals declined participation due to concerns about genetic testing and too little compensation (P<.05).

Conclusions

Collection of blood samples and concerns about genetic testing are obstacles for the recruitment of African Americans to pharmacogenomics studies. Efforts to overcome these barriers to participation are needed to improve representation of minorities in pharmacogenomic research. Enrolling participants from inpatient populations may be a solution to bolster recruitment efforts.

International Society of Psychiatric Genetics Ethics Committee: Issues facing us

Psychiatric genetics research is improving our understanding of the biological underpinnings of neurodiversity and mental illness. Using psychiatric genetics in ways that maximize benefits and minimize harms to individuals and society depends largely on how the ethical, legal, and social implications (ELSI) of psychiatric genetics are managed. The International Society of Psychiatric Genetics (ISPG) is the largest international organization dedicated to psychiatric genetics. Given its history, membership, and international reach, we believe the ISPG is well-equipped to contribute to the resolution of these ELSI challenges. As such, we recently created the ISPG Ethics Committee, an interdisciplinary group comprised of psychiatric genetics researchers, clinical geneticists, genetic counselors, mental health professionals, patients, patient advocates, bioethicists, and lawyers. This article highlights key ELSI challenges identified by the ISPG Ethics Committee to be of paramount importance for the ethical translation of psychiatric research into society in three contexts: research settings, clinical settings, and legal proceedings. For each of these arenas, we identify and discuss pressing psychiatric genetics ELSI dilemmas that merit attention and require action. The goal is to increase awareness about psychiatric genetics ELSI issues and encourage dialogue and action among stakeholders.