The phenotype of adverse drug effects: Do emergency visits due to adverse drug reactions look different in older people? Results from the ADRED study

Influence of Ageing on the Pharmacodynamics and Pharmacokinetics of Chronically Administered Medicines in Geriatric Patients: A Review

As people age, the efficiency of various regulatory processes that ensure proper communication between cells and organs tends to decline. This deterioration can lead to difficulties in maintaining homeostasis during physiological stress. This includes but is not limited to cognitive impairments, functional difficulties, and issues related to caregivers which contribute significantly to medication errors and non-adherence. These factors can lead to higher morbidity, extended hospital stays, reduced quality of life, and even mortality. The decrease in homeostatic capacity varies among individuals, contributing to the greater variability observed in geriatric populations. Significant pharmacokinetic and pharmacodynamic alterations accompany ageing. Pharmacokinetic changes include decreased renal and hepatic clearance and an increased volume of distribution for lipid-soluble drugs, which prolong their elimination half-life. Pharmacodynamic changes typically involve increased sensitivity to various drug classes, such as anticoagulants, antidiabetic and psychotropic medications. This review examines the primary age-related physiological changes in geriatrics and their impact on the pharmacokinetics and pharmacodynamics of medications.

Serious gaming as potential training tool for recognition of adverse drug reactions: side-effect exposure-medical education (SeeMe)

PURPOSE

The recognition of adverse drug reactions (ADRs) is an important part of daily clinical work. However, medical education in this field is mostly drug-based and does not address adequately the complexity of this field regarding individual risk factors and polypharmacy. This study investigates the potential of the web-based serious game SeeMe (side-effect exposure-medical education) in pharmacological education of medical students to improve the recognition of relevant ADRs.

METHODS

One hundred fifty-seven medical students were recruited to evaluate the serious game SeeMe. SeeMe was developed to improve knowledge and recognition of ADRs in clinical practice. Players take on the role of a physician trying to understand fictional patients with ADRs. Before and after an 8-week playing period, an evaluation was carried out through a pre- and post-questionnaire and a pre- and post- knowledge test.

RESULTS

The students achieved significantly better results in the knowledge test, as almost twice as many exam-relevant questions were answered correctly (p < 0.001). The serious game had a positive effect on the students' perception of the importance of ADRs.

CONCLUSION

This study demonstrates the potential of web- and case-based fictional serious games in medical education. The improved recognition of side effects represents a crucial step for education and training in clinical pharmacology. Future versions of the serious game may take this further and focus on training in the treatment of ADRs and their relevance in various healthcare professions.

Interaction of age and CYP2C19 genotypes on voriconazole steady-state trough concentration in Chinese patients

OBJECTIVES

Both age and CYP2C19 genotypes affect voriconazole plasma concentration; the interaction of age and CYP2C19 genotypes on voriconazole plasma concentration remains unknown. This study aims to investigate the combined effects of age and CYP2C19 genotypes on voriconazole plasma concentration in Chinese patients.

METHODS

A total of 480 patients who received voriconazole treatment were recruited. CYP2C19*2 (rs4244285) and CYP2C19*3 (rs4986893) polymorphisms were genotyped. Patients were divided into the young and the elderly groups by age of 60 years old. Influence of CYP2C19 genotype on steady-state trough concentration (C ss-min ) in overall patients and in age subgroups was analyzed.

RESULTS

Voriconazole C ss-min correlated positively with age, and mean voriconazole C ss-min was significantly higher in the elderly group ( P  < 0.001). CYP2C19 poor metabolizers showed significantly increased mean voriconazole C ss-min in the young but not the elderly group. The percentage of patients with subtherapeutic voriconazole C ss-min (<1.0 mg/l) was higher in the young group and that of supratherapeutic voriconazole C ss-min (>5.5 mg/l) was higher in the elderly patients. When the average C ss-min in the CYP2C19 normal metabolizer genotype was regarded as a reference, CYP2C19 genotypes showed greater impact on voriconazole C ss-min in the young group, while the influence of age on voriconazole C ss-min exceeded CYP2C19 genotypes in the elderly.

CONCLUSION

CYP2C19 genotypes affects voriconazole exposure is age dependent. Influence of CYP2C19 poor metabolizer genotype on increased voriconazoleexposure is prominent in the young, while age is a more important determinant factor for increased voriconazole exposure in the elderly patients.

[Adverse drug reactions as cause of nonspecific symptoms in patients in the emergency department]

BACKGROUND

In a large proportion of patients admitted to the emergency department (ED), the initial main symptom is nonspecific. One possible reason for this, especially in older patients, may be adverse drug reactions (ADR) due to their frequent polypharmacy.

AIM

To illustrate the incidence of ADRs, the affected patient population including risk factors, and drug classes with ADRs leading to nonspecific symptoms. To provide practice recommendations for the management of ADRs in the ED.

MATERIAL AND METHODS

Presentation of the pharmacological principles on ADRs, statistics of pharmacovigilance centers as well as original literature including experiences from clinical practice and own projects.

RESULTS

In 10% of patients with nonspecific symptoms an ADR is responsible for presentation in the ED. In 60% of cases these ADRs are not correctly identified in the ED setting. A small number of drug classes are responsible for most of these referrals. Databases, risk stratification, clinical pharmacists, or clinical decision support systems are available to improve ADR identification and management. As these options are partly associated with considerable costs or the validation for German EDs is missing, a widespread application does not take place.

CONCLUSION

Correct identification of ADRs in patients with nonspecific symptoms in the ED is necessary to initiate adequate treatment. These ADRs are often overlooked because processes and tools for identification and management are not applied in the ED, leading to a lack of awareness. For high-risk patients in the ED, the focus should be on drug history, ideally considering patient-specific risk factors and specific drug classes.

Sharing Adverse Drug Event Reports Between Hospitals and Community Pharmacists to Inform Re-dispensing: An Analysis of Reports and Process Outcomes

INTRODUCTION

Adverse drug events (ADEs) are a leading cause of unplanned hospital visits. We designed ActionADE, an online ADE reporting platform, and integrated it with PharmaNet, British Columbia's (BC's) provincial medication dispensing system, to overcome identified barriers in ADE reporting and communicate ADEs to community pharmacies. Our objectives were to characterise ADEs reported in ActionADE, explore associations between patients' age, sex and ADE characteristics, and estimate the re-dispensation rate of culprit medications in community pharmacies.

METHODS

We conducted a prospective observational study of ADE reporting in four BC hospitals between April 1, 2020 and October 31, 2022. We described the characteristics of ADEs reported into ActionADE, used logistic regression modelling to examine associations between age and sex and ADE characteristics, and calculated rates of avoided culprit drug re-dispensations using community pharmacists' responses to ActionADE alerts.

RESULTS

In total, 3591 ADE reports were initiated by hospital clinicians, 3174 of which were included in this analysis. Serious or life-threatening ADEs resulting in permanent disability, hospitalisation, extended hospitalisation, and/or death accounted for 28.5% (906/3174; 95% CI 27.0-30.1%) of reports. Males were more likely to have non-adherence reported compared to females and experienced life threatening ADEs at a younger age than females. Of 592 patients who had ≥ 1 adverse drug reaction or allergy report (a subset of ADEs) transmitted to community pharmacies, 200 subsequently attempted to re-fill the culprit or a same class drug. Community pharmacists responded to preventative alerts by avoiding re-dispensation in 33.0% (66/200; 95% CI 26.5-39.5%).

INTERPRETATION

ActionADE is the first interoperable system that communicates ADEs via a central medication database to community pharmacies. Every 10th ADE reported in ActionADE and shared to PharmaNet resulted in community pharmacists' avoiding one culprit or same class drug re-exposure. Further research is needed to understand ActionADE's impact on patient and health system outcomes.

Diabetes management in older adults who fall: a study amongst older adults presenting to the emergency department

INTRODUCTION

Type 2 diabetes mellitus (T2D) is associated with poor health outcomes whilst tight glycaemic targets are questionable in those aged over 70 years with increased frailty. Our aim was to examine whether people with T2D admitted to hospital with a fall, were more likely to have greater frailty, increased mortality and co-morbidity burden, or risk factors for falls than people without T2D, and whether these differences were associated with medications used for the treatment of T2D.

METHODS

The Older Persons Assessment Service (OPAS) is a local emergency department (ED) service, which accepts patients on frailty criteria. The OPAS accepts patients primarily aged over 70 years who present with frailty and geriatric syndromes such as falls, with retrieval from the ED department directly to the service from triage. The OPAS databank was analysed for people with T2D admitted with a fall between June 2020-September 2022. We examined clinical outcomes relating to medication, age, Charlson co-morbidity index (CCI) and clinical frailty score (CFS).

RESULTS

1081 patients were included: 294 (27.2%) with T2D and a mean HbA1c of 53.9 (± 15.8) mmol/mol [7.1%]. People with T2D had a similar mean CFS and age compared to those without T2D, but higher mean CCI (7.0 ± 2.2 vs 5.9 ± 2.1, p < 0.001). Of those people with T2D, 175 (59.5%) and 240 (81.6%) had a HbA1c ≤ 53 mmol/mol [7.0%] and ≤ 64 mmol/mol [8.0%], respectively. In total, 48 (16.3%) people with T2D were identified to have a capillary blood glucose below 4.0 mmol/L on admission to the ED. At 12 months' follow-up, 831 (76.9%) patients were alive and 250 (23.1%) had died. People with T2D treated with insulin and/or gliclazide had a greater 1-year mortality (36.6% vs 23.6%, p < 0.05), greater frequency of hypoglycaemia (35.4% vs 11.8%, p < 0.001), and greater HbA1c (65.5 ± 17.2 mmol/mol [8.2] vs 48.9 ± 12.1 mmol/mol [6.6%]) compared to those who used other agents. Logistic regression confirmed a diagnosis of T2D was associated with 1-year mortality, but mortality was not significantly associated with hypoglycaemic-inducing agents. People with T2D were not more likely to live in deprived areas.

CONCLUSIONS

A diagnosis of T2D is associated with greater 1-year mortality, and may be influenced by use of hypoglycaemia-inducing diabetes medications. Clinician awareness can support de-prescribing for patients with frailty and HbA1c < 64 mmol/mol.

Adverse drug reactions in the ambulatory internal patients at the emergency department: Focus on causality assessment and drug-drug interactions

A non-interventional retrospective study in ambulatory patients was conducted at the emergency department of the Division of internal medicine. In 2 months, 266 suspected adverse drug reactions (ADRs) were identified in 224/3453 patients (6.5 %). In 158/3453 patients (4.6 %), an ADR was the reason for emergency department visit and in 49 patients (1.4 %), ADRs led to hospitalisation. A causality assessment algorithm was developed, which included Naranjo algorithm and levels of ADR recognition by the treating physician and the investigators. Using this algorithm, 63/266 ADRs (23.7 %) were classified as "certain", whereas using solely the Naranjo score calculation, only 19/266 ADRs (7.1 %) were assessed as "probable" or "certain", and the rest of ADRs (namely, 247/266 = 92.9 %) were assessed as "possible". There were 116/266 (43.6 %) ADRs related to potential drug-drug interactions (DDIs), stated in at least one of the literature sources used. Based on the causality relationship, the rate of the clinically expressed DDIs was 19.0 %, or 12/63 "certain" ADR cases. Of these, 10 cases presented serious DDI-related ADRs. In summary, ADR causality assessment based exclusively on Naranjo algorithm demonstrated low sensitivity at an ambulatory emergency setting. Additional clinical judgment, including the opinion of the treating physician, proved necessary to avoid under-rating of the causality relationship, and enabled the determination of clinically expressed DDIs.

Which Adverse Events and Which Drugs Are Implicated in Drug-Related Hospital Admissions? A Systematic Review and Meta-Analysis

Adverse drug events (ADEs) and adverse drug reactions (ADRs) are leading causes of iatrogenic injury, which can result in emergency department (ED) visits or admissions to inpatient wards. The aim of this systematic review and meta-analysis was to provide up-to-date estimates of the prevalence of (preventable) drug-related ED visits and hospital admissions, as well as the type and prevalence of implicated ADRs/ADEs and drugs. A literature search of studies published between January 2012 and December 2021 was performed in PubMed, Medline, EMBASE, Cochrane Library, and Web of Science. Retrospective and prospective observational studies investigating acute admissions to EDs or inpatient wards due to ADRs or ADEs in the general population were included. Meta-analyses of prevalence rates were conducted using generalized linear mixed models (GLMM) with the random-effect method. Seventeen studies reporting ADRs and/or ADEs were eligible for inclusion. The prevalence rates of ADR- and ADE-related admissions to EDs or inpatient wards were estimated at 8.3% ([95% CI, 6.4-10.7%]) and 13.9% ([95% CI, 8.1-22.8%]), respectively, of which almost half (ADRs: 44.7% [95% CI: 28.1; 62.4]) and more than two thirds (ADEs: 71.0% [95% CI, 65.9-75.6%]) had been classified as at least possibly preventable. The ADR categories most frequently implicated in ADR-related admissions were gastrointestinal disorders, electrolyte disturbances, bleeding events, and renal and urinary disorders. Nervous system drugs were found to be the most commonly implicated drug groups, followed by cardiovascular and antithrombotic agents. Our findings demonstrate that ADR-related admissions to EDs and inpatient wards still represent a major and often preventable health care problem. In comparison to previous systematic reviews, cardiovascular and antithrombotic drugs remain common causes of drug-related admissions, while nervous system drugs appear to have become more commonly implicated. These developments may be considered in future efforts to improve medication safety in primary care.

The effect of structured medication review followed by face-to-face feedback to prescribers on adverse drug events recognition and prevention in older inpatients - a multicenter interrupted time series study

Background

The effectiveness of interventions to improve medication safety in older inpatients is unclear, given a paucity of properly designed intervention studies applying clinically relevant endpoints such as hospital-acquired preventable Adverse Drug Events (pADEs) and unrecognized Adverse Drug Events (uADEs). Therefore, we conducted a quality improvement study and used hospital-acquired pADEs and uADEs as main outcomes to assess the effect of an intervention aimed to improve medication safety in older inpatients.

Method

The study followed an interrupted time series design and consisted of three equally spaced sampling points during baseline and during intervention measurements. Each sampling point included between 80 to 90 patients. A total of 500 inpatients ≥65 years and admitted to internal medicine wards of three Dutch hospitals were included. An expert team retrospectively identified and assessed ADEs via a structured patient chart review. The findings from baseline measurement and meetings with the internal medicine and hospital pharmacy staff were used to design the intervention. The intervention consisted of a structured medication review by hospital pharmacists, followed by face-to-face feedback to prescribers, on average 3 days per week.

Results

The rate of hospital-acquired pADEs per 100 hospitalizations was reduced by 50.6% (difference 16.8, 95% confidence interval (CI): 9.0 to 24.6, P <  0.001), serious hospital-acquired pADEs by 62.7% (difference 12.8, 95% CI: 6.4 to 19.2, P <  0.001), and uADEs by 51.8% (difference 11.2, 95% CI: 4.4 to 18.0, P <  0.001). Additional analyses confirmed the robustness of the intervention effect, but residual bias cannot be excluded.

Conclusions

The intervention significantly decreased the overall and serious hospital-acquired pADE occurrence in older inpatients, and significantly improved overall ADE recognition by prescribers.

Trial registration

International Standard Randomized Controlled Trial Number Register, trial registration number: ISRCTN64974377, registration date (date assigned): 07/02/2011.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12877-022-03118-z.

The Trigger Tool Method for Routine Pharmacovigilance: A Retrospective Cohort Study of the Medical Records of Hospitalized Geriatric Patients

OBJECTIVE

The main objective was to assess the feasibility of the trigger tool method for the retrospective detection of adverse drug reactions (ADRs) in the Rennes University Hospital. The secondary objective was to describe the performance of the method in terms of positive predictive values (PPVs) and severity or preventability of ADRs.

METHODS

Using the Rennes University Hospital clinical data warehouse, pharmacovigilance experts performed a retrospective review of a random sample of 30 inpatient hospital medical records per month using the triggers "fall" and "delirium" to identify related ADRs among patients 65 years and older in 2018 in the geriatrics department. Using the Z test, we compared the proportion of medical records with a positive (identified) trigger related to an ADR, which were reviewed within 20 minutes using the reference of 50% reviewed within 20 minutes.

RESULTS

Among the 355 medical records reviewed, 222 had at least 1 trigger and 98 at least 1 related ADR. Among the 222 positive trigger medical records, 99.6% were reviewed in under 20 minutes (P < 0.001). The pharmacovigilance assessment took 3 months. The PPVs reached 53.9% (46.0%-61.7%) for falls and 21.0% (14.3%-27.5%) for delirium. Among the ADRs, 80% were serious and 53% were preventable.

CONCLUSIONS

Given the low PPV of the triggers used and the considerable need for technical and human resources, the trigger tool method cannot be used as a routine tool at the pharmacovigilance center. However, it could be implemented occasionally for specific purposes such as monitoring the impact of risk minimization measures to prevent ADRs.

Role of medicines management in preventing falls in older people

Falls are common in older people and are a cause of preventable morbidity and mortality. As well as causing injury, falls can result in pain, distress, loss of confidence, loss of independence and increased mortality. Older people are more likely to visit an emergency department following a fall, therefore these incidents place a high burden on these patients and their carers, as well as on healthcare systems. Appropriate risk assessment accompanied by multifactorial falls prevention interventions can reduce the risk of falls. Assessments should include a medication review because various medicines, sometimes referred to as 'falls risk increasing drugs', can precipitate or contribute to falls. This article examines some of the medicines in this group that can contribute to falls, serious injuries and fractures in older people. It also discusses the importance of medicines management as part of falls risk assessment and prevention interventions.

[Current Challenges in Pharmacotherapy]

Analysis of preoperative medication is used to assess the benefit and risk associated with continuing or discontinuing medication before and during surgery. Identifying adverse drug reactions and assessing its risks often leads to uncertainty. Typical challenges are medication underuse, but also overuse occurs and is often more difficult to recognize, especially in the context of drug interactions and individual patient characteristics.Typical consequences of multi-medication and medical overuse may include an increased potential for drug interactions, an increased risk of adverse drug reactions and medication errors, and in particular in older adults, geriatric syndromes may occur or worsen. Adverse drug reactions may occur as a result of the dose administered and as an effect of time of exposure. Older, multi-morbid, and multi-medicated patients are often affected by adverse drug reactions. For drugs primarily metabolized via the phase I enzymes CYP2D6, CYP2C9, or CYP2C19, pharmacogenetically rapid or slow metabolism may result in altered drug exposures. Clinically relevant pharmacokinetic drug interactions frequently occur with drugs primarily metabolized via the phase I enzyme CYP3A4.

Individualized versus Standardized Risk Assessment in Patients at High Risk for Adverse Drug Reactions (The IDrug Randomized Controlled Trial)-Never Change a Running System?

The aim of this study was to compare effects of an individualized with a standardized risk assessment for adverse drug reactions to improve drug treatment with antithrombotic drugs in older adults. A randomized controlled trial was conducted in general practitioner (GP) offices. Patients aged 60 years and older, multi-morbid, taking antithrombotic drugs and at least one additional drug continuously were randomized to individualized and standardized risk assessment groups. Patients were followed up for nine months. A composite endpoint defined as at least one bleeding, thromboembolic event or death reported via a trigger list was used. Odds ratios (OR) and 95% confidence intervals (CI) were calculated. In total, N = 340 patients were enrolled from 43 GP offices. Patients in the individualized risk assessment group met the composite endpoint more often than in the standardized group (OR 1.63 [95%CI 1.02-2.63]) with multiple adjustments. The OR was higher in patients on phenprocoumon treatment (OR 1.99 [95%CI 1.05-3.76]), and not significant on DOAC treatment (OR 1.52 [95%CI 0.63-3.69]). Pharmacogenenetic variants of CYP2C9, 2C19 and VKORC1 were not observed to be associated with the composite endpoint. The results of this study may indicate that the time point for implementing individualized risk assessments is of importance.

CYP2D6 in the Brain: Potential Impact on Adverse Drug Reactions in the Central Nervous System-Results From the ADRED Study

Cytochrome P450 (CYP) 2D6 is a polymorphic enzyme expressed in the central nervous system (CNS), important in drug metabolism and with a potentially constitutive role in CNS function such as vigilance. This study aimed to analyze variability in CYP2D6 activity linked to vigilance-related adverse drug reactions (ADRs) in the CNS. A dataset of N = 2939 ADR cases of the prospective multicenter observational trial in emergency departments (EDs) (ADRED; trial registration: DRKS-ID: DRKS00008979) was analyzed. Dizziness as the most frequent reported CNS ADR symptom (12.7% of patients, n = 372) related to vigilance was chosen as the outcome. The association of dizziness with CYP2D6 activity markers was analyzed. The number of CYP2D6 substrates taken, a CYP2D6 saturation score (no, moderate, and strong saturation), a CYP2D6 saturation/inhibition score (no, weak, moderate, and strong), and composed CYP2D6 activity using a genotyped subsample (n = 740) calculating additive effects of genotype and CYP2D6 saturation by drug exposure were used as CYP2D6 activity markers. Effects were compared to other frequent nonvigilance-related CNS ADR symptoms (syncope and headache). Secondary analyses were conducted to control for other ADR symptoms frequently associated with dizziness (syncope, nausea, and falls). The majority of all patients (64.5%, n = 1895) took at least one drug metabolized by CYP2D6. Around a third took a CNS drug (32.5%, n = 955). The chance to present with drug-related dizziness to the ED increased with each CYP2D6 substrate taken by OR 1.11 [1.01–1.23]. Presenting with drug-related dizziness was more likely with CYP2D6 saturation and saturation/inhibition (both OR 1.27 [1.00–1.60]). The composed CYP2D6 activity was positively associated with dizziness (p = 0.028), while poorer activity affected patients more often with dizziness as an ADR. In contrast, nonvigilance-related ADR symptoms such as syncope and nausea were not consistently significantly associated with CYP2D6 activity markers. This study shows an association between the number of CYP2D6 substrates, the predicted CYP2D6 activity, and the occurrence of dizziness as a CNS ADR symptom. As dizziness is a vigilance-related CNS symptom, patients with low CYP2D6 activity might be more vulnerable to drug-related dizziness. This study underlines the need for understanding individual drug metabolism activity and individual risks for ADRs.

The phenotype of adverse drug effects: Do emergency visits due to adverse drug reactions look different in older people? Results from the ADRED study

AIMS

Older patients in particular suffer from adverse drug reactions (ADR) when presenting in the emergency department. We aimed to characterise the phenotype of those ADRs, to be able to recognise an ADR in older patients.

METHODS

Cases of ADRs in emergency departments collected within the multicentre prospective observational study (ADRED) were analysed (n = 2215). We analysed ADR-associated diagnoses, symptoms and their risk profiles. We present frequencies and odds ratios (OR) with 95% confidence intervals for adults (18-64 years) compared to older adults (≥65 years; young-old 65-79, old-old ≥80 years) and regression coefficients (B) for each year of age.

RESULTS

Most prominent differences were seen for drug-associated confusion, dehydration, and bradycardia (OR 6.70 [1.59-28.27], B .054; OR 6.02 [2.41-15.03], B .081, and 4.82 [2.21-10.54], B .040), more likely seen in older adults. Bleedings were reported in all age groups, but gastrointestinal bleedings occurred with more than doubled chance in older adults (OR 2.46 [1.77-3.41], B .030), likewise did other bleedings such as haemorrhage from respiratory passages (OR 2.89 [1.37-6.11], B.036). Falls were more likely in older adults (OR 2.84 [1.77-4.53], B .030), while dizziness was frequent in both age groups.

CONCLUSION

Our data point to differences in symptoms of ADRs between adults and older individuals, with dangerous drug-associated phenomena in the older adult such as bleedings or falls. Physicians should consider drug-associated origins of symptoms in older adults with an increased risk for serious health problems.

Adverse Drug Reactions in the Emergency Department: Is There a Role for Pharmacogenomic Profiles at Risk?-Results from the ADRED Study

Individual differences in required drug dosages exist based on the pharmacogenomic (PGx) profiles. This study aimed to assess associations between PGx profiles and adverse drug reactions (ADR) that lead to admissions to the emergency department (ED). ADR cases of the prospective multi-center observational trial in EDs (ADRED study) were analyzed (n = 776) together with the relevant PGx phenotypes of the enzymes CYP2D6, CYP2C19, CYP2C9, and VKORC1. Overall, the allele frequency distribution in this cohort did not differ from the population frequencies. We compared the frequencies of phenotypes in the subgroups with the drugs suspected of certain ADR, in the remaining cases. The frequency distribution of CYP2C19 differed for the ADR bleeding cases suspected of clopidogrel (p = 0.020). In a logistic regression analysis, higher CYP2C19 activity (OR (95% CI): 4.97 (1.73−14.27)), together with age (1.05 (1.02−1.08)), showed an impact on the clopidogrel-suspecting ADRs, when adjusting for the clinical parameters. There was a trend for an association of phenprocoumon-risk profiles (low VKORC1 or CYP2C9 activity) with phenprocoumon-suspecting ADRs (p = 0.052). The PGx impact on serious ADRs might be highest in drugs that cannot be easily monitored or those that do not provoke mild ADR symptoms very quickly. Therefore, patients that require the intake of those drugs with PGx variability such as clopidogrel, might benefit from PGx testing.