Suspected adverse drug events requiring emergency department visits or hospital admissions

A simplified similarity-based approach for drug-drug interaction prediction

Drug-drug interactions (DDIs) are a critical component of drug safety surveillance. Laboratory studies aimed at detecting DDIs are typically difficult, expensive, and time-consuming; therefore, developing in-silico methods is critical. Machine learning-based approaches for DDI prediction have been developed; however, in many cases, their ability to achieve high accuracy relies on data only available towards the end of the molecule lifecycle. Here, we propose a simple yet effective similarity-based method for preclinical DDI prediction where only the chemical structure is available. We test the model on new, unseen drugs. To focus on the preclinical problem setting, we conducted a retrospective analysis and tested the models on drugs that were added to a later version of the DrugBank database. We extend an existing method, adjacency matrix factorization with propagation (AMFP), to support unseen molecules by applying a new lookup mechanism to the drugs' chemical structure, lookup adjacency matrix factorization with propagation (LAMFP). We show that using an ensemble of different similarity measures improves the results. We also demonstrate that Chemprop, a message-passing neural network, can be used for DDI prediction. In computational experiments, LAMFP results in high accuracy, with an area under the receiver operating characteristic curve of 0.82 for interactions involving a new drug and an existing drug and for interactions involving only existing drugs. Moreover, LAMFP outperforms state-of-the-art, complex graph neural network DDI prediction methods.

Immunogenicity of Inactivated SARS-CoV-2 Vaccine (BBIBP-CorV; Sinopharm) and Short-Term Clinical Outcomes in Vaccinated Solid Organ Transplant Recipients: A Prospective Cohort Study

BackgroundImmunocompromised patients have lower seroconversion rate in response to COVID-19 vaccination. The aim of this study is to evaluate the humoral immune response with short-term clinical outcomes in solid organ transplant recipients vaccinated with SARS-CoV-2 vaccine (BBIBP-CorV; Sinopharm).MethodsThis prospective cohort was conducted from March to December 2021 in Abu Ali Sina hospital, Iran. All transplant recipients, older than 18 years were recruited. The patients received two doses of Sinopharm vaccine 4 weeks apart. Immunogenicity was evaluated through assessment of antibodies against the receptor-binding domain (RBD) of SARS-CoV-2 after the first and second dose of vaccine. The patients were followed up for 6 months after vaccination.ResultsOut of 921 transplant patients, 115 (12.5%) and 239 (26%) had acceptable anti S-RBD immunoglobulin G (IgG) levels after the first and second dose, respectively. Eighty patients (8.68%) got infected with COVID-19 which led to 45 (4.9%) of patients being hospitalized. None of the patients died during follow-up period. Twenty-four (10.9%) liver transplant recipients developed liver enzyme elevation, and increased serum creatinine was observed in 86 (13.5%) kidney transplant patients. Two patients experienced biopsy-proven rejection without any graft loss.ConclusionOur study revealed that humoral response rate of solid organ transplant recipients to Sinopharm vaccine was low.

Predicting drug characteristics using biomedical text embedding

BACKGROUND

Drug-drug interactions (DDIs) are preventable causes of medical injuries and often result in doctor and emergency room visits. Previous research demonstrates the effectiveness of using matrix completion approaches based on known drug interactions to predict unknown Drug-drug interactions. However, in the case of a new drug, where there is limited or no knowledge regarding the drug's existing interactions, such an approach is unsuitable, and other drug's preferences can be used to accurately predict new Drug-drug interactions.

METHODS

We propose adjacency biomedical text embedding (ABTE) to address this limitation by using a hybrid approach which combines known drugs' interactions and the drug's biomedical text embeddings to predict the DDIs of both new and well known drugs.

RESULTS

Our evaluation demonstrates the superiority of this approach compared to recently published DDI prediction models and matrix factorization-based approaches. Furthermore, we compared the use of different text embedding methods in ABTE, and found that the concept embedding approach, which involves biomedical information in the embedding process, provides the highest performance for this task. Additionally, we demonstrate the effectiveness of leveraging biomedical text embedding for additional drugs' biomedical prediction task by presenting text embedding's contribution to a multi-modal pregnancy drug safety classification.

CONCLUSION

Text and concept embeddings created by analyzing a domain-specific large-scale biomedical corpora can be used for predicting drug-related properties such as Drug-drug interactions and drug safety prediction. Prediction models based on the embeddings resulted in comparable results to hand-crafted features, however text embeddings do not require manual categorization or data collection and rely solely on the published literature.

Drug Interactions Affecting Antiarrhythmic Drug Use

Antiarrhythmic drugs (AAD) play an important role in the management of arrhythmias. Drug interactions involving AAD are common in clinical practice. As AADs have a narrow therapeutic window, both pharmacokinetic as well as pharmacodynamic interactions involving AAD can result in serious adverse drug reactions ranging from arrhythmia recurrence, failure of device-based therapy, and heart failure, to death. Pharmacokinetic drug interactions frequently involve the inhibition of key metabolic pathways, resulting in accumulation of a substrate drug. Additionally, over the past 2 decades, the P-gp (permeability glycoprotein) has been increasingly cited as a significant source of drug interactions. Pharmacodynamic drug interactions involving AADs commonly involve additive QT prolongation. Amiodarone, quinidine, and dofetilide are AADs with numerous and clinically significant drug interactions. Recent studies have also demonstrated increased morbidity and mortality with the use of digoxin and other AAD which interact with P-gp. QT prolongation is an important pharmacodynamic interaction involving mainly Vaughan-Williams class III AAD as many commonly used drug classes, such as macrolide antibiotics, fluoroquinolone antibiotics, antipsychotics, and antiemetics prolong the QT interval. Whenever possible, serious drug-drug interactions involving AAD should be avoided. If unavoidable, patients will require closer monitoring and the concomitant use of interacting agents should be minimized. Increasing awareness of drug interactions among clinicians will significantly improve patient safety for patients with arrhythmias.

On the road to explainable AI in drug-drug interactions prediction: a systematic review

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A systematic review on applications of explainable AI in drug-drug interaction prediction.

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Review is conducted on a comprehensive set of 94 papers from five prestigious databases.

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Discussions on the promises and challenges of explainable AI algorithms for drug-drug interaction prediction.

Over the past decade, polypharmacy instances have been common in multi-diseases treatment. However, unwanted drug-drug interactions (DDIs) that might cause unexpected adverse drug events (ADEs) in multiple regimens therapy remain a significant issue. Since artificial intelligence (AI) is ubiquitous today, many AI prediction models have been developed to predict DDIs to support clinicians in pharmacotherapy-related decisions. However, even though DDI prediction models have great potential for assisting physicians in polypharmacy decisions, there are still concerns regarding the reliability of AI models due to their black-box nature. Building AI models with explainable mechanisms can augment their transparency to address the above issue. Explainable AI (XAI) promotes safety and clarity by showing how decisions are made in AI models, especially in critical tasks like DDI predictions. In this review, a comprehensive overview of AI-based DDI prediction, including the publicly available source for AI-DDIs studies, the methods used in data manipulation and feature preprocessing, the XAI mechanisms to promote trust of AI, especially for critical tasks as DDIs prediction, the modeling methods, is provided. Limitations and the future directions of XAI in DDIs are also discussed.

Pharmacogenomics and circadian rhythms as mediators of cardiovascular drug-drug interactions

This article summarizes the current literature and documents new evidence concerning drug-drug interactions (DDI) stemming from pharmacogenomic and circadian rhythm determinants of therapies used to treat common cardiovascular diseases (CVD), such as atherosclerosis and hypertension. Patients with CVD often have more than one pathophysiologic condition, namely metabolic syndromes, hypertension, hyperlipidemia, and hyperglycemia, among others, which necessitate polytherapeutic or polypharmaceutic management. Interactions between drugs, drugs and food/food supplements, or drugs and genetic/epigenetic factors may have adverse impacts on the cardiovascular and other systems of the body. The mechanisms underlying cardiovascular DDI may involve the formation of a complex pharmacointeractome, including the absorption, distribution, metabolism, and elimination of drugs, which affect their respective bioavailability, efficacy, and/or harmful metabolites. The pharmacointeractome of cardiovascular drugs is likely operated with endogenous rhythms controlled by circadian clock genes. Basic and clinical investigations have improved the knowledge and understanding of cardiovascular pharmacogenomics and pharmacointeractomes, and additionally they have presented new evidence that the staging of deterministic circadian rhythms, according to the dosing time of drugs, e.g., upon awakening vs. at bedtime, cannot only differentially impact their pharmacokinetics and pharmacodynamics but also mediate agonistic/synergetic or antagonistic DDI. To properly manage CVD patients and avoid DDI, it is important that clinicians have sufficient knowledge of their multiple risk factors, i.e., age, gender, and life style elements (like diet, smoking, psychological stress, and alcohol consumption), and comorbidities, such as diabetes, hypertension, dyslipidemia, and depression, and the potential interactions between genetic or epigenetic background of their prescribed therapeutics.

Adverse Medication Events Related to Hospitalization in the United States: A Comparison Between Adults With Intellectual and Developmental Disabilities and Those Without

This study examined the proportion of hospitalizations associated with adverse medication events (AMEs) for adults with intellectual and developmental disabilities (IDD) and adults from the general population in the United States using the 2013 National Inpatient Sample (NIS) dataset of the Healthcare Cost and Utilization Project (HCUP). Adults with IDD had greater odds of having a hospitalization associated with an AME than the general adult population. Unadjusted odds ratios (95% CI) for hospitalization due to any medication for IDD was 2.47 (2.31-2.65). In the multivariate logistic regression model, IDD was significantly associated, with an odds ratio of 1.28 (1.19-1.38). Adults who have IDD are at greater risk of having a hospital admission due to an AME.

Drug Therapeutic Failures as a Cause of Admission to an Intensive Care Unit at a University Hospital

Objective

Drug therapeutic failures (TFs) are included in pharmacovigilance reporting, as some authors consider them a type of adverse drug reaction. Given their high frequency in Colombia, we studied their importance as a cause of admission to an intensive care unit (ICU).

Methods

This was a cross-sectional observational study. Clinical records of patients who arrived at the emergency service of a third-care level university hospital were reviewed. Information was collected by a resident in clinical toxicology, and each case was validated and analyzed by a research team using the algorithm proposed by Vaca González and Schumock and Thornton criteria for preventability to evaluate the existence of possible medication errors.

Findings

In total, 697 clinical records were evaluated and 18 patients presented TFs (2.6%, 95% confidence interval 1.5%-4.1%) as the cause of admission to the ICU. The most frequent TFs were seizures (56%) and hypertension (28%). The most commonly associated medications were valproic acid (28%) and losartan (28%). Ten cases (56%) were associated with drug misuse and the same number of cases was preventable, according to Schumock and Thornton criteria.

Conclusion

This is the first study assessing TFs as a cause of admission to the ICU in the Colombian population. The frequency of TFs in our study was similar to that described in the literature; being the most common cause the inappropriate drug use, particularly for drugs with complex kinetics, such as antiepileptic drugs.

Detecting drug-drug interactions using artificial neural networks and classic graph similarity measures

Drug-drug interactions are preventable causes of medical injuries and often result in doctor and emergency room visits. Computational techniques can be used to predict potential drug-drug interactions. We approach the drug-drug interaction prediction problem as a link prediction problem and present two novel methods for drug-drug interaction prediction based on artificial neural networks and factor propagation over graph nodes: adjacency matrix factorization (AMF) and adjacency matrix factorization with propagation (AMFP). We conduct a retrospective analysis by training our models on a previous release of the DrugBank database with 1,141 drugs and 45,296 drug-drug interactions and evaluate the results on a later version of DrugBank with 1,440 drugs and 248,146 drug-drug interactions. Additionally, we perform a holdout analysis using DrugBank. We report an area under the receiver operating characteristic curve score of 0.807 and 0.990 for the retrospective and holdout analyses respectively. Finally, we create an ensemble-based classifier using AMF, AMFP, and existing link prediction methods and obtain an area under the receiver operating characteristic curve of 0.814 and 0.991 for the retrospective and the holdout analyses. We demonstrate that AMF and AMFP provide state of the art results compared to existing methods and that the ensemble-based classifier improves the performance by combining various predictors. Additionally, we compare our methods with multi-source data-based predictors using cross-validation. In the multi-source data comparison, our methods outperform various ensembles created using 29 different predictors based on several data sources. These results suggest that AMF, AMFP, and the proposed ensemble-based classifier can provide important information during drug development and regarding drug prescription given only partial or noisy data. Additionally, the results indicate that the interaction network (known DDIs) is the most useful data source for identifying potential DDIs and that our methods take advantage of it better than the other methods investigated. The methods we present can also be used to solve other link prediction problems. Drug embeddings (compressed representations) created when training our models using the interaction network have been made public.

Characterization and preventability of adverse drug events as cause of emergency department visits: a prospective 1-year observational study

Background

Adverse drug events (ADEs) are a significant cause of emergency department (ED) visits, with a major impact on healthcare resource utilization. A multicentre observational study, aimed to describe frequency, seriousness and preventability of ADEs reported in four EDs, was performed in Sicily (Italy) over a 1-year period.

Methods

Two trained monitors for each ED supported clinicians in identifying ADEs of patients admitted to EDs between June 1st, 2013 and May 31st, 2014 through a systematic interview of patients or their caregivers and with an additional record review. A research team analyzed each case of suspected ADE, to make a causality assessment applying the Naranjo algorithm and a preventability assessment using Schumock and Thornton criteria.

Absolute and percentage frequencies with 95% confidence interval (CI) and medians with interquartile ranges (IQR) were estimated. Logistic regression models were used to evaluate independent predictors of serious and certainly preventable ADEs.

Results

Out of 16,963 ED visits, 575 (3.4%) were associated to ADEs, of which 15.1% resulted in hospitalization. ADEs were classified as probable in 45.9%, possible in 51.7% and definite in 2.4% of the cases. Moreover, ADEs were considered certainly preventable in 12.3%, probably preventable in 58.4%, and not preventable in 29.2% of the cases. Polytherapy influenced the risk to experience a serious, as well as a certainly preventable ADE. Whilst, older age resulted an independent predictor only of serious events. The most common implicated drug classes were antibiotics (34.4%) and anti-inflammatory drugs (22.6%). ADEs due to psycholeptics and antiepileptics resulted preventable in 62.7 and 54.5% of the cases, respectively. Allergic reactions (64%) were the most frequent cause of ADE-related ED visits, followed by neurological effects (10.2%) that resulted preventable in 1.9 and 37.3% of the cases, respectively.

Conclusion

ADEs are a frequent cause of ED visits. The commonly used antibiotics and anti-inflammatory drugs should be carefully managed, as they are widely involved in mild to severe ADEs. Polytherapy is associated with the occurrence of serious, as well as certainly preventable ADEs, while older age only with serious events. A greater sensitivity to drug monitoring programs among health professionals is needed.

Are drug-drug interactions a real clinical concern?

Aim:

Although drug-drug interactions (DDIs) cause major adverse drug reactions (ADRs) in patients under polypharmacy, the risk of some specific DDIs may be overrated in literature and different software. This study was conducted to determine the frequency and type of potential and clinically significant DDIs among inpatients admitted in a tertiary care hospital in South India.

Materials and Methods:

This longitudinal study was conducted for 30 days. Preformatted forms were used to collect data on the second day of admission. “Medscape Drug Interaction Checker” was used to evaluate and grade the DDIs. All the potential serious DDIs were intimated to the treating physicians and their responses in the prescriptions were noted. The same patients were followed up to evaluate the occurrence of any clinically significant DDIs.

Results:

A total of 763 drugs with 125 discrete types were prescribed in 155 patients with an average of 4.9 drugs per patient. One hundred and eight minor, 169 significant, and 24 serious potential DDIs were identified. Patient's age did not correlate, but number of drugs prescribed strongly correlated (P < 0.001) with the incidence of different types of DDIs. The prescription was modified in only 6 (25%) cases where potential serious DDIs were reported. Interestingly, no ADRs or impaired efficacy was observed due to the potential serious DDIs.

Conclusion:

There was a disparity between the potential and clinically relevant DDIs. Hence, clinical prudency is required before changing prescription due to potential DDIs reported by different software.

Determination of Potential Drug-Drug Interactions Using Various Software Programs in a Community Pharmacy Setting

Objectives

The aim of the present study was to compare various software programs in detecting potential drug-drug interactions in a community pharmacy setting.

Materials and Methods

Details of prescriptions were collected from 50 community pharmacies located in İstanbul in March and April 2015 (two days per week). From each pharmacy, the first 20 prescriptions that included more than one drug were collected to evaluate potential drug-drug interactions. The following software programs were utilized to detect potential drug-drug interactions: micromedexsolutions.com, medscape.com, and drugs.com. The number of potential interactions detected by the software programs was determined.

Results

At least one potential drug-drug interaction was detected in 39.2% of the 1000 prescriptions by one of the software programs. According to the rates of total drug-drug interactions gathered from various software programs, these programs gave the following results: medscape.com 33.3%, drugs.com 31.3%, and micromedexsolutions.com 21.2%.

Conclusion

After comparing different software programs, the potential drug-drug interactions found by the programs proved to be different. Therefore, we recommend that pharmacists confirm with a different program before making a decision when they detect clinically significant potential drug-drug interactions.

Drugs Can Harm

Adverse drug reaction is a major clinical problem. Many patients present to hospitals because of the drugs they take. Case history of four such patients seen at an Accident & Emergency department in Hong Kong over the last three months are presented. The definition, classification and clinical implication of adverse drug reaction are reviewed. Preventive strategies with reference to the local scenario are discussed.

Medication-related visits in a pediatric emergency department: an 8-years retrospective analysis

Background

There are limited data on the characterization of medication-related visits (MRVs) to the emergency department (ED) in pediatric patients in Italy. We have estimated the frequency, severity, and classification of MRVs to the ED in pediatric patients.

Methods

We retrospectively analyzed data for children seeking medical evaluation for a MRV over an 8 years period. A medication-related ED visit was identified by using a random pharmacist assessment, emergency physician assessment, and in case of conflicting events, by a third investigators random assessment.

Results

In this study, regarding a single tertiary center in Italy, on a total of 147,643 patients from 0 to 14 years old, 497 medication-related visits were found, 54% of which occurred in children from 0 to 2 years of age. Severity was classified as mild in 21.6% of cases, moderate in 67.2% of cases, and severe in 11.2% of cases. The most common events were related to drug use without indication (51%), adverse drug reactions (30.3%), supratherapeutic dosage (13.2%) and improper drug selection (4.5%).

The medication classes most frequently implicated in an ADE were anti-infective drugs for systemic use (28.9%), central nervous system agents (22.3%) and respiratory system drugs (10.8%).

The most common symptom manifestations were dermatologic conditions (46.1%), general disorder and administration site conditions (29.7%) and gastrointestinal symptoms (16.0%).

Conclusions

To our knowledge, this is the first study in Italy evaluating the epidemiologic characteristics of MRVs confirming a significant cause of healthcare contact resulting in ED visits and hospital admissions with associated resource utilization. Our results suggests further future prospective, large-sample sized, and multicenter research is necessary to better understand the impact of MRVs and to develop strategies to provide care plans and monitor patients to prevent medication-related visits.

Trial registration

Not applicable.

Hospital admissions due to adverse drug reactions in the elderly. A meta-analysis

INTRODUCTION

It is currently admitted that adverse drug reactions (ADRs) account for a great burden of disease. Of particular concern are ADR-induced hospital admissions, particularly in the elderly; they receive most of the medications and they are the most prone to develop ADRs. Therefore, our aim was to carry out a study of ADR-induced hospital admissions focused on the elderly population.

METHODS

For the purpose, a systematic review and meta-analysis was performed of those studies addressing ADR-induced hospital admissions in patients over 60 years of age. A computerized search of the literature was carried out in the main databases. The search spans from 1988 to 2015. A pooled prevalence figure was calculated with 95% CIs; heterogeneity was also explored.

RESULTS

The final number of selected articles was 42; all of them were published between January 1988 and August 2015. The overall average percentage of hospital admissions was 8.7% (95% CI, 7.6-9.8%). NSAIDs are one of the medication classes more frequently related to these admissions (percentages range from 2.3 to 33.3%). Inappropriate medication as a risk factor was studied in nine studies, four found a statistically significant relationship between those medications and hospital admissions.

CONCLUSIONS

Circa one in ten hospital admissions of older patients are due to ADRs. A great burden of disease is due to a few and identifiable medication classes; in most of the cases, the reactions are well known and probably preventable. A sense of purpose and determination is needed by health authorities to face this problem. Doctors, on their part, should be aware when prescribing some specific identifiable medications to these patients.

KEY POINTS

1. One in ten hospital admissions in older patients are due to ADRs; NSAIDs are the medications the most related with these admissions, followed by other common medications used in patients of this age, such as beta-blockers. 2. A great burden of disease is due to medications that are intended to cure or alleviate disease; this burden of disease is not only painful for the patients but also costly. 3. Identified risk factors are particular medication classes and polymedication. In most of the cases, reactions are probably preventable.

Potential drug-drug interactions among prescriptionsfor elderly patients in primary health care

BACKGROUND/AIM

Elderly patients are at high risk from drug-drug interactions (DDIs). This study evaluates the potential DDIs in Turkish elderly patients at a primary health care outpatient clinic.

MATERIALS AND METHODS

Online database systems were used to examine DDIs on the prescriptions of patients (n = 1206). The clinical severity of DDIs was classified by the Lexi-Interact Online database.

RESULTS

Of the 5059 prescriptions, 33% were found to have DDIs. We detected 29 (0.9%) A, 380 (11.8%) B, 2494 (77.7%) C, 289 (9%) D, and 18 (0.6%) X risk rating category DDIs among the prescriptions. Prescriptions of female patients and patients aged between 65 and 72 years showed significantly higher number of DDIs. The frequency of DDIs increased both with the number of drugs and combined preparations per prescription. Acetylsalicylic acid and salbutamol were the most frequently prescribed drugs contributing to clinically important DDIs. Additionally, acetylsalicylic acid and escitalopram, which interact with each other, were found on the list of Beers criteria. The most predicted clinical outcomes of DDIs were increase in therapeutic efficacy and adverse/toxic reactions. Conclusions: Prediction of DDIs in elderly patients will provide better prescribing and drug safety. Use of nonsteroidal anti-inflammatory agents, selective serotonin reuptake inhibitors, and beta-2 adrenergic receptor agonists should be closely monitored.

Drug-Related Visits to the Emergency Department

Over the past few years, several published reports have addressed the problem of drug-related morbidity in various practice settings. Studies evaluating drug-related hospitalization have estimated that approximately 5% to 10% of all hospital admissions are drug related. Unfortunately, many of these studies have excluded patients seeking medical attention in the emergency department (ED) but not requiring hospital admission. Drug-related visits to the emergency department are a significant problem and contribute to overall pressures on our current health care system. Despite the limited information published regarding drug-related ED visits, several studies describe the impact of this issue. The purpose of this article is to review the current literature pertaining to the incidence, classification, severity, preventability, and economic impact of drug-related visits to the emergency department.

P-glycoprotein mediated drug interactions in animals and humans with cancer

Drug–drug interactions can cause unanticipated patient morbidity and mortality. The consequences of drug–drug interactions can be especially severe when anticancer drugs are involved because of their narrow therapeutic index. Veterinary clinicians have traditionally been taught that drug–drug interactions result from alterations in drug metabolism, renal excretion or protein binding. More recently, drug–drug interactions resulting from inhibition of P‐glycoprotein‐mediated drug transport have been identified in both human and veterinary patients. Many drugs commonly used in veterinary patients are capable of inhibiting P‐glycoprotein function and thereby causing an interaction that results in severe chemotherapeutic drug toxicity. The intent of this review is to describe the mechanism and clinical implications of drug–drug interactions involving P‐glycoprotein and anticancer drugs. Equipped with this information, veterinarians can prevent serious drug–drug interactions by selecting alternate drugs or adjusting the dose of interacting drugs.

Number of drugs most frequently found to be independent risk factors for serious adverse reactions: a systematic literature review

In order to reduce the numbers of medication errors (MEs) that cause adverse reactions (ARs) many authors have tried to identify patient-related risk factors. However, the evidence remains controversial. The aim was to review systematically the evidence on the relationship between patient-related risk factors and the risk of serious ARs. A systematic search in Pubmed, Embase, Cochrane Systematic Reviews, Psychinfo and SweMed+ was performed. Included full text articles were hand searched for further references. Peer reviewed papers including adults from primary and secondary healthcare were included if they clearly defined seriousness of the ARs and described correlations to risk factors by statistical analysis. A total of 28 studies were identified including 85,212 patients with 3385 serious ARs, resulting in an overall frequency of serious ARs in 4% of patients. Age, gender and number of drugs were by far the most frequently investigated risk factors. The total number of drugs was the most consistent correlated risk factor found in both univariate and multivariate analyses. The number of drugs is the most frequently documented independent patient-related risk factor for serious ARs in both the general adult population as well as in the elderly. The existing evidence is however conflicting due to heterogeneity of populations and study methods. The knowledge of patient-related risk factors for experiencing ARs could be used for electronic risk stratification of patients and thereby allocation of healthcare resources to high risk patients.

Co-prescription trends in a large cohort of subjects predict substantial drug-drug interactions

Pharmaceutical prescribing and drug-drug interaction data underlie recommendations on drug combinations that should be avoided or closely monitored by prescribers. Because the number of patients taking multiple medications is increasing, a comprehensive view of prescribing patterns in patients is important to better assess real world pharmaceutical response and evaluate the potential for multi-drug interactions. We obtained self-reported prescription data from NHANES surveys between 1999 and 2010, and confirm the previously reported finding of increasing drug use in the elderly. We studied co-prescription drug trends by focusing on the 2009-2010 survey, which contains prescription data on 690 drugs used by 10,537 subjects. We found that medication profiles were unique for individuals aged 65 years or more, with ≥98 unique drug regimens encountered per 100 subjects taking 3 or more medications. When drugs were viewed by therapeutic class, it was found that the most commonly prescribed drugs were not the most commonly co-prescribed drugs for any of the 16 drug classes investigated. We cross-referenced these medication lists with drug interaction data from Drugs.com to evaluate the potential for drug interactions. The number of drug alerts rose proportionally with the number of co-prescribed medications, rising from 3.3 alerts for individuals prescribed 5 medications to 11.7 alerts for individuals prescribed 10 medications. We found 22% of elderly subjects taking both a substrate and inhibitor of a given cytochrome P450 enzyme, and 4% taking multiple inhibitors of the same enzyme simultaneously. By examining drug pairs prescribed in 0.1% of the population or more, we found low agreement between co-prescription rate and co-discussion in the literature. These data show that prescribing trends in treatment could drive a large extent of individual variability in drug response, and that current pairwise approaches to assessing drug-drug interactions may be inadequate for predicting real world outcomes.

Medication-related emergency department visits in pediatrics: a prospective observational study

BACKGROUND AND OBJECTIVE

There are few data on the rate and characterization of medication-related visits (MRVs) to the emergency department (ED) in pediatric patients. We sought to evaluate the frequency, severity, preventability, and classification of MRVs to the ED in pediatric patients.

METHODS

We performed a prospective observational study of pediatric patients presenting to the ED over a 12-month period. A medication-related ED visit was identified by using pharmacist assessment, emergency physician assessment, and an independent adjudication committee.

RESULTS

In this study, 2028 patients were enrolled (mean age, 6.1 ± 5.0 years; girls, 47.4%). An MRV was found in 163 patients (8.0%; 95% confidence interval [CI]: 7.0%-9.3%) of which 106 (65.0%; 95% CI: 57.2%-72.3%) were deemed preventable. Severity was classified as mild in 14 cases (8.6%; 95% CI: 4.8%-14.0%), moderate in 140 cases (85.9%; 95% CI: 79.6%-90.8%), and severe in 9 cases (5.5%; 95% CI: 2.6%-10.2%). The most common events were related to adverse drug reactions 26.4% (95% CI: 19.8%-33.8%), subtherapeutic dosage 19.0% (95% CI: 13.3%-25.9%), and nonadherence 17.2% (95% CI: 11.7%-23.9%). The probability of hospital admission was significantly higher among patients with an MRV compared with those without an MRV (odds ratio, 6.5; 95% CI: 4.3-9.6) and, if admitted, the median (interquartile range) length of stay was longer (3.0 [5.0] days vs 1.5 [2.5] days, P = .02).

CONCLUSIONS

A medication-related cause was found in ∼1 of every 12 ED visits by pediatric patients, of which two-thirds were deemed preventable. Pediatric patients who present to the ED with an MRV are more likely to be admitted to hospital and when admitted have a longer length of stay.

Seriousness, preventability, and burden impact of reported adverse drug reactions in Lombardy emergency departments: a retrospective 2-year characterization

Objective

The purpose of this study was to determine the prevalence of adverse drug reactions (ADRs) reported in emergency departments (EDs) and carry out a thorough characterization of these to assess preventability, seriousness that required hospitalization, subsequent 30-day mortality, and economic burden.

Methods

This was a retrospective cohort study of data from an active pharmacovigilance project at 32 EDs in the Lombardy region collected between January 1, 2010 and December 31, 2011. Demographic, clinical, and pharmacological data on patients admitted to EDs were collected by trained and qualified monitors, and deterministic record linkage was performed to estimate hospitalizations. Pharmacoeconomic analyses were based on Diagnosis-Related Group reimbursement.

Results

8,862 ADRs collected with an overall prevalence rate of 3.5 per 1,000 visits. Of all ADRs, 42% were probably/definitely preventable and 46.4% were serious, 15% required hospitalization, and 1.5% resulted in death. The System Organ Classes most frequently associated with ADRs were: skin and subcutaneous tissue, gastrointestinal, respiratory thoracic and mediastinal, and nervous system disorders. The most common Anatomical Therapeutic Chemical classes involved in admissions were J (anti-infectives and immunomodulating agents), B (blood and blood-forming organs), and N (nervous system). Older age, yellow and red triage, higher number of concomitantly taken drugs, and previous attendance in ED for the same ADR were significantly associated with an increased risk of hospitalization. The total cost associated with ADR management was €5,184,270, with a mean cost per patient of €585. Fifty-eight percent of the economic burden was defined as probably/definitely preventable.

Conclusion

ADRs are a serious health/economic issue in EDs. This assessment provides a thorough estimation of their seriousness, preventability, and burden impact in a large population from a representative European region.

Prevalence, nature and potential preventability of adverse drug events - a population-based medical record study of 4970 adults

AIMS

To estimate the 3 month prevalence of adverse drug events (ADEs), categories of ADEs and preventable ADEs, and the preventability of ADEs among adults in Sweden. Further, to identify drug classes and organ systems associated with ADEs and estimate their seriousness.

METHODS

A random sample of 5025 adults in a Swedish county council in 2008 was drawn from the Total Population Register. All their medical records in 29 inpatient care departments in three hospitals, 110 specialized outpatient clinics and 51 primary care units were reviewed retrospectively in a stepwise manner, and complemented with register data on dispensed drugs. ADEs, including adverse drug reactions (ADRs), sub-therapeutic effects of drug therapy (STEs), drug dependence and abuse, drug intoxications from overdose, and morbidities due to drug-related untreated indication, were detected during a 3 month study period, and assessed for preventability.

RESULTS

Among 4970 included individuals, the prevalence of ADEs was 12.0% (95% confidence interval (CI) 11.1, 12.9%), and preventable ADEs 5.6% (95% CI 5.0, 6.2%). ADRs (6.9%; 95% CI 6.2, 7.6%) and STEs (6.4%; 95% CI 5.8, 7.1%) were more prevalent than the other ADEs. Of the ADEs, 38.8% (95% CI 35.8-41.9%) was preventable, varying by ADE category and seriousness. ADEs were frequently associated with nervous system and cardiovascular drugs, but the associated drugs and affected organs varied by ADE category.

CONCLUSIONS

The considerable burden of ADEs and preventable ADEs from commonly used drugs across care settings warrants large-scale efforts to redesign safer, higher quality healthcare systems. The heterogeneous nature of the ADE categories should be considered in research and clinical practice for preventing, detecting and mitigating ADEs.

Hospital admissions caused by adverse drug events: an Australian prospective study

OBJECTIVE

To assess the frequency of adverse drug event (ADE)-related admissions (ADE-RAs) during a prospective medical record review of patients admitted to a metropolitan tertiary referral hospital.

METHODS

Potential ADE-RA cases were identified by examination of case records of randomly selected patients. Cases were assessed by an expert panel to measure study outcomes, which were the frequency (ADEs and ADE-RAs) as well as type, likelihood of causality, severity, avoidability and detection of ADEs.

RESULTS

Of the 370 subjects, 59 (16.0%) had a confirmed ADE-RA, with 15 (4.1%) of these serious and preventable. The 59 ADE-RAs were a result of 72 discreet ADEs. Adverse drug reactions were the most common type of ADE, followed by non-compliance. Of the 72 discreet ADEs, 31.9% were classified as 'probable' or 'highly probable'. Most ADEs (54.2%) were classified as 'definitely avoidable', 34.7% were classified as 'severe' and 21.8% were classified as both 'definitely avoidable' and 'severe'. Half the ADEs were detected after the patient had been admitted and most were detected by medical practitioners. Antineoplastics followed by antidiabetic agents were most frequently implicated.

CONCLUSIONS

Implementing a systems approach that involves multiple strategies, such as improving tertiary-to-primary care information transfer and promoting medication adherence through education programs, is necessary to tackle the problem of avoidable ADE-RAs and the associated cost burden. WHAT IS KNOWN ABOUT THE TOPIC? It is estimated that 2-3% of Australian hospital admissions are due to adverse drug events (ADEs), but recent data are lacking. According to the Australian Statistics on Medicines, over 250 million prescriptions were dispensed in 2007, compared with just under 180 million in 1997. This 40% increase in drug utilisation over the 10 years surpasses the Australian population growth of 14% in the same period. An increase in drug use per person indicates that the rate of ADEs and possible ADE-related admissions (ADE-RAs) is likely to have increased. WHAT DOES THIS PAPER ADD? This prospective study was conducted at a large Australian metropolitan teaching hospital and we report that 59 of 370 participants (16.0%) presenting to the Emergency Department had a confirmed ADE-RA, with 15 (4.1%) presenting with a serious and preventable ADE-RA. WHAT ARE THE IMPLICATIONS FOR PRACTITIONERS? The findings of this study support implementing a systems approach involving multiple strategies to tackle the problem of avoidable ADE-RAs and the associated cost burden. This study reveals that half the ADEs were not detected until after the admission process, which reinforces the importance of focusing efforts towards preventing ADE-RAs and detecting ADE-RAs through measures such as those recommended in the Australian Pharmaceutical Advisory Council guiding principles.

Prevalence and perceived preventability of self-reported adverse drug events--a population-based survey of 7099 adults

Purpose

Adverse drug events (ADEs) are common and often preventable among inpatients, but self-reported ADEs have not been investigated in a representative sample of the general public. The objectives of this study were to estimate the 1-month prevalence of self-reported ADEs among the adult general public, and the perceived preventability of 2 ADE categories: adverse drug reactions (ADRs) and sub-therapeutic effects (STEs).

Methods

In this cross-sectional study, a postal survey was sent in October 2010 to a random sample of 13 931 Swedish residents aged ≥18 years. Self-reported ADEs experienced during the past month included ADRs, STEs, drug dependence, drug intoxications and morbidity due to drug-related untreated indication. ADEs could be associated with prescription, non-prescription or herbal drugs. The respondents estimated whether ADRs and STEs could have been prevented. ADE prevalences in age groups (18–44, 45–64, or ≥65 years) were compared.

Results

Of 7099 respondents (response rate 51.0%), ADEs were reported by 19.4% (95% confidence interval, 18.5–20.3%), and the prevalence did not differ by age group (p>0.05). The prevalences of self-reported ADRs, STEs, and morbidities due to drug-related untreated indications were 7.8% (7.2–8.4%), 7.6% (7.0–8.2%) and 8.1% (7.5–8.7%), respectively. The prevalence of self-reported drug dependence was 2.2% (1.9–2.6%), and drug intoxications 0.2% (0.1–0.3%). The respondents considered 19.2% (14.8–23.6%) of ADRs and STEs preventable. Although reported drugs varied between ADE categories, most ADEs were attributable to commonly dispensed drugs. Drugs reported for all and preventable events were similar.

Conclusions

One-fifth of the adult general public across age groups reported ADEs during the past month, indicating a need for prevention strategies beyond hospitalised patients. For this, the underlying causes of ADEs should increasingly be investigated. The high burden of ADEs and preventable ADEs from widely used drugs across care settings supports redesigning a safer healthcare system to adequately tackle the problem.

Medication-related emergency department visits and hospital admissions in pediatric patients: a qualitative systematic review

OBJECTIVE

To review and describe the current literature pertaining to the incidence, classification, severity, preventability, and impact of medication-related emergency department (ED) and hospital admissions in pediatric patients.

STUDY DESIGN

A systematic search of PubMED, Embase, and Web of Science was performed using the following terms: drug toxicity, adverse drug event, medication error, emergency department, ambulatory care, and outpatient clinic. Additional articles were identified by a manual search of cited references. English language, full-reports of pediatric (≤18 years) patients that required an ED visit or hospital admission secondary to an adverse drug event (ADE) were included.

RESULTS

We included 11 studies that reported medication-related ED visit or hospital admission in pediatric patients. Incidence of medication-related ED visits and hospital admissions ranged from 0.5%-3.3% and 0.16%-4.3%, respectively, of which 20.3%-66.7% were deemed preventable. Among ED visits, 5.1%-22.1% of patients were admitted to hospital, with a length of stay of 24-72 hours. The majority of ADEs were deemed moderate in severity. Types of ADEs included adverse drug reactions, allergic reactions, overdose, medication use with no indication, wrong drug prescribed, and patient not receiving a drug for an indication. Common causative agents included respiratory drugs, antimicrobials, central nervous system drugs, analgesics, hormones, cardiovascular drugs, and vaccines.

CONCLUSION

Medication-related ED visits and hospital admissions are common in pediatric patients, many of which are preventable. These ADEs result in significant healthcare utilization.

Risk factors for hospital admissions associated with adverse drug events

STUDY OBJECTIVE

To identify predictors of hospital admissions associated with adverse drug events (ADEs) and to determine the preventability of ADEs in patients admitted to two hospitals.

DESIGN

Prospective observational study.

SETTING

Medical admission units at two British National Health Service hospitals in the United Kingdom.

PATIENTS

3904 adults age 16 years or older who were admitted to the two hospitals between June 2006 and November 2007.

MEASUREMENTS AND MAIN RESULTS

Clinical pharmacists identified hospital admissions associated with drug-related problems by using medical record review, supplemented by patient interview for those identified as having an ADE. The contribution of ADEs to hospital admission and the causality, severity, and preventability of the events were independently assessed by a multidisciplinary clinical team. Multivariate logistic regression was used to identify predictors of hospital admissions associated with ADEs, and a maximum-likelihood multinomial model was used to examine predictors of the preventability of ADEs. Of the 3904 patients included in the analysis, 439 (11.2%) were judged by the review panel to have experienced ADEs. Of these, 209 patients (47.6%) experienced preventable ADEs. Four independent variables were found to have significant relationships with ADE admissions and preventability of ADEs: patient age, length of time since starting new drug, total number of prescription drugs, and hospital site. Drug classes most commonly associated with preventable ADEs were antiplatelet drugs, anticoagulants, diuretics (loop and thiazide diuretics), angiotensin-converting enzyme inhibitors, and antiepileptic drugs.

CONCLUSION

Adverse drug events are an important cause of hospital admission. Better systems for health care practitioners to identify patients at high risk of preventable hospital admissions associated with ADEs (e.g., age > 65 years old, receiving more than five drugs, and starting new high-risk drugs) should be implemented in order to minimize the risks to patients and the burden on the health care system.

Prevalence and associations of potentially inappropriate prescriptions in Austrian nursing home residents: secondary analysis of a cross-sectional study

BACKGROUND

Potentially inappropriate prescriptions (PIP) are an important cause of adverse medication-related events and increases morbidity, hospitalization, and health care costs, especially in nursing home residents. However, little is known about the associations between PIP and residents' characteristics.

OBJECTIVE

The aim of our study was to analyse the prevalence and associations of PIP with residents' and facilities' characteristics.

METHODS

We performed a secondary analysis of a cross-sectional study with 48 out of 50 eligible nursing homes and 1,844 out of 2,005 eligible residents in a defined rural-urban area in Austria. The Austrian list of potentially inappropriate medications was applied for the evaluation of inappropriate prescribing. Cluster-adjusted multiple regression analysis was used to investigate institutional and residents' characteristics associated with PIP.

RESULTS

Mean cluster-adjusted prevalence of residents with at least one PIP was 70.3 % (95 % CI 67.2-73.4). The number of residents with at least one psychotropic PIP was 1.014 (55 %). The most often prescribed PIP were Prothipendyl (25.9 % residents), Lorazepam (14.5 %) and Diclofenac (6.1 %). Multiple regression analysis showed an inverse association of PIP with cognitive impairment and significant positive associations with permanent restlessness and permanent negative attitude. The associations of PIP with age and male gender were inconsistent. No significant associations were found for PIP and the ratio of staff nurses to residents.

CONCLUSIONS

Our study results confirm that PIP is highly prevalent in the nursing home population. These results urgently call for effective interventions. Initiatives and successful interventions performed in other countries could serve as examples for safer prescribing in residents in Austria.

Impact of pharmacist discharge medication therapy counseling and disease state education: Pharmacist Assisting at Routine Medical Discharge (project PhARMD)

Many patients experience adverse events after discharge; numerous are medication related and preventable. The objective of this study is to evaluate the impact of pharmacist medication counseling and disease education at discharge. Pharmacist Assisting at Routine Medical Discharge is a prospective study of English- or Spanish-speaking adults discharged from internal medicine. Control patients received usual hospital discharge care; intervention patients received usual care with discharge counseling and a follow-up phone call. Evaluated outcomes included the following: 30-day hospital reutilization (combined readmissions/emergency department visits), pharmacist interventions, predictors for hospital utilization, patient satisfaction, and primary medication adherence. In all, 279 patients were enrolled: 139 in the control and 140 in the intervention group. Pharmacists made 198 interventions. The rate of hospital reutilization was 20.7% and similar between the intervention and control groups. Patients receiving the pharmacist intervention demonstrated improved primary medication adherence and increased patient satisfaction. Pharmacist-provided discharge counseling resulted in medication interventions, improved patient satisfaction, and increased medication adherence.

Prevalence of drug interactions in hospital healthcare

AIM OF THE REVIEW

To study the prevalence of drug interactions in hospital healthcare by reviewing literature.

METHOD

A review was carried out of studies written in Spanish and English on the prevalence of drug interactions in hospital care published in Pubmed between January 1990 and September 2008. The search strategy combined free text and MeSH terms, using the following keywords: "Drug interaction", "prevalence" and "hospital". For each article, we classified independent variables (pathology, age of population, whether patients were hospitalized or not, geographical location, etc.) and dependent variables (number of interactions per 100 patients studied, prevalence of patients with interactions, most common drug interactions, and others).

RESULTS

The search generated 436 articles. Finally, 47 articles were selected for the study, 3 provided results about drug interactions with real clinical consequences, 42 about potential interactions, and 2 described both. The prevalence of patients with interactions was between 15 and 45 % and the number of interactions per 100 patients was between 37 and 106, depending on the group of studies analyzed. There was a considerable increase in these rates in patients with heart diseases and elderly persons.

CONCLUSION

There is a large number of studies on the prevalence of drug interactions in hospitals but they report widely varying results. The prevalence is higher in patients with heart diseases and elderly people.

Costs of adverse drug events in German hospitals--a microcosting study

OBJECTIVE

In Germany, only limited data are available to quantify the attributable resource utilization associated with adverse drug events (ADEs). The aim of this study was twofold: first, to calculate the direct treatment costs associated with ADEs leading to hospitalization and, second, to derive the excess costs and extra hospital days attributable to ADEs of inpatient treatments in selected German hospitals.

METHODS

This was a retrospective and medical record-based study performed from the hospitals' perspective based on administrative accounting data from three hospitals (49,462 patients) in Germany. Total treatment costs ("analysis 1") and excess costs (i.e., incremental resource utilization) between patients suffering from an ADE and those without ADEs were calculated by means of a propensity score-based matching algorithm ("analysis 2").

RESULTS

Mean treatment costs ("analysis 1") of ADEs leading to hospitalization (n = 564) were €1,978 ± 2,036 (range €191-18,147; median €1,446; €843-2,480 [Q1-Q3]). In analysis 2, the mean costs of inpatients suffering from an ADE (n = 1,891) as a concomitant disease or complication (€5,113 ± 10,059; range €179-246,288; median €2,701; €1,636-5,111 [Q1-Q3]) were significantly higher (€970; P < 0.0001) than those of non-ADE inpatients (€4,143 ± 6,968; range €154-148,479; median €2,387; €1,432-4,701 [Q1-Q3]). Mean inpatient length of stay of ADE patients (12.7 ± 17.2 days) and non-ADE patients (9.8 ± 11.6 days) differed by 2.9 days (P < 0.0001). A nationwide extrapolation resulted in annual total treatment costs of €1.058 billion.

CONCLUSIONS

This is one of the first administrative data-based analyses calculating the economic consequences of ADEs in Germany. Further efforts are necessary to improve pharmacotherapy and relieve health care payers of preventable treatment costs.

Evaluation of Medication-Related Problems in Medication Reviews: A Comparative Perspective

BACKGROUND:

The elderly population is at a high risk of medication misadventure, with many studies reporting a high number of medication-related problems (MRPs) in this group.

OBJECTIVE:

To quantify MRPs in residential facilities routinely reviewed by pharmacists and compare these results with other published findings.

METHODS:

This cross-sectional study included deidentified residents' health and medication data from 6 aged-care facilities. Regular medication reviews had been conducted over 20 years in these facilities. Two hundred ninety-six pharmacist intervention report forms were completed by 3 accredited clinical pharmacists over a 2-year period. These data were then used as a baseline in analyzing other published data for residential aged-care facilities and for patients at home.

RESULTS:

A total of 802 (range 0-12 per review) MRPs were identified in patients who were prescribed 2-29 medicines per patient, with a mean of 2.7 MRPs per review (95% CI 2.43 to 2.98). An analysis of the literature showed that the length of treatment, inclusion criteria used, and the definition of MRPs greatly affected the results obtained. However, application of the different inclusion criteria used in other published studies to our data resulted in findings similar to the published Australian average for residents of aged-care facilities and patients living independently at home (3.9 and 4.8 MRPs per patient, respectively).

CONCLUSIONS:

All medicines can potentially lead to MRPs. MRPs identified during pharmacist medication reviews vary widely between studies but can be normalized by inclusion criteria, length of stay, and the nature of the identified problem. It is recommended that a minimum benchmark for best practice in a patient population receiving at least yearly reviews be less than 3 MRPs per patient. Higher benchmarks of 4 MRPs per patient should apply when the patient population is restricted to include those receiving more than 9 medications and with more than 2 MRPs.

Adverse drug reactions caused by drug-drug interactions reported to Croatian Agency for Medicinal Products and Medical Devices: a retrospective observational study

Aim

To analyze potential and actual drug-drug interactions reported to the Spontaneous Reporting Database of the Croatian Agency for Medicinal Products and Medical Devices (HALMED) and determine their incidence.

Methods

In this retrospective observational study performed from March 2005 to December 2008, we detected potential and actual drug-drug interactions using interaction programs and analyzed them.

Results

HALMED received 1209 reports involving at least two drugs. There were 468 (38.7%) reports on potential drug-drug interactions, 94 of which (7.8% of total reports) were actual drug-drug interactions. Among actual drug-drug interaction reports, the proportion of serious adverse drug reactions (53 out of 94) and the number of drugs (n = 4) was significantly higher (P < 0.001) than among the remaining reports (580 out of 1982; n = 2, respectively). Actual drug-drug interactions most frequently involved nervous system agents (34.0%), and interactions caused by antiplatelet, anticoagulant, and non-steroidal anti-inflammatory drugs were in most cases serious. In only 12 out of 94 reports, actual drug-drug interactions were recognized by the reporter.

Conclusion

The study confirmed that the Spontaneous Reporting Database was a valuable resource for detecting actual drug-drug interactions. Also, it identified drugs leading to serious adverse drug reactions and deaths, thus indicating the areas which should be in the focus of health care education.

Prospective observational evaluation of incidences and implications of drug-drug interactions induced adverse drug reactions in critically ill patients

The primary aim of this study is to identify and analyze the importance of adverse drug reaction due to drug-drug interaction as a contributing factor towards drug safety. Patients more than 18 years of age admitted in multidisciplinary intensive care unit of a tertiary care hospital were included in this study. Patients who stayed less than 48 h and patients in whom all treatment modalities have been withdrawn and were on comfort measures only (no drugs were prescribed), were excluded. All the drugs that were given during intensive care unit stay were checked for presence of potential interactions which led to adverse drug reaction. Drug-drug interactions that were detected clinically or through investigations were recorded and also any therapeutic actions taken for drug-drug interactions were noted. From June 2006 to April 2007, 400 patients-prescriptions were analyzed. Adverse drug reactions due to drug-drug interactions were identified in 64% patients. Among those patients 38.67% had a single drug-drug interaction. Potential drug-drug interactions were 602. Clinically significant drug-drug interactions among the potential were 208 (34.55%). Clinically relevant drug-drug interactions were 103 (49.52% of 208 episodes). The adverse drug reactions due to drug-drug interactions in our sample were managed either by substituting another drug (50.48% of 103 episodes) or by adjusting the dose (1% of 103 episodes) or by omitting the drug (48.54% of 103 episodes). Among the 208 observed drug-drug interactions induced adverse drug reactions 21.63% was severe drug-drug interactions induced adverse drug reactions, 23.08% was moderate drug-drug interactions induced adverse drug reactions and 55.29% was minor drug-drug interactions induced adverse drug reactions. The interactions which were life threatening and/ or require medical intervention to minimize or prevent serious adverse effects were considered as severe drug-drug interactions and those interaction which resulted in an exacerbation of the patient's condition and/ or require an alteration in therapy were considered as moderate drug-drug interactions. The interactions which were limited clinical effects and manifestations may include an increase in the frequency or severity of side effects but generally would not require a major alteration in therapy were classified as minor drug-drug interactions. The correlation coefficient was 0.86 between the number of drugs given to the patient & number of average potential adverse drug reactions found among the patients. Increase in number of prescribed drug significantly (one way) increases number of potential adverse drug reaction due to drug-drug interaction (p<0.0001). Critically ill patients are more susceptible to drug-drug interactions due to the administration of multiple drugs and complex drug combinations. Several drug-drug interactions were clinically irrelevant.

Epidemiology and characteristics of adverse drug reactions caused by drug-drug interactions

INTRODUCTION

Drug-drug interactions (DDIs) arise in numerous different ways, involving pharmacokinetic or pharmacodynamic mechanisms. Adverse drug reactions are a possible consequence of DDIs and health operators are often unaware of the clinical risks of certain drug combinations. Many papers on drug interactions have been published in recent years, but most of them focused on potential DDIs while few studies have been conducted on actual interactions.

AREAS COVERED

This paper reviews the epidemiology of actual DDIs in outpatients as well as in hospital settings and in spontaneous reporting databases. The incidence of actual DDIs is consistently lower than that of potential DDIs. However, the absolute number of patients involved is high, representing a significant proportion of adverse drug reactions. The importance of risk factors such as age, polypharmacy and genetic polymorphisms is also evaluated. The relevance and efficacy of tools for recognizing and preventing DDIs are discussed.

EXPERT OPINION

Potential DDIs far outnumber actual drug interactions. The potential for an adverse interaction to occur is often theoretical, and clinically important adverse effects occur only in the presence of specific risk factors. Several studies have shown the efficacy of computers in early detection of DDIs. However, a correct risk-benefit evaluation by the prescribing physician, together with a careful clinical, physiological and biochemical monitoring of patients, is essential. Future directions of drug interaction research include the increasing importance of pharmacogenetics in preventing DDIs and the evaluation of interactions with biological drugs.

[Pharmacotherapy negative outcomes resulting in Primary Care Emergency visits]

OBJECTIVE

Our aim was to estimate the prevalence of Pharmacotherapy negative outcomes in Primary Care Emergency visits in a rural environment, and to determine their preventability and severity.

DESIGN

Descriptive study with an analytical component. SITE: Primary Care Emergency Service (SUAP), Mula. Murcia.

PATIENTS

The study consisted of 330 patients over a 33 week period.

METHOD

Number and type of Pharmacotherapy negative outcomes: Pharmacist through the data, a validated questionnaire and medical history, assessing whether there was a relationship between the medications and the patient, and the reason for going to the Primary Care Emergency. In case of suspicion of Pharmacotherapy negative outcomes the patient is reassessed by the doctor, and the Pharmacotherapy negative outcomes confirmed or not identified.

RESULTS

Of the 330 patients, 317 were evaluable. The mean age of patients was 39.63 years and 51.42% were women. The mean number of drugs used was 1.38, and 26.50% (95% CI, 21.94% -31.62%) patients were detected with Pharmacotherapy negative outcomes as a cause of visiting the Primary Care Emergency. 53.57% of the detected Pharmacotherapy negative outcomes detected as regards efficacy was 53.75%, 40.48% as regards need. More than three-quarters (77.41%; 95% CI, 67.35% -85.01%) of emergency visits caused by Pharmacotherapy negative outcomes were avoidable. In terms of severity, 92.86% of the Pharmacotherapy negative outcomes were mild.

CONCLUSIONS

One in four Mula SUAP visits are due to a Pharmacotherapy negative outcomes, and 77.41% of them are preventable.

Warfarin drug interactions: a comparative evaluation of the lists provided by five information sources

PURPOSE

Detecting potential drug interactions can lead to early interventions that protect patients from serious drug-related problems. The aim of this study was to evaluate the agreement among the lists of warfarin interactions provided by five information sources.

METHODS

The lists of warfarin interactions and the corresponding severity ratings and documentation levels presented by the three compendia and by the World Health Organization (WHO) Model Formulary were all compared, and each list was compared to that provided on the package insert of Marevan, a brand of warfarin. The compendia used were: Drug Interaction Facts, Drug Interactions: Analysis and Management and DRUG-REAX. A kappa coefficient was used to calculate the agreement among the sources.

RESULTS

A total of 537 interactions were listed. Only 13 (2.4%) were common to the five sources. The global Fleiss' kappa coefficient was -0.0080, which indicated poor agreement. Eleven warfarin interactions appeared only in the Marevan package insert. Importantly, 243 interactions (45.3% of the total) were deemed significant in at least one compendium. Only two warfarin interactions were reported as critical by all three compendia and by WHO. The most critical interactions cited by the compendia were missing from the package insert.

CONCLUSIONS

Poor agreement was found among five sources listing warfarin interactions. Potentially severe clinical consequences might occur due to these discrepant recommendations. Finally, the lack of standard terminology and clinical guidance, as well as the possible inaccuracy of severity ratings and documentation might contribute to heterogeneous procedures in clinical practice.

Prevalence of adverse drug events in ambulatory care: a systematic review

OBJECTIVE

Most medications are prescribed, dispensed, and administered in ambulatory care settings, yet little information exists on the adverse effects of drugs in this setting. This review was conducted to estimate the prevalence of adverse drug events (ADEs) and the proportion of preventable ADEs in ambulatory care settings; compare data for different age groups including children, adults, and elderly patients; and review drug classes most commonly associated with ADEs.

DATA SOURCES

Four electronic databases-PubMed (1966-March 2011), International Pharmaceutical Abstracts (1970-March 2011), EMBASE (1980-March 2011), and the Cochrane Database of Systematic Reviews (1993-March 2011)-were systematically searched for published data. Bibliographies of retrieved articles were searched individually for additional relevant studies.

STUDY SELECTION

A standardized definition of an ADE was used to select studies in populations living in the community, with medical visits to primary care facilities, nonspecialty ambulatory care facilities, and/or admissions to a hospital for medication-related adverse events.

DATA EXTRACTION

Data were extracted using a standardized table. Forty-three studies met our inclusion criteria.

DATA SYNTHESIS

The median ADE prevalence rate for retrospective studies was 3.3% (interquartile range [IQR] 2.3-7.1%) vs 9.65% (IQR 3.3-17.35%) for prospective studies. Median preventable ADE rates in ambulatory care-based studies were 16.5%, and 52.9% for hospital-based studies. Median prevalence rates by age group ranged from 2.45% for children to 5.27% for adults, 16.1% for elderly patients, and 3.45% for studies including all ages.

CONCLUSIONS

Despite a recent increase in publications on ADEs in the ambulatory care setting, most studies remain hospital based. Notable differences in prevalence rates by age groups and by responsible drug categories provide guidance on how to direct attention toward effective targets for improvement of medication safety in ambulatory care settings.

Drug-related admissions and hospital-acquired adverse drug events in Germany: a longitudinal analysis from 2003 to 2007 of ICD-10-coded routine data

BACKGROUND

Adverse reactions and medication errors are complications of drug use. Spontaneous reporting systems and pharmacoepidemiological studies incompletely detect the occurrence of these events in daily hospital care. In this study, the frequency and type of drug-related admissions and hospital-acquired adverse drug events (ADE) in Germany were assessed using routinely collected hospital data.

METHODS

The study was based on aggregated hospital routine data covering the period 2003 to 2007 and annually recorded as part of the further development of the German Diagnosis-Related Groups. The 505 ICD-10-codes indicating an ADE were categorized in seven groups according to their certainty. Primary diagnoses were considered as a proxy for drug-related admissions, and secondary diagnoses as a proxy for hospital-acquired ADE.

RESULTS

Among all hospital admissions, 5% were found to be at least possibly drug-induced and 0.7% very likely drug-induced. There was a significant increase in the overall rate of drug-related admissions over time (p < 0.038). Enterocolitis due to Clostridium difficile infection was the most frequent cause of a drug-related admission. About 4.5% of in-patients had experienced a hospital-acquired ADE. In addition, over the course of the study period, the overall frequency of hospital-acquired ADEs significantly increased (p < 0.001).

CONCLUSIONS

In Germany, more than 5% of hospital episodes are either caused or complicated by an ADE. Between 2003 and 2007, there was a statistically significant increase in the overall rate and in some of the subcategories defined by the list of ICD-10-codes suspected to be indicative of an ADE. Before the use of routine data in pharmacovigilance and patient safety can be fully exploited, a further tailoring of both the ICD and the available variable set is needed.