Incidence Of Adverse Drug Events Research Articles

Differences in Adverse Drug Events Among Pediatric Patients With and Without Cancer: Sub-Analysis of a Retrospective Cohort Study

ObjectivesThis study investigated the differences in the incidence and severity of adverse drug events (ADEs) in pediatric patients with and without cancer.MethodsWe used data from the Japan Adverse Drug Events Study for pediatrics, a cohort study enrolling pediatric inpatients at two tertiary care teaching hospitals in Japan. ADEs were identified by on-site review of all medical charts, incident reports, and prescription queries by pharmacists. Two independent physicians reviewed all potential ADEs and classified ADEs in terms of severity and class of causative medication. We compared the incidence and characteristics of ADEs between pediatric cancer patients and non-cancer patients.ResultsWe enrolled 1189 patients during the study period, 27 with cancer and 1162 without cancer. We identified 480 ADEs in 234 patients (20%): 191 ADEs among 21 cancer patients and 289 ADEs among 213 non-cancer patients (7.1 per patient vs. 0.25 per patient, respectively; p < 0.0001). The most common medications associated with ADEs in cancer patients were antitumor agents; in contrast, medications associated with fatal or life-threatening ADEs in cancer patients were most often sedatives (25%) and blood products (25%). Medications associated with fatal or life-threatening ADEs among non-cancer patients were most often sedatives (15%). The percentages of fatal or life-threatening ADEs in cancer patients and non-cancer patients were 2.1 and 4.5%, respectively.ConclusionsPediatric patients with cancer have a higher risk for ADEs. Although the overall severity was similar between patients with and without cancer, the most common classes of causative medication and medications associated with a higher rate of severe ADEs differed. Application of this information may help minimize the impact of ADEs in pediatric patients.

Medication safety officer preparatory course: Outcomes and experiences

PurposeFew hospitals employ a medication safety officer. A medication safety officer preparatory course was planned using a structured curriculum to prepare pharmacists with the knowledge and skills to start medication safety officer activities. The current study aims to assess the outcome, as change in knowledge, of a hospital medication safety officer preparatory course. MethodsWe conducted a three-day course in February 2011 in Riyadh, Saudi Arabia. It was developed to provide attendees with the essential knowledge and skills to become a medication safety officer. Teaching methodologies included didactic teaching, group discussions, case presentations, and an independent study of medication safety materials. The content of the course focused on the various roles of a medication safety officer, the importance of medication safety in a health care setting, the incidence of adverse drug events in a hospital setting, strategies to identify and prevent adverse events, the use of root cause analysis and failure mode and effect analysis, the role of an officer in hospital accreditation, and ways for promoting safety culture. Assessment of the course outcome was accomplished by comparing scores of knowledge level before and after the course. The knowledge level was assessed by a 20-item exam which was developed and validated by course instructors. ResultsTwenty-one participants attended the course and completed both the baseline and after-course assessment questionnaires. The majority was male (N=14, %=66.7) with a job experience of 1–5 five years (N=10, %=47.6). The knowledge score increased from 14.3±1.90 (mean±standard deviation) at baseline to 18.5±1.43 after successfully completing the course (P<0.001). ConclusionA three-day medication safety officer preparatory course has been shown to significantly improve attendee knowledge about medication safety. Educating health care professionals is an important tool to help ensure the safety of patients.

The type and incidence of adverse drug events in ageing medical inpatients and their effect on length of hospital stay

AbstractAimsTo determine the proportion of older medical patients who have an adverse drug event (ADE) during admission to hospital and assess the association with hospital length of stay (LOS).MethodsA retrospective evaluation of eligible patients, aged greater than 65 years, consecutively admitted to a medical ward at the Royal Brisbane and Women's Hospital, Australia. Patient medication charts, medical notes and laboratory results were reviewed using an ADE trigger tool to identify potential ADEs during admission. A clinical panel examined and confirmed any true ADEs and the corresponding causative agents. LOS was compared between patients who did and did not have an ADE.ResultsA total of 164 patients were recruited over 30 days. The trigger tool identified a total of 69 triggers from 40 patients (24.3%) with a potential ADE during admission, of which 12 patients (7.3%) had a true ADE. The main drug categories implicated included cardiovascular, anti‐infective and haematological agents. The group of patients with an ADE had a longer median (25th, 75th percentile) LOS when compared to patients without an ADE: 6.5 (3.75, 11) versus 4 (2, 7) days (p = 0.043).ConclusionApproximately 7% of older in‐patients experience an ADE, which has a significant association with an increase in their LOS. To minimise patient harm, undesirable high‐risk drugs should be avoided and vigilant monitoring must occur if they need to be prescribed. An adequately powered, multi‐site study is required and preventative strategies should be further explored.

Evaluation of medication-related clinical decision support alert overrides in the intensive care unit

PurposeMedication-related clinical decision support (CDS) has been identified as a method to improve patient outcomes but is historically frequently overridden and may be inappropriately so. Patients in the intensive care unit (ICU) are at a higher risk of harm from adverse drug events (ADEs) and these overrides may increase patient harm. The objective of this study is to determine appropriateness of overridden medication-related CDS overrides in the ICU. Materials and methodsWe evaluated overridden medication-related alerts of four alert categories from January 2009 to December 2011. The primary outcome was the appropriateness of a random sample of overrides based on predetermined criteria. Secondary outcomes included the incidence of adverse drug events (ADEs) that resulted from the overridden alert. ResultsA total of 47,449 overridden alerts were included for evaluation. The appropriateness rate for overridden alerts varied by alert category (allergy: 94%, drug-drug interaction: 84%, geriatric: 57%, renal: 27%). A total of seven actual ADEs were identified in the random sample and where the medication(s) was administered (n=366), with an increased risk of ADEs associated with inappropriately overridden alerts (p=0.0078). ConclusionsThe appropriateness of medication-related clinical decision support overrides in the ICU varied substantially by the type of alert. Inappropriately overridden alerts were associated with an increased risk of ADEs compared to appropriately overridden alerts.

A multicenter record review of in-hospital adverse drug events requiring a higher level of care

Objective: Adverse drug events (ADEs) are a worldwide concern, particularly when leading to a higher level of care. This study defines a higher level of care as an unplanned (re)admission to an intensive care unit or an intervention by a Medical Emergency Team. The objectives are to describe the incidence and preventability of ADEs leading to a higher level of care, to assess the types of drug involved, and to identify the risk factors.Methods: A three-stage retrospective review was performed in six Belgian hospitals. Patient records were assessed by a trained clinical team consisting of a nurse, a physician, and a clinical pharmacist. Descriptive statistics, univariate, and multiple logistic regressions were used.Results: In this study, 830 patients were detected for whom a higher level of care had been needed. In 160 (19.3%) cases, an ADE had occurred; 134 (83.8%) of these were categorized as preventable adverse drug events (pADEs). The overall incidence rate of patients transferred to a higher level of care because of a pADE was 33.9 (95% CI: 28.5–39.3) per 100,000 patient days at risk. Antibiotics and antithrombotic agents accounted both for one-fifth of all pADEs. Multivariate analysis indicated American Society of Anaesthesiologists physical status score as a risk factor for pADEs.Conclusions: The high number of pADE with patient harm shows that there is a need for structural improvement of pharmacotherapeutic care. Detection of these pADEs can be the basis for the implementation of these improvements.

Valproic Acid: Special Considerations and Targeted Monitoring.

Valproic acid (VPA) is a medication used to treat multiple neuroscience conditions. It is an inexpensive and useful medication, with a low incidence of adverse drug events. Nonetheless, optimal clinical outcomes require that a series of screening and laboratory steps be followed before the initiation of VPA therapy. An additional aspect of pharmacovigilance is to recognize clinical patterns signaling genetic traits that preclude VPA, background of the black box warnings, targeted assessments, and laboratory monitoring indicated while on VPA. The intention of this article is to provide a focused summary of published information clinically relevant to prescribing and monitoring these patients.

ISQUA16-1524IMPACT OF AGE AND RENAL FUNCTION ON INCIDENCE OF ADVERSE DRUG EVENT: THE JADE STUDY:

Appropriate use of medication is special a concern in geriatric patients or patients with chronic kidney disease, but the relationship between such risk factors and incidence of adverse drug events (ADEs) is not well known. We investigated the effects of elderly and renal functions on the incidences of ADEs. The Japan Adverse Drug Events (JADE) study was a prospective cohort study of patients admitted in 3 tertiary care hospitals, enrolling 3,459 patients. There were 1,010 ADEs during the hospitalization (1). We calculated the estimated glomerular filtration rate (eGFR) of 3,389 patients with creatinine values on admission. We divided the age into categories ( =65 years) and the eGFR into …

The epidemiology of adverse drug events and medication errors among psychiatric inpatients in Japan: the JADE study

BackgroundKnowledge of the epidemiology of adverse drug events (ADEs) and medication errors in psychiatric inpatients is limited outside Western countries. The nature of ADEs and medication errors are important for improving the quality of care worldwide; therefore, we conducted the Japan Adverse Drug Events Study, a series of cohort studies at several settings in Japan.MethodsThis report included 448 inpatients with 22,733 patient-days in a psychiatric hospital and psychiatric units at a tertiary care teaching hospital over 1 year. Four psychiatrists and two other physicians reviewed all medical charts and related documents to identify suspected incidents. The physicians later classified those incidents into ADEs, potential ADEs, medication errors, or exclusions and evaluated the severity and preventability if the incidents were events.ResultsDuring the study period, we identified 955 ADEs and 398 medication errors (incidence: 42.0 and 17.5 per 1000 patient-days, respectively). Among ADEs, 1.4 %, 28 %, and 71 % were life-threatening, serious, and significant, respectively. Antipsychotics were associated with half of all ADEs. The incidence of medication errors was higher in medical care units than in acute and nursing care units (40.9, 15.6, and 17.4 per 1000 patient-days, respectively). The monitoring and ordering stages were the most common error stages (39 % and 34 % of all medication errors, respectively), and 76 % of medication errors with ADEs were found at the monitoring stage. Non-psychiatric drugs were three times as likely to cause ADEs with errors compared to psychiatric drugs.ConclusionsAntipsychotic use, inadequate monitoring, and treatment of physical ailments by psychiatrists may contribute to the high incidence of medication errors and ADEs among psychiatric inpatients in Japan. Psychiatrists should be cautious in prescribing antipsychotics or unfamiliar medications for physical problems in their psychiatric patients, and should monitor patients after medication administration.

Study Suggests Nursing Home UTI Policies Lack Consistency

Study Suggests Nursing Home UTI Policies Lack Consistency

Incidence of adverse drug events in public and private hospitals in Riyadh, Saudi Arabia: the (ADESA) prospective cohort study.

ObjectivesTo determine the incidence of adverse drug events (ADEs) and assess their severity and preventability in four Saudi hospitals.DesignProspective cohort study.SettingThe study included patients admitted to medical, surgical and intensive care units (ICUs) of four hospitals in Saudi Arabia. These hospitals include a 900-bed tertiary teaching hospital, a 400-bed private hospital, a 1400-bed large government hospital and a 350-bed small government hospital.ParticipantsAll patients (≥12 years) admitted to the study units over 4 months.Primary and secondary outcome measuresIncidents were collected by pharmacists and reviewed by independent clinicians. Reviewers classified the identified incidents as ADEs, potential ADEs (PADEs) or medication errors and then determined their severity and preventability.ResultsWe followed 4041 patients from admission to discharge. Of these, 3985 patients had complete data for analysis. The mean±SD age of patients in the analysed cohort was 43.4±19.0 years. A total of 1676 ADEs were identified by pharmacists during the medical chart review. Clinician reviewers accepted 1531 (91.4%) of the incidents identified by the pharmacists (245 ADEs, 677 PADEs and 609 medication errors with low risk of causing harm). The incidence of ADEs was 6.1 (95% CI 5.4 to 6.9) per 100 admissions and 7.9 (95% CI 6.9 to 8.9) per 1000 patient-days. The occurrence of ADEs was most common in ICUs (149 (60.8%)) followed by medical (67 (27.3%)) and surgical (29 (11.8%)) units. In terms of severity, 129 (52.7%) of the ADEs were significant, 91 (37.1%) were serious, 22 (9%) were life-threatening and three (1.2%) were fatal.ConclusionsWe found that ADEs were common in Saudi hospitals, especially in ICUs, causing significant morbidity and mortality. Future studies should focus on investigating the root causes of ADEs at the prescribing stage, and development and testing of interventions to minimise harm from medications.

Creating a scalable clinical pharmacogenomics service with automated interpretation and medical record result integration - experience from a pediatric tertiary care facility.

This paper outlines the implementation of a comprehensive clinical pharmacogenomics (PGx) service within a pediatric teaching hospital and the integration of clinical decision support in the electronic health record (EHR). An approach to clinical decision support for medication ordering and dispensing driven by documented PGx variant status in an EHR is described. A web-based platform was created to automatically generate a clinical report from either raw assay results or specified diplotypes, able to parse and combine haplotypes into an interpretation for each individual and compared to the reference lab call for accuracy. Clinical decision support rules built within an EHR provided guidance to providers for 31 patients (100%) who had actionable PGx variants and were written for interacting medications. A breakdown of the PGx alerts by practitioner service, and alert response for the initial cohort of patients tested is described. In 90% (355/394) of the cases, thiopurine methyltranferase genotyping was ordered pre-emptively. This paper outlines one approach to implementing a clinical PGx service in a pediatric teaching hospital that cares for a heterogeneous patient population. There is a focus on incorporation of PGx clinical decision support rules and a program to standardize report text within the electronic health record with subsequent exploration of clinician behavior in response to the alerts. The incorporation of PGx data at the time of prescribing and dispensing, if done correctly, has the potential to impact the incidence of adverse drug events, a significant cause of morbidity and mortality.

Safety and immunogenicity of intradermal rabies vaccination for post exposure prophylaxis

Background: The affordability to anti-rabies vaccine (ARV) for intramuscular administration in post exposure prophylaxis (PEP) is a major constraint. Therefore, in countries, where there are financial constraints, WHO recommends intradermal rabies vaccination (IDRV) that reduces the quantity and cost of vaccination. The aim of the study was to evaluate the safety and immunogenicity of IDRV implemented under National pilot project. Methods: A longitudinal study was conducted at anti rabies clinic (Government referral hospital), India where IDRV is implemented. The study included 515 animal bite cases who received PEP as recommended by WHO. ARV was administered intradermally using updated Thai red-cross regimen. Results: The incidence of adverse drug events was 9.7% and all resolved without any complication. The geometric mean concentration of rabies virus neutralizing antibodies among the vaccinees was 11.89IU/mL on day 14, which was above the WHO recommended titers of ≥ 0.5IU/mL. Conclusions: IDRV was found to be safe and immunogenic in PEP.

Evaluation of Perioperative Medication Errors and Adverse Drug Events.

The purpose of this study is to assess the rates of perioperative medication errors (MEs) and adverse drug events (ADEs) as percentages of medication administrations, to evaluate their root causes, and to formulate targeted solutions to prevent them. In this prospective observational study, anesthesia-trained study staff (anesthesiologists/nurse anesthetists) observed randomly selected operations at a 1,046-bed tertiary care academic medical center to identify MEs and ADEs over 8 months. Retrospective chart abstraction was performed to flag events that were missed by observation. All events subsequently underwent review by two independent reviewers. Primary outcomes were the incidence of MEs and ADEs. A total of 277 operations were observed with 3,671 medication administrations of which 193 (5.3%; 95% CI, 4.5 to 6.0) involved a ME and/or ADE. Of these, 153 (79.3%) were preventable and 40 (20.7%) were nonpreventable. The events included 153 (79.3%) errors and 91 (47.2%) ADEs. Although 32 (20.9%) of the errors had little potential for harm, 51 (33.3%) led to an observed ADE and an additional 70 (45.8%) had the potential for patient harm. Of the 153 errors, 99 (64.7%) were serious, 51 (33.3%) were significant, and 3 (2.0%) were life-threatening. One in 20 perioperative medication administrations included an ME and/or ADE. More than one third of the MEs led to observed ADEs, and the remaining two thirds had the potential for harm. These rates are markedly higher than those reported by retrospective surveys. Specific solutions exist that have the potential to decrease the incidence of perioperative MEs.

Simplification of the standard three-bag intravenous acetylcysteine regimen for paracetamol poisoning results in a lower incidence of adverse drug reactions

Context: Adverse reactions to intravenous (IV) acetylcysteine treatment in paracetamol overdose, are common. Previous studies suggest the incidence and severity of non-allergic anaphylactic reactions (NAARs) are influenced by the rate of acetylcysteine infusion. Objective: We compared the incidence of adverse drug events of a two-bag IV acetylcysteine regimen with that of the traditional three-bag regimen. Materials and methods: This was a retrospective analysis of patients presenting with paracetamol overdose requiring treatment with acetylcysteine to three emergency departments. We prospectively identified all presentations where IV acetylcysteine was administered using a 20 h, two-bag regimen (200 mg/kg over 4 h followed by 100 mg/kg over 16 h) from February 2014 to June 2015. We compared this to an historical cohort treated with the 21 h three-bag IV regimen (150 mg/kg over 1 h, 50 mg/kg over 4 h and 100 mg/kg over 16 h) from October 2009 to October 2013. Medical and nursing notes were searched retrospectively for entries suggesting the presence of an adverse reaction. The primary outcome was incidence of NAARs and gastrointestinal reactions in each group. Results: 389 presentations were treated with the three-bag regimen and 210 presentations received the two-bag regimen. NAARs were recorded more commonly with the three-bag acetylcysteine regimen than the two-bag regimen (10% vs 4.3%, p = 0.02, OR 2.5, 95% CI 1.1–5.8). There was no difference in reports of gastrointestinal reactions between cohorts (three-bag 39% vs two-bag 41%, p = 0.38, OR 1.17 95% CI (0.83–1.65)). Discussion: The incidence of NAARs was significantly reduced by combining the first two bags of the traditional three-bag regimen and infusing these over 4 h at 50 mg/kg/hr. Simplifying the administration of acetylcysteine may have other benefits such as better utilisation of nursing time and reduced infusion administration errors. Conclusions: A two-bag 20 h acetylcysteine regimen was well tolerated and resulted in significantly fewer and milder NAARs than the standard three-bag regimen.

Identification and prevalence of adverse drug events caused by potentially inappropriate medication in homebound elderly patients: a retrospective study using a nationwide survey in Japan

ObjectivesA nationwide large-scale survey was conducted to identify the prevalence and causal medications of adverse drug events (ADEs) that are caused by potentially inappropriate medications (PIMs) given to homebound elderly...

Adverse drug events in hospitalized children at Ethiopian University Hospital: a prospective observational study.

BackgroundThe nature and magnitude of adverse drug events (ADEs) among hospitalized children in low-income countries is not well described. The aim of this study was thus, to assess the incidence and nature of ADEs in hospitalized children at a teaching hospital in Ethiopia.MethodsWe used prospective observational method to study children that were hospitalized to Jimma University Specialized Hospital between 1 February and 1 May 2011. ADEs were identified using review of treatment charts, interview of patient and care-giver, attendance at ward rounds and/or meetings and voluntary staff reports. Two senior pediatric residents evaluated the severity and preventability of ADEs using preset criteria. Logistic regression analysis was employed to determine predictors of ADEs.ResultsThere were 634 admissions with 6182 patient-days of hospital stay. There were 2072 written medication orders accounting for 35,117 medication doses. Fifty eight ADEs were identified with an incidence of 9.2 per 100 admissions, 1.7 per 1000 medication doses and 9.4 per 1000 patient-days. One-third of ADEs were preventable; 47 % of these were due to errors in the administration stage of medication use process. Regarding the severity of ADEs, 91 % caused temporary harms and 9 % resulted in permanent harm/death. Anti-infective drugs were the most common medications associated with ADEs. The occurrence of ADEs increased with age, length of hospital stay, and use of CNS, endocrine and antihistamine medicines.ConclusionADEs are common in hospitalized children in low-income settings; however, one-third deemed preventable. A strategy to prevent the occurrence and consequences of ADEs including education of nurses/physicians is of paramount importance.Electronic supplementary materialThe online version of this article (doi:10.1186/s12887-015-0401-0) contains supplementary material, which is available to authorized users.

Effect of a ward-based pharmacy team on preventable adverse drug events in surgical patients (SUREPILL study).

Surgical patients are at risk of adverse drug events (ADEs) causing morbidity and mortality. Much harm is preventable. Ward-based pharmacy interventions to reduce medication-related harm have not been evaluated in surgical patients. This multicentre prospective clinical trial evaluated a protocolled, ward-based pharmacy method compared with standard pharmaceutical care in surgical patients. Allocation of study group was done by one-time randomization at ward level. Consecutive patients admitted for elective surgery with an expected hospital stay longer than 48 h were included. Pharmacy practitioners performed bedside medication reconciliation at admission and discharge, and hospital pharmacists undertook regular medication reviews in the study wards. Preventable ADEs and clinical outcomes were assessed. A total of 1094 surgical patients were studied. Some 880 specific interventions were made by the hospital pharmacist to improve pharmacotherapy in 309 of 547 patients on study wards. A further 547 patients were included on control wards. A crude non-significant reduction in incidence of preventable ADEs was seen on intervention wards in comparison with control wards (2.74 versus 3.84 preventable ADEs per 100 admissions; incidence rate ratio 0.71, 95 per cent c.i. 0.37 to 1.39; P = 0.324). After adjustment for differences in treatment groups and for potential confounding, the incidence rate ratio remained non-significant (0.82, 0.39 to 1.72; P = 0.598). No differences were seen for other outcomes, such as duration of hospital stay, number of complications and quality of life. The present prospective controlled trial showed no significant reduction in medication-related harm or changes in clinical outcomes when surgical patients received protocolled ward-based pharmacy interventions.

Identification and evaluation of potentially inappropriate medications (PIMs) in hospitalized geriatric patients using Beers criteria.

The aim of the study was to identify and evaluate potentially inappropriate medication (PIM) in geriatric patients using Beers criteria and also to identify adverse drug events (ADEs) due to PIMs and various drug-drug interactions. The medications in the prescriptions of patients above 60 years of age, their dosage regimen respective of their diagnosis were analyzed. Each medication was then checked with Beers list tables, and any medication if mentioned in the Beers list, was noted along with its strength of recommendation and quality of evidence. Any adverse drug event (ADE) due to PIM was identified. Causality of the events was assessed by Naranjo's Scale. The number of drug-drug interactions per prescription and the severity of each interaction were also analyzed. The collected data from 200 subjects were subjected to statistical treatments using Statistical Package for Social Sciences (SPSS) software version 16.0 for WINDOWS. Based on the Beers criteria 2012, 106 out of 200 (53%) prescriptions had at least one PIM prescribed. A sum of 1690 medications was prescribed as a whole for the entire study subjects. Among which, 134 PIMs were identified. Most commonly prescribed PIMs were benzodiazepines (39, 19.5%), followed by sliding scale use of insulin (31, 15.5%), and prazosin at a rate of 11.5% (23). A total of 10 ADEs were identified during the study. The average number of drug interactions observed among total samples was found to be 3.0±6.0 with 0±5.0 serious interactions, 2±4.0 significant interactions requiring close monitoring, and 0±6.0 minor interactions. The study shows high prevalence of prescribing PIMs in hospitalized elderly patients; PIM also caused incidence of ADEs; and serious drug-drug interactions were scarce among the patients.

Meaningful use stage 2 e-prescribing threshold and adverse drug events in the Medicare Part D population with diabetes.

Evidence supports the potential for e-prescribing to reduce the incidence of adverse drug events (ADEs) in hospital-based studies, but studies in the ambulatory setting have not used occurrence of ADE as their outcome. Using the "prescription origin code" in 2011 Medicare Part D prescription drug events files, the authors investigate whether physicians who meet the meaningful use stage 2 threshold for e-prescribing (≥50% of prescriptions e-prescribed) have lower rates of ADEs among their diabetic patients. Risk of any patient with diabetes in the provider's panel having an ADE from anti-diabetic medications was modeled adjusted for prescriber and patient panel characteristics. Physician e-prescribing to Medicare beneficiaries was associated with reduced risk of ADEs among their diabetes patients (Odds Ratio: 0.95; 95% CI, 0.94-0.96), as were several prescriber and panel characteristics. However, these physicians treated fewer patients from disadvantaged populations.

An individual patient data meta-analysis on factors associated with adverse drug events in surgical and non-surgical inpatients.

The incidence of adverse drug events (ADEs) in surgical and non-surgical patients may differ. This individual patient data meta-analysis (IPDMA) identifies patient characteristics and types of medication most associated with patients experiencing ADEs and suggests target areas for reducing harm and implementing focused interventions. Authors of eligible studies on preventable ADEs (pADEs) were approached for collaboration. For assessment of differences among (non-)surgical patients and identification of associated factors descriptive statistics, Pearson chi-square, Poisson and logistic regression analyses were performed. For identification of high risk drugs (HRDs), a model was developed based on frequency, severity and preventability of medication related to ADEs. Included were 5367 patients from four studies. Patients aged ≥ 77 years experienced more ADEs and pADEs compared with patients aged ≤ 52 years (odds ratios (OR) 2.12 (95% CI 1.70, 2.65) and 2.55 (95% CI 1.70, 3.84), respectively, both P < 0.05). Polypharmacy on admission also increased the risk of ADEs (OR 1.21 (95% CI 1.03, 1.44), P < 0.05) and pADEs (OR 1.85 (95% CI 1.34, 2.56), P < 0.05). pADEs were associated with more severe harm than non-preventable ADEs (54% vs. 32%, P < 0.05). The top five HRDs were antibiotics, sedatives, anticoagulants, diuretics and antihypertensives. Events associated with HRDs included diarrhoea or constipation, abnormal liver function test and central nervous system events. Most pADEs resulted from prescribing errors (90%). Elderly patients with polypharmacy on admission and receiving antibiotics, sedatives, anticoagulants, diuretics or antihypertensives were more prone to experiencing ADEs. Efficiency in prevention of ADEs may be improved by targeted vigilance systems for alertness of physicians and pharmacists.