Prospective evaluation of adverse drug interactions in the emergency department

Prevalence of clinically manifested drug interactions in hospitalized patients: A systematic review and meta-analysis

AIMS

This review aims to determine the prevalence of clinically manifested drug-drug interactions (DDIs) in hospitalized patients.

METHODS

PubMed, Scopus, Embase, Web of Science, and Lilacs databases were used to identify articles published before June 2019 that met specific inclusion criteria. The search strategy was developed using both controlled and uncontrolled vocabulary related to the following domains: "drug interactions," "clinically relevant," and "hospital." In this review, we discuss original observational studies that detected DDIs in the hospital setting, studies that provided enough data to allow us to calculate the prevalence of clinically manifested DDIs, and studies that described the drugs prescribed or provided DDI adverse reaction reports, published in either English, Portuguese, or Spanish.

RESULTS

From the initial 5,999 articles identified, 10 met the inclusion criteria. The pooled prevalence of clinically manifested DDIs was 9.2% (CI 95% 4.0-19.7). The mean number of medications per patient reported in six studies ranged from 4.0 to 9.0, with an overall average of 5.47 ± 1.77 drugs per patient. The quality of the included studies was moderate. The main methods used to identify clinically manifested DDIs were evaluating medical records and ward visits (n = 7). Micromedex® (27.7%) and Lexi-Comp® (27.7%) online reference databases were commonly used to detect DDIs and none of the studies evaluated used more than one database for this purpose.

CONCLUSIONS

This systematic review showed that, despite the significant prevalence of potential DDIs reported in the literature, less than one in ten patients were exposed to a clinically manifested drug interaction. The use of causality tools to identify clinically manifested DDIs as well as clinical adoption of DDI lists based on actual adverse outcomes that can be identified through the implementation of real DDI notification systems is recommended to reduce the incidence of alert fatigue, enhance decision-making for DDI prevention or resolution, and, consequently, contribute to patient safety.

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.

Potential Drug-drug Interactions at a Referral Pediatric Oncology Ward in Iran: A Cross-sectional Study

Incidence of drug-drug interactions (DDIs) has been widely reported; however, such reports in pediatric oncology patients still remain scarce. We studied frequency and demographic correlates of moderate and major DDIs at a pediatric oncology ward in Isfahan, Iran. All pediatric oncology patients admitted to the Omid hospital during a 6-month period (2017) who received at least 2 anticancer or non-anticancer drugs concomitantly were included in our study. Potential DDIs between anticancer and non-anticancer drugs during hospitalization was identified using Lexi-Interact on-line software. We detected 194 DDIs with moderate or major severity for our included 115 patients. Mechanistically, most of DDIs (56.4%) were pharmacodynamic. Systematic use of corticosteroids (82.0%), antimetabolites (77.0%), and antiemetic drugs (69.5%) were the most frequent medication classes responsible for detected DDIs. The interaction between aminoglycosides and the third generation cephalosporins was the most common (13.9%) non-anticancer DDI. The only identified interaction between 2 anticancer drugs was doxorubicin with cyclophosphamide. Age, sex, and the number of administered medications were associated with DDIs. Potential moderate or major DDIs occur frequently among pediatric cancer patients. More studies are needed to assess clinical and economic implications of DDIs in pediatric oncology patients.

Descriptive study of drug-drug interactions attributed to prescriptions written upon discharge from the emergency department

OBJECTIVE

The primary purpose of this study was to identify the most common drug-drug interactions (DDI'S) in patients prescribed medications upon discharge from the emergency department.

METHODS

We conducted a respective chart review of patients discharged home with a prescription from an academic emergency department. The study period was from August 1, 2015 to August 31, 2015. Patients will be excluded if they meet the following criteria: age under 20 years; discharge home without a prescription; inpatient hospital admission; transfer to another inpatient facility; or sign out against medical advice. The primary endpoint is the identification and characterization of drug-drug interactions caused by discharge prescriptions written by the treating physician.

RESULTS

A total of 500 patient charts were included, with 38% having at least one DDI. Overall, there were 429 DDIs among 858 prescriptions written. 15.6% (n = 67) of the DDI's were classified as B, no modification of therapy needed. 60% (n = 260) of the DDIs were risk-rating category C, requiring monitoring of therapy. 22% (n = 95) of the DDI's identified were category D, which are consider modification of therapy. Lastly, we identified 1.6% (n = 7) category X DDI's. The top 3 most commonly associated drugs were oxycodone/acetaminophen, ibuprofen, and ciprofloxacin.

CONCLUSION

DDIs are occurring upon discharge from a large, urban, tertiary care, academic medical center. Many of the DDI's identified do not require any modification to therapy. However, 23.6% of identified DDI's required modification or were contraindicated. A majority of the category X drug interactions involved QT prolongation.

Prevalence study on potential drug–drug interaction in cancer patients in Piacenza hospital’s Onco-Haematology department

Background

Cancer patients can be a human model of potential drug interactions. Usually they receive a large number of different medications, including antineoplastic agents, drugs for comorbid illness and medication for supportive care, however information about these interactions are fragmented and poor.

Objective

We assessed a prospective study to evaluate the prevalence of drug interaction among patients hospitalized in the Onco-Haematology department, Hospital of Piacenza.

Methods

Data on drugs administered for cancer, comorbidities, or supportive care were collected from different computerized prescription software in use in the department; we compared them with a database to focus on the co-administration of drugs. A literature review was performed to identify major potential drug interaction and to classify them by level of severity and by strengths of scientific evidence.

Results

In this study 284 cancer patients were enrolled; patients had taken an average of seven drugs on each day of therapy plus chemotherapeutic agents, we identified 67 potential drug interactions. At least 53 patients had one potential drug interaction. Of all potential drug interactions 63 were classified as moderate severity and only four as major. In 55 cases chemotherapeutic agents were involved in possible interactions with supportive care drugs, meanwhile in 12 cases the potential drug interactions were between supportive care drugs.

Conclusions

In our centre, thanks to a computerized prescription software, integrated with caution alarm in case of possible interaction, we had a lower rate of potential drug interactions than the one from literature. It is possible to improve the software integrating the alarm with the potential drug interactions between chemotherapy agents and supportive care drugs.

A study on drug-drug interactions through prescription analysis in a South Indian teaching hospital

OBJECTIVE

The objective of this study was to assess the drug-drug interactions (DDIs) through prescription analysis among the inpatients of a South Indian teaching hospital.

METHODS

The study was a prospective observational prescription analysis conducted for a period of 6 months, from October 2010 to March 2011. The prescriptions having two or more drugs and where a DDI was suspected were selected by the physician in charge of the ward. The drugs in the prescription were then entered into the drug interaction checker software. The DDIs were classified based on the mechanism of interactions, severity of interactions, relation to the number of drugs prescribed, and disease conditions were also determined.

RESULTS

A total of 204 prescriptions were analyzed, of which 186 prescriptions had 856 DDIs. Most of the DDIs were pharmacokinetic drug interactions (42%) followed by unknown mechanisms (34%) and pharmacodynamic mechanisms (24%). The study findings showed that the prescriptions for cardiovascular with respiratory disease conditions had the greatest number of drug interactions on average. A severity assessment showed that majority of the DDIs were moderate (70%) followed by minor (28%). The study results showed that as the number of drugs increases in a prescription, the number of DDIs also increases. The interventions determined showed that dosage adjustment (12%) was to be followed in most of the DDIs.

CONCLUSION

This study assists in understanding the factors associated with DDIs that can help in safe and effective use of drugs in the future.

Potential drug-drug interactions at a referral hematology-oncology ward in Iran: a cross-sectional study

PURPOSE

To assess the pattern and probable risk factors for moderate and major drug-drug interactions in a referral hematology-oncology ward in Iran.

METHODS

All patients admitted to hematology-oncology ward of Dr. Shariati Hospital during a 6-month period and received at least two anti-cancer or non-anti-cancer medications simultaneously were included. All being scheduled anti-cancer and non-anti-cancer medications both prescribed and administered during ward stay were considered for drug-drug interaction screening by Lexi-Interact On-Desktop software.

RESULTS

One hundred and eighty-five drug-drug interactions with moderate or major severity were detected from 83 patients. Most of drug-drug interactions (69.73 %) were classified as pharmacokinetics. Fluconazole (25.95 %) was the most commonly offending medication in drug-drug interactions. Interaction of sulfamethoxazole-trimethoprim with fluconazole was the most common drug-drug interaction (27.27 %). Vincristine with imatinib was the only identified interaction between two anti-cancer agents. The number of administered medications during ward stay was considered as an independent risk factor for developing a drug-drug interaction.

CONCLUSIONS

Potential moderate or major drug-drug interactions occur frequently in patients with hematological malignancies or related diseases. Performing larger standard studies are required to assess the real clinical and economical effects of drug-drug interactions on patients with hematological and non-hematological malignancies.

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.

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.

Drug interactions in oncology: how common are they?

BACKGROUND

Drug-drug interactions (DDIs) comprise an important problem in medical oncology practice. We systematically reviewed the frequency of DDIs in oncology.

METHODS

We searched PubMed for eligible articles and on-line databases for abstracts of major oncology meetings.

RESULTS

Eight studies reported on the frequency of DDIs: six evaluated the frequency of potential DDIs, while two studies reported on real DDIs, i.e. interactions that had clinical consequences. Studies of potential DDIs found that approximately one-third of patients are exposed to dangerous drug doublets, with the most common ones involving warfarin and anticonvulsants. One study of real DDIs found that 2% of hospitalized cancer patients had a DDI as the cause of admission.

CONCLUSIONS

Drug interactions comprise an important issue in oncology, with approximately one-third of ambulatory cancer patients being at risk of DDIs. Data are limited on the clinical consequences of drug interactions among cancer patients.

Medication reconciliation in hospice: a pilot study

BACKGROUND

The Joint Commission required implementation of medication reconciliation processes by January 2006. Medication reconciliation is the practice of acquiring an accurate medication history at each transitional point of care. Potential for errors increases with inaccurate medication histories. This study determined the extent of medication reconciliation errors in hospice.

METHODS

Patients were enrolled from 2 hospices in Maryland (January 2007). An initial medication history was completed by the nurse on hospice admission. The pharmacist did another medication history within 5 days of admission and compared the medication histories. All differences were reported as medication discrepancies.

RESULTS

There were 504 medication discrepancies. Medication omissions occurred most commonly. All patients had at least 1 medication discrepancy (average 8.7 per patient). Overall, 190 drug interactions were identified; most were moderately severe.

CONCLUSION

Terminal patients often use numerous medications increasing the risk of medication errors. Accurate medication histories reduce errors and potential for harm.

Potential drug interactions in cancer patients receiving supportive care exclusively

Cancer patients at the end of life often take many medications and are at risk for drug interactions. The purpose of this study was to describe the epidemiology of potential drug interactions in cancer patients receiving supportive care exclusively. We retrospectively reviewed the charts of consecutive adult cancer outpatients attending palliative care clinics at the Princess Margaret Hospital, Toronto, Canada. Drugs were screened for interactions by the Drug Interaction Facts software, which classifies interactions by levels of severity (major, moderate, and minor) and scientific evidence (1-5, with 1=the strongest level of evidence). Among 372 eligible patients, 250 potential drug interactions were identified in 115 patients (31%, 95% confidence interval 26%-36%). The most common involved warfarin and phenytoin. Most interactions were classified as being of moderate severity (59%) and 42% of them were supported by Levels 1-3 of evidence. In multivariable analysis, increasing age (P<0.001), presence of comorbidity (P=0.001), cancer type (brain tumors, P<0.001), and increasing number of drugs (P<0.001) were associated with risk of drug interactions. Potential drug interactions are common in palliative care and mostly involve warfarin and anticonvulsants. Older patients, those with comorbid conditions, brain tumor patients, and those taking many medications are at greater risk of drug interactions.

The quality of pharmacotherapy in older veterans discharged from the emergency department or urgent care clinic

OBJECTIVES

To determine the prevalence and type of suboptimal pharmacotherapy that older veterans discharged from the emergency department (ED) or urgent care clinic (UCC) receive and to examine factors associated with suboptimal pharmacotherapy in this population.

DESIGN

Retrospective, cohort study.

SETTING

An academically affiliated Department of Veterans' Affairs (VA) Medical Center.

PARTICIPANTS

Four hundred twenty-one veterans aged 65 and older who were prescribed a new medication at the time of discharge from the ED or UCC.

MEASUREMENTS

The primary dependent variable, suboptimal pharmacotherapy, was a composite measure defined as one or more drug-related problems, based on drugs-to-avoid criteria, drug-drug interactions, drug-disease interactions, and failure to satisfy an explicit quality indicator for prescribing or medication monitoring.

RESULTS

A total of 757 drugs were prescribed to the 421 patients at the time of discharge from the ED or UCC (mean number+/-standard deviation per patient 1.65+/-1.1). The most frequently prescribed medications were nonsteroidal antiinflammatory drugs (n=59), opioid analgesics (n=47), and fluoroquinolone antibiotics (n=46). Overall, 134 (31.8%) subjects were found to have suboptimal pharmacotherapy with regard to their discharge medications; 49 (11.6%) were prescribed a drug to avoid, 53 (12.6%) received a drug that introduced a new drug-drug interaction, 24 (5.7%) were given a drug that introduced a drug-disease interaction, and 74 (17.6%) did not have a quality indicator satisfied (61% of these evaluated prescribing and 39% evaluated medication monitoring). No consistent associations between patient or visit characteristics and suboptimal pharmacotherapy were identified in multivariable models.

CONCLUSION

A substantial number of older adults discharged from the ED or UCC may be at risk for adverse events due to suboptimal prescribing and inadequate medication monitoring. Further study is needed to examine the relationship between suboptimal pharmacotherapy and adverse clinical outcomes.

Hospitalisations and emergency department visits due to drug-drug interactions: a literature review

PURPOSE

Our objective was to evaluate the incidence of adverse patient outcomes due to drug-drug interactions (D-DIs), the type of drugs involved and the underlying reason. As a proxy for adverse patient outcomes, emergency department (ED) visits, hospital admissions and re-hospitalisations were assessed.

METHODS

A literature search in the Medline and Embase database (1990-2006) was performed and references were tracked. An overall cumulative incidence was estimated by dividing the sum of the cases by the sum of the study populations.

RESULTS

Twenty-three studies were found assessing the relationship between D-DIs and ED-visits, hospitalisations or re-hospitalisations. The studies with a large study size showed low incidences and vice versa. D-DIs were held responsible for 0.054% of the ED-visits, 0.57% of the hospital admissions and 0.12% of the re-hospitalisations. In the elderly population, D-DIs were held responsible for 4.8% of the admissions. Drugs most often involved were NSAIDs and cardiovascular drugs. The reasons for admissions or ED-visits, which were most often found were GI-tract bleeding, hyper- or hypotension and cardiac rhythm disturbances.

CONCLUSION

This review provides information on the overall incidence of D-DIs as a cause of adverse patient outcomes, although there is still uncertainty about the impact of D-DIs on adverse patient outcomes. Our results suggest that a limited number of drugs are involved in the majority of cases and that the number of reasons for admission as a consequence of D-DIs seems to be modest.

Potential drug–drug interactions within Veterans Affairs medical centers

PURPOSE

This study assessed the prevalence of 25 clinically important drug-drug interactions (DDIs) in the ambulatory care clinics of the Department of Veterans Affairs medical centers (VAMCs).

METHODS

This study was a retrospective, cross-sectional database analysis of pharmacy records to assess the prevalence of 25 clinically important DDIs. For each DDI, the object drug was defined as the medication that has its therapeutic effect modified by the drug interaction process. The precipitant drug was defined as the medication responsible for affecting the pharmacologic action or the pharmacokinetic properties of the object drug. Rates of interactions for each VAMC facility were calculated as the number of patients with a DDI divided by the total number of individual patients exposed to the object or precipitant medications. The 25 DDIs were categorized into four main categories on the basis of the therapeutic classification of the medications involved in the drug pairs.

RESULTS

The study population included 2,795,345 patients who filled prescriptions for medications involved in potential DDIs across 128 VAMCs. The highest DDI exposure rate was 129.2 per 1,000 recipients of monoamine oxidase inhibitors (MAOIs) that occurred with combinations of selective serotonin-reuptake inhibitors (SSRIs). The lowest DDI exposure rate was 0.01 per 1,000 warfarin recipients who had the warfarin and sulfinpyrazone combination.

CONCLUSION

The analysis of pharmacy records of veterans who filled prescriptions at the outpatient settings within VAMC found an overall rate of 2.15% for potential DDIs. Case-exposure rates were greatest for veterans receiving SSRIs and MAOIs, ganciclovir and zidovudine, anticoagulants and thyroid hormones, and warfarin and nonsteroidal antiinflammatory drugs.

Potential drug interactions and duplicate prescriptions among cancer patients

BACKGROUND

Cancer patients receive numerous medications, including antineoplastic agents, drugs for supportive care, and medications for comorbid illnesses. Therefore, they are at risk for drug interactions and duplicate prescribing.

METHODS

A questionnaire eliciting information on demographics and medications taken in the previous 4 weeks was given to adult outpatients receiving systemic anticancer therapy for solid tumors. The Drug Interaction Facts software, version 4.0, was used to identify potential drug interactions and to classify them by level of severity (major, moderate, or minor) and the strength of scientific evidence for them (using categories [1-5] of decreasing certainty). Summary statistics and logistic regression were used to analyze the data. All statistical tests were two-sided.

RESULTS

The survey was completed by 405 patients. We observed 276 potential drug interactions, and at least one potential interaction was identified in 109 patients (27%; 95% confidence interval [CI] = 23% to 31%). Of the potential interactions, 25 (9%) were classified as major and 211 (77%) as moderate. Nearly half (49%) of potential interactions were supported by level 1 or 2 scientific evidence. Most potential drug interactions (87%) involved non-anticancer agents such as warfarin, antihypertensive drugs, corticosteroids, and anticonvulsants, but some (n = 36, 13%) involved antineoplastic agents. In multivariable analysis, increased risk of receiving drug combinations in which there were potential drug interactions was associated with receipt of increasing numbers of drugs (odds ratio [OR] = 1.4 per additional drug, 95% CI = 1.26 to 1.58, P<.001 from the Wald chi-square test), type of medication (drugs to treat comorbid conditions versus supportive care medications only; OR = 8.6, 95% CI = 2.9 to 25, P<.001), and the presence of brain tumors. Thirty-two (8%) patients were exposed to duplicate medications, most often corticosteroids, proton pump inhibitors, or benzodiazepines.

CONCLUSION

Potential drug interactions were common among cancer patients and most often involved medications to treat comorbid conditions. Duplicate medications were infrequent.

Experience in adverse events detection in an emergency department: incidence and outcome of events

OBJECTIVES

The study was performed to determine the incidence, outcome and preventability of adverse events (AE) in an ED.

METHODS

The Quality in Australian Health Care Study methodology, modified to the ED, was utilized. Case histories of patients presenting to a tertiary hospital ED were screened for events. Events detected were classified, using a 104-item data collection instrument, entered on Excel and analysed statistically using MINITAB.

RESULTS

A total of 5345 patients presented during the study period. Three thousand three hundred and thirty-two patients completed full evaluation and comprised the study population. One hundred and ninety-four events were detected. Except where specified, events with management causation < or = 3 were excluded. This excluded 24 events (12.4%) leaving 170 for analysis. Of patients suffering an event, 53.5% occurred prior ED attendance, 41.7% of AE occurred within the ED, and 4.7% had contributions from both. The overall event rate, detected by the screening process, was 5.1%, with an incident rate of 1.98% and AE rate of 3.12%. The ED AE rate was 1.0%. If only those with management causation = 1 are excluded, then the overall event rate was 5.52%, with an AE rate of 3.33%. Fifty-five per cent of events were judged to be preventable (preventability score > or = 3). Events resulting in death and disability were more likely to be preventable (P < or = 0.04).

CONCLUSION

In conclusion, the Quality in Australian Health Care Study methodology has been utilized to provide data on incidents and AE in an ED.

A systematic review on drug interactions in oncology

OBJECTIVES

To systematically review drug interactions in oncology.

METHODS

We searched PubMed for eligible articles and online databases abstracts of major oncology meetings from 2002 to 2005.

RESULTS

One study reported on the frequency of drug interactions. Interactions between chemotherapy and nonchemotherapy agents have been reported mostly in small clinical trials and case series. Interactions between chemotherapic agents have been reported mostly in Phase I studies. Few studies described fatal outcomes of drug interactions in cancer patients.

CONCLUSION

Drug interactions comprise an important issue in oncology, but very limited data exist on their frequency and clinical consequences.

Frequency of potential azole drug-drug interactions and consequences of potential fluconazole drug interactions

PURPOSE

To assess the frequency of potential azole-drug interactions and consequences of interactions between fluconazole and other drugs in routine inpatient care.

METHODS

We performed a retrospective cohort study of hospitalized patients treated for systemic fungal infections with an oral or intravenous azole medication between July 1997 and June 2001 in a tertiary care hospital. We recorded the concomitant use of medications known to interact with azole antifungals and measured the frequency of potential azole drug interactions, which we considered to be present when both drugs were given together. We then performed a chart review on a random sample of admissions in which patients were exposed to a potential moderate or major drug interaction with fluconazole. The list of azole-interacting medications and the severity of interaction were derived from the DRUGDEX System and Drug Interaction Facts.

RESULTS

Among the 4,185 admissions in which azole agents (fluconazole, itraconazole or ketoconazole) were given, 2,941 (70.3%) admissions experienced potential azole-drug interactions, which included 2,716 (92.3%) admissions experiencing potential fluconazole interactions. The most frequent interactions with potential moderate to major severity were co-administration of fluconazole with prednisone (25.3%), midazolam (17.5%), warfarin (14.7%), methylprednisolone (14.1%), cyclosporine (10.7%) and nifedipine (10.1%). Charts were reviewed for 199 admissions in which patients were exposed to potential fluconazole drug interactions. While four adverse drug events (ADEs) caused by fluconazole were found, none was felt to be caused by a drug-drug interaction (DDI), although in one instance fluconazole may have contributed.

CONCLUSIONS

Potential fluconazole drug interactions were very frequent among hospitalized patients on systemic azole antifungal therapy, but they had few apparent clinical consequences.

Procedural Sedation and Analgesia in the Emergency Department: What Are the Risks?

The practitioner of emergency medicine is routinely faced with patients in need of emergent procedures and pain control and sedation. Our challenge is to make our patients' experiences as painless and as safe as possible, while maximizing our ability to perform the procedure at hand; this is not always an easy task given the propensity of each human body to react differently to interventions and stimuli. We can best meet this challenge by understanding how our patients and pharmaceutical agents intermingle in the risk-benefit equation we formulate before starting our "experiment." Coupling this information with fundamentally sound patient care and monitoring will minimize bad experiences with PSA for both the patient and practitioner.

Potential for drug interactions in hospitalized cancer patients

OBJECTIVES

To quantify the frequency of potential drug interactions unrelated to chemotherapy in cancer patients admitted to our institution, and to define risk factors for such interactions.

METHODS

Charts of 100 consecutive hospitalized cancer patients were reviewed. Patients receiving chemotherapy and/or hormone therapy were excluded, as were patients admitted for intensive care. Drug-drug interactions were screened with Drug Interaction Facts software, and manually by the authors. Potential interactions were graded by levels of severity (severe, moderate, minor) and significance (one to five, with one representing the highest level of evidence).

RESULTS

The median age of the patients was 67 years, and the length of hospital stay and the number of drugs per patient were 6 days and eight drugs, respectively. In 63 patients 180 potential interactions were detected. Of the potential interactions, 18.3% were severe, 56.7% were moderate, and 25% were minor. Approximately 7%, 18% and 13% of potential interactions were graded as level 1, 2 and 3, respectively. In multivariate analysis, prescriptions with eight or more drugs (P=0.0004) and six or more days of hospital stay (P=0.014) were independent risk factors for potential interactions.

CONCLUSION

Potential drug interactions are common among hospitalized cancer patients. Length of hospital stay and number of prescribed drugs are risk factors.

Deadly drug interactions in emergency medicine

Many life-threatening drug interactions are predictable, avoidable events. Emergency medicine physicians have a responsibility to recognize and prevent drug interactions. Keeping current on the many pharmaceutical therapies,their pharmacology, and potential drug interactions currently represents one of the biggest challenges for emergency medicine practitioners. Using current drug interaction resources and knowing the limited number of medications that are responsible for the most serious drug interactions can ease this seemingly overwhelming burden greatly. Clinicians need to be particularly vigilant when prescribing drugs for patients who are taking medications with potential for drug interactions leading to serious consequences.

Inappropriate Medication Administration to the Acutely Ill Elderly: A Nationwide Emergency Department Study, 1992–2000

OBJECTIVES

To determine the national rate and trend of inappropriate medication administration to elderly emergency department (ED) patients. Secondary objectives were to identify risk factors for receiving an inappropriate medication and to determine whether administration is sometimes justified based on diagnosis.

DESIGN

Retrospective analysis of ED visits in the 1992-2000 National Hospital Ambulatory Medical Care Survey. Inappropriate medications identified using Beers' 1997 explicit criteria.

SETTING

EDs of U.S. noninstitutionalized general and short-stay hospitals.

PARTICIPANTS

ED survey patients aged 65 and older.

MEASUREMENTS

Magnitude and rate of administration of 36 medications.

RESULTS

Inappropriate medications were administered in an estimated 16.1 million (95% confidence interval (CI)=14.9-17.3 million) or 12.6% (95% CI=11.6-13.5%) of elderly ED visits from 1992 to 2000. The rate of inappropriate administration was unchanged throughout the study period (P=.40). Six drugs accounted for 70.8% of inappropriate administration: promethazine (22.2%), meperidine (18.0%), propoxyphene (17.2%), hydroxyzine (10.3%), diphenhydramine (7.1%), and diazepam (6.0%). In multivariate analysis, number of ED medications was the strongest predictor, with an odds ratio for two to three medications of 6.0 (95% CI=5.3-6.7) and for four to six medications of 8.1 (95% CI=7.2-9.2). Diagnoses indicating potentially appropriate uses of these medications were rarely present. For example, only 42.4% of patients receiving diphenhydramine and 7.4% receiving hydroxyzine were diagnosed with an allergic process.

CONCLUSION

Elderly ED patients are frequently administered inappropriate medications. Potentially appropriate uses of generally inappropriate drugs cannot account for such administrations. Inappropriate administration rates remain unchanged despite the 1997 publication of explicit criteria.

Understanding and preventing drug interactions in elderly patients

The elderly consume a disproportionate amount of prescription and nonprescription medications. Alterations in physiology, polypharmacy, multiple prescribers, and other factors place the elderly population at risk of developing clinically significant drug-drug interactions. The incidence of potential drug-drug interactions increases with increased drug use and are responsible for numerous emergency room and physician visits. Drug interactions have been shown to cause a decline in functional abilities in older people. Drugs can interact to alter the absorption, distribution, metabolism, or excretion of a drug or interact in a synergistic or antagonist fashion altering their pharmacodynamics. Drug interactions are often clinically unrecognized and responsible for increased morbidity in elderly patients. Prudent use of medications and vigilant drug monitoring are essential to avoid drug-drug interactions.

Potential drug-drug interactions in the medication of medical patients at hospital discharge

OBJECTIVE

Information on the frequency of drug combinations with the potential to induce dangerous drug-drug interactions (DDIs) in patients discharged from the hospital is scarce. With the present study, we assessed the frequency and potential clinical significance of DDIs in the prescriptions of discharged medical patients.

METHODS

We retrospectively screened the medication for potential DDIs of 500 patients consecutively discharged with at least two prescriptions using a computerised drug-interaction program.

RESULTS

The 500 patients (56.6% male, mean age 67.0+/-15.9 years, median length of stay 13 days) were prescribed a median of six drugs (range 2-18) at discharge. Three hundred patients (60.0%; 95% confidence interval 55.7-64.3%) had at least one potentially interacting drug combination. Of 747 potential DDIs at discharge overall, 402 (53.8%) were new at the time of discharge due to a change of the medication during the hospital stay. Of these, 72 (17.9%) were of potentially minor, 281 (69.9%) of moderate and 49 (12.2%) of major severity. Of 44 patients with a potential DDI with major severity, 1 patient was re-hospitalised within 2 months after discharge due to a probable drug-related problem associated with the potential DDI.

CONCLUSIONS

Using a computerised drug-interaction program, a high proportion of patients was detected with at least one potential DDI in the medication prescribed at discharge. However, the proportion of DDIs associated with potentially relevant clinical consequences appeared to be relatively low.

Adverse drug events in emergency department patients

STUDY OBJECTIVE

Adverse drug events (ADEs) have been studied in hospitalized patients. Less is known about this common type of injury in emergency department patients. This study seeks to measure the risks, incidence, severity, and costs of ADEs in an ED population.

METHODS

ED charts of visits to a university-affiliated tertiary-care ED occurring between March 1 and May 31, 1997, were retrospectively reviewed. The main outcome measures were ADE incidence, severity, and total cost. Visits identified by investigators as containing a suspected ADE were further assessed by using the Naranjo Adverse Drug Reaction (ADR) probability scale. Events judged as probable ADEs (Naranjo ADR probability scale score of >4) were compared with ED control visits best matched by age for disposition, survival, severity, payer, sex, race, age, number of drugs, and total cost.

RESULTS

Of 13,602 visits, 13,004 records were available. Three hundred twenty-one had suspected and 217 had probable ADEs (1.7% of evaluable encounters); these were compared with visits by 217 age-matched control patients. Insulin and warfarin were the most commonly responsible drugs. Patients with ADEs were older (mean age 45.1 versus 36.8 years; mean difference 8.3; 95% confidence interval [CI] 3.7 to 12.9), were more often women (odds ratio [OR] 1.48; 95% CI 1.01 to 2.16), took more drugs (mean number of drugs 4.1 versus 1.9; mean difference 2.2; 95% CI 1.7 to 2.8), and were hospitalized more frequently (OR 2.29; 95% CI 1.33 to 3.94) than control patients.

CONCLUSION

ADEs encompassed an important segment of ED encounters and annual health care costs. ED screening may provide useful information about the epidemiology of outpatient ADEs.

Incidence and risk of potential adverse drug interactions in the emergency room

OBJECTIVE

To determine the incidence and risk factors of potential adverse drug interactions occurring in patients in the emergency department.

DESIGN

Survey of a random sample of medical records of elderly persons and other adults seeking care at an emergency department. The interactions were determined by a computer programme, reviewed using explicit criteria, and excluded if of uncertain or trivial clinical significance.

SETTING

University Hospital Medical Emergency Department.

PATIENTS

A total of 423 randomly selected adults seeking care at a university hospital emergency department. Attendances made by 195 persons over age 60 and 228 younger adults were evaluated. All subjects were treated on an outpatient basis.

MAIN OUTCOME MEASURES

Seventy percent of attendances led to the prescription of an added medication. In 5.4% of the attendances in which at least one medication was added, the new medication introduced a potential adverse interaction. The number of medications used at attendance was the best predictor of whether a potential interaction would occur. Additional medications prescribed in the emergency department that accounted for most of the added interactions were theophylline, macrolid antibiotics, digitalis glycosides, nonsteroidal anti-inflammatory agents, angiotensin converting-enzyme inhibitors and calcium antagonists.

CONCLUSIONS

Potential adverse drug interactions were more common in elderly patients because of the higher number of concurrent medications rather than age-based factors. Safeguards need to be introduced to prevent patients from receiving medications in the emergency departments that have the potential to cause adverse interactions.

Physician versus computer knowledge of potential drug interactions in the emergency department

INTRODUCTION

Proliferation of Food and Drug Administration-approved drugs makes it impossible for emergency medicine (EM) faculty to stay current on potential interactions between drugs, and with diseases, laboratory tests, and ethanol. A computer database may augment physician knowledge.

OBJECTIVES

To compare the performance of EM faculty and an "expert" emergency physician (EP) with that of a criterion standard computer database in identifying potential drug interactions, and to report the incidence of drug-ethanol and drug-laboratory test interactions.

METHODS

This was a retrospective review of 276 emergency department charts for drug, ethanol, lab, and medical history. Evaluation by both EM faculty and an "expert" EP of patient history was done to identify potential interactions, and comparison with the Micromedex Drug-Reax database for potential interactions (graded minor, moderate, or major) was made. Clinical significance of potential interactions was judged by a second EM faculty member.

RESULTS

Seventeen percent of the patients had potential drug-drug interactions, and 25% of these were judged to be clinically significant. Up to 52% of the patients had potential drug-ethanol interactions, while 38% of the patients could have potential drug-lab interactions. Sensitivity, specificity, and positive and negative predictive values of the EM faculty for potential drug-drug interactions compared with the computer were poor, at 14%, 58%, 6%, and 23%, respectively. The corresponding values for the "expert" EP were 25%, 86%, 26%, and 85%. The "expert" EP was statistically better than the EM faculty, but still less sensitive and predictive than the computer.

CONCLUSIONS

A computer can aid the physician in avoiding potential drug interactions. Prospective validation of these findings should be done.

Promoting patient safety and preventing medical error in emergency departments

An estimated 108,000 people die each year from potentially preventable iatrogenic injury. One in 50 hospitalized patients experiences a preventable adverse event. Up to 3% of these injuries and events take place in emergency departments. With long and detailed training, morbidity and mortality conferences, and an emphasis on practitioner responsibility, medicine has traditionally faced the challenges of medical error and patient safety through an approach focused almost exclusively on individual practitioners. Yet no matter how well trained and how careful health care providers are, individuals will make mistakes because they are human. In general medicine, the study of adverse drug events has led the way to new methods of error detection and error prevention. A combination of chart reviews, incident logs, observation, and peer solicitation has provided a quantitative tool to demonstrate the effectiveness of interventions such as computer order entry and pharmacist order review. In emergency medicine (EM), error detection has focused on subjects of high liability: missed myocardial infarctions, missed appendicitis, and misreading of radiographs. Some system-level efforts in error prevention have focused on teamwork, on strengthening communication between pharmacists and emergency physicians, on automating drug dosing and distribution, and on rationalizing shifts. This article reviews the definitions, detection, and presentation of error in medicine and EM. Based on review of the current literature, recommendations are offered to enhance the likelihood of reduction of error in EM practice.

Appropriateness of medication selection for older persons in an urban academic emergency department

OBJECTIVES

To determine the frequency of potentially inappropriate medication selection for older persons presenting to the ED, the most common problematic drugs, risk factors for suboptimal medication selection, and whether use of these medications is associated with worse outcomes.

METHODS

The authors performed a prospective cohort study of 898 patients 65 years or older who presented to an urban academic ED in 1995 and 1996. Seventy-nine percent of the patients were African-American and 43% did not graduate from high school. Potentially inappropriate medications and adverse drug-disease interactions were identified using the 1997 Beers explicit criteria for elders. During the three months after the initial visit, revisits to the ED or hospital, death, and changes in health-related quality of life were analyzed as measured by validated questions adapted from the Medical Outcomes Study.

RESULTS

Upon presentation, 10.6% of the patients were taking a potentially inappropriate medication, 3.6% were given one in the ED, and 5.6% were prescribed one upon discharge from the ED. The most frequently prescribed potentially inappropriate medications in the ED were diphenhydramine, indomethacin, meperidine, and cyclobenzaprine. Emergency physicians added potentially inappropriate medications most often to patients with discharge diagnoses of musculoskeletal disorder, back pain, gout, and allergy or urticaria. Potentially adverse drug-disease interactions were relatively uncommon at presentation (5.2%), in the ED (0.6%), and on discharge from the ED (1.2%). Potentially inappropriate medications and adverse drug-disease interactions prescribed in the ED were not associated with higher rates of revisit to the ED, hospitalization, or death, but were correlated with worse physical function and pain. However, confidence intervals were wide for analyses of revisits and death.

CONCLUSIONS

Suboptimal medication selection was fairly common and was associated with worse patient-reported health-related quality of life.

Pearls, pitfalls, and updates in toxicology

Pearls and pitfalls learned from our practical experiences caring for poisoned patients are presented. Clinical pearls include the following: using diagnostic tests to detect end-organ toxicity, applying physiologic principles to the management of hemodynamically unstable poisoned patients, and dealing with psychologic injuries from hazardous materials incidents. Recognizing serious complications from poisoning and adverse drug effects, including the serotonin syndrome, are offered as pitfalls. Pharmaceutical companies are rapidly developing and marketing new therapies. Therefore, updates on the evolving role of NAC as an antidote for acetaminophen poisoning, new psychotropic medications, and new antidotes were included in this article. These pearls, pitfalls, and updates are intended to provide practical information that is readily applicable to the clinical practice of emergency medicine.

Drug-drug and drug-disease interactions in the ED: analysis of a high-risk population

A study was undertaken to determine the potential for adverse drug interactions (ADIs) and drug-disease interactions (DDIs) in a high-risk population of emergency department (ED) patients and to characterize drug-drug and drug-disease interactions in terms of percentage of patients at risk from existing drug regimens, percentage of patients at risk from ED treatment, relation between number of drugs and potential for interactions, types of drugs and diseases posing greatest potential for interaction, and the differences in a general versus community hospital population with respect to these parameters. Records of 205 consecutive patients, 111 from a general hospital teaching facility ED (Facility 1) and 94 from a community hospital ED (Facility 2) were retrospectively reviewed. The records of all patients receiving three or more medications and all patients older than 50 years of age receiving two or more medications were analyzed by two computer programs for the presence of potential drug-drug and drug-disease interactions. A total of 226 potential ADIs were found in 89 patients (47%), with 50% of ADIs being related to ED treatment. A total of 94 potential DDIs were found in 44 patients (21%), with 34% of DDIs being related to ED treatment. The risk of an ADI rose from 13% for patients taking 2 medications to 82% for patients taking 7 or more medications. Eleven medications and four disease categories were identified as having particular potential for interactions. No significant differences were found between the general and the community hospital populations in these respects. ED patients taking three or more medications and patients older than 50 years of age taking two or more medications are at substantial risk for adverse drug-drug and drug-disease interactions. The risk is increased in patients taking particular drugs or having particular disease states.

Potential drug interactions in a physical medicine and rehabilitation clinic

Potentially preventable adverse drug-drug interactions increase morbidity and financial costs to hospitals and third party payers. This study's purpose is to document the prevalence of potential drug-drug interactions (PDDI) in patients referred to a Physical Medicine and Rehabilitation (PM&R) clinic, to identify risk factors associated with PDDI, and to evaluate physicians' ability to correctly identify these PDDI. Current medication lists were obtained by questionnaire and confirmed by chart review for 121 consecutive new patients. The physician-identified PDDI were compared with computer-identified PDDI. Twenty-seven patients (22%; 95% confidence interval, 15-31%) had PDDI. PDDI were associated with number of medications (P = 0.0011) and PM&R subspecialty clinic (P = 0.012). Twenty-nine of the 46 computer-identified interactions (63%) were not identified by the physicians, and the physicians falsely identified 28 other drug combinations as PDDI. Potential drug-drug interactions occur at high rates in PM&R outpatient populations, and physicians are inadequately prepared to identify these PDDI.

A comparison of drug interaction software programs: applicability to the emergency department

STUDY OBJECTIVE

To compare the features of available drug interaction software programs in terms of general applicability to an emergency department setting.

DESIGN

Prospective evaluation of drug interaction software programs based on presence or absence of a variety of performance features.

SETTING

University and community hospital EDs.

PARTICIPANTS

Eight commercially available drug interaction software programs.

RESULTS

Programs were evaluated according to designated performance and data base features. Tabulated results were compiled for purposes of comparison.

CONCLUSION

Although no computer program tested completely met the specific needs of a busy ED, many programs have features with at least some general applicability.