Potential Drug-Drug Interactions Associated with Prolonged Stays in the Intensive Care Unit

An Assessment of Medication Errors Among Pediatric Patients in Three Hospitals in Freetown Sierra Leone: Findings and Implications for a Low-Income Country

Background

Pediatric patients are prone to medicine-related problems like medication errors (MEs), which can potentially cause harm. Yet, this has not been studied in this population in Sierra Leone. Therefore, this study investigated the prevalence and nature of MEs, including potential drug-drug interactions (pDDIs), in pediatric patients.

Methods

The study was conducted in three hospitals among pediatric patients in Freetown and consisted of two phases. Phase one was a cross-sectional retrospective review of prescriptions for completeness and accuracy based on the global accuracy score against standard prescription writing guidelines. Phase two was a point prevalence inpatient chart review of MEs categorized into prescription, administration, and dispensing errors and pDDIs. Data was analyzed using frequency, percentages, median, and interquartile range. Kruskal-Wallis H and Mann-Whitney U-tests were used to compare the prescription accuracy between the hospitals, with p<0.05 considered statistically significant.

Results

Three hundred and sixty-six (366) pediatric prescriptions and 132 inpatient charts were reviewed in phases one and two of the study, respectively. In phase one, while no prescription attained the global accuracy score (GAS) gold standard of 100%, 106 (29.0%) achieved the 80-100% mark. The patient 63 (17.2%), treatment 228 (62.3%), and prescriber 33 (9.0%) identifiers achieved an overall GAS range of 80-100%. Although the total GAS was not statistically significant (p=0.065), the date (p=0.041), patient (p=<0.001), treatment (p=0.022), and prescriber (p=<0.001) identifiers were statistically significant across the different hospitals. For phase two, the prevalence of MEs was 74 (56.1%), while that of pDDIs was 54 (40.9%). There was a statistically positive correlation between the occurrence of pDDI and number of medicines prescribed (r=0.211, P=0.015).

Conclusion

A Low GAS indicates poor compliance with prescription writing guidelines and high prescription errors. Medication errors were observed at each phase of the medication use cycle, while clinically significant pDDIs were also reported. Thus, there is a need for training on prescription writing guidelines and medication errors.

Are polypharmacy side effects predicted by public data still valid in real-world data?

Background and Objective

Although interest in predicting drug-drug interactions is growing, many predictions are not verified by real-world data. This study aimed to confirm whether predicted polypharmacy side effects using public data also occur in data from actual patients.

Methods

We utilized a deep learning-based polypharmacy side effects prediction model to identify cefpodoxime-chlorpheniramine-lung edema combination with a high prediction score and a significant patient population. The retrospective study analyzed patients over 18 years old who were admitted to the Asan medical center between January 2000 and December 2020 and took cefpodoxime or chlorpheniramine orally. The three groups, cefpodoxime-treated, chlorpheniramine-treated, and cefpodoxime & chlorpheniramine-treated were compared using inverse probability of treatment weighting (IPTW) to balance them. Differences between the three groups were analyzed using the Kaplan-Meier method and Cox proportional hazards model.

Results

The study population comprised 54,043 patients with a history of taking cefpodoxime, 203,897 patients with a history of taking chlorpheniramine, and 1,628 patients with a history of taking cefpodoxime and chlorpheniramine simultaneously. After adjustment, the 1-year cumulative incidence of lung edema in the patient group that took cefpodoxime and chlorpheniramine simultaneously was significantly higher than in the patient groups that took cefpodoxime or chlorpheniramine only (p=0.001). Patients taking cefpodoxime and chlorpheniramine together had an increased risk of lung edema compared to those taking cefpodoxime alone [hazard ratio (HR) 2.10, 95% CI 1.26-3.52, p<0.005] and those taking chlorpheniramine alone, which also increased the risk of lung edema (HR 1.64, 95% CI 0.99-2.69, p=0.05).

Conclusions

Validation of polypharmacy side effect predictions with real-world data can aid patient and clinician decision-making before conducting randomized controlled trials. Simultaneous use of cefpodoxime and chlorpheniramine was associated with a higher long-term risk of lung edema compared to the use of cefpodoxime or chlorpheniramine alone.

Drug-Drug Interactions among Patients Hospitalized with COVID-19 in Greece

The modulation of the pharmacological action of drugs due to drug-drug interactions (DDIs) is a critical issue in healthcare. The aim of this study was to evaluate the prevalence and the clinical significance of potential DDIs in patients admitted to the University Hospital of Heraklion in Greece with coronavirus disease 2019 (COVID-19). Cardiovascular disorders (58.4%) and diabetes (types I and II) (29.6%) were the most common comorbidities. A high occurrence of DDIs was observed, and clinically significant DDIs that may hamper response to treatment represented 40.3% of cases on admission, 21% during hospitalization, and 40.7% upon discharge. Polypharmacy and comorbidities were associated with a higher prevalence of DDIs in a statistically significant way (p < 0.05, 95% CI). Clinically significant DDIs and increased C-reactive protein values upon admission were associated with prolonged hospitalization. The results reveal that patients admitted due to COVID-19 in Greece often have an additional burden of DDIs that healthcare teams should approach and resolve.

Prevalence of polypharmacy and risk of potential drug-drug interactions among hospitalized patients with emphasis on the pharmacokinetics

BACKGROUND

Both polypharmacy and potential drug-drug interactions (pDDIs), especially those at the pharmacokinetic level, are common in hospitalized patients and are associated with adverse effects and failure of therapy.

OBJECTIVE

The aim of the present study is to investigate retrospectively the prevalence of polypharmacy and the risk of potential pharmacokinetic drug-drug interaction among hospitalized patients.

METHODS

The medical documentation of hospitalized patients in the unit of internal diseases at the hospital "St Marina" in Varna, Bulgaria for a period of six months (January-July 2016) was retrospectively reviewed. Lexicomp® Drug Interaction software was used for the detection of pDDI. Descriptive statistic and logistic regression were used for data analysis.

RESULTS

In this study, 294 patients out of 510 (57%) were selected with polypharmacy. The number of detected potential pharmacokinetic DDIs (pPKDDIs) was only 216 (or 12,4%), but almost 40% of patients with polypharmacy were exposed to at least one pPKDDIs. The most common pPKDDIs occur at the biotransformation level - 78 (36,1%), and the most common enzyme form that is involved in these interactions is cytochrome 3A4 (44 or 20,4%). The number of prescribed medications (>7) was found to increase the possibility of having pDDIs (OR 25.535, 95% CI 12.529 to 52.042; p = <0.001) and pPKDDIs (OR 5.165, 95% CI 3.430 to 7.779; p = <0.001) as well.

CONCLUSION AND RELEVANCE

Caution should be taken in patients taking more than seven drugs and careful assessment of the pPKDDIs should be made. When such interactions are detected, they need to be properly evaluated and managed.

Heterogeneity in the identification of potential drug-drug interactions in the intensive care unit: A systematic review, critical appraisal, and reporting recommendations

Patients admitted to the intensive care unit (ICU) are frequently exposed to potential drug‐drug interactions (pDDIs). However, reported frequencies of pDDIs in the ICU vary widely between studies. This can be partly explained by significant variation in their methodological approach. Insight into methodological choices affecting pDDI frequency would allow for improved comparison and synthesis of reported pDDI frequencies. This study aimed to evaluate the association between methodological choices and pDDI frequency and formulate reporting recommendations for pDDI frequency studies in the ICU. The MEDLINE database was searched to identify papers reporting pDDI frequency in ICU patients. For each paper, the pDDI frequency and methodological choices such as pDDI definition and pDDI knowledge base were extracted, and the risk of bias was assessed. Each paper was categorized as reporting a low, medium, or high pDDI frequency. We sought associations between methodological choices and pDDI frequency group. Based on this comparison, reporting recommendations were formulated. Analysis of methodological choices showed significant heterogeneity between studies, and 65% of the studies had a medium to high risk of bias. High risk of bias, small sample size, and use of drug prescriptions instead of administrations were related to a higher pDDI frequency. The findings of this review may support researchers in designing a reliable methodology assessing pDDI frequency in ICU patients. The reporting recommendations may contribute to standardization, comparison, and synthesis of pDDI frequency studies, ultimately improving knowledge about pDDIs in and outside the ICU setting.

The Prevalence of Drug-Drug Interactions with Antiretroviral Therapy in Human Immunodeficiency Virus-Infected Patients in the Intensive Care Unit

Background: Persons living with human immunodeficiency virus (HIV) (PWH) on antiretroviral therapy (ART) are frequently admitted to the intensive care unit (ICU). Persons living with HIV on ART may be at higher risk for potential drug-drug interactions (pDDIs) due to polypharmacy in the ICU. We determined the prevalence of pDDI with ART in critically ill PWH. Objectives: The primary outcome was prevalence of pDDI between ART and ICU medications. Secondary outcomes included pDDI per ICU admission, pDDI severity, ICU, and hospital length of stay (LOS). Methods: A single-center, retrospective cohort evaluating PWH ≥ 18 years old admitted to the ICU for > 24 hours who received ART during ICU admission, between January 2013 and 2015 at a tertiary care hospital in the United States. Each ICU admission was counted as a separate encounter. Medication databases and chart review were used to identify pDDI. Results: We included 77 PWH encounters; mean age was 55 ± 9 years and 65% were male. We identified 208 pDDIs among 53/77 (68.8%), with a mean 4 ± 2 pDDI per ICU admission. Antipsychotics (20%), analgesics (20%), and anti-lipemics (11%) were the most common ICU medications with ART-related pDDI. Of the pDDI, 64% were major, 24% moderate, and 12% contraindicated. Median ICU and hospital LOS were 4 days (IQR: 3-5) and 11 days (IQR: 7-31), respectively. Conclusion: Most PWH had at least one pDDI during ICU admission. Collaborations among pharmacists, intensivists, and infectious disease/HIV specialists to develop effective, actionable strategies, such as electronic health record alerts, could reduce pDDIs for PWH on ART in the ICU.

Potentially inappropriate medications and medication combinations before, during and after hospitalizations: an analysis of pathways and determinants in the Swiss healthcare setting

Background

A hospitalization phase represents a challenge to medication safety especially for multimorbid patients as acute medical needs might interact with pre-existing medications or evoke adverse drug effects. This project aimed to examine the prevalence and risk factors of potentially inappropriate medications (PIMs) and medication combinations (PIMCs) in the context of hospitalizations.

Methods

Analyses are based on claims data of patients (≥65 years) with basic mandatory health insurance at the Helsana Group, and on data from the Hirslanden Swiss Hospital Group. We assessed PIMs and PIMCs of patients who were hospitalized in 2013 at three different time points (quarter prior, during, after hospitalization). PIMs were identified using the PRISCUS list, whereas PIMCs were derived from compendium.ch. Zero-inflated Poisson regression models were applied to determine risk factors of PIMs and PIMCs.

Results

Throughout the observation period, more than 80% of patients had at least one PIM, ranging from 49.7% in the pre-hospitalization, 53.6% in the hospitalization to 48.2% in the post-hospitalization period. PIMCs were found in 46.6% of patients prior to hospitalization, in 21.3% during hospitalization, and in 25.0% of patients after discharge. Additional medication prescriptions compared to the preceding period and increasing age were the main risk factors, whereas managed care was associated with a decrease in PIMs and PIMCs.

Conclusion

We conclude that a patient’s hospitalization offers the possibility to increase medication safety. Nevertheless, the prevalence of PIMs and PIMCs is relatively high in the study population. Therefore, our results indicate a need for interventions to increase medication safety in the Swiss healthcare setting.

Assessment of Physician's Knowledge of Potential Drug-Drug Interactions: An Online Survey in China

Background: Drug interactions are the most common preventable cause of adverse drug reaction, which may result in drug toxicity or undesired therapeutic effect with harmful outcomes to patients. Given the rising use of combination therapies, the main objectives of this study were to estimate the degree to which physicians can identify potential drug-drug interactions (PDDIs) correctly and to describe the common source of information used by physicians when they need to check PDDIs. Methods: A cross-sectional survey utilizing a self-administered online questionnaire was conducted among physicians in China. Participants were asked to classify 20 drug pairs as "no interaction," "may be used together with monitoring," "contraindication," and "not sure." We also collected data on the physician's source of information and altitude toward the PDDIs. An ordinary least square regression model was performed to investigate the potential predictors of PDDI knowledge. Results: Eligible questionnaires were obtained from 618 physicians. The respondents classified correctly 6.7 out of 20 drug pairs, or 33.4% of the drug interactions investigated. The number of drug pairs recognized by respondents was ranged from 0 to 16. The percentage of physicians who recognized specific drug pairs ranged from 8.3% for no interactions between conjugated estrogens and raloxifene, to 64.0% for the interaction between dopamine and phenytoin. When the respondents want to check PDDI information, the most commonly used source of information was package inserts (n = 572, 92.6%), followed by the Internet or mobile Apps (n = 424, 68.6%), consultation with clinical pharmacists (n = 384, 62.1%), medical textbooks (n = 374, 60.5%), knowledge base in Chinese (n = 283, 45.8%), and other physicians (n = 366, 59.2%). In the multiple regression analysis, the significant predictors of a higher number of recognized drug pairs were years of practice and altitudes toward PDDIs. Conclusion: In this online survey accessing physician's ability to detect PDDIs, less than half of the drug pairs were recognized, indicating unsatisfactory level of knowledge about the clinically significant drug interactions. Continuing education and accessible electronic database can help physicians detecting PDDIs and improve drug safety.

Severe Potential Drug-Drug Interactions and the Increased Length of Stay of Children in Intensive Care Unit

Children are exposed to drug-drug interactions (DDI) risks due to their organism’s complexity and the need for several medicines prescriptions in pediatric intensive care units (PICU). This study aimed to assess the prevalence of potential DDIs in a Brazilian PICU. We carried out a cross-sectional study at a pediatric teaching hospital from Rio de Janeiro (Brazil) over one year. Potential DDIs (pDDIs) between prescribed medicines for hospitalized children in PICU (n = 143) were analyzed according to severity using Micromedex^®. Sex, age group, number of drugs prescribed, vasoactive amines use (a proxy of clinical complexity), and the PICU length of stay were summarized using descriptive statistics. Association between the PICU length stay, and variables sex, age, clinical condition complexity, number of drugs prescribed, and severity of pDDI were examined by univariate and multiple linear regression. Seventy percent of patients aged three days to 14 years old were exposed at least one potential DDIs during PICU stay. Two hundred eighty-four different types of pDDIs were identified, occurring 1,123 times. Nervous system drugs were implicated in 55% of the interactions, and fentanyl (10%) was most involving in pDDIs. Most pDDIs were classified as higher severity (56.2%), with reasonable documentation (64.6%) and unspecified onset time (63.8%). Worse clinical condition, ten or more drugs prescribed, and most severe pDDIs were associated with a longer PICU length of stay. Multiple linear regression analysis showed an increase of 9.83 days (95% confidence interval: 3.61–16.05; p = 0.002) in the PICU length of stay in children with major or contraindicated pDDIs. The results of this research may support the monitoring and prevention of pDDIs related to adverse events in children in intensive care and the design and conduction of new studies.

Medication errors and drug knowledge gaps among critical-care nurses: a mixed multi-method study

BACKGROUND

Medication errors are a serious and complex problem in clinical practice, especially in intensive care units whose patients can suffer potentially very serious consequences because of the critical nature of their diseases and the pharmacotherapy programs implemented in these patients. The origins of these errors discussed in the literature are wide-ranging, although far-reaching variables are of particular special interest to those involved in training nurses. The main objective of this research was to study if the level of knowledge that critical-care nurses have about the use and administration of medications is related to the most common medication errors.

METHODS

This was a mixed (multi-method) study with three phases that combined quantitative and qualitative techniques. In phase 1 patient medical records were reviewed; phase 2 consisted of an interview with a focus group; and an ad hoc questionnaire was carried out in phase 3.

RESULTS

The global medication error index was 1.93%. The main risk areas were errors in the interval of administration of antibiotics (8.15% error rate); high-risk medication dilution, concentration, and infusion-rate errors (2.94% error rate); and errors in the administration of medications via nasogastric tubes (11.16% error rate).

CONCLUSIONS

Nurses have a low level of knowledge of the drugs they use the most and with which a greater number of medication errors are committed in the ICU.

Quality assessment of adult intensive care services: application of a tool adjusted to the reality of low-income countries

Objective

To assess the quality of adult intensive care units.

Methods

This population-based, cross-sectional, observational, analytical study evaluated management type in Maranhão, Brazil. An assessment instrument was applied that assigned scores to each service (maximum 124 points). The units were categorized as insufficient (< 50% of the maximum score), typical (≥ 50% and <80% of the maximum score), or sufficient (≥ 80% of the maximum score).

Results

Of the 26 intensive care units in Maranhão, 23 were evaluated; 15 (65.2%) were located in the state capital, and 14 (60.9%) were public. The mean final score was 67.2 (54.2% of the maximum). The worst performance was observed with regard to processes (50.9%) in the units located outside the capital (p = 0.037) and for hospitals with 68 beds or fewer (p = 0.027). The result of the assessment categorized services as a function of the overall total points earned. Specifically, 8 (34.8%) services were assessed as insufficient, 13 (56.5%) were assessed as typical, and 2 (8.7%) were assessed as sufficient.

Conclusion

The majority of the intensive care units in this study were assessed as typical. These services must be better qualified. The priorities are the processes of the units located outside the capital and in small hospitals.

The prevalence of potentially beneficial and harmful drug-drug interactions in intensive care units

Background The present study was conducted with the aim of investigating the prevalence of potentially beneficial and harmful drug-drug interactions (DDIs) in intensive care units (ICUs). Methods The present cross-sectional prospective study was conducted in two ICUs in Shahr-e Kord city, Iran. The study sample was consisted of 300 patients. The Drug Interaction Facts reference text book [Tatro DS. Drug interaction facts. St Louis, MO: Walters Kluwer Health, 2010.] was used to determine the type and the frequency of the DDIs. Results The participants consisted of 189 patients men and 111 women. The mean age of patients was 44.2 ± 24.6 years. Totally, 60.5% of patients had at least one drug-drug interaction in their profile. The total number of DDIs found was 663 (the mean of the total number of drug-drug interactions was 2.4 interactions per patient). Of all the 663 interactions, 574 were harmful and others were beneficial. In terms of starting time, 98 of the potential interactions were rapid and 565 of them were delayed. In terms of severity, 511 of the potential interactions were moderate. Some of the drugs in the patients' medical records including phenytoin, dopamine, ranitidine, corticosteroid, dopamine, heparin, midazolam, aspirin, magnesium, calcium gluconate, and antibiotics, the type of ventilation, the type of nutrition and the duration of hospital stay were among the factors that were associated with high risk of potential DDIs (p < 0.05). Conclusions The prevalence of potentially beneficial and harmful DDIs, especially harmful drug-drug interactions, is high in ICUs and it is necessary to reduce these interactions by implementing appropriate programs and interventions.

Clinical trials on drug-drug interactions registered in ClinicalTrials.gov reported incongruent safety data in published articles: an observational study

OBJECTIVE

To assess safety data of trials on drug-drug interactions (DDIs) reported in ClinicalTrials.gov and published in journal articles, since DDIs are a growing concern.

STUDY DESIGN AND SETTING

In an observational study of clinical trials retrieved by the search term "drug-drug interaction(s)," we collected the information on registration and on adverse events (AEs) from ClinicalTrials.gov and corresponding publications. Trials were included if they primarily investigated DDIs, had a National Clinical Trial identifier, and were closed and completed by October 16, 2015. Publication data were extracted until March 2017.

RESULTS

Among 1,110 eligible trials, most were in phase 1 (76.8%), industry-funded (68.8%), and started before registration (56.9%). Results were not reported in the registry for 86.8% and not published for 68.1% trials. Published AE data were completely identical to the data submitted to ClinicalTrials.gov for only 15.6% trials. Among 64 trials with results reported both in ClinicalTrials.gov and publications, 34.4% published concordant number for other AEs.

CONCLUSION

Discrepancies that emerge from incomplete or changed reporting of AEs in publications emphasize the need to amend and enforce regulatory requirements for timely and complete submission of results, clearer AE reporting for trials focusing on DDIs, and regular assessment of the congruence of AE data submitted to ClinicalTrials.gov and scientific journals during the publication process.

Preventable adverse drug events in critically ill HIV patients: Is the detection of potential drug-drug interactions a useful tool?

OBJECTIVES

The aim of this study was to develop a strategy to identify adverse drug events associated with drug-drug interactions by analyzing the prescriptions of critically ill patients.

METHODS

This retrospective study included HIV/AIDS patients who were admitted to an intensive care unit between November 2006 and September 2008. Data were collected in two stages. In the first stage, three prescriptions administered throughout the entire duration of these patients' hospitalization were reviewed, with the Micromedex database used to search for potential drug-drug interactions. In the second stage, a search for adverse drug events in all available medical, nursing and laboratory records was performed. The probability that a drug-drug interaction caused each adverse drug events was assessed using the Naranjo algorithm.

RESULTS

A total of 186 drug prescriptions of 62 HIV/AIDS patients were analyzed. There were 331 potential drug-drug interactions, and 9% of these potential interactions resulted in adverse drug events in 16 patients; these adverse drug events included treatment failure (16.7%) and adverse reactions (83.3%). Most of the adverse drug reactions were classified as possible based on the Naranjo algorithm.

CONCLUSIONS

The approach used in this study allowed for the detection of adverse drug events related to 9% of the potential drug-drug interactions that were identified; these adverse drug events affected 26% of the study population. With the monitoring of adverse drug events based on prescriptions, a combination of the evaluation of potential drug-drug interactions by clinical pharmacy services and the monitoring of critically ill patients is an effective strategy that can be used as a complementary tool for safety assessments and the prevention of adverse drug events.

Potential drug-drug interactions and their risk factors in pediatric patients admitted to the emergency department of a tertiary care hospital in Mexico

Background

Drug-drug interactions (DDIs) detected in a patient may not be clinically apparent (potential DDIs), and when they occur, they produce adverse drug reactions (ADRs), toxicity or loss of treatment efficacy. In pediatrics, there are only few publications assessing potential DDIs and their risk factors. There are no studies in children admitted to emergency departments (ED). The present study estimates the prevalence and describes the characteristics of potential DDIs in patients admitted to an ED from a tertiary care hospital in Mexico; in addition, potential DDI-associated risk factors are investigated.

Methods

A secondary analysis of data from 915 patients admitted to the ED of the Hospital Infantil de México “Federico Gómez” was conducted. The Medscape Drug Interaction Checker software was used to identify potential DDIs. The results are expressed as number of cases (%), means (95% CI) and medians (25-75^th percentiles). Count data regressions for number of total and severity-stratified potential DDIs were performed adjusting for patient characteristics, number of administered drugs, days of stay, presence of ADRs and diagnoses.

Results

The prevalence of potential DDIs was 61%, with a median of 4 (2–8). A proportion of 0.2% of potential DDIs was “Contraindicated”, 7.5% were classified as “Serious”, 62.8% as “Significant” and 29.5% as “Minor”. Female gender, age, days of stay, number of administered drugs and diagnoses of Neoplasms (C00-D48), Congenital malformations (Q00-Q99), Diseases of the Blood, Blood-forming Organs and Immunity (D50-D89) and Diseases of the nervous system (G00-G99) were significantly associated with potential DDIs.

Conclusion

The prevalence of potential DDIs in the ED is high, and strategies should therefore be established to monitor patients’ safety during their stay, in addition to conducting investigations to estimate the real harm potential DDIs inflict on patients.

Drug-drug interactions and their harmful effects in hospitalised patients: a systematic review and meta-analysis

PURPOSE

Drug-drug interactions (DDIs) are often avoidable and, if undetected, can lead to patient harm. This review aimed to determine the prevalence of potential DDIs (pDDIs), clinically relevant DDIs (DDIs that could lead to measurable patient harm, taking into account the patient's individual clinical profile) and DDIs that resulted in actual patient harm during hospitalisation.

METHOD

Four databases were scanned for English papers published from 2000 to 2016. Papers that reported prevalence of DDIs in the outpatient setting, at admission or discharge, involving only specific drugs, or in specific disease populations or age groups were excluded.

RESULTS

Twenty-seven papers met the inclusion criteria and were graded for quality using the Critical Appraisal Skills Programme (CASP) cohort study checklist. Ten papers were rated as 'poor', 14 as 'fair' and only three papers as 'good'. Overall, the meta-analysis revealed that 33% of general patients and 67% of intensive care patients experienced a pDDI during their hospital stay. It was not possible to determine the prevalence of clinically relevant DDIs or DDIs that resulted in actual patient harm as data on these categories were limited. Of the very few studies that reported on harm, only a small proportion of DDIs were found to have resulted in actual patient harm.

CONCLUSIONS

Standardisation of DDI definitions and research methods are required to allow meaningful prevalence rates to be obtained and compared. Studies that go further than measuring pDDIs are critically needed to determine the impact of DDIs on patient safety.

Risk factors for potential drug-drug interactions in intensive care unit patients

PURPOSE

To determine risk factors for each severity-based category of potential drug-drug interactions (DDIs) encountered at intensive care unit (ICU) patients.

METHODS

This was a retrospective cohort analysis of patients treated at the ICU of the Clinical Center Kragujevac, a public tertiary care hospital in Kragujevac, Serbia. Three interaction checkers were used to reveal drug-drug interactions: Medscape, Epocrates and Micromedex.

RESULTS

The study included 201 patients, 66.19±16.11 years of age. Average number of DDIs per patient ranged from 10.49±8.80 (Micromedex) to 29.43±21.51 (Medscape). Antiarrhythmic or anticonvulsant drug prescription, Charlson Comorbidity Index, male sex, length of hospitalization, number of drugs or therapeutic groups prescribed and surgery increased the risk of DDIs in ICU patients, while presence of delirium or dementia and transfer from emergency department to ICU protected against.

CONCLUSIONS

The rate of the DDIs in ICU patients at a tertiary care hospital is high, and adversely influenced by number of drugs or drug groups prescribed per patient, antiarrhythmic or anticonvulsant drug prescription, comorbidities, length of hospitalization and surgery. On the other hand, presence of cognitive deficit and transfer from emergency department to ICU protect ICU patients from the DDIs.

Potential intravenous drug interactions in intensive care

OBJECTIVE

To analyze potential intravenous drug interactions, and their level of severity associated with the administration of these drugs based on the prescriptions of an intensive care unit.

METHOD

Quantitative study, with aretrospective exploratory design, and descriptive statistical analysis of the ICU prescriptions of a teaching hospital from March to June 2014.

RESULTS

The sample consisted of 319 prescriptions and subsamples of 50 prescriptions. The mean number of drugs per patient was 9.3 records, and a higher probability of drug interaction inherent to polypharmacy was evidenced. The study identified severe drug interactions, such as concomitant administration of Tramadol with selective serotonin reuptake inhibitor drugs (e.g., Metoclopramide and Fluconazole), increasing the risk of seizures due to their epileptogenic actions, as well as the simultaneous use of Ranitidine-Fentanyl®, which can lead to respiratory depression.

CONCLUSION

A previous mapping of prescriptions enables the characterization of the drug therapy, contributing to prevent potential drug interactions and their clinical consequences.

OBJETIVO

Analisar as potenciais interações medicamentosas intravenosas e seu grau de severidade associadas à administração desses medicamentos a partir das prescrições do Centro de Terapia Intensiva.

MÉTODO

Estudo quantitativo, tipologia retrospectiva exploratória, com análise estatística descritiva das prescrições medicamentosas do Centro de Terapia Intensiva de um Hospital Universitário, no período de março-junho/2014.

RESULTADOS

A amostra foi composta de 319 prescrições e subamostras de 50 prescrições. Constatou-se que a média de medicamentos por paciente foi de 9,3 registros, e evidenciou-se maior probabilidade para ocorrência de interação medicamentosa inerente à polifarmácia. O estudo identificou interações medicamentosas graves, como a administração concomitante de Tramadol com medicamentos inibidores seletivos da recaptação da serotonina, (exemplo: Metoclopramida e Fluconazol), aumentando o risco de convulsões devido às suas ações epileptogênicas, além do uso simultâneo de Ranitidina-Fentanil®, que pode ocasionar depressão respiratória.

CONCLUSÃO

O mapeamento prévio das prescrições possibilita a caracterização da terapêutica medicamentosa, contribuindo para obstar as potenciais interações medicamentosas e suas consequências clínicas.

Drug-drug interactions in the intensive care unit: Do they really matter?

PURPOSE

To describe prevalence and patterns of potential drug-drug interactions (pDDIs) in the intensive care unit (ICU), occurrence of adverse drug events (ADEs), and agreement between different compendia and intensivists' perceptions.

METHODS

A cross-sectional study. Drug profiles of all adult patients from 2 academic ICUs were screened on day 3 upon admission. We identified pDDIs using 3 compendia (Stockley's, Micromedex, and Epocrates) and documented their mechanism of action, clinical consequences, severity, level of evidence, and management. Medical records were searched to identify ADEs potentially related to major pDDIs. Agreement between information sources (compendia, intensivists) was evaluated.

RESULTS

We identified 1120 pDDIs among 275 patients. Median number of pDDIs per patient was 3.0 (interquartile range, 1-6), with 79% of patients presenting with at least 1 pDDI. Major pDDIs were detected in 18% of patients, with potentially related to ADEs in 4% of patients. Only 13% of all pDDIs were documented simultaneously in all 3 compendia. Different information sources (compendia, clinicians) showed "no" to "fair" agreement.

CONCLUSIONS

Potential drug-drug interactions occurred in most ICU patients, contrasting with low rates of potentially related ADEs, which may have been underestimated. Sources of information are inconsistent, challenging the identification of pDDIs.

Severe potential drug-drug interactions in older adults with dementia and associated factors

OBJECTIVE

To identify the main severe potential drug-drug interactions in older adults with dementia and to examine the factors associated with these interactions.

METHOD

This was a cross-sectional study. The enrolled patients were selected from six geriatrics clinics of tertiary care hospitals across Mexico City. The patients had received a clinical diagnosis of dementia based on the current standards and were further divided into the following two groups: those with severe drug-drug interactions (contraindicated/severe) (n=64) and those with non-severe drug-drug interactions (moderate/minor/absent) (n=117). Additional socio-demographic, clinical and caregiver data were included. Potential drug-drug interactions were identified using Micromedex Drug Reax 2.0® database.

RESULTS

A total of 181 patients were enrolled, including 57 men (31.5%) and 124 women (68.5%) with a mean age of 80.11±8.28 years. One hundred and seven (59.1%) patients in our population had potential drug-drug interactions, of which 64 (59.81%) were severe/contraindicated. The main severe potential drug-drug interactions were caused by the combinations citalopram/anti-platelet (11.6%), clopidogrel/omeprazole (6.1%), and clopidogrel/aspirin (5.5%). Depression, the use of a higher number of medications, dementia severity and caregiver burden were the most significant factors associated with severe potential drug-drug interactions.

CONCLUSIONS

Older people with dementia experience many severe potential drug-drug interactions. Anti-depressants, antiplatelets, anti-psychotics and omeprazole were the drugs most commonly involved in these interactions. Despite their frequent use, anti-dementia drugs were not involved in severe potential drug-drug interactions. The number and type of medications taken, dementia severity and depression in patients in addition to caregiver burden should be considered to avoid possible drug interactions in this population.

The prevalence of major potential drug-drug interactions at a University health centre pharmacy in Jamaica

OBJECTIVE

To identify major potential drug-drug interactions (DDIs) on prescriptions filled at the University Health Centre Pharmacy, Mona Campus, Jamaica.

METHODS

This investigation utilised a cross-sectional analysis on all prescriptions with more than one drug that were filled at the Health Centre Pharmacy between November 2012 and February 2013. Potential DDIs were identified using the online Drug Interactions Checker database of Drugs.com.

RESULTS

During the period of the study, a total of 2814 prescriptions were analysed for potential DDIs. The prevalence of potential DDIs found during the study period was 49.82%. Major potential DDIs accounted for 4.7 % of the total number of interactions detected, while moderate potential DDIs and minor potential DDIs were 80.8 % and 14.5 % respectively. The three most frequently occurring major potential DDIs were amlodipine and simvastatin (n=46), amiloride and losartan (n=27) and amiloride and lisinopril (n=16).

CONCLUSION

This study has highlighted the need for educational initiatives to ensure that physicians and pharmacists collaborate in an effort to minimise the risks to the patients. These interactions are avoidable for the most part, as the use of online tools can facilitate the selection of therapeutic alternatives or guide decisions for closer patient monitoring and thus reduce the risks of adverse events.

Drug interaction databases in medical literature: transparency of ownership, funding, classification algorithms, level of documentation, and staff qualifications. A systematic review

PURPOSE

It is well documented that drug-drug interaction databases (DIDs) differ substantially with respect to classification of drug-drug interactions (DDIs). The aim of this study was to study online available transparency of ownership, funding, information, classifications, staff training, and underlying documentation of the five most commonly used open access English language-based online DIDs and the three most commonly used subscription English language-based online DIDs in the literature.

METHODS

We conducted a systematic literature search to identify the five most commonly used open access and the three most commonly used subscription DIDs in the medical literature. The following parameters were assessed for each of the databases: Ownership, classification of interactions, primary information sources, and staff qualification. We compared the overall proportion of yes/no answers from open access databases and subscription databases by Fisher's exact test-both prior to and after requesting missing information.

RESULTS

Among open access DIDs, 20/60 items could be verified from the webpage directly compared to 24/36 for the subscription DIDs (p = 0.0028). Following personal request, these numbers rose to 22/60 and 30/36, respectively (p < 0.0001). For items within the "classification of interaction" domain, proportions were 3/25 versus 11/15 available from the webpage (P = 0.0001) and 3/25 versus 15/15 (p < 0.0001) available upon personal request.

CONCLUSION

Available information on online available transparency of ownership, funding, information, classifications, staff training, and underlying documentation varies substantially among various DIDs. Open access DIDs had a statistically lower score on parameters assessed.

A two-year utilization of the pharmacist-operated drug information center in Iran

Objective:

To assess and describe the call services delivered by drug and poison information call center (DPIC) of 13-Aban pharmacy, which is closely operated by the Department of Clinical Pharmacy, College of Pharmacy affiliated to Tehran University of Medical Sciences.

Methods:

All calls services including counseled and follow-up calls provided by 13-Aban DPIC to health care professionals and public were collected, documented, and evaluated in a 2 years period from July 2010 to June 2012 using the designed software. Data analysis was done by SPSS version 16.0.

Findings:

Totally 110,310 calls services delivered during a 2 years period. Among healthcare professionals, pharmacists, general physicians, and nurses requested more call services respectively (P = 0.001). DPIC could detect 585 potential cases of adverse drug reactions (ADRs) and 420 cases of major drug-drug interactions (DDIs).

Conclusion:

This study by analyzing and reporting the two-years activities of one of the major DPICs in Iran, showed that DPICs can offer drug consultation for healthcare professional and public as well as detect and prevent ADRs and DDIs, and therefore can promote patients’ health regarding drug therapy.

Impact of specific Beers Criteria medications on associations between drug exposure and unplanned hospitalisation in elderly patients taking high-risk drugs: a case-time-control study in Western Australia

BACKGROUND

Certain broad medication classes have previously been associated with high rates of hospitalisation due to related adverse events in elderly Western Australians, based on clinical coding recorded on inpatient summaries. Similarly, some medications from the Beers Criteria, considered potentially inappropriate in older people, have been linked with an increased risk of unplanned hospitalisation in this population.

OBJECTIVE

Our objective was to determine whether risk estimates of drug-related hospitalisations are altered in elderly patients taking 'high-risk drugs' (HRDs) when specific Beers potentially inappropriate medications (PIMS) are taken into consideration.

METHODS

Using the pharmaceutical claims of 251,305 Western Australians aged ≥65 years (1993-2005) linked with other health data, we applied a case-time-control design to estimate odds ratios (ORs) for unplanned hospitalisations associated with anticoagulants, antirheumatics, opioids, corticosteroids and four major cardiovascular drug groups, from which attributable fractions (AFs), number and proportion of drug-related admissions were derived. The analysis was repeated, taking into account exposure to eight specific PIMs, and results were compared.

RESULTS

A total of 1,899,699 index hospitalisations were involved. Of index subjects, 12-57 % were exposed to each HRD at the time of admission, although the proportions taking both an HRD and one of the selected PIMs were much lower (generally ≤2 %, but as high as 8 % for combinations involving temazepam and for most PIMs combined with hypertension drugs). Included PIMs (indomethacin, naproxen, temazepam, oxazepam, diazepam, digoxin, amiodarone and ferrous sulphate) all tended to increase ORs, AFs and drug-related hospitalisation estimates in HRD combinations, although this was less evident for opioids and corticosteroids. Indomethacin had the greatest overall impact on HRD ORs/AFs. Indomethacin (OR 1.40; 95 % confidence interval [CI] 1.27-1.54) and naproxen (OR 1.22; 1.14-1.31) were associated with higher risks of unplanned hospitalisation than other antirheumatics (overall OR 1.09; 1.06-1.12). Similarly, among cardiac rhythm regulators, amiodarone (OR 1.22; 1.13-1.32) was riskier than digoxin (OR 1.08; 1.04-1.13). For comparisons of drug-related hospitalisation estimates, temazepam yielded the greatest absolute increases, especially with hypertension drugs.

CONCLUSIONS

Indomethacin and temazepam should be prescribed cautiously in elderly patients, especially in drug combinations. Furthermore, it appears other antirheumatics should be favoured over indomethacin/naproxen and, in situations where both drugs may be appropriate, digoxin over amiodarone. Our methodology may help assess the safety of new medications in drug combinations in preliminary pharmacovigilance investigations.

Comparison of two databases to detect potential drug-drug interactions between prescriptions of HIV/AIDS patients in critical care

WHAT IS KNOWN AND OBJECTIVE

Adverse drug events (ADE), common and underestimated in ICU patients, have direct consequences on length of stay, mortality and hospital costs. Critically ill patients with HIV/AIDS are at a high risk of ADE because of their need for multiple drug therapies. ADE can be prevented, especially by the identification of potentially harmful drug-drug interactions (DDIs). Electronic databases are useful tools for the investigation of DDIs to avoid potential ADEs, thereby increasing patient safety. The purpose of this study was to compare the classification and severity rating of potential adverse drug interactions seen in the prescriptions for patients with HIV/AIDS in two databases, one with free access (Drugs.com(™)) and another requiring payment for access (Micromedex(®)).

METHODS

A cross-sectional retrospective study of the prescriptions issued for 40 ICU HIV/AIDS patients on mechanical ventilation, admitted for more than 48 h, in a referral hospital for infectious diseases in Rio de Janeiro, Brazil, was undertaken. One prescription was reviewed each week for each patient from the second day after admission. A list of all drug-drug interactions was generated for each patient using the two drug-drug interactions databases. The weighted kappa index was estimated to assess the agreement between the classifications of DDIs identified by both databases and qualitative assessment made of any discordant classification of recorded drug-drug interactions.

RESULTS AND DISCUSSION

Of the 106 prescriptions analysed, Micromedex(®) and Drugs.com identified 347 and 615 potential DDIs, respectively. A predominance of moderate interactions and pharmacokinetic interactions was observed. The agreement between the databases regarding the severity rating was only 68.3%. The weighted kappa of 0.44 is considered moderate. Better agreement (82.4%) was observed in the classification of mechanism of interaction, with a weighted kappa of 0.61.

WHAT IS NEW AND CONCLUSION

DDIs are common between the prescriptions of patients with HIV/AIDS admitted to the ICU. Although both databases were able to identify the clinically relevant DDIs, we observed a significant discrepancy in the classification of the severity of DDIs in the two bases. The free access database could serve as an alternative to the identification of DDIs in resource-limited settings; however, there is a need for better evidence-based assessments for your use on clinical management of more serious DDIs.

Severity and management of drug-drug interactions in acute geriatric patients

BACKGROUND

Previous studies have investigated the prevalence of drug-drug interactions (DDIs) among the elderly in different care settings, but data describing the frequency and management of DDIs among acute geriatric patients appear to be absent.

OBJECTIVE

The aim of this study was to investigate the severity and interdisciplinary management of DDIs in patients admitted to an acute geriatric ward.

METHODS

The study was conducted at Oslo University Hospital, Norway, over a period of 19 weeks in 2010/11. On admission and daily during the hospital stay, prescribed medications were reviewed by pharmacists to identify DDIs with the aid of web-based databases. DDIs defined to be of potential clinical relevance, i.e., those classified as "major" (generally avoid) or "moderate" (precautions recommended), were following assessments by pharmacists presented at interdisciplinary meetings with geriatricians and nurses, and discussed in relation to the possible implementation of monitoring actions or changes in prescribing. The odds for prescribing changes were compared in relation to DDI type ("pharmacokinetic" vs. "pharmacodynamic") and severity ("major" vs. "moderate"). The project group retrospectively assessed the possible causal relationships between hospitalizations and DDIs.

RESULTS

The pharmacists identified 245 DDIs of major (n = 13) or moderate (n = 232) severity in 80 (63.5 %) of the 126 patients included on admission and/or during hospitalization. In 94 of 162 cases where the pharmacists alerted the geriatricians (58.0 %), prescribing changes or monitoring actions were implemented. Prescribing changes (n = 38) were performed significantly more often for major than for moderate DDIs [odds ratio (OR) 3.8; 95 % confidence interval (CI) 1.2-12.2, p = 0.03], and significantly more often for pharmacokinetic than for pharmacodynamic DDIs (OR 4.9; 95 % CI 2.2-10.9, p < 0.01). For 28 of 126 patients (22.2 %), a causal relationship between hospitalizations and DDIs was assessed as "possible".

CONCLUSIONS

The present study shows that acute geriatric patients are frequently exposed to DDIs for which active management is recommended in order to avoid unfavorable clinical outcomes. The integration of pharmacists into interdisciplinary teams could prevent potentially severe DDIs in the elderly.

Cost comparison of drug-drug and drug-condition interactions in patients with painful diabetic peripheral neuropathy treated with pregabalin versus duloxetine

PURPOSE

The frequency and financial impact of potential drug-drug interactions (DDIs) and drug-condition interactions (DCIs) in patients with painful diabetic peripheral neuropathy (DPN) treated with either pregabalin or duloxetine were compared.

METHODS

This retrospective cohort study was conducted using a large U.S. administrative claims database. Patients selected for study inclusion had a diagnosis of DPN and were newly initiated on either pregabalin or duloxetine between July 1, 2008, and October 1, 2010. Data on potential DDIs and DCIs were collected. Health care costs were measured as the sum of gross covered payments for all medical and prescription claims incurred during the six months after the index date.

RESULTS

The study sample comprised 2499 pregabalin users and 1354 duloxetine users. Among pregabalin users, 48 (1.8%) had at least one potential pregabalin DCI; none had potential pregabalin DDIs. Among duloxetine users, 966 (71%) had at least one potential duloxetine DDI or DCI. The frequencies of potential DDIs and DCIs differed significantly between pregabalin and duloxetine users (p < 0.001). Potential duloxetine DDIs and DCIs were associated with a significant increase in mean health care costs in duloxetine users (p = 0.002). Potential pregabalin DDIs and DCIs were not associated with additional health care costs in pregabalin users.

CONCLUSION

Among patients with painful DPN treated with either pregabalin or duloxetine, the frequency of potential duloxetine DDIs and DCIs was substantially higher than that of pregabalin. Potential DDIs and DCIs were associated with significantly increased health care costs in duloxetine users.

Potential drug-drug and drug-condition interactions among fibromyalgia patients initiating pregabalin or duloxetine: prevalence and health care expenditure impact

OBJECTIVE

To quantify the prevalence of potential drug-drug/drug-condition interactions (DDI/DCI) among fibromyalgia patients initiating pregabalin or duloxetine, and to determine the impact of potential DDI/DCI on health care expenditures.

DESIGN

Retrospective cohort study.

SETTING

U.S. clinical practice, as reflected within a large administrative claims database.

SUBJECTS

Fibromyalgia patients newly initiating pregabalin or duloxetine between July 1, 2008 and October 1, 2010 (initiation date = index).

OUTCOME MEASURES

Potential DDI measured using clinical software that identifies co-prescription of medications that potentially interact with pregabalin or duloxetine. Potential DCI, drawn from the contraindications and warnings and precautions sections of pregabalin and duloxetine prescribing information, measured using administrative claims-based algorithms. All-cause health care expenditures measured throughout a 6-month postindex period. Analyses included univariate, bivariate, and multivariable statistical approaches.

RESULTS

Seven thousand seven hundred fifty-one pregabalin and 7,785 duloxetine initiators were selected for study: mean age 49 years, 88% female. Only 1.4% of pregabalin initiators had ≥1 potential pregabalin DCI; none had potential pregabalin DDI. In contrast, 67% of duloxetine initiators had potential duloxetine DDI/DCI, driven mostly by potential duloxetine DDI (62% of duloxetine initiators). Compared between pregabalin and duloxetine initiators, differences in the prevalence of potential DDI/DCI were statistically significant (P < 0.001). Multivariable analyses indicated that, among duloxetine initiators, those with potential duloxetine DDI/DCI had postinitiation health care expenditures that were $670 higher (P < 0.001) than those without potential duloxetine DDI/DCI. Among pregabalin initiators, potential pregabalin DDI/DCI were not associated with health care expenditures.

CONCLUSIONS

Among fibromyalgia patients initiating pregabalin or duloxetine, potential duloxetine DDI could be highly prevalent. Among duloxetine initiators, potential duloxetine DDI/DCI were significantly associated with increased health care expenditures.

Avaliação de interações medicamentosas potenciais em prescrições da atenção primária de Vitória da Conquista (BA), Brasil

As interações medicamentosas são fatores de risco para a ocorrência de reações adversas a medicamentos. Este estudo teve o objetivo de avaliar as interações medicamentosas potenciais em prescrições da atenção primária de Vitória da Conquista (BA), visando preencher a lacuna de conhecimento sobre essa temática no Brasil. Foram coletadas informações sobre diversas variáveis de prescrições oriundas da atenção primária e as interações medicamentosas avaliadas a partir dos bancos de dados do Medscape e Micromedex(r). Verificou-se ainda a frequência de polifarmácia e associação desta com a ocorrência de interações medicamentosas. Os resultados mostraram frequência de 48,9% de interações medicamentosas, 74,9% delas de gravidade moderada ou maior, e 8,6% de prescrições em polifarmácia que, em teste qui-quadrado, mostrou associação positiva com ocorrência de interações medicamentosas potenciais (p < 0,001). As prescrições oriundas da atenção primária de Vitória da Conquista (BA) apresentaram uma alta frequência de interações medicamentosas, porém faz-se necessária a análise de outros fatores de risco para ocorrência destas nesse nível de atenção à saúde.

Avaliação da qualidade do cuidado hospitalar no Brasil: uma revisão sistemática

A avaliação da qualidade de serviços hospitalares vem ganhando importância no mundo, sendo impulsionada pela demanda de financiadores, prestadores, profissionais e pacientes. O objetivo deste estudo é revisar a literatura sobre estudos de avaliação da qualidade hospitalar no Brasil e analisar as principais abordagens, metodologias e indicadores utilizados. Foi aplicada revisão sistemática de artigos científicos, dissertações e teses com análises empíricas sobre o tema, publicados entre 1990 e 2011. Foram identificados 2.169 documentos e incluídos 62 documentos na revisão, que representam 48 estudos distintos. Predominou o uso de fontes de dados secundárias com análise das dimensões efetividade, adequação, segurança e eficiência, destacando-se a aplicação da taxa de mortalidade, taxa de adequação, taxa de eventos adversos e tempo de permanência. Métodos que controlam diferenças de risco dos pacientes foram majoritariamente aplicados. Busca-se com esta revisão contribuir apontando elementos centrais para o desenvolvimento do tema no país e para a qualificação do cuidado prestado.

The Study of Harmful and Beneficial Drug Interactions in Intensive Care, Kerman, Iran

Since multidrug therapy is common in the intensive care unit (ICU), the risk of drug interactions is high. This study aimed to examine the prevalence of drug interactions and risk factors in patients who were admitted to ICUs. In a cross-sectional study, the medication flow sheet of 101 patients was investigated in terms of the number and the type of drug interactions. The Drug Interaction Facts reference text book (2010 edition) was used to determine the type and the number of drug interactions. In total, 609 potential drug interactions were found. The mean number of drug interactions per patient was 6.1 (SD=5.6). Of all observed drug interactions, 66.9% were classified as harmful and 33.1% beneficial. In terms of the nature of interactions, delayed, moderate, and possible were the most common types. The most frequent harmful interaction was between phenytoin and omeprazole (63 occasions). Critically ill patients are at a higher risk of drug interactions. Although 33.1% of the drug interactions were considered beneficial, medical teams should be aware that even beneficial interactions can have undesirable side-effects in the critically ill.

[Hospital readmissions related to drug interactions: a retrospective study in a hospital setting]

OBJECTIVE

To examine the relationship between potential drug interactions and hospital readmissions.

METHODS

Retrospective study with 1,487 adult patients (> 18 years old) admitted to a general hospital in the city of Vitória da Conquista, Northeastern Brazil, from January to December 2007. Data were collected from Hospital Admission Authorization (AIH) forms in the Brazilian National Health System Hospital Database (SIH/SUS). Probabilistic linkage was used to combine multiple AIH forms from the same admission into a single record and to identify readmissions. Information on prescriptions was manually added to the SIH/SUS records. Logistic regression was used to quantitatively assess the impact of drug interactions on hospital readmissions. Cox regression was performed to test the impact of this variable on time to first readmission.

RESULTS

A total of 99 readmissions (7% of all patients) were identified. Potential drug interactions were found in 35% of all prescriptions evaluated. Patients with potential drug interactions in a prior admission were more likely to be readmitted. The adjusted odds ratio indicated a 2.4-fold increase in odds of being readmitted; and the adjusted hazard ratio showed that this risk was increased by 79% in patients with potential drug interactions (p < 0.01).

CONCLUSIONS

The study results suggest an association between prior drug interactions and increased risk of readmission. Health professionals should be aware of potential hazard of certain drug combinations and closely monitor high-risk patients such as elderly patients and those with renal impairment.

Drug-drug interactions in the medical intensive care unit: an assessment of frequency, severity and the medications involved

OBJECTIVES

Mortality and morbidity are increased in patients experiencing drug-drug interactions (DDIs). Critically ill patients are at an increased risk of adverse events from DDIs due to the large number of medications that they take and their changes in organ function. Currently, there is a lack of literature describing DDIs in the intensive care unit (ICU). The purpose of this study is to evaluate frequency, severity and drug combinations involved in DDIs occurring in a medical ICU (MICU).

METHODS

This was a 4-week, prospective, observational study that was conducted in the MICU of an academic medical centre. Lexi-Interact and Micromedex interaction databases were utilized daily to screen patients' medication profiles for DDIs, and severity was assessed using each database's severity rating scale.

KEY FINDINGS

Of 240 patient medication profiles evaluated, 457 DDIs were identified. The rate of DDIs was 190.4 DDIs/100 patient days with 297 of these interactions being unique drug pairs. About 25% (114/457) were considered major DDIs. The most commonly involved medications were antihypertensive medications (106/457) and anticoagulants/antiplatelet agents (80/457).

CONCLUSIONS

DDIs occur frequently in the MICU. Severity and drug combinations related to DDIs in the MICU differ from DDIs published in other ICU settings. When developing a DDI alerting system, patient characteristics and location should be considered.