Identification of adverse drug reactions in geriatric inpatients using a computerised drug database

Performance of a trigger tool for detecting adverse drug reactions in patients with polypharmacy acutely admitted to the geriatric ward

Aim

To investigate the performance of an adverse drug reaction (ADR) trigger tool in patients with polypharmacy acutely admitted to our geriatric ward.

Findings

The ADR trigger tool had a positive predictive value (PPV) of 41.8%. Usual care recognised 83.5% of ADRs considered as possible, probable or certain, increasing to 97.1% when restricted to probable and certain ADRs.

Message

It is unlikely that implementation of the ADR trigger tool will improve detection of unrecognised ADRs in older patients acutely admitted to our geriatric ward.

Supplementary Information

The online version contains supplementary material available at 10.1007/s41999-022-00649-x.

Purpose

Adverse drug reactions (ADRs) account for 10% of acute hospital admissions in older people, often under-recognised by physicians. The Dutch geriatric guideline recommends screening all acutely admitted older patients with polypharmacy with an ADR trigger tool comprising ten triggers and associated drugs frequently causing ADRs. This study investigated the performance of this tool and the recognition by usual care of ADRs detected with the tool.

Methods

A cross-sectional study was performed in patients ≥ 70 years with polypharmacy acutely admitted to the geriatric ward of the University Medical Centre Utrecht. Electronic health records (EHRs) were screened for trigger–drug combinations listed in the ADR trigger tool. Two independent appraisers assessed causal probability with the WHO-UMC algorithm and screened EHRs for recognition of ADRs by attending physicians. Performance of the tool was defined as the positive predictive value (PPV) for ADRs with a possible, probable or certain causal relation.

Results

In total, 941 trigger–drug combinations were present in 73% (n = 253/345) of the patients. The triggers fall, delirium, renal insufficiency and hyponatraemia covered 86% (n = 810/941) of all trigger–drug combinations. The overall PPV was 41.8% (n = 393/941), but the PPV for individual triggers was highly variable ranging from 0 to 100%. Usual care recognised the majority of ADRs (83.5%), increasing to 97.1% when restricted to possible and certain ADRs.

Conclusion

The ADR trigger tool has predictive value; however, its implementation is unlikely to improve the detection of unrecognised ADRs in older patients acutely admitted to our geriatric ward. Future research is needed to investigate the tool’s clinical value when applied to older patients acutely admitted to non-geriatric wards.

Supplementary Information

The online version contains supplementary material available at 10.1007/s41999-022-00649-x.

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.

Clinical Pharmacokinetics and Pharmacodynamics of Bortezomib

Proteasome inhibitors disrupt multiple pathways in cells and the bone marrow microenvironment, resulting in apoptosis and inhibition of cell-cycle progression, angiogenesis, and proliferation. Bortezomib is a first-in-class proteasome inhibitor approved for the treatment of multiple myeloma and mantle cell lymphoma after one prior therapy. It is also effective in other plasma cell disorders and non-Hodgkin lymphomas. The main mechanism of action of bortezomib is to inhibit the chymotrypsin-like site of the 20S proteolytic core within the 26S proteasome, thereby inducing cell-cycle arrest and apoptosis. The pharmacokinetic profile of intravenous bortezomib is characterized by a two-compartment model with a rapid initial distribution phase followed by a longer elimination phase and a large volume of distribution. Bortezomib is available for subcutaneous and intravenous administration. Pharmacokinetic studies comparing subcutaneous and intravenous bortezomib demonstrated that systemic exposure was equivalent for both routes; pharmacodynamic parameters of 20S proteasome inhibition were also similar. Renal impairment does not influence the intrinsic pharmacokinetics of bortezomib. However, moderate or severe hepatic impairment causes an increase in plasma concentrations of bortezomib. Therefore, patients with moderate or severe hepatic impairment should start at a reduced dose. Because bortezomib undergoes extensive metabolism by hepatic cytochrome P450 3A4 and 2C19 enzymes, certain strong cytochrome P450 3A4 inducers and inhibitors can also alter the systemic exposure of bortezomib. This article critically reviews and summarizes the clinical pharmacokinetics and pharmacodynamics of bortezomib at various dosing levels and routes of administration as well as in specific patient subsets. In addition, we discuss the clinical efficacy and safety of bortezomib.

Prevalence of drug interactions in hospitalised elderly patients: a systematic review

BACKGROUND

The prevalence of drug-drug interactions (DDIs) in hospital settings is variable, and elderly patients are considered a high risk population for DDIs. There are no systematic reviews describing the prevalence of DDIs in hospitalised elderly patients.

OBJECTIVES

To assess and summarise the available data on the prevalence of DDIs in hospitalised elderly patients and to describe which drugs, drug classes and drug combinations are most commonly involved in DDIs.

DATA SOURCE

A systematic electronic literature search was conducted on Medline/PubMed, Embase, Lilacs, SciElo, Web of Science, Cinahl, Scopus, Cochrane, OpenGrey, Capes Thesis Bank, OasisBR, OpenAire and abstracts from scientific events, without limitation on language or period of publication. Study selection was completed on 21 September 2018.

STUDY ELIGIBILITY CRITERIA, PARTICIPANTS AND INTERVENTIONS

Original observational studies that reported the prevalence of actual or potential DDIs during hospitalisation in patients aged 60 years or older were included. The main outcome measure was prevalence of DDIs and number of DDIs per patient. Subgroup analysis was performed in studies that reported the prevalence of DDIs in geriatric units.

STUDY APPRAISAL AND SYNTHESIS METHODS

Study quality was assessed using the Agency for Healthcare Research and Quality methodological checklist for cross sectional and prevalence studies.

RESULTS

34 studies were included, involving 9577 patients. The prevalence of DDIs ranged from 8.34% to 100%. In studies conducted in geriatric units, the prevalence ranged from 80.5% to 90.5%. The number of DDIs per patient ranged from 1.2 to 30.6. Single drugs most commonly involved in DDIs were furosemide, captopril, warfarin and dipyrone. Drug classes mostly involved were potassium sparing diuretics and angiotensin converting enzyme inhibitors.

LIMITATIONS

The main limitation is the heterogeneity between the included studies that precluded a meta-analysis. Several different methods were used to identify DDIs, majorly, and potential DDIs. Few studies have reported measures to control the quality of the collected data.

CONCLUSIONS AND IMPLICATIONS OF KEY FINDINGS

The prevalence of DDIs ranged widely, and the variation may reflect differences in the conditions of the elderly patients and level of attention (or complexity of care), as well as methodological differences, especially the methods and/or software used to identify DDIs.

SYSTEMATIC REVIEW REGISTRATION NUMBER

CRD42018096720.

[Pharmacist rounds on geriatric wards : Assessment of 1 year of pharmaceutical counseling]

BACKGROUND

Older patients suffer more often from drug-induced complications.

OBJECTIVE

What are the precise recommendations pharmacists can give to geriatricians?

MATERIAL AND METHODS

Two pharmacists conducted clinical rounds on 2 geriatric wards over a period of 54 weeks. Protocols of conspicuous medications for geriatric patients were analyzed and suggestions were made.

RESULTS

Particularly frequent were the questionable medical indications for proton pump inhibitors, allopurinol, pregabalin and gabapentin. Adjustment of the dosage of heparin and its analogs to impaired renal function of patients was often lacking. This was also occasionally the case for metformin, some antibiotics and simvastatin. There were several interactions of drug combinations with a high risk for QT prolongation. The inhibition of resorption of bisphosphonates and L‑thyroxin by the simultaneous intake of magnesium and calcium seemed to be probable. Furthermore, it was noticed that for some medications for patients treated by percutaneous endoscopic gastrostomy (PRG) administration by feeding tubes was not possible and combinations of different eye drops which should not be applied simultaneously but at delayed time intervals.

CONCLUSION

An additional medication-related visit provides an interventional option for avoidance of medication errors.

Epidemiology of adverse drug reactions in Europe: a review of recent observational studies

Adverse drug reactions (ADRs) cause considerable mortality and morbidity but no recent reviews are currently available for the European region. Therefore, we performed a review of all epidemiological studies quantifying ADRs in a European setting that were published between 1 January 2000 and 3 September 2014. Included studies assessed the number of patients who were admitted to hospital due to an ADR, studies that assessed the number of patients who developed an ADR during hospitalization, and studies that measured ADRs in the outpatient setting. In total, 47 articles were included in the final review. The median percentage of hospital admissions due to an ADR was 3.5 %, based on 22 studies, and the median percentage of patients who experienced an ADR during hospitalization was 10.1 %, based on 13 studies. Only five studies were found that assessed ADRs occurring in the outpatient setting. These results indicate that the occurrence of ADRs in the European hospital setting—both ADRs that result in hospitalization and ADRs that occur during the hospital stay—is significant. Furthermore, the limited number of studies that were performed in the outpatient setting identify a lack of information regarding the epidemiology of ADRs in this setting.

A limited number of prescribed drugs account for the great majority of drug-drug interactions

PURPOSE

The purpose of this study was to investigate the prevalence of prescribed combinations of interacting drugs in the Swedish population.

METHODS

This study design was retrospective and cross-sectional, based on a national register of dispensed prescription drugs during the period from January 1 to April 30, 2010. Prescription data was linked to the drug-drug interaction database SFINX to yield the prevalence of interacting combinations dispensed in the population. The study focused in particular on C- (clinically relevant interactions that can be handled, e.g. by dose adjustments), and D-interactions (clinically relevant interactions that should be avoided).

RESULTS

Thirty-eight and 3.8 % of the population were dispensed combinations of drugs classified as C- or D- interactions, respectively, i.e. clinically relevant, involving all therapeutic areas. Half of the D-interactions were associated with increased risk of adverse drug reactions whereas the other half were considered interactions with a potential to cause therapeutic failure. We identified a top 15 list of D-interactions that included 80 % of the total number of interacting drug combinations. Regarding individual drugs, a group of only ten drugs was involved in as much as 94 % of all D-interactions.

CONCLUSIONS

This study reveals that the majority of prescribed interacting drug combinations in Sweden involve a limited number of drugs. The findings may increase the awareness among prescribers of these most common drug interactions in clinical practice and highlight an area for pharmacological education. It may also serve as an inventory of potential interactions within different therapeutic areas for further research.

Data mining for potential adverse drug-drug interactions

INTRODUCTION

Patients, in particular elderly ones, frequently receive more than one drug at a time. With each drug added to a regime, the number of potential drug-drug interactions (DDIs) increases by a power law. Early prediction of relevant interactions by computerized tools greatly aids clinicians and can guide their prescribing choices.

AREAS COVERED

In this article, we discuss different types of DDIs, on which levels they can arise and what efforts have been made in the past to detect and predict them. The emphasis is on data mining technology and network analysis, but overlaps with traditional pharmacovigilance are also discussed. Finally, we discuss strategies to focus and simplify mining efforts to get meaningful results with less effort.

EXPERT OPINION

The necessary technology for detecting adverse DDIs exists and is quite refined, although it is more often implied in lower risk scenarios (such as syntactic analysis in web searches and online libraries). Data mining for DDIs, on the other hand, still requires a great deal of human intervention, not only to validate the results but also, more importantly, to separate the relevant from the spurious. The fields of network analysis and graph theory show great promise but have not yet shown much beyond descriptive analyses.

Detection of medication-related problems in hospital practice: a review

This review examines the effectiveness of detection methods in terms of their ability to identify and accurately determine medication-related problems in hospitals. A search was conducted of databases from inception to June 2012. The following keywords were used in combination: medication error or adverse drug event or adverse drug reaction, comparison, detection, hospital and method. Seven detection methods were considered: chart review, claims data review, computer monitoring, direct care observation, interviews, prospective data collection and incident reporting. Forty relevant studies were located. Detection methods that were better able to identify medication-related problems compared with other methods tested in the same study included chart review, computer monitoring, direct care observation and prospective data collection. However, only small numbers of studies were involved in comparisons with direct care observation (n = 5) and prospective data collection (n = 6). There was little focus on detecting medication-related problems during various stages of the medication process, and comparisons associated with the seriousness of medication-related problems were examined in 19 studies. Only 17 studies involved appropriate comparisons with a gold standard, which provided details about sensitivities and specificities. In view of the relatively low identification of medication-related problems with incident reporting, use of this method in tracking trends over time should be met with some scepticism. Greater attention should be placed on combining methods, such as chart review and computer monitoring in examining trends. More research is needed on the use of claims data, direct care observation, interviews and prospective data collection as detection methods.

Treatment of HIV infection in the older patient

The number of HIV patients over the age of 50 years is increasing due to increased longevity in patients treated with highly active antiretroviral therapy (HAART), in addition to new primary infections in older patients. Numerous studies have demonstrated worse HIV disease progression and mortality in older HIV patients compared with younger patients. While HAART therapy has been shown to be effective at reducing HIV-1 RNA, the immunologic benefits in older patients may be reduced compared to younger patients. Older patients are more likely to suffer comorbidities requiring concomitant medications than younger patients. Toxicities from HAART, particularly dyslipdemia, insulin resistance, and pancreatitis may also be worse in older HIV patients. Controlled trials on epidemiology, pathogenesis, and therapeutic and clinical outcomes in the elderly are needed. As the HIV-infected population ages, there is a growing need to better determine the efficacy of HAART in older patients, and to investigate factors associated with a more rapid course of HIV infection in patients over the age of 50 years.

Adverse drug events in older hospitalized patients: results and reliability of a comprehensive and structured identification strategy

BACKGROUND

Older patients are at high risk for experiencing Adverse Drug Events (ADEs) during hospitalization. To be able to reduce ADEs in these vulnerable patients, hospitals first need to measure the occurrence of ADEs, especially those that are preventable. However, data on preventable ADEs (pADEs) occurring during hospitalization in older patients are scarce, and no 'gold standard' for the identification of ADEs exists.

METHODOLOGY

The study was conducted in three hospitals in the Netherlands in 2007. ADEs were retrospectively identified by a team of experts using a comprehensive and structured patient chart review (PCR) combined with a trigger-tool as an aid. This ADE identification strategy was applied to a cohort of 250 older hospitalized patients. To estimate the intra- and inter-rater reliabilities, Cohen's kappa values were calculated.

PRINCIPAL FINDINGS

In total, 118 ADEs were detected which occurred in 62 patients. This ADE yield was 1.1 to 2.7 times higher in comparison to other ADE studies in older hospitalized patients. Of the 118 ADEs, 83 (70.3%) were pADEs; 51 pADEs (43.2% of all ADEs identified) caused serious patient harm. Patient harm caused by ADEs resulted in various events. The overall intra-rater agreement of the developed strategy was substantial (κ = 0.74); the overall inter-rater agreement was only fair (κ = 0.24).

CONCLUSIONS/SIGNIFICANCE

The ADE identification strategy provided a detailed insight into the scope of ADEs occurring in older hospitalized patients, and showed that the majority of (serious) ADEs can be prevented. Several strategy related aspects, as well as setting/study specific aspects, may have contributed to the results gained. These aspects should be considered whenever ADE measurements need to be conducted. The results regarding pADEs can be used to design tailored interventions to effectively reduce harm caused by medication errors. Improvement of the inter-rater reliability of a PCR remains challenging.

Polypharmacy in the elderly from the clinical toxicologist perspective

INTRODUCTION

Polypharmacy is closely associated with multimorbidity in the elderly and can lead to problems and drug interactions.

AIM

This study assessed polypharmacy in the elderly, tracking inquiries to the Poison Information Centre Nuremberg (PICN) and patients needing toxicological intensive care therapy.

METHODS

From 2006-2009, all PICN inquiries involving individuals > 70 years were tracked, as were cases at the Toxicological Intensive Care Unit (T-ICU) regarding adverse drug reactions (ADRs) and drug poisoning.

RESULTS

Of 11,683 PICN calls about pharmaceuticals, 175 (1.5%) were from people > 70 years; 156 (4.8%) of 3,272 T-ICU patients were > 70 years. Calls about psychopharmaceuticals (46.9%) and analgesics (25.7%) were most frequent. Among the T-ICU patients, psychopharmaceuticals like sedatives and hypnotics were frequently involved (20.5%), as were tricyclic antidepressants (17.9%) and analgesics (29.5%). Ethanol was co-ingested by 18.3%.

CONCLUSION

Population-specific poison prevention strategies are needed to reduce toxic exposures. Such strategies could include pharmacist intervention, improved prescriber communication and education regarding the geriatric population, and computerized drug databases.

Effect of abiraterone acetate plus prednisone on the pharmacokinetics of dextromethorphan and theophylline in patients with metastatic castration-resistant prostate cancer

PURPOSE

To assess the effect of abiraterone acetate plus prednisone on the pharmacokinetics of dextromethorphan HBr (CYP2D6 substrate) and theophylline (CYP1A2 substrate) in patients with metastatic castration-resistant prostate cancer (mCRPC).

METHODS

Men with progressive metastatic mCRPC who failed gonadotropin-releasing hormone therapy and ≥1 lines of chemotherapy were enrolled. Patients received two doses of dextromethorphan HBr-30 mg (n = 18; group A) or theophylline-100 mg (n = 16; group B) under fasting conditions; one dose on cycle 1, day -8, and the other dose on cycle 1, day 8. Only patients with extensive CYP2D6 metabolizing status were assigned to group A. All patients received continuous daily oral abiraterone acetate (1,000 mg) plus prednisone (10 mg) starting on cycle 1, day 1.

RESULTS

Coadministration of abiraterone acetate plus prednisone increased the systemic exposure of dextromethorphan by approximately 100%. Ratios of geometric means for maximum plasma concentration (C(max)) (275.36%) and area under plasma concentration-time curves from time 0 to 24 h (AUC(24h)) (268.14%) of dextromethorphan were outside the bioequivalence limit. The pharmacokinetics of theophylline was unaltered following coadministration of abiraterone acetate plus prednisone. Ratios of geometric means [C(max); 102.36% and AUC(24h); 108.03%] of theophylline exposure parameters were within the bioequivalence limit. The safety profile of abiraterone acetate was consistent with reported toxicities.

CONCLUSION

Abiraterone acetate plus prednisone increased the exposure of dextromethorphan, suggesting a need for caution when coadministrating with known CYP2D6 substrates. The pharmacokinetics of theophylline was unaffected when coadministered with abiraterone acetate plus prednisone.

Importance of cytochrome P450 (CYP450) in adverse drug reactions due to drug-drug interactions: a PharmacoVigilance study in France

OBJECTIVE

Our aim was to characterize Adverse Drug Reactions (ADRs) related to drug-drug interactions (DDIs) related to involvement of cytochrome P450 (CYP450) isoenzymes in a pharmacovigilance database.

METHODS

ADRs recorded by Midi-Pyrénées PharmacoVigilance center (France) between 1 January and 31 August 2008 were extracted from the French PharmacoVigilance Database (FPVD).

RESULTS

Among the 1,205 reported ADRs, 16 (1.3 %), can be explained by involvement of CYP450 isoenzymes (including 4 "serious"). All interactions involved CYP inhibitors, mainly for CYP3A4/5.

CONCLUSION

The percentage of ADRs reported in the pharmacovigilance database and related to CYP450-induced DDIs appears to be relatively low (~ 1-2 %).

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.

HIV infection and older Americans: the public health perspective

HIV disease is often perceived as a condition affecting young adults. However, approximately 11% of new infections occur in adults aged 50 years or older. Among persons living with HIV disease, it is estimated that more than half will be aged 50 years or older in the near future. In this review, we highlight issues related to HIV prevention and treatment for HIV-uninfected and HIV-infected older Americans, and outline unique considerations and emerging challenges for public health and patient management in these 2 populations.

Frequency of adverse drug reactions in hospitalized patients: a systematic review and meta-analysis

PURPOSES

To perform a comprehensive systematic review of prospective studies about frequency of adverse drug reactions (ADRs) occurring during hospitalization (ADR(In) ), including a thorough study quality assessment, meta-analysis and heterogeneity evaluation.

METHODS

Systematic review of several databases: Pubmed, EMBASE, CINAHL, Cochrane, ISI, International Pharmaceutical Abstracts, Scirus, NHS economic, and others, as well as manual search. Inclusion criteria were: prospective studies (assessing all patients before discharge, by a specialized team, at least once a week); with data about ADRs occurring during hospitalization, using WHO's or similar definition of ADR. Two independent reviewers assessed eligibility criteria, extracted data, and evaluated risk of bias.

RESULTS

From 4139 studies initially found, 22 were included. Meta-analysis indicate that ADRs may occur in 16.88% (CI95%: 13.56,20.21%) of patients during hospitalization; however, this estimate has to be viewed with caution because there was significant heterogeneity (I²  = 99%). The most significant moderators of heterogeneity were risk of bias, population, ward, and methodology for ADR identification. Low risk of bias studies adjusted for population (pediatric versus adult) had I²  = 0%.

CONCLUSIONS

These data are useful as a broad characterization of in-hospital ADRs and their frequency. However, due to heterogeneity, our estimates are crude indicators. The wide variation in methodologies was one of the most important moderators of heterogeneity (even among studies using intensive monitoring). We suggest criteria to standardize methodologies and reduce the risk of bias.

Recognition of adverse drug events in older hospitalized medical patients

Objective

To assess medical teams’ ability to recognize adverse drug events (ADEs) in older inpatients.

Methods

The study cohort comprised 250 patients aged 65 years or older consecutively admitted to Internal Medicine wards of three hospitals in the Netherlands between April and November 2007. An independent expert team identified ADEs present upon admission or occurring during hospitalization by a structured retrospective patient chart review. For all ADEs identified, the expert team assessed causality, severity, preventability, and recognition by medical teams.

Results

The medical teams did not recognize 19.9 % of all ADEs present upon admission {60.4 ADEs [95 % confidence interval (CI) 51.5–70.8] per 100 hospitalizations} and 20.3 % of all ADEs occurring during the hospital stay [47.2 ADEs (95 % CI 39.4–56.5) per 100 hospitalizations]. Unrecognized ADEs were significantly more often ADEs with possible causality (p=0.014, df=1), ADEs caused by medication errors (p<0.001, df=1), and ADEs not manifesting as new symptoms (p<0.001, df=1). The medical teams did not recognize 23.2 % of mild to moderately severe ADEs and 16.5 % of severe, life-threatening, or fatal ADEs. The recognition of ADEs varied with event type.

Conclusions

The recognition of ADEs by medical teams was substantial for those ADEs with evident causality and with clinically apparent and severe consequences. ADEs mimicking underlying pathologies with a lower severity went unrecognized much more often, as did those resulting only in abnormal laboratory values. Tools to improve the recognition of ADEs by medical teams should, therefore, focus on those ADEs that are more challenging to detect.

A systematic review to evaluate the accuracy of electronic adverse drug event detection

OBJECTIVE

Adverse drug events (ADEs), defined as adverse patient outcomes caused by medications, are common and difficult to detect. Electronic detection of ADEs is a promising method to identify ADEs. We performed this systematic review to characterize established electronic detection systems and their accuracy.

METHODS

We identified studies evaluating electronic ADE detection from the MEDLINE and EMBASE databases. We included studies if they contained original data and involved detection of electronic triggers using information systems. We abstracted data regarding rule characteristics including type, accuracy, and rationale.

RESULTS

Forty-eight studies met our inclusion criteria. Twenty-four (50%) studies reported rule accuracy but only 9 (18.8%) utilized a proper gold standard (chart review in all patients). Rule accuracy was variable and often poor (range of sensitivity: 40%-94%; specificity: 1.4%-89.8%; positive predictive value: 0.9%-64%). 5 (10.4%) studies derived or used detection rules that were defined by clinical need or the underlying ADE prevalence. Detection rules in 8 (16.7%) studies detected specific types of ADEs.

CONCLUSION

Several factors led to inaccurate ADE detection algorithms, including immature underlying information systems, non-standard event definitions, and variable methods for detection rule validation. Few ADE detection algorithms considered clinical priorities. To enhance the utility of electronic detection systems, there is a need to systematically address these factors.

Preventable and non-preventable adverse drug events in hospitalized patients: a prospective chart review in the Netherlands

BACKGROUND

Medication safety research and clinical pharmacy practice today is primarily focused on managing preventable adverse drug events (pADEs). Determinants of both pADEs and non-preventable adverse drug reactions (ADRs) have been identified. However, relatively little is known on the overlap between these determinants and the balance of preventable and non-preventable harm inpatients experience in modern computerized hospitals.

OBJECTIVE

The aim of this study was to analyse the prevalence of pADEs and non-preventable ADRs as well as the determinants, including multimorbidity, of these ADEs, i.e. both pADEs and ADRs.

METHODS

Adverse events experienced by patients admitted to two Dutch hospitals with functioning computerized physician order entry (CPOE) systems were prospectively identified through chart review. Adverse events were divided into pADEs (i.e. as a result of a medication error) and non-preventable ADRs. In both cases, a causal relationship between adverse events and patients' drugs was established using the simplified Yale algorithm. Study data were collected anytime between April 2006 and May 2008 over a 5-month period at each hospital ward included in the study, beginning from 8 weeks after CPOE was implemented at the ward.

RESULTS

pADEs and non-preventable ADRs were experienced by 349 (58%) patients, of whom 307 (88%) had non-preventable ADRs. Multimorbidity (adjusted odds ratio [OR(adj)] 1.90; 95% CI 1.44, 2.50; OR(adj) 1.28; 95% CI 1.14, 1.45, respectively), length of stay (OR(adj) 1.13; 95% CI 1.06, 1.21; OR(adj) 1.11; 95% CI 1.07, 1.16, respectively), admission to the geriatric ward (OR(adj) 7.78; 95% CI 2.15, 28.13; OR(adj) 3.82; 95% CI 1.73, 8.45, respectively) and number of medication orders (OR(adj) 1.25; 95% CI 1.16, 1.35; OR(adj) 1.13; 95% CI 1.06, 1.21, respectively) were statistically significantly associated with pADEs and ADRs. Admission to the gastroenterology/rheumatology ward (OR(adj) 0.22; 95% CI 0.06, 0.77; OR(adj) 0.40; 95% CI 0.24, 0.65, respectively) was inversely related to both pADEs and ADRs. Other determinants for ADRs only were female sex (OR(adj) 1.77; 95% CI 1.12, 2.80) and use of drugs affecting the nervous system (OR(adj) 1.83; 95% CI 1.09, 3.07). Age was a significant determinant for pADEs only (OR(adj) 1.07; 95% CI 1.03, 1.11).

CONCLUSIONS

In this study more than half of the patients admitted to the hospitals are harmed by drugs, of which most are non-serious, non-preventable ADRs (after the introduction of CPOE). Determinants of both pADEs and ADRs overlap to a large extent. Our results imply the need for signalling early potential adverse events that occur during the normal use of drugs in multimorbid patients or those in geriatric wards. Subsequent therapeutic interventions may improve the well-being of hospitalized patients to a greater extent than focusing on errors in the medication process only.

Identifying adverse drug reactions associated with drug-drug interactions: data mining of a spontaneous reporting database in Italy

BACKGROUND

Drug-drug interactions (DDIs) are an important cause of adverse drug reactions (ADRs). Many studies have recently considered this issue, but most of them focus only on potential interactions and are often related to the hospital setting. A spontaneous reporting database could be a valuable resource for detection of ADRs associated with DDIs; however, data in the literature are limited.

OBJECTIVE

To detect those patients treated with potentially interacting drugs and the cases where reported adverse reactions are a possible consequence of DDIs, using an Italian spontaneous reporting database.

METHODS

The data were obtained from a database containing all reports of suspected ADRs from five Italian regions (January 1990 to December 2007) that are the main contributors to the Italian spontaneous reporting system. All reports containing at least two drugs, reported as being suspected of causing the ADR or as concomitant medication, were selected and a list of drug pairs was drawn up. We performed a search to verify which drug pairs are considered a potential DDI, using the Internet version of the DRUGDEX(R) system. For each report containing a potential DDI, we verified whether the description of the adverse reaction corresponded to the interaction effect.

RESULTS

The database contained 45 315 reports, of which 17 700 (39.1%) had at least two reported drugs. We identified 5345 (30.2%) reports with potential DDIs, and in 1159 (21.7%) of these reports a related ADR was reported. The percentage of reports with potential DDIs increased in relation to the number of concomitantly administered drugs, ranging from 9.8% for two drugs to 88.3% for eight or more drugs. The percentages of serious or fatal reports of ADRs associated with a DDI were significantly higher than other reports analysed. The mean age, percentage of male patients and the mean number of drugs were also significantly higher in reports with DDIs than in other reports. In 235 of 1159 reports (20.3%), both interacting drugs were recognized as suspect by the reporter. This percentage varies in relation to the drugs involved, ranging from 2% to about 65%. The most frequently reported interaction was digoxin and diuretics, but no fatal ADRs were reported with this combination. The combination of anticoagulant and antiplatelet agents was responsible for the greatest number of serious reactions and deaths.

CONCLUSIONS

This study validates that spontaneous reporting, despite its limitations, can be an important resource for detecting ADRs associated with the concomitant use of interacting drugs. Moreover, our data confirm that DDIs could be a real problem in clinical practice, showing that more than one in five patients exposed to a potential DDI experienced a related ADR.

Adverse drug reactions in inpatients of internal medicine wards at a tertiary care hospital: A prospective cohort study

OBJECTIVE

To find out incidence of adverse drug reactions (ADR) in patients of internal medicine wards and study various aspects of ADR, e.g., causality, mortality, drugs commonly causing ADR in internal medicine wards of Guru Gobind Singh Hospital, Jamnagar, a tertiary care hospital.

MATERIALS AND METHODS

This was prospective, observational study carried out at Department of Medicine, Shri Meghji Pethraj Shah Medical College attached with Guru Gobind Singh Hospital, a tertiary care teaching hospital, Jamnagar, Gujarat over a period of 6 months. For statistical analysis, ADR were analyzed by using Chi-square test.

RESULTS

Out of total 860 patients admitted, 830 were analyzed as they met the inclusion criteria. A total of 45 (5.42%) patients developed 47 ADR. Among them, 27 (3.25 %) (95% CI, 2.03, 4.47%) patients due to ADR required hospital admission in medicine ward (ADR Ad), 18 (2.17%) (95% CI, 1.17%-3.17%) patients developed ADR while already hospitalized in medicine ward (ADR In). Most of the fatal and life-threatening reactions occurred due to chemotherapeutic agents. Majority of patients discontinued suspected drug and recovered from ADR.

CONCLUSION

Fatal and life-threatening adverse reactions reported in the present as well as other studies underline the importance of such studies and need for creating awareness among health professionals about looking for and reporting such reactions.

Drug-drug interactions in general hospital and psychiatric hospital in-patients prescribed psychotropic medications

Abstract Objectives. Drug-drug interactions (DDIs) present a serious, ever increasing clinical problem. Previous studies identified DDIs among psychiatric inpatients prescribed psychotropics, but none have focused on psychotropics prescribed to General Hospital inpatients. This study aimed to identify: putative drug-drug interactions; mechanisms; potential seriousness among patients prescribed psychotropes in both psychiatric and general hospital inpatients settings. We hypothesised that potential interactions per person would be greater in General Hospital inpatients on psychotropics, due to polypharmacy. Method. We surveyed psychotropic prescribing in hospital wards in a public sector mental health organisation and a 500-bed general hospital. Ward pharmacists collected drug prescription data. A computer based protocol evaluated DDIs. Results. A total of 7.4% of General Hospital inpatients and 100% of Psychiatric Unit inpatients surveyed were prescribed psychotropic medication. The General Hospital group had significantly more potential interactions per person (3.0) than Psychiatric inpatients (1.3) (P<0.05). There were significantly more potentially serious interactions in the general hospital group (P<0.025). Conclusions. DDIs affect those prescribed psychotropics in both General and Psychiatric Hospitals. The General Hospital patients had a higher number per person and more serious potential interactions, yet are often poorly served by psychiatric services, suggesting that liaison psychiatrists have a role in physician education and DDI assessment.

Polypharmacy in older adults with cancer

The definition of "polypharmacy" ranges from the use of a large number of medications; the use of potentially inappropriate medications, which can increase the risk for adverse drug events; medication underuse despite instructions to the contrary; and medication duplication. Older adults are particularly at risk because they often present with several medical conditions requiring pharmacotherapy. Cancer-related therapy adds to this risk in older adults, but few studies have been conducted in this patient population. In this review, we outline the adverse outcomes associated with polypharmacy and present polypharmacy definitions offered by the geriatrics literature. We also examine the strengths and weaknesses of these definitions and explore the relationships among these definitions and what is known about the prevalence and impact of polypharmacy.

Effect of the cytochrome P450 2C19 inhibitor omeprazole on the pharmacokinetics and safety profile of bortezomib in patients with advanced solid tumours, non-Hodgkin's lymphoma or multiple myeloma

BACKGROUND AND OBJECTIVE

Bortezomib, an antineoplastic for the treatment of relapsed multiple myeloma and mantle cell lymphoma, undergoes metabolism through oxidative deboronation by cytochrome P450 (CYP) enzymes, primarily CYP3A4 and CYP2C19. Omeprazole, a proton-pump inhibitor, is primarily metabolized by and demonstrates high affinity for CYP2C19. This study investigated whether coadministration of omeprazole affected the pharmacokinetics, pharmacodynamics and safety profile of bortezomib in patients with advanced cancer. The variability of bortezomib pharmacokinetics with CYP enzyme polymorphism was also investigated.

PATIENTS AND METHODS

This open-label, crossover, pharmacokinetic drug-drug interaction study was conducted at seven institutions in the US and Europe between January 2005 and August 2006. Patients who had advanced solid tumours, non-Hodgkin's lymphoma or multiple myeloma, were aged >/=18 years, weighed >/=50 kg and had a life expectancy of >/=3 months were eligible. Patients received bortezomib 1.3 mg/m2 on days 1, 4, 8 and 11 for two 21-day cycles, plus omeprazole 40 mg in the morning of days 6-10 and in the evening of day 8 in either cycle 1 (sequence 1) or cycle 2 (sequence 2). On day 21 of cycle 2, patients benefiting from therapy could continue to receive bortezomib for six additional cycles. Blood samples for pharmacokinetic/pharmacodynamic evaluation were collected prior to and at various timepoints after bortezomib administration on day 8 of cycles 1 and 2. Blood samples for pharmacogenomics were also collected. Pharmacokinetic parameters were calculated by noncompartmental analysis of plasma concentration-time data for bortezomib administration on day 8 of cycles 1 and 2, using WinNonlin version 4.0.1.a software. The pharmacodynamic profile was assessed using a whole-blood 20S proteasome inhibition assay.

RESULTS

Twenty-seven patients (median age 64 years) were enrolled, 12 in sequence 1 and 15 in sequence 2, including eight and nine pharmacokinetic-evaluable patients, respectively. Bortezomib pharmacokinetic parameters were similar when bortezomib was administered alone or with omeprazole (maximum plasma concentration 120 vs 123 ng/mL; area under the plasma concentration-time curve from 0 to 72 hours 129 vs 135 ng . h/mL). The pharmacodynamic parameters were also similar (maximum effect 85.8% vs 93.7%; area under the percent inhibition-time curve over 72 hours 4052 vs 3910 % x h); the differences were not statistically significant. Pharmacogenomic analysis revealed no meaningful relationships between CYP enzyme polymorphisms and pharmacokinetic/pharmacodynamic parameters. Toxicities were generally similar between patients in sequence 1 and sequence 2, and between cycle 1 and cycle 2 in both treatment sequences. Among 26 evaluable patients, 13 (50%) were assessed as benefiting from bortezomib at the end of cycle 2 and continued to receive treatment.

CONCLUSION

No impact on the pharmacokinetics, pharmacodynamics and safety profile of bortezomib was seen with coadministration of omeprazole. Concomitant administration of bortezomib and omeprazole is unlikely to cause clinically significant drug-drug interactions and is unlikely to have an impact on the efficacy or safety of bortezomib.

Epidemiology of HIV and response to antiretroviral therapy in the middle aged and elderly

HIV is increasing in prevalence in the middle aged and older population owing to both increased longevity, and new infections in these populations. Highly active antiretrorival therapy (HAART) therapy may be less effective at restoring immune function in older patients compared with younger patients. There are significant toxicities associated with HAART therapy that, combined with decreased renal and liver function in older patients, may be more problematic in older HIV-infected patients. Comorbid disease is becoming an increasing problem with coadministration of multiple drugs and significant drug-drug interactions. Psychosocial issues in the older patient are often different than those in younger HIV-infected patients and providers should try to address these issues early. Finally, future research should work to identify the ideal timing and type of HAART regimens for older HIV-infected individuals.

Drug-drug interactions in a geriatric outpatient cohort: prevalence and relevance

BACKGROUND

The prevalence of drug-drug interactions (DDIs) in a geriatric population may be high because of polypharmacy. However, wide variance in the clinical relevance of these interactions has been shown.

OBJECTIVES

To explore whether adverse drug reactions (ADRs) as a result of DDIs can be identified by clinical evaluation, to describe the prevalence of ADRs and diminished drug effectiveness as a result of DDIs and to verify whether the top ten most frequent potential DDIs known to public pharmacies are of primary importance in geriatric outpatients in the Netherlands.

METHOD

All adverse events classified by the Naranjo algorithm as being a possible ADR and drug combinations resulting in diminished drug effectiveness were identified prospectively in 807 geriatric outpatients (mean age 81 years) at their first visit. The setting was a diagnostic day clinic. The Medication Appropriateness Index (MAI) and Beers criteria were used to evaluate drug use and identify possible DDIs. The ten most frequent potential interactions, according to a 1997 national database of public pharmacies ('Top Ten') in the Netherlands, and possible adverse events as a result of other interactions, were described. The effects of changes in medication regimen were recorded by checking the medical records.

RESULTS

In 300 patients (44.5% of the 674 patients taking more than one drug), 398 potential DDIs were identified. In 172 (25.5%) of patients taking more than one drug, drug combinations were identified that were responsible for at least one ADR or which possibly resulted in reduced effectiveness of therapy. Eighty-four of the 158 possible ADRs resulting from enhanced action of drugs forming combinations listed in the 'Top Ten' were seen in 73 patients. Only four DDIs resulting in less effective therapy that involved drug combinations in the 'Top Ten' were identified. Changes in drug regimens pertaining to possible interactions were proposed or put into effect in 111 of the 172 (65%) patients with possible DDIs. Sixty-one (55%) of these patients returned for follow-up. Of these, 49 (80%) were shown to have improved after changes were made to their medication regimen.

CONCLUSION

In this study, nearly half of the geriatric outpatients attending a diagnostic day clinic who were taking more than one drug were candidates for DDIs. One-quarter of these patients were found to have possible adverse events or diminished treatment effectiveness that may have been at least partly caused by these DDIs. These potential interactions can be identified through clinical evaluation. In the majority of patients (99 of 172) the potential interactions resulting in possible ADRs or diminished effectiveness were not present in the 'Top Ten' interactions described by a national database of public pharmacies, a finding that emphasizes that the particular characteristics of geriatric patients (e.g. frequent psychiatric co-morbidities) need to be considered when evaluating their drug use. At least 7% of all patients taking more than one drug, and 80% of those with possible drug interactions whose drug regimen was adjusted, benefited from changes made to their drug regimens.

Identification of drug interactions in hospitals--computerized screening vs. bedside recording

BACKGROUND AND OBJECTIVE

Managing drug interactions in hospitalized patients is important and challenging. The objective of the study was to compare two methods for identification of drug interactions (DDIs)--computerized screening and prospective bedside recording--with regard to capability of identifying DDIs.

METHODS

Patient characteristics were recorded for patients admitted to five hospitals. By bedside evaluation drug-related problems, including DDIs, were prospectively recorded by pharmacists and discussed in multidisciplinary teams. A computer screening programme was used to identify DDIs retrospectively--dividing DDIs into four classes: A, avoid; B, avoid/take precautions; C, take precautions; D, no action needed.

RESULTS

Among 827 patients, computer screening identified DDIs in 544 patients (66%); 351 had DDIs introduced in hospital. The 1513 computer-identified DDIs had the following distribution: type A 78; type B 915; type C 38; type D 482. By bedside evaluation, 99 DDIs were identified in 73 patients (9%). The proportions of computer recorded DDIs which were also identified at the bedside were: 5%, 8%, 8%, 2% DDIs of types A, B, C and D respectively. In 10 patients, DDIs not registered by computer screening were identified by bedside evaluation. The drugs most frequently involved in DDIs, identified by computerized screening were acetylsalicylic acid, warfarin, furosemide and digitoxin compared with warfarin, simvastatin, theophylline and carbamazepine, by bedside evaluation.

CONCLUSION

Despite an active prospective bedside search for DDIs, this approach identified less than one in 10 of the DDIs recorded by computer screening, including those regarded as hazardous. However, computer screening overestimates considerably when the objective is to identify clinically relevant DDIs.

Role of p-glycoprotein inhibition for drug interactions: evidence from in vitro and pharmacoepidemiological studies

OBJECTIVES

We determined in vitro the potency of macrolides as P-glycoprotein inhibitors and tested in hospitalised patients whether coadministration of P-glycoprotein inhibitors leads to increased serum concentrations of the P-glycoprotein substrates digoxin and digitoxin.

METHODS

In vitro, the effect of macrolides on polarised P-glycoprotein-mediated digoxin transport was investigated in Caco-2 cells. In a pharmacoepidemiological study, we analysed the serum digoxin and digitoxin concentrations with and without coadministration of P-glycoprotein inhibitors in hospitalised patients.

RESULTS

All macrolides inhibited P-glycoprotein-mediated digoxin transport, with concentrations producing 50% inhibition (IC(50)) values of 1.8, 4.1, 15.4, 21.8 and 22.7 micromol/L for telithromycin, clarithromycin, roxithromycin, azithromycin and erythromycin, respectively. Coadministration of P-glycoprotein inhibitors was associated with increased serum concentrations of digoxin (1.3 +/- 0.6 vs 0.9 +/- 0.5 ng/mL, p < 0.01). Moreover, patients receiving macrolides had higher serum concentrations of cardiac glycosides (p < 0.05).

CONCLUSION

Macrolides are potent inhibitors of P-glycoprotein. Drug interactions between P-glycoprotein inhibitors and substrates are likely to occur during hospitalisation.

The impact of clinical pharmacists on drug-related problems and clinical outcomes

Drug-related problems are frequent and may result in reduced quality of life, and even morbidity and mortality. Many studies have shown that clinical pharmacists can effectively identify and prevent clinically significant drug-related problems and that physicians acknowledge and act on the clinical pharmacist's suggestions for interventions to the drug-related problems. A pro-active rather than a reactive approach on the part of the pharmacists seems prudent for obtaining most benefit. This includes participation of pharmacists in the multidisciplinary team discussions - at the stage of ordering and prescribing - where all types of drug-related problems, including also potential problems, should be discussed. In addition, counselling by pharmacists about medication on discharge and follow-up after discharge resulted in better outcomes. Furthermore, clinical pharmacists can positively influence other outcomes, such as improvement of levels of markers for drug use (e.g. optimization of lipid levels, anticoagulation levels and blood pressure). Some studies have reported positive effects on hard clinical outcomes, such as reduced length of stay, fewer re-admissions and fewer disease events (e.g. heart failure events and thromboembolism). However, more studies should be undertaken with larger patient populations, including patients from multiple sites. More knowledge about patient-specific factors that predict improved care is also needed. In conclusion, there is increasing evidence that participation and interventions of clinical pharmacists in health care positively influence clinical practice.

[Prospective assessment of drug interactions in hospitalized patients using a computer programme]

OBJECTIVE

To describe the implementation, functioning and results of a prospective automated system monitoring clinically relevant interactions in hospitalised patients in a 400-bed hospital for the period between 1 January 2005 and 31 March 2006.

METHOD

We created a computer programme in Access(R) 97 that checks, twice daily, the drug treatments of all of the patients admitted to the hospital in order to search for the 198 pairs of drugs previously selected from: a validated tertiary source (Hansten PD, Horn JR. Hansten and Horn's Drug Interactions Analysis and Management. St. Louis, MO: Facts and Comparisons; 2001 and updates), most relevant primary sources, expert opinions and alerts from the Spanish Agency of Medicines and Health Products. The clinical pharmacist will assess the drug-drug interaction (DDI) taking into account the timeline sequence, dose, administration route, management opportunities, patient diagnosis, clinical relevance, etc. If necessary, the doctor is contacted by phone and/or letter to inform him/her of the type of interaction, the mechanism and possible management. The programme files the following variables every day: interaction, sex, age, service, number of drugs, pharmaceutical intervention and doctor response.

RESULTS

Clinically relevant drug interactions were detected in 3% of patients during their stay in hospital. These patients were an average of 10 years older and received an average of four drugs more than other patients. A total of 538 interactions were detected in 15 months. Forty-three of 198 possible DDls appeared at some time. The pharmacist intervened on 126 (23%) occasions. The doctor accepted the recommendation on at least 66 (52%) occasions. Fourteen drugs were responsible for 91% of the interactions reported.

CONCLUSIONS

The patients with interactions are older and receive more drugs. The prior intervention of the pharmacist eliminated 77% of unnecessary alerts.

Management of drug-interaction alerts in community pharmacies

BACKGROUND AND OBJECTIVE

Drug-interaction alert systems are commonly used in community pharmacies to identify potential drug-drug interactions. However, depending on the software default setting, pharmacists may override alerts because they are too numerous. We explored the handling of drug-interaction alerts by community pharmacies in Switzerland.

METHODS

Data were collected by 15 trained pharmacy students in 15 Swiss community pharmacies. The medication history and the drug-interaction alerts of 600 patients who had >or=2 drugs on prescription were assessed, and the pharmacists in charge were interviewed about their management of drug-interaction alerts.

RESULTS

In the 15 pharmacies studied, the computer systems were programmed to flag only 'severe' drug interactions in four, 'severe or moderate' in six or 'severe, moderate or minor' in five pharmacies. The median frequency of drug-interaction alerts increased with decreasing default severity level from 0.5 to 40, respectively, to 76 per 40 patient visits and pharmacy. Because of these default settings, 277 (35 x 2%) of 787 potential drug-interaction alerts on new or repeated prescriptions were overridden by the computer systems. Only 256 (32 x 5%) of 787 potential drug interactions emerged from new prescriptions. The alert systems produced 656 alerts of which 146 were irrelevant because of multiple alerting of the same interaction or of drug combinations currently no longer taken. Of the 510 remaining relevant drug-interaction alerts, 289 (56 x 7%) were overridden by community pharmacists without any action taken. If the pharmacist took care of a patient's prescription him- or herself (as opposed to just controlling a prescription after a technician took care of the patient), fewer drug-interaction alerts were overridden by the pharmacist [Odds ratio (OR) 0 x 6, 95% confidence interval (CI) 0 x 42-0 x 98; P=0 x 042). Technical overrides (by default settings) and pharmacists' overrides together accounted for 71 x 9% (566 of 787 potential drug interactions). Of the remaining 211 interactions alerts, 87 (41 x 2%) were checked more closely by consulting the literature, contacting the prescribing physician or discussion with the patient. This led to 55 (63 x 2%) interventions (close monitoring, adjustment of dose or ingestion time, therapy stop or switching to alternative therapy). Determinants associated with action taken after an interaction alert were potential high severity (severe or moderate) (OR 3 x 34, 95% CI 1 x 77-6 x 31; P<0 x 001) and alert flagged for the first time (OR 3 x 76, 95% CI 1 x 98-7 x 14; P<0 x 001). All severe potential drug interactions (n=10) generated an alert and all caused an intervention.

CONCLUSIONS

Pharmacists override a substantial proportion of drug-interaction alerts of minor or moderate potential severity by ignoring them or by programming the system to only flag drug interactions of potentially high severity. More sophisticated systems with improved sensitivity and specificity are required. Until these become available, it is important to ensure that at least potentially severe drug interactions are not missed; a goal that seems to be largely achieved.

Age-related differences in the prevalence of potential drug-drug interactions in ambulatory dyslipidaemic patients treated with statins

BACKGROUND AND OBJECTIVE

Elderly patients may be at higher risk of drug-drug interactions (DDIs) because of polypharmacy. This study evaluated age-specific differences in the prevalence of clinically relevant potential DDIs (pDDIs) in ambulatory dyslipidaemic patients treated with an HMG-CoA reductase inhibitor (statin). We hypothesised that elderly patients are at higher risk for pDDIs because of the presence of more drugs and drugs with a higher potential for DDIs in this age group.

METHODS

A total of 2742 dyslipidaemic ambulatory patients treated with a statin were included in this cross-sectional study. Drug treatment was screened for clinically relevant pDDIs using an electronic drug interaction program (DRUG-REAX System).

RESULTS

The study sample consisted of 483 (17.6%) patients aged < or = 54 years, 732 (26.7%) aged 55-64 years, 924 (33.7%) aged 65-74 years and 603 (22.0%) patients aged > or = 75 years. Patients > or =75 years had significantly more pharmacologically active substances prescribed than patients aged < or =54 years (mean 5.8 vs 3.8, respectively; p < 0.001). Cardiovascular diseases such as coronary heart disease, heart failure or arrhythmias were also significantly more prevalent in patients aged > or = 75 years than in younger patients. The overall prevalence of pDDIs increased significantly from 7.9% in those aged < or = 54 years to 18.4% in patients aged > or = 75 years (p < 0.001). The frequency of both pDDIs associated with statins and non-statin pDDIs increased with age. Risk factors for pDDIs in patients aged > or = 75 years were arrhythmias, heart failure and the number of pharmacologically active substances prescribed. The more frequent prescription of cardiovascular drugs with a high potential for pDDIs (e.g. amiodarone and digoxin) in patients aged > or = 75 years was mainly responsible for the observed increases in statin and non-statin pDDIs in this age group.

CONCLUSIONS

Compared with younger patients, elderly dyslipidaemic patients are at a higher risk for clinically relevant pDDIs, mainly because of a higher number of drugs prescribed. In addition, patients aged > or = 75 years were prescribed more drugs with a high potential for DDIs, especially drugs used for the treatment of arrhythmias and heart failure. The risk for adverse reactions associated with pDDIs may often be reduced by dose adjustment, close monitoring or selection of an alternative drug.

Using trigger phrases to detect adverse drug reactions in ambulatory care notes

BACKGROUND

As medical care moves towards an outpatient focus, monitoring systems for ambulatory patients are increasingly important. Because adverse outcomes due to medications are an important problem in outpatients, the authors developed an automated monitoring system for detecting adverse drug reactions (ADRs) in ambulatory patients.

METHODS

The authors obtained a set of approximately 110,000 ambulatory care notes from the medicine clinic at Bellevue Hospital Centre for 2003-4, and manually analysed a representative sample of 1250 notes to obtain a gold standard. To detect ADRs in the text of electronic ambulatory notes, the authors used a "trigger phrases" methodology, based on a simple grammar populated with a limited set of keywords.

RESULTS

Under current functionality, this system detected 38 of 54 cases in the authors' gold standard set, of which 17 were true positives, for a sensitivity of 31%, a specificity of 98%, and a positive predictive value of 45%. Their proxy measure correlated with 70% of the ADRs in the gold standard. These values are comparable or superior to other systems described in the literature.

CONCLUSIONS

These results show that an automated system can detect ADRs with moderate sensitivity and high specificity, and has the potential to serve as the basis for a larger scale reporting system.

Pharmacists versus nonpharmacists in adverse drug event detection: A meta-analysis and systematic review

PURPOSE

A systematic review and metaanalysis were conducted to determine if studies that included pharmacists as chart reviewers detected higher rates of adverse drug events (ADEs) than studies that included other health care professionals or hospital personnel as chart reviewers.

METHODS

A systematic review and metaanalysis of studies using chart review as the method of detection of ADEs were conducted. Pooled estimates of the ADE rates were calculated using the inverse variance weight method. Meta-analysis was performed using a random effects model. Using the Mann-Whitney U test, weighted rates of studies in which pharmacists versus other clinicians were the chart reviewers were compared.

RESULTS

Thirteen studies satisfied the inclusion criteria. Using random effects metaanalysis, the mean of the weighted incidence rate detected by pharmacists was 0.33 ADE per admission (95% confidence interval [CI], 0.17-0.50); the mean was 0.16 ADE per admission (95% CI, 0.11-0.22) with detection by nonpharmacists. Significant heterogeneity was present between studies in both groups. A significant difference (p=0.003) existed between the ADE rate reported by pharmacists (median=0.23; interquartile range [IQR], 0.18-0.44) and that of nonpharmacists (median=0.12; IQR, 0.02-0.49). Although there is overwhelming evidence of statistical heterogeneity, the numbers pertaining to the ADE rates detected by the two groups were large enough to indicate significant differences. Despite the heterogeneity, there is strong evidence that pharmacist-led interventions based on chart review report a higher ADE rate among inpatients.

CONCLUSION

A review of the literature revealed that pharmacists make a salient contribution as manual chart reviewers in inpatient ADE interventions.

Drug-Related Problems in Hospitals

Problems associated with pharmacotherapy (in particular, medication errors and adverse drug events) are frequent and are associated with increased costs for treatment. Analysis of original publications published between 1990 and 2005 on the topics of medication errors and/or adverse drug events in hospitalised patients, focusing on the frequency of, risk factors for and avoidance of such problems associated with pharmacotherapy, indicated that medication errors occurred in a mean of 5.7% of all episodes of drug administration, but with a high variability among the 35 studies retrieved. This variability was explained by the methods by which medication errors were detected (systematic screening of patients versus chart review or spontaneous reporting) and by the way drugs were administered (intravenously administered drugs are associated with the highest error frequencies). Errors occurred throughout the whole medication process, with administration errors accounting for more than half of all errors. Important risk factors included insufficient pharmacological knowledge of health professionals, errors in the patient charts or documentation by nurses and inadequate pharmacy services.Adverse events or reactions, on the other hand, affected 6.1 patients per 100 hospitalised and also showed a high variability among the 46 studies retrieved. This variability could also be explained by the different methods of assessment of the frequency of adverse drug events or reactions, as well as by the different wards on which the studies were performed. Important risk factors for adverse drug events or reactions included polypharmacy, female sex, drugs with a narrow therapeutic range, renal elimination of drugs, age >65 years and use of anticoagulants or diuretics. Since medication errors are strong risk factors for preventable adverse drug events or reactions, strategies have to be put in place for their reduction. Such strategies include ensuring that all persons involved in the medication process (nurses, pharmacists and physicians) have good pharmacological knowledge, computerisation of the entire medication process, and the engagement of a sufficient number of clinical pharmacists on the wards.

HIV and Aging

Between 2001 and 2004, the percentage of all HIV cases in patients aged >or=50 years increased from 17% to 23%. This concerning increase is expected to continue over the next decade. The increasing prevalence of HIV in these patients is a result of increased longevity in patients treated with highly active antiretroviral therapy (HAART) as well as new primary infections in older patients. While older patients may achieve virological suppression at the same rate as younger patients, the immunological benefit of HAART in older patients may be reduced compared with younger patients. In addition, the toxicities associated with HAART may be worse in older HIV patients, particularly those with underlying renal or hepatic insufficiency. All previous studies evaluating the virological and immunological benefits of HAART in older patients have had relatively small sample sizes and none has compared efficacy or rates of toxicity by HAART treatment class. Co-morbidities are more common in older than in younger patients and can impact on the management of HIV in these patients. Providers must be cognisant of drug-drug interactions and potential adverse effects of HAART regimens when selecting an ideal antiretroviral regimen for older HIV patients. Given the increased longevity and rates of malignancies in HIV-infected patients, providers should also be particularly vigilant in maintaining routine health screening in older HIV patients. Controlled trials on HIV epidemiology, pathogenesis, and therapeutic and clinical outcomes are also needed in older patients. As the HIV-infected population ages, there is a growing need to better determine the effectiveness of HAART in older patients, and to investigate factors associated with a more rapid course of HIV infection in patients aged >50 years.

Adverse drug reactions causing hospitalization can be monitored from computerized medical records and thereby indicate the quality of drug utilization

PURPOSE

To use computerized medical records to study the frequency of adverse drug reactions (ADR) as a cause for acute admission to a university hospital.

METHODS

Computerized medical records in 168 consecutively acutely admitted cases to a short-term internal medicine ward at a university hospital were retrospectively evaluated to see if an ADR could have caused the admission.

RESULTS

In 18 cases (11%), an ADR was judged to be the reason for acute admission to the hospital. Augmented pharmacological effects (type A reactions) accounted for 89% of the cases. An additional eight cases (5%) were intentional intoxications with prescription drugs. ADR-associated hospital admissions were age-related (average age 72 compared to 65 in patients admitted for other reasons) and also associated with poly-pharmacy (8.3 drugs compared to 5.2). The ADR was considered to arise from a drug-drug interaction in four cases (22%). Although all ADRs fulfilled the criteria for mandatory reporting, none of them were reported to the Swedish Adverse Drug Reactions Advisory Committee (SADRAC).

CONCLUSIONS

The observed frequency of ADR-related acute hospital admissions in this pilot study is similar to earlier reported data from Sweden and abroad. Almost all of these reactions were known pharmacological (type A) reactions and many therefore theoretically preventable. In contrast to many prospective and costly studies, this retrospective analysis of computerized medical records offered a simple method that can be used in routine health care and also serve as an indicator of the quality of drug use.

The Prevalence of Potential Drug-Drug Interactions in Patients with Heart Failure at Hospital Discharge

BACKGROUND/OBJECTIVE

Pharmacotherapy for heart failure is complex and, due to polypharmacy, is associated with a large risk of potential drug-drug interactions (DDIs). The objective of the present study was to assess the prevalence of potential DDIs in the medication of hospitalised heart failure patients and to evaluate their clinical relevance.

STUDY DESIGN/METHODS

The medication of 400 patients was retrospectively analysed for potential DDIs at hospital admission and discharge using a computerised drug interaction program. Main inclusion criteria were the diagnosis of heart failure and a minimum of two drug prescriptions at discharge.

RESULTS

In the study population of 400 heart failure patients (median age 79 years, 55.5% men), the median number of drugs per patient was lower at admission than at discharge (6 [interquartile range {IQR} 4-9] vs 8 [IQR 6-10]; p < 0.001). At hospital admission, a total of 863 potential DDIs were detected in 272 patients (68.0%; 95% CI 63.4, 72.6). At discharge, 1171 potential DDIs were detected in 355 patients (88.8%; 95% CI 85.7, 91.8). This corresponds with a significant increase in the median number of potential DDIs per patient from admission to discharge (1.5 [IQR 0-3] vs 3 [IQR 1-4]; p < 0.001). Of the 1171 potential DDIs at discharge, 432 (36.9%) were prevalent at admission and 739 (63.1%) resulted from a medication change during the hospital stay. Of these 739 new potential DDIs, the severity of the potential adverse effect was rated as 'major' in 190 (25.7%) patients, 'moderate' in 482 (65.2%) and 'minor' in 67 (9.1%). The 190 potential DDIs with major severity were recorded in a total of 145 patients (36.3%; 95% CI 31.5, 41.0%). Hyperkalaemia was the most prevalent potential adverse effect of major severity (n = 93) and the combination of an ACE inhibitor with a potassium-sparing diuretic was recorded in 64 (16.0%) patients.

CONCLUSIONS

The study shows that hospitalisation of patients with heart failure results in an increase in the number of drugs prescribed per patient and, thereby, also in the number of potentially interacting drug combinations per patient. Although electronic drug interaction programs are a valuable tool to check for potential DDIs, the clinical relevance of most potential DDIs can only be judged by assessment of the individual patient.

Cytochrome P450 Polymorphisms in Geriatric Patients

BACKGROUND AND OBJECTIVE

Up to 23% of the population, depending on their ethnic background, has genetically determined differences in the metabolism of drugs by the cytochrome P450 (CYP) enzymes CYP2C9, CYP2C19 and CYP2D6. The aim of this survey was to determine the relationship between genetical polymorphisms in these CYP enzymes and adverse drug reactions (ADRs) in geriatric patients.

STUDY DESIGN

In a prospective 6-month cohort study of 243 patients in a geriatric rehabilitation ward, mean age 80.2 +/- 7.7 years, ADRs were identified by intensive monitoring by a pharmacoepidemiological team, consisting of pharmacists and physicians. 125 out of these 243 patients were genotyped cross-sectionally for polymorphisms of CYP2C9, CYP2C19 and CYP2D6 by the TaqMan-polymerase chain reaction. The main outcome measures were the prevalence of genetical polymorphisms and the patients' risk for developing an ADR as related to the genotype.

RESULTS

Patients received an average of 14.2 drugs during hospitalisation which led to 251 ADRs in the whole cohort and 149 ADRs in the cross-sectional genotyping study. Genotype frequencies of CYP2C9 enzyme were 25.9% (n = 29) intermediate metabolisers (IMs) and 2.7% (n = 3) poor metabolisers (PMs). For the enzyme CYP2C19, 26.8% (n = 33) IMs and 0.8% (n = 1) PMs were detected. For the enzyme CYP2D6, 24.1% (n = 26) IMs and 3.7% (n = 4) PMs were found in the analysed patient population. In total, 61.6% (n = 77) of genotyped patients experienced mutations in at least one of the three cytochrome enzymes. The ADR rate did not differ significantly between patients with genetic mutations and wild-type genotype patients. Moreover, only eight out of 40 ADRs which were associated with drugs metabolised by CYP2C9, CYP2C19 or CYP2D6 were detected in patients with IM genotype and none in patients with PM genotype.

CONCLUSION

In this investigation geriatric patients showed a high rate of ADRs. However, no association between the ADR rate and the patients' genotype could be detected, which most likely was a result of the small number of patient samples analysed. Although prophylactic genotyping would have not prevented ADRs in this pilot study, physicians nevertheless have to be aware of potential genetic mutations in patients with polypharmacy.

Readmissions and adverse drug reactions in internal medicine: the economic impact

BACKGROUND

Recent studies show that nearly half of the hospitalized patients are readmitted within 6 months from discharge. No data exist about the relationship between adverse drug reactions (ADRs) and readmittance to a department of internal medicine.

OBJECTIVES

The primary aims of the study were to determine if ADRs could be used as predictors for recurrent hospitalizations in internal medicine and to evaluate the economic impact of ADRs on hospitalization costs.

DESIGN AND SETTING

A cohort-based, prospective, 18-month pharmacoepidemiological survey was conducted in the Department I of Internal Medicine at the University Hospital of Erlangen. All patients were intensively monitored for ADRs by a pharmacoepidemiological team. ADRs were evaluated for their offending drugs, probability, severity, preventability and classified by WHO-ART. During a 6-month period ADR-positive patients were matched to non-ADR patients applying diagnosis-related group categorization in order to measure the impact of ADRs on the duration and frequency of hospitalization.

RESULTS

Of 1000 admissions 424 patients had single admissions and 206 patients had recurrent readmissions (min 1, max 9). The prevalence of readmissions was 37% (n = 370). In 145 (23%) of 630 patients, 305 ADRs were observed. The ADR incidence was similar in first admissions and readmissions. ADRs were not found to predict further readmissions and lack of ADRs did not preclude readmissions. ADRs caused hospitalizations in 6.2% of first admissions and in 4.2% of readmissions. According to the Schumock algorithm 135 (44.3%) ADRs were found to be preventable. The occurrence and numbers of ADRs per admission were found to prolong hospitalization period significantly (r = 0.48 and 0.51, P < 0.001, n = 135). Of 9107 treatment days 20% were caused by in-house (1130 days) and community-acquired ADRs (669 days). In admissions and readmissions 11% (>973 days) of all treatment days were judged to be preventable.

CONCLUSIONS

Intensified drug monitoring supported by information technology in internal medicine is essential for early detecting and prevention of ADRs and saving hospital resources.

Implementation of a computer-assisted monitoring system for the detection of adverse drug reactions in gastroenterology

AIM

To investigate the effectiveness of a computer monitoring system that detects adverse drug reactions (ADRs) by laboratory signals in gastroenterology.

METHODS

A prospective, 6-month, pharmaco-epidemiological survey was carried out on a gastroenterological ward at the University Hospital Erlangen-Nuremberg. Two methods were used to identify ADRs. (i) All charts were reviewed daily by physicians and clinical pharmacists. (ii) A computer monitoring system generated a daily list of automatic laboratory signals and alerts of ADRs, including patient data and dates of events.

RESULTS

One hundred and nine ADRs were detected in 474 admissions (377 patients). The computer monitoring system generated 4454 automatic laboratory signals from 39 819 laboratory parameters tested, and issued 2328 alerts, 914 (39%) of which were associated with ADRs; 574 (25%) were associated with ADR-positive admissions. Of all the alerts generated, signals of hepatotoxicity (1255), followed by coagulation disorders (407) and haematological toxicity (207), were prevalent. Correspondingly, the prevailing ADRs were concerned with the metabolic and hepato-gastrointestinal system (61). The sensitivity was 91%: 69 of 76 ADR-positive patients were indicated by an alert. The specificity of alerts was increased from 23% to 76% after implementation of an automatic laboratory signal trend monitoring algorithm.

CONCLUSION

This study shows that a computer monitoring system is a useful tool for the systematic and automated detection of ADRs in gastroenterological patients.