Frequency and nature of drug–drug interactions in a Dutch university hospital

Abstract

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT • Drug–drug interactions (DDIs) may lead to often preventable adverse drug events and health damage. • In Dutch community pharmacies approximately 6% of all prescriptions generate a DDI alert. • Hospitalized patients may be especially at risk, as they are more severely ill and multiple medications may be prescribed simultaneously; however, only limited data are available on the frequency and nature of DDIs during hospitalization. WHAT THIS STUDY ADDS • In a Dutch university hospital 10% of all prescriptions generated a DDI alert; overall 25% of patients encountered at least one potential DDI. • Besides the risk of decreased effectiveness (25% of the DDIs), the most frequently occurring potential clinical consequence of the DDIs was an increased risk of side‐effects, such as an increased bleeding risk (22% of DDIs), hypotension (15%) and nephrotoxicity (13%). • Almost half of the DDIs could be managed by monitoring laboratory values. AIM Drug–drug interactions (DDIs) may lead to often preventable adverse drug events and health damage. Especially within hospitals, this might be an important factor, as patients are severely ill and multiple medications may be prescribed simultaneously. The objective of this study was to measure the frequency and nature of DDI alerts in a Dutch university hospital. METHODS All patients hospitalized in the University Medical Centre Utrecht in 2006 who were prescribed at least one medication were included. The frequency of DDIs was calculated as: (i) the percentage of patients experiencing at least one DDI, and (ii) the percentage of prescriptions generating a DDI alert. Based on the national professional guideline, DDIs were classified into categories of potential clinical outcome, management advice, clinical relevance (A–F) and available evidence (0–4). RESULTS Of the 21 277 admissions included, 5909 (27.8%) encountered at least one DDI. Overall, the prescribing physician received a DDI alert in 9.6% of all prescriptions. The most frequently occurring potential clinical consequence of the DDIs was an increased risk of side‐effects such as increased bleeding risk (22.0%), hypotension (14.9%), nephrotoxicity (12.6%) and electrolyte disturbances (10.5%). Almost half (48.6%) of the DDIs could be managed by monitoring laboratory values. CONCLUSIONS Computerized DDI alerts may be a useful tool to prevent adverse drug events within hospitals, but they may also result in ‘alert fatigue’. The specificity of alerts could significantly improve by the use of more sophisticated clinical decision support systems taking into account, for example, laboratory values.

Potential Drug-Drug Interactions in Psychiatric Ward of a Tertiary Care Hospital: Prevalence, Levels and Association with Risk Factors

“…The results of our study show that the prevalence of pDDIs in the psychiatric ward (64.8%) was higher compared to other hospitalized patients (49.7 % [3] and 27.8 % [2]) or patients of other wards such as internal medicine wards (51 % [4] and 60 % [13] ) and oncology wards (63 % [5]). In our study, prevalence of pDDIs of major severity (27.2 %) was also higher compared to other studies.…”

“…The issue of DDIs needs more attention in the case of hospitalized patients due to severity of disease, polypharmacy, co-morbid conditions, chronic diseases, complex therapeutic regime, and frequent modification in therapy [2]. Prevalence of potential DDIs (pDDIs) in hospital settings has been estimated in some recent studies to be in the range of 27.8 to 51.4 % [2][3][4]. Old age, taking increased number of medications, long hospital stay, gender and comorbid conditions have been reported as common risk factors for DDIs [5][6][7][8][9][10][11].…”

A prospective analysis of the preventability of adverse drug reactions reported in Sweden

“…In our study this factor only accounted for 5% of the preventable ADRs. Most drug-drug interactions can be handled with dose adjustment or monitoring of laboratory values [24]. Also there is an increasing use of electronic medical records with automatic systems to detect some of these drug interactions that could potentially lead to an ADR.…”

Clinical impact of the hospital pharmacy drug information service: how does information on drug–drug interaction enquiries translate into clinical decisions?

“…Experience from participation in ward rounds and previous studies30 suggest that potential DDI are frequently underestimated. Recently published large studies from university and primary care hospitals reported DDIs (ranging from contraindicated to no clinical relevance) in 27%–28% of all inpatients 29 31…”