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

Wu Yi Zheng*, L. C. Richardson, L. Li, R. O. Day, J. I. Westbrook, M. T. Baysari

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

92 Citations (Scopus)


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.

Original languageEnglish
Pages (from-to)15–27
Number of pages13
JournalEuropean Journal of Clinical Pharmacology
Issue number1
Early online date23 Oct 2017
Publication statusPublished - Jan 2018


  • Clinical relevance
  • Drug-drug interaction
  • Medication errors
  • Patient safety


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