Morbidity and mortality of multimorbid patients are raised by increased drug-drug and drug-disease interactions

Abstract

Purpose: Multimorbid patients often take many different medicaments at the same time. Those can have clinically relevant interactions or can be overdosed, due to neglected interactions or organ insufficiency. Especially in patients with renal insufficiency this can happen very easily. The aim of this study is to investigate whether multimorbid patients suffer from more medication errors than non-multimorbid patients.
Methods: Anonymous patient data of 2014 from the University Hospital of Zurich were used to perform a retrospective data analysis. There are different kinds of medication interactions. First, there are drug-drug-interactions, which happen when two contraindicated medicaments are falsely given together and can lead to an adverse drug reaction. Other interactions covered in this study are drug-disease interactions and dose adjustment errors, where a drug has not been dose adjusted correctly in a patient with renal impairment. These interactions were identified for in the data and along their effects on patients’ mortality and morbidity.
Results: We could show that the more diagnoses a patient has, the more likely it is that the patient has a medication error. The mortality of patients who had medication errors was 5.1% whereas the mortality of patients without medication error was at 2.3% (p<10-12). It was also shown that patients with medication errors stayed longer in the hospital (15.6 days) versus the patients without medication errors (6.5 days) (p<10-15).
Conclusions: Medication errors are a big problem in today’s hospitals. Due to increased life expectancy multimorbidity is increasing and thus also medication lists are getting longer. In the environment of a hospital drugs are often falsely prescribed in a contraindicated combination or not dose adjusted for renal impairment. Those have a clinically relevant impact on the patient who is more likely to have an exaggerated course of disease leading to a higher mortality. The average length of hospital stay is also getting longer which implies that the medication interactions have an impact on patients’ morbidity and thus success of treatment.