Adverse drug events in the critical care unit

Introduction

Mistakes and errors may occur during the care process, particularly in the ICU as characterized by its large number of drugs administered to the single patient. One of the most important influencing factors on intramural morbidity and mortality is indeed a harmful or unpredicted reaction to a drug, a so-called adverse drug event (ADE) [1]. By far the largest proportion (70%) of these ADEs is dose related [1]. The objectives of this study are to measure the frequency and severity of ADEs in the ICU and to determine the influence of severity of illness and nursing workload on their prevalence.

Methods

A cross-sectional study in the ICU of a tertiary referral hospital, based on a retrospective chart review. A tool was developed for measuring the incidence and characteristics of ADEs based on the Global Trigger Tool for Measuring Adverse Drug Events [2]. If an ADE was identified the severity was evaluated using the categories based on the system for classifying medication errors by the National Coordination Council for Medication Error Reporting and Prevention [3]. The severity of illness was calculated using the Sepsis-related Organ Failure Assessment score [4] and the nursing workload by the classical Therapeutic Intervention Scoring System-28 [5].

Results

The review of 1,009 nursing days in 79 patients revealed 230 ADEs, which occurred in a total of 175 nursing days. The most commonly identified ADE was a hypoglycemia of <50 mg/dl (n = 75), followed by hypokalemia (n = 67). Ninety-six percent of the ADEs were classified as category E, whereas only 4% of ADEs were classified as category F. The mean severity of illness and nursing workload scores were significant higher on nursing days when an ADE occurred (P < 0.001 and P = 0.002, respectively).

Conclusions

ADEs are common in the ICU. The lack of a golden standard for reporting and collecting ADEs makes it difficult to compare with other studies and to assess the real value of this study. However, these date strongly and clearly indicate the influence of severity of illness and nursing workload on the prevalence of ADEs.