Negative clinical outcomes of medication resulting in emergency department visits.

Purpose: The results of analyses of patients' health problems related to medication use have been highly variable due to various factors, such as different study methodology, diverse variables determined, fields of study. The aim of our study was to determine the prevalence and preventability of negative clinical outcomes of medication (NCOMs).

Methods: This was a cross-sectional study performed in the emergency departments (EDs) of nine Spanish hospitals during a 3-month period. A two-stage probabilistic sampling method was used , and a systematic appraisal tool was used to identify the NCOMs based on information gathered through patient interview and review of the medical records. Case evaluations were conducted in two phases by pharmacists and physicians. The prevalence and preventability of NCOM were calculated. A homogeneity test was performed to assess potential differences in the prevalence for each hospital.

Results: A total of 4,611 patients were included in the study. The overall prevalence of NCOMs was 35.7 % [95 % confidence interval (CI) 33.3-38.1]. These NCOMs could be divided into three categories: ineffectiveness (18.2 %; 95 % CI 16.2-20.1), necessity (14.9 %; 95 % CI 13.4-16.6), and lack of safety (2.4 %; 95 % CI 1.9-2.8). About 81 % (95 % CI 80.1-82.3) of the NCOMs could have been prevented.

Conclusions: NCOMs provoked approximately one-third of visits to the EDs, and a high percentage of these were preventable. Implementation of strategies for patient safety and pharmaceutical care could help to prevent these problems and optimize the use of medications.