Risk of medication safety incidents with antibiotic use measured by defined daily doses

Background Medication incidents (MIs) account for 11.3 % of all reported patient-safety incidents in England and Wales. Approximately one-third of inpatients are prescribed an antibiotic at some point during their hospital stay. The WHO has identified incident reporting as one solution to reduce the recurrence of adverse incidents. Objectives The aim of this study was to determine the number and nature of reported antibiotic-associated MIs occurring in inpatients and to use defined daily doses (DDDs) to calculate the incident rate for the antibiotics most commonly associated with MIs at each hospital. Setting Two UK acute NHS teaching hospitals. Methods Retrospective quantitative analysis was performed on antibiotic-associated MIs reported to the risk management system over a 2-year period. Quality-assurance measures were undertaken before analysis. The study was approved by the clinical audit departments at both hospitals. Drug consumption data from each hospital were used to calculate the DDD for each antibiotic. Main outcome measures The number of antibiotic-related MIs reported and the incident rate for the 10 antibiotics most commonly associated with MIs at each hospital. Results Healthcare staff submitted 6,756 reports, of which 885 (13.1 %) included antibiotics. This resulted in a total of 959 MIs. Most MIs occurred during prescribing (42.4 %, n = 407) and administration (40.0 %, n = 384) stages. Most common types of MIs were omission/delay (26.3 %, n = 252), and dose/frequency (17.9 %, n = 172). Penicillins (34.5 %, n = 331) and aminoglycosides (16.6 %, n = 159) were the most frequently reported groups with co-amoxiclav (16.8 %, n = 161) and gentamicin (14.1 %, n = 135) the most frequently reported drugs. Using DDDs to assess the incident rate showed that cefotaxime (105.4/10,000 DDDs), gentamicin (25.7/10,000 DDDs) and vancomycin (23.7/10,000 DDDs) had the highest rates. Conclusions This study highlights that detailed analysis of data from reports is essential in understanding MIs and developing strategies to prevent their recurrence. Using DDDs in the analysis of MIs allowed determination of an incident rate providing more useful information than the absolute numbers alone. It also highlighted the disproportionate risk associated with less commonly prescribed antibiotics not identified using MI reporting rates alone.