Observational Evidence of the Prevalence and Association of Polypharmacy and Drug Administration Errors in Hospitalized Adult Patients.

To describe the prevalence of polypharmacy and medication administration errors (MAEs) in adult inpatients and explore the association between polypharmacy and MAEs. Polypharmacy and MAEs are common phenomena in hospital settings. Different MAE contributing factors have been suggested by previous studies. Polypharmacy, however, is not always assessed by studies exploring medication error risk factors, and it may deserve further attention. This was a descriptive observational study. The medication administration process in two adult medical wards of a tertiary hospital was recorded by two observers, with parallel review of patients' medication records. Any deviation from prescriber's order, manufacturers' administration instructions, or relevant institutional policies were recorded as errors. Chi square and regression analysis were used to explore associations between polypharmacy and MAEs. Six hundred sixty-five medication administrations were observed. The mean number of drugs prescribed per patient was 8.7. Most inpatients were prescribed more than 5 drugs (92.6%). Almost half of the inpatients were prescribed more than 9 drugs (45.1%) and some more than 12 drugs (22.6%). In total, 2,371 errors were detected, and the mean number of errors per administration was 3.5. When patients received more than 9 (the odds ratio is 1.57, [95%] CI 1.08-2.27; = 0.02) or more than 12 (the odds ratio is 1.53, [95%] CI 1.04-2.30; = 0.04) drugs, the occurrence of a higher number of errors per administration was significantly increased. Polypharmacy is common in adult medical wards and can be associated with the occurrence of a higher number of MAEs. Future interventions aiming for the prevention of MAEs should consider addressing polypharmacy by improving prescribing practices and optimizing pharmacotherapy.