Frequency of and risk factors for preventable medication-related hospital admissions in the Netherlands

Background: Medication-related problems that lead to hospitalization have been the subject of many studies, many of which were limited to 1 hospital or lacked patient follow-up. Furthermore, little information exists on potential risk factors associated with preventable medication-related hospitalizations. Methods: A prospective multicenter study was conducted to determine the frequency and patient outcomes of medication-related hospital admissions. A case-control design was used to determine risk factors for potentially preventable admissions. All unplanned admissions in 21 hospitals were assessed during 40 days. Controls were patients admitted for elective surgery. Cases and controls were followed up until hospital discharge. The frequency of medication-related hospital admissions, potential preventability, and outcomes were assessed. For potentially preventable medication-related admissions, risk factors were identified in the case-control study. Results: Almost 13 000 unplanned admissions were screened, of which 714 (5.6%) were medication related. Almost half (46.5%) of these admissions were potentially preventable, resulting in 332 case patients matched with 332 controls. Outcomes were favorable in most patients. The main determinants of preventable medication-related hospital admissions were impaired cognition (odds ratio, 11.9; 95% confidence interval, 3.9-36.3), 4 or more comorbidities (8.1; 3.1-21.7), dependent living situation (3.0; 1.4-6.5), impaired renal function (2.6; 1.6-4.2), nonadherence to medication regimen (2.3; 1.4-3.8), and polypharmacy (2.7; 1.6-4.4). Conclusions: Adverse drug events are an important cause of hospitalizations, and almost half are potentially preventable. The identified risk factors provide a starting point for preventing medication-related hospital admissions.