Unintentional Continuation of Medications Intended for Acute Illness After Hospital Discharge: A Population-Based Cohort Study

Damon C. Scales, Hadas D. Fischer, Ping Li, Arlene S. Bierman, Olavo Fernandes, Muhammad Mamdani, Paula Rochon, David R. Urbach, Chaim M. Bell

Patients are vulnerable to medication-related errors during transitions in care. Patients discharged from acute care hospitals may be at an elevated risk for the unintentional continuation of medications prescribed to prevent or treat complications that are associated with acute illness but are no longer indicated. We sought to evaluate rates of (primary objective) and risk factors for (secondary objective) potentially unintentional medication continuation following hospitalization. A population-based cohort study of more than one million patients 66 years of age or older who were hospitalized in Ontario, Canada, between 2003 and 2011 and followed for 1 year (2004 to 2012). We created distinct cohorts by identifying seniors not previously receiving four classes of medications typically used to treat or prevent complications of acute illness: (1) antipsychotic medications, (2) gastric acid suppressants (histamine-2 blockers and proton pump inhibitors), (3) benzodiazepines, and (4) inhaled bronchodilators and steroids. After excluding documented indications, we followed patients to ascertain whether these medications were continued after hospital discharge, and assessed risk factors for their continuation using generalized estimating equations. The primary outcome was the new dispensation of any of the selected medications within 7 days of hospital discharge. Prescription without documented indication occurred across all medication classes, from 12,209 patients (1.4 %) for antipsychotic medications to 34,140 patients (6.1 %) for gastric acid suppressants. Risk factors for unintentional continuation varied across medication groups, but rates were consistently higher for older patients, those with multiple comorbidities, and emergency hospitalizations. The largest absolute risk factor across all medications was a hospitalization > 7 days [OR 2.03 (95 % CI 1.94-2.11) for respiratory inhalers, 6.35 (95 % CI 5.91-6.82) for antipsychotic medications]. These medications were often continued at 1 year of follow-up, and accounted for a total additional medication cost of over CAD$18 million for the study population. Discharged patients are at risk of being prescribed and dispensed medications that are typically intended to prevent or treat complications of acute illness, despite having no documented indication for chronic use.