Incidence and Economic Burden of Adverse Drug Reactions among Elderly Patients in Ontario Emergency Departments

Abstract

Background: The rapid rise in the availability and use of pharmaceutical agents, and particularly polypharmacy, directly increases the risk for patients to experience adverse drug reactions (ADRs). There are few studies on the overall incidence and costs of ADRs.Objective: The aim of this study was to estimate the incidence and costs of emergency department (ED) visits related to ADRs for patients greater than 65 years of age using administrative data, and to describe risk factors for experiencing severe ADRs.Methods: We employed a retrospective cohort design based on population-based healthcare administrative clinical databases. Identification of ADR-related ED visits from the administrative database was based on International Classification of Diseases, 10th Revision-Canadian Enhancement (ICD-10-CA) codes for each ED visit. The incidence and costs of ADR-related ED visits and subsequent hospital admissions were estimated for all adults aged 66 years and above for the period April 2003–March 2008. Costs were standardized and reported in 2008 Canadian dollars. Logistic regression was used to detect risk factors for severe ADRs.Results: Approximately 0.75% of total annual ED visits among adults aged 66 years and above were found to be ADR-related, and among these patients 21.6% were hospitalized. In 2007, the cost of ADR-related visits was $333 per ED visit and $7528 per hospitalization for a total annual cost of $13.6 million in Ontario, or an estimated $35.7 million in Canada. Severe ADRs were associated with sex, age, comorbid disease burden, multiple drugs, multiple pharmacies, newly prescribed drugs, recent ED visit, recent hospitalization and long-term care (LTC) residence.Conclusions: ADRs are an important public health issue that threaten the safety of drug therapy and results in significant economic burden to the healthcare system. ED visits related to ADRs may be underestimated in retrospective studies using administrative data compared with prospective studies. Further research is needed to better understand the risk of experiencing severe ADRs among LTC residents.

Adverse drug reactions in a tertiary care teaching hospital in India: analysis of spontaneously reported cases

“…Female gender is considered important risk factors for ADRs. 3,4 Other Indian spontaneous reporting studies had also observed high percentage of ADRs in female. 15,16,20 However, Jose and Rao observed similar incidence of 0.15% for both genders.…”

“…1,2 The female gender, elderly age group, multiple medications and the recent introduction of new drugs are important risk factors for ADRs. 3 Other important factors for their occurrence are race, pregnancy, breastfeeding, alcohol intake, and state of liver and kidney functions. 4 Antimicrobial drugs and analgesics are most frequently responsible for ADRs.…”

Diagnosis-based and external cause-based criteria to identify adverse drug reactions in hospital ICD-coded data: application to an Australia population-based study

“…7,8,11 The Y40-Y59 external cause codes captured about 80% of hospitalisations with "drug-induced" or "due to drug" diagnosis codes, a much higher concordance than the 12-15% reported using English hospital statistics more than a decade ago. 11 Adding high-probability ADR-related diagnosis codes to external cause-based selection yielded a 10.4% increase in ADR numbers on a frequency basis, such that 2.2% of hospitalisations, in this Australian context, were classified as an ADR-related event; this is consistent with a 2-3% national figure based on a recent review.…”

“…5 ADR surveillance may use International Classification of Diseases (ICD) codes (9th or 10th revisions) to ascertain ADRs from routinely collected data on deaths, hospitalisations and emergency department visits. [6][7][8][9][10][11][12][13] These ICD codes comprise diagnoses describing specific clinical symptoms and signs indicating any ADRs (e.g. D61.1 -drug-induced aplastic anaemia), and supplementary classifications documenting external causes to ADR indications (e.g.…”

“…Most commonly, ADR ascertainment uses external cause-based criteria alone 9,10 , but external cause codes and/or diagnosis codes are also used. 7,8,12,13 The implications of using different approaches are unclear, and may differ by location and over time. 7,9,11,13 This study aims to quantify the impact of using different external cause code combinations and hospital diagnosis-based criteria to ascertain ADR-related hospitalisations.…”