Abstracts from the 7th Canadian Conference on Dementia (CCD) held in Vancouver, October 2013
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Overview
abstract
Objectives:
To assess the association between medication use and the incidence of delirium among residents residing in long-term care facilities (LTCFs).
Methods:
This study was completed as part of a larger multisite, prospective observational study conducted within 7 LTCFs in Quebec. Delirium was assessed via nurse interviews, chart review, and weekly resident assessments for up to 24 weeks using the Confusion Assessment Method. Data were collected pertaining to both molecule and dose of all prescribed medications taken by residents on each day of study. Drugs were categorized by level of cholinergic activity both categorically (anticholinergic drugs, drugs with anticholinergic side effects, agents with published evidence of association with delirium, medications whose indication is either for or associated with delirium) and by the Anticholinergic Cognitive Burden (ACB) Scale. The study cohort was analyzed using a nested-case control method, with each incident case of delirium (the date of which was assigned as the index date) matched to up to 33 controls by institution and study time. Residents were defined as being currently exposed to a drug if they had taken the medication in the 28 days leading up to the index date. The rate ratio (RR) of delirium associated with current and new use of medications was estimated using conditional logistic regression, adjusting for age, sex, dementia severity, time since institutionalization, Charlson Co-morbidity Index score, documentation of a new medical problem or hospital visit, number of drugs being taken, and the number of environmental risk factors for delirium exposed to at the index date.
Results:
The study cohort included 279 residents, of whom 83 were classified as having incident delirium. Cases were more likely than controls to have a chart diagnosis of dementia, have a lower Mini-Mental State Examination (MMSE) score, and to be exposed to more environmental risk factors. The adjusted risk of current medication use for the group of drugs categorized as having anticholinergic side effects was (RR, 3.16; 95% CI, 1.8–5.4). More specifically, current exposure to antidepressants and antipsychotic medications was associated with an elevated risk of delirium (RR, 2.53; 95% CI, 1.4–4.6) and (RR, 2.53; 95% CI, 1.6–4.1), respectively. The risk associated with specific antipsychotic drugs did not seem be related to their associated ACB score. Among antidepressant drugs, exclusive exposure to tricyclics, selective serotonin reuptake inhibitors, and venlafaxine (the only serotonin-norepinephrine reuptake inhibitor under study) was found to be associated with incident delirium (RR, 7.27; 95% CI, 1.2–44.4), (RR, 2.18; 95% CI, 1.1–4.3), and (RR, 6.88; 95% CI, 1.9–24.3), respectively. No association was found between incident delirium and use of medications within other drug categories. An overall trend showing a positive association between total ACB score for all medications currently being taken and delirium was found but it was not statistically significant.
Conclusions:
Current use of antipsychotic medications and antidepressants appears to be associated with the incidence of delirium among residents residing in LTCFs after adjusting for the emergence of new medical conditions. These findings should be verified by future research.
