3126 Antidepressant and anxiolytic use and mortality risk in people with dementia in Northern Ireland: a nested case-control study

Introduction Limited evidence exists to support the use of antidepressant and anxiolytic medications in people with dementia; these medications may contribute to potentially inappropriate prescribing and be associated with mortality. This study aimed to investigate trends in prescribing of these medications and the association between exposure to antidepressants and anxiolytics and mortality risk among people with dementia. Method A nested case–control study was conducted using record linkage of five administrative population-based data sources in Northern Ireland between 2010 and 2020. Dementia cases (identified if a medication indicated for dementia management was prescribed from 2012) were matched to one control (based on age and sex). Exposure to antidepressants and anxiolytics was assessed from prescribing records two years prior to dementia diagnosis until six months prior to death or end of study. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using conditional logistic regression after adjusting for demographic factors and comorbidities. Sensitivity analyses were undertaken assessing exposure period and number of prescriptions. Results In total, 14,420 dementia cases and 14,361 controls were included. A greater proportion of study participants were prescribed antidepressants (59.2% of cases, 54.7% of controls) than anxiolytics (44.8% of cases, 36.0% of controls). There was evidence of an increased risk of mortality in people with dementia who were prescribed antidepressants (fully adjusted OR = 1.08; 95% CI 1.02–1.14) and in those prescribed anxiolytics (fully adjusted OR = 1.26; 95% CI 1.19–1.33) compared to nonusers. Sensitivity analyses demonstrated neither exposure period nor number of prescriptions had a significant impact on mortality risk. Conclusion In this large population-based study, the use of antidepressants and anxiolytics in people with dementia was high. The use of antidepressants was associated with a slightly increased risk of mortality whilst the use of anxiolytics was more strongly associated with mortality. Further studies are warranted to support these findings.