Central Nervous System-Acting Medicines and Risk of Hospital Admission for Confusion, Delirium, or Dementia

Abstract Background Most studies assessing the effect of central nervous system (CNS)-acting medicines on cognitive disturbances have focused on the use of individual medicines. The impact on cognitive function when another CNS-acting medicine is added to a patient's treatment regimen is not well known. Objective To determine risk of hospitalization for confusion, delirium, or dementia in older people associated with increasing numbers of CNS-acting medicines taken concurrently, as well as the number of standard doses taken each day (measured as defined daily doses). Design Retrospective cohort study, from July 2011 to June 2012, using health claims data. Setting Australian veteran population. Participants A total of 74,321 community-dwelling individuals aged 65 years and over, who were dispensed at least 1 CNS-acting medicine in the year before study entry. Patients with prior hospitalization for confusion or delirium, and those with dementia or receiving palliative care, were excluded. Main outcome measure Hospitalization for confusion, delirium, or dementia. Results Over the 1-year study period, 401 participants were hospitalized with confusion, delirium, or dementia. Adjusted analyses showed the risk of hospitalization was 2.4 times greater with the use of 2 CNS-acting medicines compared with no use [incident rate ratio (IRR) 2.39, 95% confidence interval (CI) 1.79–3.19, P