Dose-response relationship between selective serotonin re-uptake inhibitors and injurious falls: a study in nursing home residents with dementia.

Aim: The contribution of selective serotonin re-uptake inhibitors (SSRIs) to injurious fall risk in patients with dementia has not been quantified precisely until now. Our objective was to determine whether a dose-response relationship exists for the use of SSRIs and injurious falls in a population of nursing home residents with dementia.

Methods: Daily drug use and daily falls were recorded in 248 nursing home residents with dementia from 1 January 2006 until 1 January 2008. For each resident and for each day of the study period, data on drug use were abstracted from the prescription database, and information on falls and subsequent injuries was retrieved from a standardized incident report system, resulting in a dataset of 85,074 person-days.

Results: We found a significant dose-response relationship between injurious falls and the use of SSRIs. The risk of an injurious fall increased significantly with 31% at 0.25 of the Defined Daily Dose (DDD) of a SSRI, 73% at 0.50 DDD, and 198% at 1.00 DDD (Hazard ratio = 2.98; 95% confidence interval 1.94, 4.57). The risk increased further in combination with a hypnotic or sedative.

Conclusions: Even at low doses, SSRIs are associated with increased risk of an injurious fall in nursing home residents with dementia. Higher doses increase the risk further with a three-fold risk at 1.00 DDD. New treatment protocols might be needed that take into account the dose-response relationship between SSRIs and injurious falls.