Off-label use of antipsychotics and associated factors in community living older adults*

Background: Given the common off-label use of antipsychotics (AP), we aimed to assess the factors associated with this use in community living older adults. Methods: The study sample consisted of a large representative sample of older adults (n = 4108), covered under a public drug insurance plan in Canada. Off-label use of antipsychotics was defined by the absence of an approved indication for this use, according to Health Canada's drug product database. Multinomial logistic regression was used to assess the factors associated with off-label use. Results: The prevalence of antipsychotics use was 2.5%, of which 78% was off-label. Compared to non-use, off-label antipsychotics use was negatively associated with advanced age (>= 75 vs. 65-74 years old) (OR: 0.46; 95%CI: 0.27-0.78); and positively associated with higher education level (OR: 2.68; 95% CI: 1.64-4.40), higher number of outpatient visits (>= 6) (OR: 2.39; 95%CI: 1.34-4.25), antidepressant or benzodiazepine use (OR: 5.81; 95%CI: 3.31-10.21), and the presence of an organic brain syndrome & Alzheimer's (OR: 5.73; 95%CI: 1.74-18.89). Compared to labeled use, off-label use was less likely in those with major depression (OR: 0.02; 95%CI: <0.01-0.11) and with insomnia (OR: 0.13; 95%CI: 0.02-0.91). Conclusions: The majority of antipsychotics prescribed to community living older adults were off-label. This off-label use was more likely in complex clinical cases with multiple outpatient visits and other psychotropic drugs use. Further research should focus on the long-term effects associated with off-label use of antipsychotics.