Psychotropic Medicine Utilization in Older People in New Zealand from 2005 to 2013

Background Psychotropic medicine utilization has increased worldwide among older people (aged 65 years or older), in relation to utilization of other medicines. Objective The aim of this population-level study was to describe and characterize the national utilization of psychotropic medicines in older people in New Zealand between 2005 and 2013. Methods Repeated cross-sectional analysis of population-level dispensing data was conducted from 1 January 2005 to 31 December 2013. Data on utilization of psychotropic medicines were extracted and categorized in accordance with the World Health Organization Collaborating Centre for Drug Statistics Methodology's Anatomical Therapeutic Chemical classification system. Utilization was measured in terms of the defined daily dose (DDD) per 1,000 older people per day (TOPD). Results Overall, utilization of psychotropic medicines showed a 22.5 % increase between 2005 and 2013. Utilization increased for antidepressants (from 81.9 to 110.4 DDD/TOPD), antipsychotics (from 6.8 to 8.7 DDD/TOPD) and hypnotics and sedatives (from 59.4 to 65.5 DDD/TOPD); in contrast, utilization of anxiolytics decreased (from 11.4 to 10.7 DDD/TOPD). Utilization of atypical antipsychotics increased (from 4.6 to 6.8 DDD/TOPD), with the highest percentage change in DDD/TOPD being contributed by olanzapine (112.1 %), while utilization of typical antipsychotics declined (from 2.0 to 1.5 DDD/TOPD). Utilization of tetracyclic antidepressants and venlafaxine grew rapidly by 1.5 and 4.5 times, respectively, between 2005 and 2013. Utilization of zopiclone was greater than that of other hypnotics in 2013. Conclusion Utilization of psychotropic medicines in older people increased by one fifth between 2005 and 2013. Important findings of this study were that: (1) there was a marked increase in utilization of recently funded antidepressants; (2) utilization of atypical antipsychotics increased; (3) there was a move towards utilization of selective serotonin reuptake inhibitors; (4) utilization of zopiclone remained high; and (5) low, standard and high DDD utilization all increased with time.