Suboptimal use of antidepressants in the elderly: A population-based studyin Nova Scotia

This descriptive, retrospective, population-based study assessed patterns o f antidepressant medication use in elderly patients in Nova Scotia during f iscal years 1993 through 1996. Individuals greater than or equal to 65 year s of age who were registered with Nova Scotia's Seniors Pharmacare program and filled a prescription for an antidepressant medication during the speci fied period were included in the study. We determined the number of individ uals who filled greater than or equal to 1 prescription for an antidepressa nt, the number whose prescription for an antidepressant could be matched wi th a diagnosis of depression in the physician's billing database, the numbe r who used antidepressants that were judged inappropriate based on publishe d criteria for medication prescribing in the elderly, the number who used a therapeutic antidepressant dose based on published dosing guidelines for t he elderly, and the number who used antidepressants for greater than or equ al to 6 months. A total of 12,048, 12,317, and 13,419 individuals filled pr escriptions for antidepressants during the 1993 to 1994, 1994 to 1995, and 1995 to 1996 fiscal years, respectively. In each fiscal year, similar to 70 % had received a diagnosis of depression based on the International Classif ication of Diseases, Ninth Revision, Clinical Modification, making it likel y that 70% of antidepressant users were receiving these drugs for a primary diagnosis of depression. The number of antidepressant prescriptions that w ere classified as inappropriate for use in the elderly was 67% in 1993 to 1 994, 61% in 1994 to 1995, and 55% in 1995 to 1996. These decreases over tim e were statistically significant (P < 0.001). Among those using serotonin r euptake inhibitors, secondary tricyclic antidepressants, or tertiary tricyc lic antidepressants, 79%, 45%, and 31%, respectively, appeared to be using therapeutic doses. Of 23,555 antidepressant treatment courses, 11,028 (47%) were for less than or equal to 180 days. During the study, a significant n umber of elderly individuals were prescribed antidepressant medications tha t are judged by expert consensus to be inappropriate for use in this popula tion because of an unfavorable toxicity profile, although the number declin ed significantly from year to year (P < 0.001 for year-to-year comparisons) . Many individuals also appeared to be using antidepressant doses that are probably subtherapeutic, but this finding seemed heavily dependent on the c lass of antidepressant used. Nearly half of the individuals studied appeare d to be treated for inadequately short periods.