The effect of antidepressant warnings on prescribing trends in Ontario, Canada

Objectives. We studied whether 5 regulatory agency advisories concerning the possible increased risk of suicidal behavior during antidepressant therapy had an effect on antidepressant prescription trends in Ontario. Methods. We conducted a population-based, time-series analysis of new monthly antidepressant prescriptions dispensed by the Ontario Drug Benefits program in 3 age groups (younger than 20 years, 20-65 years old, and older than 65 years) over a 7-year period (April 1998 to March 2005). The impact of five advisories about the possible risk of suicide during antidepressant therapy was also analyzed. Results. The number of new prescriptions for selective serotonin reuptake inhibitors as a group did not change after any antidepressant warning in any age group. However, the rate of new paroxetine prescriptions in patients younger than 20 years declined by 54% immediately after the first warning for paroxetine was issued in the United Kingdom in June 2003. That same warning had no effect on new paroxetine prescriptions in the other age categories. Conclusion. The warning about paroxetine use in depressed patients younger than 18 years that was issued in the United Kingdom led to a significant decrease in new paroxetine prescriptions for young patients in this country. By contrast, warnings in North America did not influence new antidepressant prescription rates in any patient group.