SAN DIEGO — A specific warning issued in June 2003 by the United Kingdom Committee on Safety of Medicines that advised physicians not to use paroxetine in patients younger than 18 years of age significantly influenced how the drug was prescribed in young patients in Ontario.
Yet subsequent, more generalized warnings about selective serotonin reuptake inhibitors (SSRIs) issued in the United States and Canada did not influence antidepressant prescription trends in any age group of Ontario residents, Paul A. Kurdyak, M.D., reported during a poster session at the American Psychiatric Association's Institute on Psychiatric Services.
“From a policy perspective, vague warnings don't do anything in Ontario,” Dr. Kurdyak, a research fellow in the department of psychiatry at the University of Toronto, said in an interview. “I don't know about the United States. It might be different there because you're more litigious here than we [in Canada] are.”
In a study supported by AstraZeneca Pharmaceuticals and the Canadian Institute of Health Research, Dr. Kurdyak and his associates analyzed new antidepressant prescriptions dispensed by the Ontario Drug Benefits Program between April 1998 and March 2005. Three age groups were studied: younger than 20 years, 20–65 years, and 66 years and older.
The investigators conducted a time-series analysis to assess the impact of five advisory dates on the prescription of antidepressants. Those dates were:
▸ June 10, 2003. The UK Committee on the Safety of Medicine advises against the use of paroxetine in patients with depression younger than 18 years of age.
▸ Oct. 27, 2003. The U.S. Food and Drug Administration issues a more general public health advisory emphasizing that newer antidepressants should be used with caution in pediatric patients.
▸ March 22, 2004. The FDA issues a public health advisory about the need to closely monitor patients of all ages for worsening depression or suicidality after initiation of antidepressant therapy.
▸ June 3, 2004. Health Care Canada follows suit with a similar warning.
▸ Oct. 15, 2004. The FDA issues a black box warning for the use of antidepressants in pediatric patients.
Analysis revealed that the mean number of monthly new prescriptions for any SSRI per 10,000 individuals was 5.5 for patients younger than 20 years; 29.7 for patients aged 20–65 years, and 16.4 for patients aged 66 years and older.
“The number of new prescriptions for SSRIs as a group did not change after any antidepressant warning in any age group,” the investigators wrote in the text of their poster.
“However, the rate of new paroxetine prescriptions in patients younger than 20 years of age declined by 54% immediately following the first UK warning for paroxetine in June 2003.”
That particular warning “had no effect on new paroxetine prescriptions in the other age categories, [and] no warnings influenced new prescription rates for any other antidepressants in any other age group,” they added.