Communicating the harmful effects of medicines

In 2004 the US Food and Drug Administration warned that antidepressants could increase suicidality in children and adolescents.1 Three years later it ordered that all antidepressants should carry an expanded black box warning, incorporating information about an increased risk of suicidal symptoms in young adults aged 18-24 years.2 These warnings were associated with widespread media coverage.3 4 5

Warnings from regulatory agencies about harms from drugs are known to reduce prescribing rates. In a linked paper Lu and colleagues (doi:10.1136/bmj.g3596) show that not only did prescribing rates decrease in this age group but there was a modest but significant increase in the rate of self poisoning, an important suicidal behavior.6 The net effect of the warning was probably counterproductive and led to more harm.

Completed suicide is such a rare event that even this large observational study lacked the power to investigate this outcome. Nevertheless, self poisoning is a major event for patients, their family, and health services. Lu and colleagues’ study is a good example of the value of a quasiexperimental pharmacoepidemiological design following a timed intervention in investigating important but uncommon adverse events.6 The findings are not only relevant to …