A target trial emulation comparing the antidepressant effectiveness of selective serotonin reuptake inhibitors (SSRIs) highlighting the importance of patent-related confounding by indication.

Sertraline, citalopram, and escitalopram do not seem to have differential effectiveness in the treatment of depression. Taking potential patent-related, time varying, confounding by indication (via severity) into account is critical for pharmacoepidemiological studies, including those employing target trial emulation.