What to Expect When Switching to a Second Antidepressant Medication Following an Ineffective Initial SSRI

Abstract

An antidepressant medication switch often follows a failed initial trial with selective serotonin reuptake inhibitors (SSRIs). When, for whom, and how often second-step response and remission occur are unclear, as is preferred second-step trial duration. As more treatments are approved for use following 2 failed "adequate" trials, researchers and clinicians require an evidence-based definition of "adequate." Following citalopram in the randomized Sequenced Treatment Alternatives to Relieve Depression (STAR*D) clinical trial (which ran July 2001-September 2006), participants with score ≥ 11 on the 16-item Quick Inventory of Depressive Symptomatology-Self-Rated (QIDS-SR₁₆) were randomized to bupropion sustained release, sertraline, or venlafaxine extended release (up to 14 weeks). The QIDS-SR₁₆ defined response, remission, and no clinically meaningful benefit based on the modified intent-to-treat sample. About 80% of 438 participants completed ≥ 6 weeks of treatment with the switch medication. All treatments had comparable outcomes. Overall, 21% (91/438) remitted, 9% (40/438) responded without remission, and 58% (255/438) had no meaningful benefit. Half of the responses and two-thirds of remissions occurred after 6 weeks of treatment. Overall, 33% of responses (43/131) occurred after ≥ 9 weeks of treatment. No baseline features differentiated early from later responders or remitters. No early triage point was found, but those with at least 20% reduction from baseline in QIDS-SR₁₆ score around week 2 were 6 times more likely to respond or remit than those without this reduction. Following nonefficacy with an initial SSRI, only about 20% remit and more than half achieve no meaningful benefit with a second-step switch to another monoaminergic antidepressant. A 12-week trial duration seems necessary to capture as many second-step switch responders as possible. ClinicalTrials.gov identifier: NCT00021528.