Real-world data for intranasal esketamine in treatment-resistant depression (TRD) are needed to characterize effectiveness, suicidality, and tolerability in routine care. We evaluated induction phase outcomes in outpatients with TRD treated at the University Hospital Vienna.

This retrospective single-center registry study included adults with TRD initiating supervised intranasal esketamine. The primary endpoint was the change in clinician-rated depressive symptom severity (MADRS) from the pre-treatment (PV) to the end of induction (EOI) visit. MADRS scores across baseline (BL), PV, and EOI were analyzed using a mixed model for repeated measures. Secondary outcomes included MADRS three-factor change, self-rated depression score trajectories (PHQ-9), response/remission rates, suicidal ideation, and tolerability.

Of 229 screened patients, 176 initiated esketamine and 156 completed induction. MADRS at BL was 31.5 (SD 6.4), PHQ-9 was 18.5 (SD 4.7). In the primary model, adjusted mean MADRS was 30.3 at PV and 17.7 at EOI, yielding a change of −12.5 points (95%CI −14.1 to −11.0; p < 0.001; Hedges’ g = 1.8). All MADRS factors improved, with the largest reduction in the affective–anhedonic domain. PHQ-9 decreased steadily across treatments. Remission was 27.2% and response 57.4% at EOI. Suicidal ideation decreased significantly; no suicide or serious self-harm occurred during induction. Adverse events (AEs) were recorded in 34.7%, with AE-related discontinuation in 3.4%.

Esketamine induction was associated with marked improvement in depressive symptoms and suicidality, with acceptable tolerability under supervised administration. Longer-term registry follow-up and controlled comparative studies are needed to further define the benefit–risk profile beyond induction phase.