Psychological intervention in individuals with subthreshold depression: individual participant data meta-analysis of treatment effects and moderators
Mathias Harrer, Antonia A Sprenger, Susan Illing, Marcel C. Adriaanse, Steven M. Albert, Esther Allart, Osvaldo P. Almeida, Julian Basanovic, K.M.P. van Bastelaar, Philip J. Batterham, Harald Baumeister, Thomas Berger, Vanessa Blanco, Ragnhild Bø, Robin J. Casten, Dicken Chan, Helen Christensen, Markéta Čihařová, Lorna Cook, John E. Cornell, Elysia Poggi Davis, Keith S. Dobson, Els Dozeman, Simon Gilbody, Benjamin L. Hankin, Rimke Haringsma, Kristof Hoorelbeke, Michael R. Irwin, Femke Jansen, Rune Jonassen, Eirini Karyotaki, Norito Kawakami, Jan Philipp Klein, Candace Konnert, Kotaro Imamura, Nils Inge Landrø, Ma. Asunción Lara, Huynh Nhu Le, Dirk Lehr, Juan V. Luciano, Steffen Moritz, Jana Mossey, Ricardo F. Muñoz, Anna Muntingh, Stephanie Nobis, Richard Olmstead, Patricia Otero, Mirjana Pibernik-Okanović, Anne Margriet Pot, Charles F. Reynolds, Barry W. Rovner, Juan P. Sanabria‐Mazo, Lasse Sander, Filip Smit, Frank J. Snoek, Viola Spek, Philip Spinhoven, Liza Stelmach, Yannik Terhorst, Fernando L. Vázquez, Irma M. Verdonck‐de Leeuw, Edward Watkins, Wenhui Yang, Samuel Yeung Shan Wong, Johannes Zimmermann, Masatsugu Sakata, Toshi A. Furukawa, Stefan Leucht, Pim Cuijpers, Claudia Buntrock, David Daniel Ebert
Abstract
Background It remains unclear which individuals with subthreshold depression benefit most from psychological intervention, and what long-term effects this has on symptom deterioration, response and remission. Aims To synthesise psychological intervention benefits in adults with subthreshold depression up to 2 years, and explore participant-level effect-modifiers. Method Randomised trials comparing psychological intervention with inactive control were identified via systematic search. Authors were contacted to obtain individual participant data (IPD), analysed using Bayesian one-stage meta-analysis. Treatment–covariate interactions were added to examine moderators. Hierarchical-additive models were used to explore treatment benefits conditional on baseline Patient Health Questionnaire 9 (PHQ-9) values. Results IPD of 10 671 individuals (50 studies) could be included. We found significant effects on depressive symptom severity up to 12 months (standardised mean-difference [s.m.d.] = −0.48 to −0.27). Effects could not be ascertained up to 24 months (s.m.d. = −0.18). Similar findings emerged for 50% symptom reduction (relative risk = 1.27–2.79), reliable improvement (relative risk = 1.38–3.17), deterioration (relative risk = 0.67–0.54) and close-to-symptom-free status (relative risk = 1.41–2.80). Among participant-level moderators, only initial depression and anxiety severity were highly credible ( P > 0.99). Predicted treatment benefits decreased with lower symptom severity but remained minimally important even for very mild symptoms (s.m.d. = −0.33 for PHQ-9 = 5). Conclusions Psychological intervention reduces the symptom burden in individuals with subthreshold depression up to 1 year, and protects against symptom deterioration. Benefits up to 2 years are less certain. We find strong support for intervention in subthreshold depression, particularly with PHQ-9 scores ≥ 10. For very mild symptoms, scalable treatments could be an attractive option.