{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,20]],"date-time":"2026-10-20T16:50:33Z","timestamp":1792515033394,"version":"4.5.0"},"reference-count":52,"publisher":"Public Library of Science (PLoS)","issue":"6","license":[{"start":{"date-parts":[[2026,6,25]],"date-time":"2026-06-25T00:00:00Z","timestamp":1782345600000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100017519","name":"Werner Otto Stiftung","doi-asserted-by":"publisher","award":["04\/103"],"award-info":[{"award-number":["04\/103"]}],"id":[{"id":"10.13039\/501100017519","id-type":"DOI","asserted-by":"publisher"}]},{"name":"Peter M\u00c3\u00b6hrle Stiftung, the Hamburger Spendenparlament","award":["A23\/004"],"award-info":[{"award-number":["A23\/004"]}]}],"content-domain":{"domain":["www.plosone.org"],"crossmark-restriction":false},"short-container-title":["PLoS One"],"abstract":"<jats:sec id=\"sec001\">\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>Obsessive\u2013compulsive disorder (OCD) is a prevalent and highly disabling mental disorder. Worldwide, it is associated with substantial individual suffering and long-term societal costs. Although exposure and response prevention (ERP) is the recommended first-line treatment, access to effective care remains limited for reasons such as long treatment duration. These barriers contribute to persistent global treatment gaps. The Bergen 4-Day Treatment (B4DT) is a brief, concentrated form of ERP (cERP) designed to improve treatment efficiency and access. Although initial outcomes are promising, long-term data from countries other than Norway are limited. This study evaluated the 12-month outcomes of the B4DT in a German day-patient treatment setting, exploring its sustained effectiveness and feasibility outside its original context.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec id=\"sec002\">\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>Fifty-eight adults with OCD received B4DT in an uncontrolled study and were reassessed 12 months after treatment. The primary outcome was OCD severity, assessed with the Yale-Brown Obsessive Compulsive Scale (Y-BOCS). Secondary outcomes included depressive symptoms, global functioning, self-efficacy, experiential avoidance, self-esteem, quality of life, and mental health service utilization.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec id=\"sec003\">\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      Large reductions in OCD symptom severity (Y-BOCS) and significant improvements across most secondary outcomes were sustained at the 12-month follow-up. One year after treatment, 69% of participants met criteria for treatment response, 51% had achieved remission, and 78% showed reliable clinical improvement. No clinically relevant symptom deterioration was observed, and treatment acceptability and follow-up retention were high. Importantly, only a small proportion of patients (\n                      <jats:italic>n<\/jats:italic>\n                      \u2009=\u20094; 7%) required inpatient treatment during the follow-up period.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec id=\"sec004\">\n                    <jats:title>Conclusion<\/jats:title>\n                    <jats:p>These findings demonstrate that brief cERP can achieve durable clinical benefits for patients with OCD when implemented outside its original context. From a global mental health and health policy perspective, the combination of short treatment duration, sustained effectiveness, and low subsequent use of inpatient services suggests that cERP represents a scalable and resource-efficient strategy to expand access to evidence-based OCD treatment across diverse health care systems.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1371\/journal.pone.0350615","type":"journal-article","created":{"date-parts":[[2026,6,25]],"date-time":"2026-06-25T17:32:18Z","timestamp":1782408738000},"page":"e0350615","update-policy":"https:\/\/doi.org\/10.1371\/journal.pone.corrections_policy","source":"Crossref","is-referenced-by-count":5,"title":["Brief intervention, lasting impact: One-year outcomes of the Bergen 4-day treatment for OCD in Germany"],"prefix":"10.1371","volume":"21","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-5292-350X","authenticated-orcid":true,"given":"Lena","family":"Jelinek","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0648-2170","authenticated-orcid":true,"given":"Amir H.","family":"Yassari","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Saskia","family":"Pampuch","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Franziska","family":"Miegel","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Josephine","family":"Schultz","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Bjarne","family":"Hansen","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kristen","family":"Hagen","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"J\u00fcrgen","family":"Gallinat","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jakob","family":"Scheunemann","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"340","published-online":{"date-parts":[[2026,6,25]]},"reference":[{"issue":"4","key":"pone.0350615.ref001","doi-asserted-by":"crossref","DOI":"10.4088\/JCP.19r13085","article-title":"Women are at greater risk of OCD than men","volume":"81","author":"EJ Fawcett","year":"2020","journal-title":"J Clin Psychiatry"},{"issue":"3","key":"pone.0350615.ref002","doi-asserted-by":"crossref","first-page":"169","DOI":"10.1002\/mpr.1359","article-title":"Twelve-month and lifetime prevalence and lifetime morbid risk of anxiety and mood disorders in the United States","volume":"21","author":"RC Kessler","year":"2012","journal-title":"Int J Methods Psychiatr Res"},{"key":"pone.0350615.ref003","volume-title":"Obsessive-compulsive disorder in adults","author":"JS Abramowitz","year":"2014"},{"issue":"4","key":"pone.0350615.ref004","doi-asserted-by":"crossref","first-page":"417","DOI":"10.1017\/S1352465810000275","article-title":"Generic and illness-specific quality of life in obsessive-compulsive disorder","volume":"38","author":"M Hauschildt","year":"2010","journal-title":"Behav Cogn Psychother"},{"issue":"8","key":"pone.0350615.ref005","doi-asserted-by":"crossref","first-page":"989","DOI":"10.1007\/s00127-019-01779-7","article-title":"Four-year course of quality of life and obsessive-compulsive disorder","volume":"55","author":"KCP Remmerswaal","year":"2020","journal-title":"Soc Psychiatry Psychiatr Epidemiol"},{"issue":"3","key":"pone.0350615.ref006","doi-asserted-by":"crossref","first-page":"253","DOI":"10.1016\/j.genhosppsych.2013.01.004","article-title":"Quality of life, family burden and associated factors in relatives with obsessive-compulsive disorder","volume":"35","author":"E Cicek","year":"2013","journal-title":"Gen Hosp Psychiatry"},{"key":"pone.0350615.ref007","doi-asserted-by":"crossref","first-page":"156","DOI":"10.1016\/j.cpr.2015.06.003","article-title":"Cognitive behavioral treatments of obsessive-compulsive disorder. 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Silver","year":"2023","journal-title":"Psychiatr Fenn"},{"key":"pone.0350615.ref021","doi-asserted-by":"crossref","first-page":"639","DOI":"10.3389\/fpsyg.2018.00639","article-title":"The Bergen 4-day OCD treatment delivered in a group setting: 12-month follow-up","volume":"9","author":"B Hansen","year":"2018","journal-title":"Front Psychol"},{"key":"pone.0350615.ref022","doi-asserted-by":"crossref","first-page":"1069","DOI":"10.3389\/fpsyg.2019.01069","article-title":"The Bergen 4-day treatment for obsessive-compulsive disorder: Does it work in a new clinical setting?","volume":"10","author":"G Launes","year":"2019","journal-title":"Front Psychol"},{"issue":"5","key":"pone.0350615.ref023","doi-asserted-by":"crossref","first-page":"626","DOI":"10.1080\/16506073.2025.2453722","article-title":"Preliminary effectiveness of the Bergen 4-day treatment for OCD in Iceland","volume":"54","author":"SD Davidsdottir","year":"2025","journal-title":"Cogn Behav 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Jelinek","year":"2024","journal-title":"Journal of Obsessive-Compulsive and Related Disorders"},{"issue":"3","key":"pone.0350615.ref027","doi-asserted-by":"crossref","first-page":"162","DOI":"10.1159\/000545178","article-title":"Exploring the black box: What happens during brief concentrated exposure and response prevention for obsessive-compulsive disorder?","volume":"94","author":"F Miegel","year":"2025","journal-title":"Psychother Psychosom"},{"issue":"2","key":"pone.0350615.ref028","doi-asserted-by":"crossref","first-page":"153","DOI":"10.1080\/16506073.2024.2395829","article-title":"A concentrated approach for treating OCD: A pilot study examining the feasibility and potential effectiveness of the Bergen Four Day Treatment in the U.S","volume":"54","author":"T Bj\u00f6rgvinsson","year":"2025","journal-title":"Cogn Behav Ther"},{"key":"pone.0350615.ref029","first-page":"226","article-title":"Yale-Brown Obsessive Compulsive Scale (Y-BOCS)","volume":"1","author":"W Goodman","year":"1991","journal-title":"Verhaltenstherapie"},{"key":"pone.0350615.ref030","first-page":"22","article-title":"The MINI International Neuropsychiatric Interview (M.I.N.I.): The development and validation of a structured diagnostic psychiatric interview","volume":"59","author":"DV Sheehan","year":"1998","journal-title":"J Clin Psychiatry"},{"issue":"4","key":"pone.0350615.ref031","doi-asserted-by":"crossref","first-page":"319","DOI":"10.1016\/j.jocrd.2014.08.002","article-title":"Concentrated ERP delivered in a group setting: An effectiveness study","volume":"3","author":"A Havnen","year":"2014","journal-title":"Journal of Obsessive-Compulsive and Related Disorders"},{"issue":"1","key":"pone.0350615.ref032","doi-asserted-by":"crossref","first-page":"323","DOI":"10.1186\/s12888-018-1887-4","article-title":"Successfully treating 90 patients with obsessive compulsive disorder in eight days: The Bergen 4-day treatment","volume":"18","author":"G Kvale","year":"2018","journal-title":"BMC Psychiatry"},{"key":"pone.0350615.ref033","doi-asserted-by":"crossref","first-page":"395","DOI":"10.1055\/s-2007-970894","article-title":"Das Zwangsinventar OCI-R-die deutsche Version des Obsessive-Compulsive Inventory-Revised","volume":"57","author":"S G\u00f6nner","year":"2007","journal-title":"PPmP-Psychother Psychosom Med Psychol"},{"issue":"4","key":"pone.0350615.ref034","doi-asserted-by":"crossref","first-page":"485","DOI":"10.1037\/1040-3590.14.4.485","article-title":"The Obsessive-Compulsive Inventory: Development and validation of a short version","volume":"14","author":"EB Foa","year":"2002","journal-title":"Psychol Assess"},{"issue":"1","key":"pone.0350615.ref035","doi-asserted-by":"crossref","first-page":"61","DOI":"10.1016\/S0165-0327(03)00198-8","article-title":"Measuring depression outcome with a brief self-report instrument: Sensitivity to change of the Patient Health Questionnaire (PHQ-9)","volume":"81","author":"B L\u00f6we","year":"2004","journal-title":"J Affect Disord"},{"issue":"9","key":"pone.0350615.ref036","doi-asserted-by":"crossref","first-page":"606","DOI":"10.1046\/j.1525-1497.2001.016009606.x","article-title":"The PHQ-9: Validity of a brief depression severity measure","volume":"16","author":"K Kroenke","year":"2001","journal-title":"J Gen Intern Med"},{"key":"pone.0350615.ref037","volume-title":"WHOQOL-100 und WHOQOL-Bref. Handbuch f\u00fcr die deutschsprachige Version der WHO Instrumente zur Erfassung von Lebensqualit\u00e4t","author":"MC Angermeyer","year":"2000"},{"issue":"2","key":"pone.0350615.ref038","doi-asserted-by":"crossref","first-page":"299","DOI":"10.1023\/B:QURE.0000018486.91360.00","article-title":"The World Health Organization\u2019s WHOQOL-BREF quality of life assessment: psychometric properties and results of the international field trial. A report from the WHOQOL group","volume":"13","author":"WHOQOL Group","year":"2004","journal-title":"Qual Life Res"},{"key":"pone.0350615.ref039","doi-asserted-by":"crossref","DOI":"10.1515\/9781400876136","volume-title":"Society and the adolescent self-image","author":"M Rosenberg","year":"1965"},{"issue":"1","key":"pone.0350615.ref040","doi-asserted-by":"crossref","first-page":"35","DOI":"10.1037\/a0034473","article-title":"The brief experiential avoidance questionnaire: development and initial validation","volume":"26","author":"W G\u00e1mez","year":"2014","journal-title":"Psychol Assess"},{"issue":"7","key":"pone.0350615.ref041","doi-asserted-by":"crossref","first-page":"1406","DOI":"10.1177\/10731911211010955","article-title":"Psychometric properties of the German Brief Experiential Avoidance Questionnaire (BEAQ)","volume":"29","author":"C Schaeuffele","year":"2022","journal-title":"Assessment"},{"key":"pone.0350615.ref042","article-title":"SWE. Skala zur allgemeinen Selbstwirksamkeitserwartung [GSES. General Self-Efficacy Scale]","author":"R Schwarzer","year":"2003","journal-title":"Open Test Archive"},{"key":"pone.0350615.ref043","unstructured":"APA. Diagnostic and statistical manual of mental disorders. Herausgeber, editor. AP; 1994."},{"issue":"3","key":"pone.0350615.ref044","first-page":"233","article-title":"The Client Satisfaction Questionnaire. Psychometric properties and correlations with service utilization and psychotherapy outcome","volume":"5","author":"CC Attkisson","year":"1982","journal-title":"Eval Program Plann"},{"key":"pone.0350615.ref045","first-page":"248","article-title":"Fragebogen zur Messung der Patientenzufriedenheit - ZUF-8","author":"J Schmidt","year":"2008","journal-title":"Diagnostische Verfahren in der Rehabilitation"},{"issue":"1","key":"pone.0350615.ref046","doi-asserted-by":"crossref","first-page":"12","DOI":"10.1037\/0022-006X.59.1.12","article-title":"Clinical significance: A statistical approach to defining meaningful change in psychotherapy research","volume":"59","author":"NS Jacobson","year":"1991","journal-title":"J Consult Clin Psychol"},{"issue":"1","key":"pone.0350615.ref047","doi-asserted-by":"crossref","first-page":"80","DOI":"10.1002\/wps.20299","article-title":"Towards an international expert consensus for defining treatment response, remission, recovery and relapse in obsessive-compulsive disorder","volume":"15","author":"D Mataix-Cols","year":"2016","journal-title":"World Psychiatry"},{"key":"pone.0350615.ref048","volume-title":"SPSS 16 made simple","author":"PR Kinnear","year":"2009"},{"key":"pone.0350615.ref049","volume-title":"Statistical power analysis for the behavioural sciences","author":"J Cohen","year":"1988"},{"issue":"2","key":"pone.0350615.ref050","doi-asserted-by":"crossref","first-page":"123","DOI":"10.1159\/000520454","article-title":"Effectiveness of individual cognitive-behavioral therapy and predictors of outcome in adult patients with obsessive-compulsive disorder","volume":"91","author":"N Kathmann","year":"2022","journal-title":"Psychother Psychosom"},{"issue":"2","key":"pone.0350615.ref051","doi-asserted-by":"crossref","first-page":"313","DOI":"10.1007\/s00406-021-01284-6","article-title":"Determining prognostic variables of treatment outcome in obsessive-compulsive disorder: effectiveness and its predictors in routine clinical care","volume":"272","author":"P Herzog","year":"2022","journal-title":"Eur Arch Psychiatry Clin Neurosci"},{"issue":"4","key":"pone.0350615.ref052","doi-asserted-by":"crossref","first-page":"547","DOI":"10.1037\/a0028226","article-title":"Premature discontinuation in adult psychotherapy: A meta-analysis","volume":"80","author":"JK Swift","year":"2012","journal-title":"J Consult Clin Psychol"}],"container-title":["PLOS One"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/dx.plos.org\/10.1371\/journal.pone.0350615","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,6,25]],"date-time":"2026-06-25T17:32:30Z","timestamp":1782408750000},"score":1,"resource":{"primary":{"URL":"https:\/\/dx.plos.org\/10.1371\/journal.pone.0350615"}},"subtitle":[],"editor":[{"given":"Chongzeng","family":"Bi","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"editor"}]}],"short-title":[],"issued":{"date-parts":[[2026,6,25]]},"references-count":52,"journal-issue":{"issue":"6","published-online":{"date-parts":[[2026,6,25]]}},"URL":"https:\/\/doi.org\/10.1371\/journal.pone.0350615","relation":{},"ISSN":["1932-6203"],"issn-type":[{"value":"1932-6203","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,6,25]]}}}