Thomas Clausen

Image of Thomas Clausen
Norwegian version of this page
Phone +47 23368978
Visiting address Kirkeveien 166 Bygg 45 0450 Oslo
Postal address Postboks 1039 Blindern 0315 Oslo

Academic interests

  • Treatment approaches and treatment effects in the addictions
  • Opioid maintenance treatment (OMT) as treatment for opioid addiction
  • Overdoses; causes, mechanisms and effective interventions
  • Evaluations of new interventions, with a focus on importance of “local evidence”
  • Alcohol consumption patterns and mental health in low- and middle income countries
  • Development of research methods in the drug addiction field
  • Multidisciplinary research and complimentary methods
  • Research leadership


  • Epidemiology and terminology in the addictions
  • Research methodology and dissemination of research results
  • The treatment of drug addiction
  • Opioid maintenance treatment
  • Drug use and pregnancy
  • Overdoses and prevention
  • Treatment results and long-term outcomes
  • Compulsory treatment
  • Quality of life in the addictions


Professor Thomas Clausen has his MD from the University of Oslo (2000), and earned his PhD ( also at the University of Oslo (2005). He has worked within the addiction field with academic duties and research as a fulltime University of Oslo employee since 2006, and as a Professor since 2010. He is the head of the research group at SERAF focusing on opioid addiction, overdoses and opioid maintenance treatment (OMT). Since 2016 he has been the Head of the Norwegian Addiction Research centre. During the academic year 2014-15 he was a Fulbright Scholar at the Alcohol Research Group (ARG) in Emeryville California, USA. Leads multiple research projects and engages in many national and international collaborations and networks.



Professor Clausen serves as the national expert for “drug-related-deaths”  DRD-indicator in the European Monitoring Centre for Drugs and Drug Addiction (EMCDDA) with annual representation in expert meetings in Lisbon, Portugal.


  • Collaboration with the World Health Organization (WHO) including projects on alcohol consumption patterns in low-and middle income countries
  • Collaboration with Europe and American partners (EUROPAD/RADARS) in a joint project monitoring drug consumption patterns among persons entering opioid drug treatment
  • Collaboration with Nordic colleagues studying overdoses, and outcomes of opioid maintenance treatment in the Nordic countries and context.
  • Ongoing collaboration with the Sørlandet Sykehus, Kristiansand, Norway for outcomes studies from drug-treatment, including coercive treatment, 12-step utilization and Opioid maintenance treatment
  • Collaboration with all regional health enterprises in Norway for ongoing annual monitoring of outcomes of opioid maintenance treatment
  • Collaboration with the Directorate for Health, Oslo and Bergen Municipalities as a joint effort to distribute nasal naloxone to drug users will be monitored by SERAF
  • Collaboration with the ARG in California on alcohol use and consequenses with a focus on low-and middle income countries


Ongoing PhD projects:

Marianne Riksheim; Longitudinal analyses of opioid maintenance treatment outcomes

Kristine Jonassen; (Medical student-researcher) Overdoses in Oslo

Adrian Razvan Pasareanu; Coercive treatment in the addictions and long-term outcomes

Ingeborg Skjærvø; Crime and drug treatment: the NorCOMT-project

Desiree Madah-Amiri; Distribution of nasal naloxone to opioid drug users

Ashley Muller; Quality of life, social networks and drug treatment: the NorCOMT-project

Anne Bech; Mortality during Opioid Maintenance Treatment (OMT) in Norway

Completed PhD-projects

Christian Tjagvad (2016); Addictive medication in relation to drug treatment and overdose death

Ingrid A. Havnes (2015); Violence and diversion of prescribed opioids among individuals in opioid maintenance treatment. A complementary methods study of violent crime convictions in a national cohort and qualitative interviews among prisoners

Priscilla Martinez (2013); Alcohol use in special populations in Africa: Data from the World Health Survey and Study on Global AGEing and adult health

Anne Opsal (2013); Involuntarily admitted patients with substance use disorders

Anne Bukten (2012); Criminal convictions among patients in opioid maintenance treatment in Norway. A national cohort study

John-Kåre Vederhus (2012); Addiction professionals’ and substance abuse patients’ attitudes towards and usage of 12-step-based self-help groups

Linn Gjersing (2011); Staff attitudes towards opioid maintenance treatment (OMT) and the associations with treatment

Tags: Nordic, USA


View all works in Cristin

  • Lobmaier, Philipp Paul; Skeie, Ivar; Lillevold, Pål Henrik; Bussesund, Kari; Waal, Helge & Clausen, Thomas (2020). Statusrapport 2019 Nye medisiner - nye muligheter?.
  • Eide, Desiree Soraya; Muller, Ashley Elizabeth & Clausen, Thomas (2019). Behandling av opioiddominert ruslidelse: et prøveprosjekt med heroinassistert behandling.
  • Muller, Ashley Elizabeth; Bukten, Anne & Clausen, Thomas (2019). How can we measure the quality of life of high-risk groups in Norway?. Scandinavian Journal of Public Health.  ISSN 1403-4948.  47, s 10- 10 Full text in Research Archive.
  • Opsal, Anne; Kristensen, Øistein & Clausen, Thomas (2019). Perceived coercion to enter treatment among involuntarily and voluntarily admitted patients with substance use disorders.
  • Stavseth, Marianne Riksheim; Clausen, Thomas & Røislien, Jo (2019). Annual assessment data from the Norwegian opioid maintenance programme: A methodological perspective. Show summary
  • Edvardsen, Hilde Marie Erøy; Rogde, Sidsel; Clausen, Thomas & Vindenes, Vigdis (2018). GHB-, fentanyl- og oksykodonrelaterte dødsfall.
  • Edvardsen, Hilde Marie Erøy; Tverborgvik, Torill; Frost, Joachim; Rogde, Sidsel; Morild, Inge; Waal, Helge; Clausen, Thomas; Slørdal, Lars & Vindenes, Vigdis (2018). Corrigendum to "Differences in combinations and concentrations of drugs of abuse in fatal intoxication and driving under the influence cases". Forensic Science International.  ISSN 0379-0738.  283, s 219- 219 . doi: 10.1016/j.forsciint.2017.12.040
  • Kristensen, Øistein; Opsal, Anne & Clausen, Thomas (2018). Tvangsinnleggelse for rusbehandling?. Tidsskrift for Den norske legeforening.  ISSN 0029-2001.  138(8) . doi: 10.4045/tidsskr.17.1114
  • Medved, David; Clausen, Thomas & Muller, Ashley Elizabeth (2018). Disease burden in ageing long-term opioid maintenance treatment patients; the triple burden.
  • Muller, Ashley Elizabeth & Clausen, Thomas (2018). Somatiske helseutfordringer i LAR: NorComt-studien.
  • Muller, Ashley Elizabeth; Medved, David & Clausen, Thomas (2018). Long-term opioid maintenance treatment patients and the role of benzodiazepines.
  • Muller, Ashley Elizabeth; Odsbu, Ingvild; Sjøgren, Per; Clausen, Thomas & Skurtveit, Svetlana (2018). Prescribed opioid analgesic use developments in the Scandinavian countries, 2006-2017.
  • Skjærvø, Ingeborg; Bukten, Anne; Skurtveit, Svetlana & Clausen, Thomas (2018). Substance use and crime - Characteristics of victim and offender roles in a longitudinal study of patients entering substance use treatment.
  • Madah-Amiri, Desiree; Clausen, Thomas & Lobmaier, Philipp Paul (2017). Opioid overdoses and overdose prevention: The establishment of take-home naloxone in Norway.
  • Muller, Ashley Elizabeth & Clausen, Thomas (2017). Social network changes predict adherence to opioid maintenance treatment.
  • Muller, Ashley Elizabeth; Skurtveit, Svetlana & Clausen, Thomas (2017). Quality of life, substance use disorders, and social lives: Exploring one-year outcomes and intrinsic links. Full text in Research Archive. Show summary
  • Muller, Ashley; Clausen, Thomas & Skurtveit, Svetlana (2017). Building an abstinent network to support quality of life gains through treatment. Show summary
  • Bukten, Anne; Stavseth, Marianne Riksheim; Skurtveit, Svetlana; Kunøe, Nikolaj; Lobmaier, Philipp Paul; Lund, Ingunn Olea & Clausen, Thomas (2016). Rusmiddelbruk og helsesituasjon blant innsatte i norske fengsel. Resultater fra The Norwegian offender mental health and addiction study (NorMA). Full text in Research Archive.
  • Havnes, Ingrid Amalia; Clausen, Thomas & Bukten, Anne (2016). Anabolic androgenic steroid use prior to and during imprisonment - findings from a Norwegian national prison survey.
  • Lobmaier, Philipp Paul & Clausen, Thomas (2016). Radical red tape reduction by government supported nasal naloxone: the Norwegian pilot project is innovative, safe and an important contribution to further development and dissemination of take-home naloxone. Addiction.  ISSN 0965-2140.  11(4), s 586- 587 . doi: 10.1111/add.13261
  • Madah-Amiri, Desiree & Clausen, Thomas (2016). The use of public health infrastructure probably the best strategy for national and large-scale naloxone distribution programmes. Addiction.  ISSN 0965-2140.  111(7), s 1309- 1310 . doi: 10.1111/add.13400
  • Tjagvad, Christian; Clausen, Thomas & Skurtveit, Svetlana (2016). Addictive medication in relation to drug treatment and overdose death. Full text in Research Archive. Show summary
  • Clausen, Thomas (2015). Coherent long-term treatment approaches–superior in the treatment of opioid dependence. Addiction.  ISSN 0965-2140.  110(6), s 1006- 1007 . doi: 10.1111/add.12922
  • Havnes, Ingrid Amalia; Clausen, Thomas; Middelthon, Anne-Lise Orvin & Waal, Helge (2015). Violence and diversion of prescribed opioids among individuals in opioid maintenance treatment.A complementary methods study of violent crime convictions in a national cohort and qualitative interviews among prisoners.
  • Clausen, Thomas; Kristensen, Øistein; Clausen, Thomas & Åsland, Reidun (2014). Re: Pasienter som avbryter LAR-behandling - hvordan går det med dem?. Tidsskrift for Den norske legeforening.  ISSN 0029-2001.  134(16), s 1548- 1549 . doi: 10.4045/tidsskr.14.0927
  • Skeie, Ivar; Clausen, Thomas & Bukten, Anne (2014). I. Skeie og medarbeidere svarer: :. Tidsskrift for Den norske legeforening.  ISSN 0029-2001.  134(16), s 1548 . doi: 10.4045/tidsskr.14.0922
  • Skeie, Ivar; Clausen, Thomas & Bukten, Anne (2014). Legemiddelassistert rehabilitering – viktig behandling med dilemmaer :. Tidsskrift for Den norske legeforening.  ISSN 0029-2001.  134(11), s 1156- 1158 . doi: 10.4045/tidsskr.13.1429
  • Tjagvad, Christian; Petersen, Helle; Thylstrup, Birgitte; Biong, Stian & Clausen, Thomas (2014). Forgiftningsdødsfald og øvrige narkotikarelaterede dødsfald i Danmark 2008-2011.
  • Martinez, Priscilla; Lien, Lars; Clausen, Thomas & Landheim, Anne (2013). Alcohol use in special populations in Africa: Data from the World Health Survey and Study on Global AGEing and adult health.
  • Opsal, Anne; Clausen, Thomas & Larsen, Tor Ketil (2013). Involuntarily admitted patients with substance use disorders.

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Published Apr. 13, 2011 2:55 PM - Last modified Jan. 11, 2017 4:57 PM