Harald Weedon-Fekjær

  • Researcher (Statistician); PhD
  • +47 975 70 081

Academic interests

  • Statistical modeling and simulation
  • Applied statistics
  • Statistical computing and software
  • Teaching of statistics

Ongoing work

  • Evaluating the potential effect of mammography screening on breast cancer mortality (main project)
  • Estimating the natural progression of breast cancer and DCIS and its implications
  • Developing good methods for Cancer mortality predictions
  • Studying breast cancer epidemiology


Higher education and employment history

  • PhD in medical statistics, University of Oslo, Norway (2008)
  • Master in mathematical statistics, University of Oslo, Norway (1999)


  • "Breast cancer tumor growth estimated through mammography screening data” (by Weedon-Fekjær et. al., 2008) was selected as article of the year 2008 by the Norwegian Epidemiological Association.  


  • Part of US NCI-sponsored CISNET (The Cancer Intervention and Surveillance Modeling Network) consortium though Dana-Farber Cancer Institute / Harvard University (USA).  


For full CV for Harald Weedon-Fekjær see: 
For more on Harald Weedon-Fekjær see:

University home page: http://www.med.uio.no/imb/personer/vit/hfe/index.html

Key publications:

  1. “Modern mammography screening and breast cancer mortality: population study”, Weedon-Fekjær et. al., BMJ 2014
  2. “Understanding recent invasive breast cancer incidence trends using Age-Period-Cohort analysis and  registry data on mammography screening and hormone treatment use”, Weedon-Fekjær et. al., BMJ 2012
  3. “Breast cancer tumor growth estimated through mammography screening data”, Weedon-Fekjær et. al., Breast Cancer Research 2008
  4. “Prediction of cancer incidence in the Nordic countries up to years 2022; A collaborative study of the five Nordic Cancer Registries”, Møller, Fekjær et al., 2002

Publications 2020

Chootipongchaivat S, van Ravesteyn NT, Li X, Huang H, Weedon-Fekjær H, Ryser MD, Weaver DL, Burnside ES, Heckman-Stoddard BM, de Koning HJ, Lee SJ (2020)
Modeling the natural history of ductal carcinoma in situ based on population data
Breast Cancer Res, 22 (1), 53
DOI 10.1186/s13058-020-01287-6, PubMed 32460821

Fredwall SO, Steen U, de Vries O, Rustad CF, Eggesbø HB, Weedon-Fekjær H, Lidal IB, Savarirayan R, Månum G (2020)
High prevalence of symptomatic spinal stenosis in Norwegian adults with achondroplasia: a population-based study
Orphanet J Rare Dis, 15 (1), 123
DOI 10.1186/s13023-020-01397-6, PubMed 32450891

Sverre E, Peersen K, Weedon-Fekjær H, Perk J, Gjertsen E, Husebye E, Gullestad L, Dammen T, Otterstad JE, Munkhaugen J (2020)
Preventable clinical and psychosocial factors predicted two out of three recurrent cardiovascular events in a coronary population
BMC Cardiovasc Disord, 20 (1), 61
DOI 10.1186/s12872-020-01368-6, PubMed 32024471

Villmones HC, Halland A, Stenstad T, Ulvestad E, Weedon-Fekjær H, Kommedal Ø (2020)
The cultivable microbiota of the human distal ileum
Clin Microbiol Infect (in press)
DOI 10.1016/j.cmi.2020.08.021, PubMed 32835795

Weedon-Fekjær H, Li X, Lee S (2020)
Estimating the natural progression of non-invasive ductal carcinoma in situ breast cancer lesions using screening data
J Med Screen, 0969141320945736
DOI 10.1177/0969141320945736, PubMed 32854582

Publications 2019

Henriksen TH, Abebe W, Amogne W, Getachew Y, Weedon-Fekjær H, Klein J, Woldeamanuel Y (2019)
Association between antimicrobial resistance among Enterobacteriaceae and burden of environmental bacteria in hospital acquired infections: analysis of clinical studies and national reports
Heliyon, 5 (7), e02054
DOI 10.1016/j.heliyon.2019.e02054, PubMed 31372534

Henriksen TH, Abebe W, Amogne W, Getachew Y, Weedon-Fekjær H, Klein J, Woldeamanuel Y (2019)
Corrigendum to "Association between antimicrobial resistance among Enterobacteriaceae and burden of environmental bacteria in hospital acquired infections: analysis of clinical studies and national reports" [Heliyon 5 (7) (July 2019) e02054]
Heliyon, 5 (8), e02383
DOI 10.1016/j.heliyon.2019.e02383, PubMed 31508528

Kjønigsen LJ, Harneshaug M, Fløtten AM, Karterud LK, Petterson K, Skjolde G, Eggesbø HB, Weedon-Fekjær H, Henriksen HB, Lauritzen PM (2019)
Reproducibility of semiautomated body composition segmentation of abdominal computed tomography: a multiobserver study
Eur Radiol Exp, 3 (1), 42
DOI 10.1186/s41747-019-0122-5, PubMed 31664547

Konst B, Weedon-Fekjaer H, Båth M (2019)
Image quality and radiation dose in planar imaging - Image quality figure of merits from the CDRAD phantom
J Appl Clin Med Phys, 20 (7), 151-159
DOI 10.1002/acm2.12649, PubMed 31152576

Publications 2018

Löffeler S, Halland A, Weedon-Fekjær H, Nikitenko A, Ellingsen CL, Haug ES (2018)
High Norwegian prostate cancer mortality: evidence of over-reporting
Scand J Urol, 52 (2), 122-128
DOI 10.1080/21681805.2017.1421260, PubMed 29325479

Majak GB, Reisæter AV, Weedon-Fekjær H, Henriksen T, Michelsen TM (2018)
The Effect of Pregnancy on the Long-term Risk of Graft Loss, Cardiovascular Disease, and Death in Kidney Transplanted Women in Norway: A Retrospective Cohort Study
Transplantation, 102 (9), e391-e396
DOI 10.1097/TP.0000000000002167, PubMed 29528968

Mandelblatt JS, Near AM, Miglioretti DL, Munoz D, Sprague BL, Trentham-Dietz A, Gangnon R, Kurian AW, Weedon-Fekjaer H, Cronin KA, Plevritis SK (2018)
Common Model Inputs Used in CISNET Collaborative Breast Cancer Modeling
Med Decis Making, 38 (1_suppl), 9S-23S
DOI 10.1177/0272989X17700624, PubMed 29554466

Sundby ØH, Irgens I, Høiseth LØ, Mathiesen I, Lundgaard E, Haugland H, Weedon-Fekjær H, Sundhagen JO, Sandbæk G, Hisdal J (2018)
Intermittent mild negative pressure applied to the lower limb in patients with spinal cord injury and chronic lower limb ulcers: a crossover pilot study
Spinal Cord, 56 (4), 372-381
DOI 10.1038/s41393-018-0080-4, PubMed 29497177

van Ravesteyn NT, van den Broek JJ, Li X, Weedon-Fekjær H, Schechter CB, Alagoz O, Huang X, Weaver DL, Burnside ES, Punglia RS, de Koning HJ, Lee SJ (2018)
Modeling Ductal Carcinoma In Situ (DCIS): An Overview of CISNET Model Approaches
Med Decis Making, 38 (1_suppl), 126S-139S
DOI 10.1177/0272989X17729358, PubMed 29554463

Westvik ÅS, Weedon-Fekjær H, Mæhlen J, Liestøl K (2018)
Evaluating different breast tumor progression models using screening data
BMC Cancer, 18 (1), 209
DOI 10.1186/s12885-018-4130-2, PubMed 29463227

Publications 2017

Sundby ØH, Høiseth LØ, Irgens I, Mathiesen I, Lundgaard E, Haugland H, Weedon-Fekjær H, Sundhagen JO, Sanbæk G, Hisdal J (2017)
Intermittent negative pressure applied to the lower limb increases foot macrocirculatory and microcirculatory blood flow pulsatility in people with spinal cord injury
Spinal Cord, 56 (4), 382-391
DOI 10.1038/s41393-017-0049-8, PubMed 29284796

Sundby ØH, Høiseth LØ, Mathiesen I, Weedon-Fekjær H, Sundhagen JO, Hisdal J (2017)
The acute effects of lower limb intermittent negative pressure on foot macro- and microcirculation in patients with peripheral arterial disease
PLoS One, 12 (6), e0179001
DOI 10.1371/journal.pone.0179001, PubMed 28591174

Trewin CB, Strand BH, Weedon-Fekjær H, Ursin G (2017)
Changing patterns of breast cancer incidence and mortality by education level over four decades in Norway, 1971-2009
Eur J Public Health, 27 (1), 160-166
DOI 10.1093/eurpub/ckw148, PubMed 28177482

Publications 2016

Boldingh MI, Maniaol AH, Brunborg C, Weedon-Fekjær H, Verschuuren JJ, Tallaksen CM (2016)
Increased risk for clinical onset of myasthenia gravis during the postpartum period
Neurology, 87 (20), 2139-2145
DOI 10.1212/WNL.0000000000003339, PubMed 27770065

Sundby ØH, Høiseth LØ, Mathiesen I, Jørgensen JJ, Weedon-Fekjær H, Hisdal J (2016)
Application of intermittent negative pressure on the lower extremity and its effect on macro- and microcirculation in the foot of healthy volunteers
Physiol Rep, 4 (17)
DOI 10.14814/phy2.12911, PubMed 27630148

Publications 2015

Berner K, Hall KS, Monge OR, Weedon-Fekjær H, Zaikova O, Bruland ØS (2015)
Prognostic factors and treatment results of high-grade osteosarcoma in norway: a scope beyond the "classical" patient
Sarcoma, 2015, 516843
DOI 10.1155/2015/516843, PubMed 25784831

Fosså SD, Dahl AA, Langhammer A, Weedon-Fekjær H (2015)
Cancer patients' participation in population-based health surveys: findings from the HUNT studies
BMC Res Notes, 8, 649
DOI 10.1186/s13104-015-1635-5, PubMed 26541408

Gangnon RE, Sprague BL, Stout NK, Alagoz O, Weedon-Fekjær H, Holford TR, Trentham-Dietz A (2015)
The contribution of mammography screening to breast cancer incidence trends in the United States: an updated age-period-cohort model
Cancer Epidemiol Biomarkers Prev, 24 (6), 905-12
DOI 10.1158/1055-9965.EPI-14-1286, PubMed 25787716

Löffeler S, Weedon-Fekjaer H, Wang-Hansen MS, Sebakk K, Hamre H, Haug ES, Fosså SD (2015)
"Natural course" of disease in patients with metastatic castrate-resistant prostate cancer: Survival and prognostic factors without life-prolonging treatment
Scand J Urol, 49 (6), 440-445
DOI 10.3109/21681805.2015.1059881, PubMed 26139461

Zaikova O, Sundby Hall K, Styring E, Eriksson M, Trovik CS, Bergh P, Bjerkehagen B, Skorpil M, Weedon-Fekjaer H, Bauer HC (2015)
Referral patterns, treatment and outcome of high-grade malignant bone sarcoma in Scandinavia--SSG Central Register 25 years' experience
J Surg Oncol, 112 (8), 853-60
DOI 10.1002/jso.24074, PubMed 26482729

Publications 2014

Solheim O, Gershenson DM, Tropé CG, Rokkones E, Sun CC, Weedon-Fekjaer H, Fosså SD (2014)
Prognostic factors in malignant ovarian germ cell tumours (The Surveillance, Epidemiology and End Results experience 1978-2010)
Eur J Cancer, 50 (11), 1942-50
DOI 10.1016/j.ejca.2014.03.288, PubMed 24857045

Weedon-Fekjær H, Romundstad PR, Vatten LJ (2014)
Modern mammography screening and breast cancer mortality: population study
BMJ, 348, g3701
DOI 10.1136/bmj.g3701, PubMed 24951459

Publications 2012

Weedon-Fekjær H, Bakken K, Vatten LJ, Tretli S (2012)
Understanding recent trends in incidence of invasive breast cancer in Norway: age-period-cohort analysis based on registry data on mammography screening and hormone treatment use
BMJ, 344, e299
DOI 10.1136/bmj.e299, PubMed 22290099

Publications 2011

Weedon-Fekjær H (2011)
Effectiveness of population-based service screening with mammography for women ages 40 to 49 years: evaluation of the Swedish Mammography Screening in Young Women (SCRY) Cohort
Cancer, 118 (4), 1169; author reply 1170-1
DOI 10.1002/cncr.26163, PubMed 21766290

Publications 2010

Weedon-Fekjaer H, Tretli S, Aalen OO (2010)
Estimating screening test sensitivity and tumour progression using tumour size and time since previous screening
Stat Methods Med Res, 19 (5), 507-27
DOI 10.1177/0962280209359860, PubMed 20356856

Publications 2009

Weedon-Fekjaer H, Sørum R, Brenn MK (2009)
Hormone therapy use may explain recent results regarding tumor regression
Arch Intern Med, 169 (10), 996-7
DOI 10.1001/archinternmed.2009.90, PubMed 19468094

Publications 2008

Weedon-Fekjaer H, Lindqvist BH, Vatten LJ, Aalen OO, Tretli S (2008)
Estimating mean sojourn time and screening sensitivity using questionnaire data on time since previous screening
J Med Screen, 15 (2), 83-90
DOI 10.1258/jms.2008.007071, PubMed 18573776

Weedon-Fekjaer H, Lindqvist BH, Vatten LJ, Aalen OO, Tretli S (2008)
Breast cancer tumor growth estimated through mammography screening data
Breast Cancer Res, 10 (3), R41
DOI 10.1186/bcr2092, PubMed 18466608

Publications 2006

Andersson G, Noack T, Seierstad A, Weedon-Fekjaer H (2006)
The demographics of same-sex marriages in Norway and Sweden
Demography, 43 (1), 79-98
DOI 10.1353/dem.2006.0001, PubMed 16579209

Fosen J, Borgan O, Weedon-Fekjaer H, Aalen OO (2006)
Dynamic analysis of recurrent event data using the additive hazard model
Biom J, 48 (3), 381-98
DOI 10.1002/bimj.200510217, PubMed 16845903

Wibe A, Carlsen E, Dahl O, Tveit KM, Weedon-Fekjaer H, Hestvik UE, Wiig JN, Norwegian Rectal Cancer Group (2006)
Nationwide quality assurance of rectal cancer treatment
Colorectal Dis, 8 (3), 224-9
DOI 10.1111/j.1463-1318.2005.00924.x, PubMed 16466564

Publications 2005

Møller B, Weedon-Fekjaer H, Hakulinen T, Tryggvadóttir L, Storm HH, Talbäck M, Haldorsen T (2005)
The influence of mammographic screening on national trends in breast cancer incidence
Eur J Cancer Prev, 14 (2), 117-28
DOI 10.1097/00008469-200504000-00007, PubMed 15785315

Møller B, Weedon-Fekjaer H, Haldorsen T (2005)
Empirical evaluation of prediction intervals for cancer incidence
BMC Med Res Methodol, 5, 21
DOI 10.1186/1471-2288-5-21, PubMed 15949034

Noack T, Seierstad A, Weedon-Fekjaer H (2005)
A demographic analysis of registered partnerships (legal same-sex unions): The case of Norway
Eur. J. Popul.-Rev. Eur. Demogr., 21 (1), 89-109

Weedon-Fekjaer H, Vatten LJ, Aalen OO, Lindqvist B, Tretli S (2005)
Estimating mean sojourn time and screening test sensitivity in breast cancer mammography screening: new results
J Med Screen, 12 (4), 172-8
DOI 10.1258/096914105775220732, PubMed 16417693

Publications 2004

Aalen OO, Fosen J, Weedon-Fekjaer H, Borgan O, Husebye E (2004)
Dynamic analysis of multivariate failure time data
Biometrics, 60 (3), 764-73
DOI 10.1111/j.0006-341X.2004.00227.x, PubMed 15339300

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