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Bounding the per-protocol effect in randomized trials: an application to colorectal cancer screening.

https://arctichealth.org/en/permalink/ahliterature274407
Source
Trials. 2015;16:541
Publication Type
Article
Date
2015
Author
Sonja A Swanson
Øyvind Holme
Magnus Løberg
Mette Kalager
Michael Bretthauer
Geir Hoff
Eline Aas
Miguel A Hernán
Source
Trials. 2015;16:541
Date
2015
Language
English
Publication Type
Article
Keywords
Clinical Protocols
Colorectal Neoplasms - mortality - pathology
Data Interpretation, Statistical
Early Detection of Cancer - methods - statistics & numerical data
Female
Humans
Male
Middle Aged
Norway
Patient Selection
Predictive value of tests
Prognosis
Research Design
Risk assessment
Risk factors
Sigmoidoscopy - statistics & numerical data
Time Factors
Abstract
The per-protocol effect is the effect that would have been observed in a randomized trial had everybody followed the protocol. Though obtaining a valid point estimate for the per-protocol effect requires assumptions that are unverifiable and often implausible, lower and upper bounds for the per-protocol effect may be estimated under more plausible assumptions. Strategies for obtaining bounds, known as "partial identification" methods, are especially promising in randomized trials.
We estimated bounds for the per-protocol effect of colorectal cancer screening in the Norwegian Colorectal Cancer Prevention trial, a randomized trial of one-time sigmoidoscopy screening in 98,792 men and women aged 50-64 years. The screening was not available to the control arm, while approximately two thirds of individuals in the treatment arm attended the screening. Study outcomes included colorectal cancer incidence and mortality over 10 years of follow-up. Without any assumptions, the data alone provide little information about the size of the effect. Under the assumption that randomization had no effect on the outcome except through screening, a point estimate for the risk under no screening and bounds for the risk under screening are achievable. Thus, the 10-year risk difference for colorectal cancer was estimated to be at least -0.6 % but less than 37.0 %. Bounds for the risk difference for colorectal cancer mortality (-0.2 to 37.4 %) and all-cause mortality (-5.1 to 32.6 %) had similar widths. These bounds appear helpful in quantifying the maximum possible effectiveness, but cannot rule out harm. By making further assumptions about the effect in the subpopulation who would not attend screening regardless of their randomization arm, narrower bounds can be achieved.
Bounding the per-protocol effect under several sets of assumptions illuminates our reliance on unverifiable assumptions, highlights the range of effect sizes we are most confident in, and can sometimes demonstrate whether to expect certain subpopulations to receive more benefit or harm than others.
Clinicaltrials.gov identifier NCT00119912 (registered 6 July 2005).
Notes
Cites: BMJ. 2009;338:b184619483252
Cites: Epidemiology. 2006 Jul;17(4):360-7216755261
Cites: Clin Trials. 2012 Feb;9(1):48-5521948059
Cites: Scand J Gastroenterol. 2002 May;37(5):568-7312059059
Cites: Ann Intern Med. 2013 Oct 15;159(8):560-224018844
Cites: JAMA. 2014 Aug 13;312(6):606-1525117129
Cites: Am J Epidemiol. 2002 Jan 15;155(2):176-8411790682
Cites: Biometrics. 2002 Mar;58(1):21-911890317
Cites: Int J Biostat. 2011;7(1). pii: Article 28. doi: 10.2202/1557-4679.132921841939
Cites: N Engl J Med. 2012 Oct 4;367(14):1355-6023034025
PubMed ID
26620120 View in PubMed
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Source
Ann Intern Med. 2017 10 03;167(7):524
Publication Type
Article
Date
10-03-2017
Author
Karsten Juhl Jørgensen
Peter C Gøtzsche
Mette Kalager
Per-Henrik Zahl
Source
Ann Intern Med. 2017 10 03;167(7):524
Date
10-03-2017
Language
English
Publication Type
Article
Keywords
Breast Neoplasms
Denmark
Early Detection of Cancer
Humans
Mammography
Mass Screening
Notes
Comment On: Ann Intern Med. 2017 Mar 7;166(5):313-32328114661
Comment On: Ann Intern Med. 2017 Oct 3;167(7):52228973198
Comment On: Ann Intern Med. 2017 Oct 3;167(7):523-52428973197
Comment On: Ann Intern Med. 2017 Oct 3;167(7):52328973199
PubMed ID
28973200 View in PubMed
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Breast Cancer Screening in Denmark: A Cohort Study of Tumor Size and Overdiagnosis.

https://arctichealth.org/en/permalink/ahliterature282568
Source
Ann Intern Med. 2017 Mar 07;166(5):313-323
Publication Type
Article
Date
Mar-07-2017
Author
Karsten Juhl Jørgensen
Peter C Gøtzsche
Mette Kalager
Per-Henrik Zahl
Source
Ann Intern Med. 2017 Mar 07;166(5):313-323
Date
Mar-07-2017
Language
English
Publication Type
Article
Keywords
Adult
Aged
Aged, 80 and over
Breast Neoplasms - diagnosis - epidemiology
Carcinoma, Intraductal, Noninfiltrating - diagnosis - epidemiology
Cohort Studies
Denmark - epidemiology
Early Detection of Cancer
Female
Humans
Incidence
Mammography
Mass Screening
Medical Overuse - statistics & numerical data
Middle Aged
Abstract
Effective breast cancer screening should detect early-stage cancer and prevent advanced disease.
To assess the association between screening and the size of detected tumors and to estimate overdiagnosis (detection of tumors that would not become clinically relevant).
Cohort study.
Denmark from 1980 to 2010.
Women aged 35 to 84 years.
Screening programs offering biennial mammography for women aged 50 to 69 years beginning in different regions at different times.
Trends in the incidence of advanced (>20 mm) and nonadvanced (=20 mm) breast cancer tumors in screened and nonscreened women were measured. Two approaches were used to estimate the amount of overdiagnosis: comparing the incidence of advanced and nonadvanced tumors among women aged 50 to 84 years in screening and nonscreening areas; and comparing the incidence for nonadvanced tumors among women aged 35 to 49, 50 to 69, and 70 to 84 years in screening and nonscreening areas.
Screening was not associated with lower incidence of advanced tumors. The incidence of nonadvanced tumors increased in the screening versus prescreening periods (incidence rate ratio, 1.49 [95% CI, 1.43 to 1.54]). The first estimation approach found that 271 invasive breast cancer tumors and 179 ductal carcinoma in situ (DCIS) lesions were overdiagnosed in 2010 (overdiagnosis rate of 24.4% [including DCIS] and 14.7% [excluding DCIS]). The second approach, which accounted for regional differences in women younger than the screening age, found that 711 invasive tumors and 180 cases of DCIS were overdiagnosed in 2010 (overdiagnosis rate of 48.3% [including DCIS] and 38.6% [excluding DCIS]).
Regional differences complicate interpretation.
Breast cancer screening was not associated with a reduction in the incidence of advanced cancer. It is likely that 1 in every 3 invasive tumors and cases of DCIS diagnosed in women offered screening represent overdiagnosis (incidence increase of 48.3%).
None.
PubMed ID
28114661 View in PubMed
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Colorectal cancer death after adenoma removal in Scandinavia.

https://arctichealth.org/en/permalink/ahliterature292361
Source
Scand J Gastroenterol. 2017 Dec; 52(12):1377-1384
Publication Type
Journal Article
Date
Dec-2017
Author
Louise Emilsson
Magnus Løberg
Michael Bretthauer
Øyvind Holme
Katja Fall
Henriette C Jodal
Hans-Olov Adami
Mette Kalager
Author Affiliation
a Institute of Health and Society , University of Oslo , Oslo , Norway.
Source
Scand J Gastroenterol. 2017 Dec; 52(12):1377-1384
Date
Dec-2017
Language
English
Publication Type
Journal Article
Keywords
Adenoma - mortality - surgery
Adult
Age Distribution
Aged
Aged, 80 and over
Colorectal Neoplasms - mortality - surgery
Female
Follow-Up Studies
Humans
Incidence
Male
Middle Aged
Multivariate Analysis
Norway - epidemiology
Proportional Hazards Models
Registries
Risk assessment
Risk factors
Sex Distribution
Sweden - epidemiology
Abstract
Improved understanding of the subsequent risk death from colorectal cancer (CRC) among individuals who had adenomas removed is needed. We aimed to quantify this risk using prospectively collected data from population-based cohorts.
Using Norwegian and Swedish registries, a cohort of 90,864 individuals with colorectal adenomas removed between 1980 and 2013 was identified. Surveillance was only recommended for high-risk adenomas. The validity of the registry data did not allow classification into low- and high-risk adenomas. Virtually complete follow-up was achieved through linkage to nationwide registers. We calculated incidence-based standardised mortality ratios (SMRs) with 95% confidence intervals (CI).
The median follow-up was 7.2 years; 48,058 individuals were followed for more than 10 years. We observed 819 deaths (0.9%) from CRC and expected 731 CRC deaths (0.8%), corresponding to an absolute excess risk of 88 cases (0.1%) and a relative risk of 12% (SMR 1.12; 95%CI 1.05-1.20). The relative risk of CRC death following adenoma removal was slightly higher in Sweden (SMR 1.22; 95%CI 1.11-1.34) than in Norway (SMR 1.03; 95%CI 0.93-1.14), and higher in women (SMR 1.24; 95%CI 1.12-1.36) than in men (SMR 1.02; 95%CI 0.93-1.13). Among individuals with more than 10 years of follow-up, the estimates were similar to the overall cohort, absolute excess risk 0.1% (SMR 1.15; 95%CI 1.06-1.24).
The excess risk of CRC death following adenoma removal is small. Optimal surveillance recommendations should be tested in randomised trials.
PubMed ID
28906163 View in PubMed
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The COVID-19 pandemic in Norway and Sweden - threats, trust, and impact on daily life: a comparative survey.

https://arctichealth.org/en/permalink/ahliterature304371
Source
BMC Public Health. 2020 Oct 23; 20(1):1597
Publication Type
Comparative Study
Journal Article
Date
Oct-23-2020
Author
Lise M Helsingen
Erle Refsum
Dagrun Kyte Gjøstein
Magnus Løberg
Michael Bretthauer
Mette Kalager
Louise Emilsson
Author Affiliation
Clinical Effectiveness Research group, Institute for Health and Society, University of Oslo and Oslo University Hospital, PO Box 1089, Blindern, 0318, Oslo, Norway. lisemhe@medisin.uio.no.
Source
BMC Public Health. 2020 Oct 23; 20(1):1597
Date
Oct-23-2020
Language
English
Publication Type
Comparative Study
Journal Article
Keywords
Adolescent
Adult
COVID-19
Coronavirus Infections - epidemiology - prevention & control
Female
Humans
Life Style
Male
Middle Aged
Norway - epidemiology
Pandemics - prevention & control
Pneumonia, Viral - epidemiology - prevention & control
Risk assessment
Schools - organization & administration
Surveys and Questionnaires
Sweden - epidemiology
Trust
Young Adult
Abstract
Norway and Sweden have similar populations and health care systems, but different reactions to the COVID-19 pandemic. Norway closed educational institutions, and banned sports and cultural activities; Sweden kept most institutions and training facilities open. We aimed to compare peoples' attitudes towards authorities and control measures, and perceived impact of the pandemic and implemented control measures on life in Norway and Sweden.
Anonymous web-based surveys for individuals age 15 or older distributed through Facebook using the snowball method, in Norway and Sweden from mid-March to mid-April, 2020. The survey contained questions about perceived threat of the pandemic, views on infection control measures, and impact on daily life. We performed descriptive analyses of the responses and compared the two countries.
3508 individuals participated in the survey (Norway 3000; Sweden 508). 79% were women, the majority were 30-49?years (Norway 60%; Sweden 47%), and about 45% of the participants in both countries had more than 4 years of higher education. Participants had high trust in the health services, but differed in the degree of trust in their government (High trust in Norway 17%; Sweden 37%). More Norwegians than Swedes agreed that school closure was a good measure (Norway 66%; Sweden 18%), that countries with open schools were irresponsible (Norway 65%; Sweden 23%), and that the threat from repercussions of the mitigation measures were large or very large (Norway 71%; Sweden 56%). Both countries had a high compliance with infection preventive measures (>?98%). Many lived a more sedentary life (Norway 69%; Sweden 50%) and ate more (Norway 44%; Sweden 33%) during the pandemic.
Sweden had more trust in the authorities, while Norwegians reported a more negative lifestyle during the pandemic. The level of trust in the health care system and self-reported compliance with preventive measures was high in both countries despite the differences in infection control measures.
PubMed ID
33097011 View in PubMed
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Effect of flexible sigmoidoscopy screening on colorectal cancer incidence and mortality: a randomized clinical trial.

https://arctichealth.org/en/permalink/ahliterature102988
Source
JAMA. 2014 Aug 13;312(6):606-15
Publication Type
Article
Date
Aug-13-2014
Author
Øyvind Holme
Magnus Løberg
Mette Kalager
Michael Bretthauer
Miguel A Hernán
Eline Aas
Tor J Eide
Eva Skovlund
Jørn Schneede
Kjell Magne Tveit
Geir Hoff
Author Affiliation
Department of Medicine, Sorlandet Hospital Kristiansand, Kristiansand, Norway2Institute of Health and Society, University of Oslo, Oslo, Norway3Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts4Department of Biostatistics Harvard School of Public Health, Boston, Massachusetts.
Source
JAMA. 2014 Aug 13;312(6):606-15
Date
Aug-13-2014
Language
English
Publication Type
Article
Keywords
Colorectal Neoplasms - diagnosis - epidemiology - mortality - prevention & control
Early Detection of Cancer
Female
Humans
Incidence
Intention to Treat Analysis
Male
Middle Aged
Norway - epidemiology
Occult Blood
Sigmoidoscopy - instrumentation
Abstract
Colorectal cancer is a major health burden. Screening is recommended in many countries.
To estimate the effectiveness of flexible sigmoidoscopy screening on colorectal cancer incidence and mortality in a population-based trial.
Randomized clinical trial of 100,210 individuals aged 50 to 64 years, identified from the population of Oslo city and Telemark County, Norway. Screening was performed in 1999-2000 (55-64-year age group) and in 2001 (50-54-year age group), with follow-up ending December 31, 2011. Of those selected, 1415 were excluded due to prior colorectal cancer, emigration, or death, and 3 could not be traced in the population registry.
Participants randomized to the screening group were invited to undergo screening. Within the screening group, participants were randomized 1:1 to receive once-only flexible sigmoidoscopy or combination of once-only flexible sigmoidoscopy and fecal occult blood testing (FOBT). Participants with positive screening test results (cancer, adenoma, polyp =10 mm, or positive FOBT) were offered colonoscopy. The control group received no intervention.
Colorectal cancer incidence and mortality.
A total of 98,792 participants were included in the intention-to-screen analyses, of whom 78,220 comprised the control group and 20,572 comprised the screening group (10,283 randomized to receive a flexible sigmoidoscopy and 10,289 to receive flexible sigmoidoscopy and FOBT). Adherence with screening was 63%. After a median of 10.9 years, 71 participants died of colorectal cancer in the screening group vs 330 in the control group (31.4 vs 43.1 deaths per 100,000 person-years; absolute rate difference, 11.7 [95% CI, 3.0-20.4]; hazard ratio [HR], 0.73 [95% CI, 0.56-0.94]). Colorectal cancer was diagnosed in 253 participants in the screening group vs 1086 in the control group (112.6 vs 141.0 cases per 100,000 person-years; absolute rate difference, 28.4 [95% CI, 12.1-44.7]; HR, 0.80 [95% CI, 0.70-0.92]). Colorectal cancer incidence was reduced in both the 50- to 54-year age group (HR, 0.68; 95% CI, 0.49-0.94) and the 55- to 64-year age group (HR, 0.83; 95% CI, 0.71-0.96). There was no difference between the flexible sigmoidoscopy only vs the flexible sigmoidoscopy and FOBT screening groups.
In Norway, once-only flexible sigmoidoscopy screening or flexible sigmoidoscopy and FOBT reduced colorectal cancer incidence and mortality on a population level compared with no screening. Screening was effective both in the 50- to 54-year and the 55- to 64-year age groups.
clinicaltrials.gov Identifier: NCT00119912.
Notes
Comment In: JAMA. 2014 Aug 13;312(6):601-225117127
Erratum In: JAMA. 2014 Sep 3;312(9):964
PubMed ID
25117129 View in PubMed
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Effect of screening mammography on breast-cancer mortality in Norway.

https://arctichealth.org/en/permalink/ahliterature140588
Source
N Engl J Med. 2010 Sep 23;363(13):1203-10
Publication Type
Article
Date
Sep-23-2010
Author
Mette Kalager
Marvin Zelen
Frøydis Langmark
Hans-Olov Adami
Author Affiliation
Cancer Registry of Norway, Oslo, Norway. mkalager@hsph.harvard.edu
Source
N Engl J Med. 2010 Sep 23;363(13):1203-10
Date
Sep-23-2010
Language
English
Publication Type
Article
Keywords
Adult
Aged
Aged, 80 and over
Breast Neoplasms - mortality - prevention & control - radiography
Female
Humans
Incidence
Mammography
Mass Screening
Middle Aged
Norway - epidemiology
Young Adult
Abstract
A challenge in quantifying the effect of screening mammography on breast-cancer mortality is to provide valid comparison groups. The use of historical control subjects does not take into account chronologic trends associated with advances in breast-cancer awareness and treatment.
The Norwegian breast-cancer screening program was started in 1996 and expanded geographically during the subsequent 9 years. Women between the ages of 50 and 69 years were offered screening mammography every 2 years. We compared the incidence-based rates of death from breast cancer in four groups: two groups of women who from 1996 through 2005 were living in counties with screening (screening group) or without screening (nonscreening group); and two historical-comparison groups that from 1986 through 1995 mirrored the current groups.
We analyzed data from 40,075 women with breast cancer. The rate of death was reduced by 7.2 deaths per 100,000 person-years in the screening group as compared with the historical screening group (rate ratio, 0.72; 95% confidence interval [CI], 0.63 to 0.81) and by 4.8 deaths per 100,000 person-years in the nonscreening group as compared with the historical nonscreening group (rate ratio, 0.82; 95% CI, 0.71 to 0.93; P
Notes
Comment In: N Engl J Med. 2010 Sep 23;363(13):1276-820860510
Comment In: N Engl J Med. 2011 Jan 20;364(3):282-3; author reply 285-621247323
Comment In: N Engl J Med. 2011 Jan 20;364(3):283; author reply 285-621247322
Comment In: N Engl J Med. 2011 Jan 20;364(3):284; author reply 285-621247320
Comment In: N Engl J Med. 2011 Jan 20;364(3):281-2; author reply 285-621247324
Comment In: N Engl J Med. 2011 Jan 20;364(3):283; author reply 285-621247321
PubMed ID
20860502 View in PubMed
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Incentives and participation in a medical survey.

https://arctichealth.org/en/permalink/ahliterature280639
Source
Tidsskr Nor Laegeforen. 2016 Jul;136(12-13):1082-7
Publication Type
Article
Date
Jul-2016
Author
Dagrun Kyte Gjøstein
Anders Huitfeldt
Magnus Løberg
Hans-Olov Adami
Kjetil Garborg
Mette Kalager
Michael Bretthauer
Source
Tidsskr Nor Laegeforen. 2016 Jul;136(12-13):1082-7
Date
Jul-2016
Language
English
Norwegian
Publication Type
Article
Keywords
Colonoscopy
Colorectal Neoplasms - epidemiology
Female
Health Surveys
Humans
Life Style
Male
Middle Aged
Motivation
Norway - epidemiology
Patient Participation
Reminder Systems
Reward
Risk factors
Surveys and Questionnaires
Telephone
Abstract
BACKGROUND Questionnaire surveys are important for surveying the health and disease behaviour of the population, but recent years have seen a fall in participation. Our study tested whether incentives can increase participation in these surveys.MATERIAL AND METHOD We sent a questionnaire on risk factors for colorectal cancer (height, weight, smoking, self-reported diagnoses, family medical history) to non-screened participants in a randomised colonoscopy screening study for colorectal cancer: participants who were invited but did not attend for colonoscopy examination (screening-invited) and persons who were not offered colonoscopy (control group). The persons were randomised to three groups: no financial incentive, lottery scratch cards included with the form, or a prize draw for a tablet computer when they responded to the form. We followed up all the incentive groups with telephone reminder calls, and before the prize draw for the tablet computer.RESULTS Altogether 3 705 of 6 795 persons (54.5??%) responded to the questionnaire; 43.5??% of those invited for screening and 65.6??% of the control group (p
PubMed ID
27381786 View in PubMed
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Lifestyle changes at middle age and mortality: a population-based prospective cohort study.

https://arctichealth.org/en/permalink/ahliterature289552
Source
J Epidemiol Community Health. 2017 01; 71(1):59-66
Publication Type
Journal Article
Randomized Controlled Trial
Research Support, Non-U.S. Gov't
Date
01-2017
Author
Paula Berstad
Edoardo Botteri
Inger Kristin Larsen
Magnus Løberg
Mette Kalager
Øyvind Holme
Michael Bretthauer
Geir Hoff
Author Affiliation
Department of Colorectal Cancer Screening, Cancer Registry of Norway, Oslo, Norway.
Source
J Epidemiol Community Health. 2017 01; 71(1):59-66
Date
01-2017
Language
English
Publication Type
Journal Article
Randomized Controlled Trial
Research Support, Non-U.S. Gov't
Keywords
Cardiovascular Diseases - mortality
Cause of Death
Colonoscopy
Colorectal Neoplasms - diagnosis
Female
Follow-Up Studies
Healthy Lifestyle
Humans
Male
Middle Aged
Neoplasms - mortality
Norway
Prospective Studies
Risk factors
Surveys and Questionnaires
Survival Analysis
Abstract
The effect of modifying lifestyle at middle age on mortality has been sparsely examined.
Men and women aged 50-54 years randomised to the control group (no intervention) in the population-based Norwegian Colorectal Cancer Prevention trial were asked to fill in lifestyle questionnaires in 2001 and 2004. Lifestyle scores were estimated ranging from 0 (poorest) to 4 (best) based on health recommendations (non-smoking, daily physical activity, body mass index
PubMed ID
27312250 View in PubMed
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20 records – page 1 of 2.