Publications by authors named "Silje Sagstad"

5 Publications

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Factors associated with attendance and attendance patterns in a population-based mammographic screening program.

J Med Screen 2021 06 17;28(2):169-176. Epub 2020 Jun 17.

Section for Breast Cancer Screening, Cancer Registry of Norway, Oslo, Norway.

Objective: To explore the factors associated with attendance and attendance pattern in BreastScreen Norway.

Methods: We evaluated the number of invitations (n = 1,253,995) and attendances, 2015-2019, stratified by age, invitation method, screening unit and time of appointment. Attendance pattern was analysed for women invited 10 times (n = 47,979), 1996-2019. The association of education level, body mass index, physical activity and smoking status with attendance was analysed for a sub-sample of women (n = 37,930). Descriptive statistics were used to analyse attendance, and negative binomial regression was used to analyse the association between the total number of attendances and education level and lifestyle factors.

Results: The attendance rate was 76.0%, 2015-2019. The rate was 78.0% for women aged >64 and 73.9% for those <55 . We found a rate of 82.0% for women who received a digital invitation, while it was 73.7% for those invited by post. The rate was 78.1% for invitations in the late afternoon, 3-6 p.m., while later appointments reached a rate of 73.7%. Half of the women invited 10 times attended all times. The predicted total number of attendances was 9 out of 10 for the factors investigated.

Conclusion: The highest attendance rates were shown for women aged >64, those who received digital invitations and those having appointments in late afternoon. The differences in predicted number of attendances between the investigated factors were minor. Overall, BreastScreen Norway has a high attendance rate. However, efforts aimed at increasing the attendance in specific groups should be considered.
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June 2021

Validity and reliability of self-reported health indicators among women attending organized mammographic screening.

Scand J Public Health 2018 Nov 24;46(7):744-751. Epub 2018 Jan 24.

1 Cancer Registry of Norway, Oslo, Norway.

Aims: Risk factors for breast cancer are often used for adjustment in epidemiological studies, including in the evaluation of early performance measures in mammographic screening. Information about risk factors among participants in the Norwegian Breast Cancer Screening Program has been collected since 2006. We aimed to examine the validity of self-reported history of breast cancer and mammographic screening, as well as the reliability of weight and height amongt women attending the program.

Methods: Information from a questionnaire handed in by participants in the program, 2006-2015, was linked to outcomes from the Cancer Registry of Norway. Sensitivity, specificity, and positive predictive values (PPV) were calculated for self-reported histories of breast cancer and screening. Results were stratified by five-year age groups and evaluated using the χ statistic. The reliability of self-reported weight and height were assessed using descriptive statistics, histograms, and mean differences.

Results: A total of 538,907 of 611,711 (88%) women attending the program during the study period returned at least one part of the questionnaire. The overall sensitivity, specificity, and PPV for breast cancer and mammography were 96.5%, 99.8%, and 81.3%; and 99.9%, 84.4%, and 97.6% respectively. The mean difference in self-reported weight was 0.35 kg and for height was -0.14 cm, over a period of up to 10 years.

Conclusions: Norwegian women attending the screening program are reasonably accurate in self-reporting their breast cancer and mammography histories. On average, women consistently reported weight and height within one kg/cm.
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November 2018

Interval Breast Cancer Rates and Histopathologic Tumor Characteristics after False-Positive Findings at Mammography in a Population-based Screening Program.

Radiology 2018 Apr 14;287(1):58-67. Epub 2017 Dec 14.

From the Cancer Registry of Norway, PO 5313 Majorstuen, 0304 Oslo, Norway (S.H., S. Sagstad, S. Sebuødegård); Department of Pathology, Akershus Universitetssykehus HF, Lorenskog, Norway (Y.C.); Department of Epidemiology and Evaluation, Hospital del Mar Medical Research Institute, Barcelona, Spain (M.R.); and Department of Radiology, University of Washington, Seattle Cancer Care Alliance, Seattle, Wash (C.I.L.).

Purpose To compare rates and tumor characteristics of interval breast cancers (IBCs) detected after a negative versus false-positive screening among women participating in the Norwegian Breast Cancer Screening Program. Materials and Methods The Cancer Registry Regulation approved this retrospective study. Information about 423 445 women aged 49-71 years who underwent 789 481 full-field digital mammographic screening examinations during 2004-2012 was extracted from the Cancer Registry of Norway. Rates and odds ratios of IBC among women with a negative (the reference group) versus a false-positive screening were estimated by using logistic regression models adjusted for age at diagnosis and county of residence. Results A total of 1302 IBCs were diagnosed after 789 481 screening examinations, of which 7.0% (91 of 1302) were detected among women with a false-positive screening as the most recent breast imaging examination before detection. By using negative screening as the reference, adjusted odds ratios of IBCs were 3.3 (95% confidence interval [CI]: 2.6, 4.2) and 2.8 (95% CI: 1.8, 4.4) for women with a false-positive screening without and with needle biopsy, respectively. Women with a previous negative screening had a significantly lower proportion of tumors that were 10 mm or less (14.3% [150 of 1049] vs 50.0% [seven of 14], respectively; P < .01) and grade I tumors (13.2% [147 of 1114] vs 42.9% [six of 14]; P < .01), but a higher proportion of cases with lymph nodes positive for cancer (40.9% [442 of 1080] vs 13.3% [two of 15], respectively; P = .03) compared with women with a previous false-positive screening with benign biopsy. A retrospective review of the screening mammographic examinations identified 42.9% (39 of 91) of the false-positive cases to be the same lesion as the IBC. Conclusion By using a negative screening as the reference, a false-positive screening examination increased the risk of an IBC three-fold. The tumor characteristics of IBC after a negative screening were less favorable compared with those detected after a previous false-positive screening. RSNA, 2017 Online supplemental material is available for this article.
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April 2018

Monthly variation in mammographic screening attendance in Norway.

Eur J Public Health 2017 12;27(6):1095-1097

Department of Breast Cancer Screening, Cancer Registry of Norway, Institute of Population-based Cancer Research, Oslo, Norway.

Breast Cancer Awareness Month (BCAM) increases screening attendance in the USA. However, this effect has not been investigated in Europe, where organized screening is widespread. We examined monthly attendance within the Norwegian Breast Cancer Screening Programme, 2005-15. Relative to October, the odds of attending screening in January, February, March, August, September or December were slightly decreased (ORadj 0.93-0.98, P ≤ 0.003 for all). BCAM may marginally increase attendance in October but seasonal factors such as weather may also explain this observed variation. Furthermore, it is possible that organized screening with predetermined appointments evens out the effect BCAM has on screening attendance.
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December 2017

[Attendance in the Norwegian Breast Cancer Screening Programme].

Tidsskr Nor Laegeforen 2016 09 27;136(17):1448-51. Epub 2016 Sep 27.

Screeningseksjonen Kreftregisteret og Seksjon for radiografi og tannteknikk Høgskolen i Oslo og Akershus.

Background: A high rate of attendance among women invited to the Norwegian Breast Cancer Screening Programme (NBCSP) is essential to achieve optimal effect, including reduction in breast cancer mortality. This article describes attendance in the programme by county, period and women’s age at invitation.

Material And Method: All women in the age group 50 – 69 years who are registered in the National Population Register are invited to attend the NBCSP every second year. In the study period 2007 – 2014, 2 142 369 invitations were sent, and 1 600 293 screening examinations were performed for 710 169 women. Use of the data is pursuant to the Cancer Registry Regulations.

Results: Altogether 84 % of the women invited attended at least once in the study period. The average attendance rate per screening round was 75 %. In Rogaland, Nordland and Sogn og Fjordane counties more than 80 % attended, while in Oslo the figure was 62 %. The highest rate of attendance recorded was for women in the age group 62 – 67 years. The attendance in the prior screening round was of influence for reattendance.

Interpretation: The mammography screening programme has a high level of acceptance among women in the target group. Possible reasons for the variation in attendance among the county districts should be identified.
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September 2016