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Overdetection in breast cancer screening: development and preliminary evaluation of a decision aid
  1. Jolyn Hersch1,
  2. Jesse Jansen1,
  3. Alexandra Barratt2,
  4. Les Irwig3,
  5. Nehmat Houssami3,
  6. Gemma Jacklyn4,
  7. Hazel Thornton5,
  8. Haryana Dhillon6,
  9. Kirsten McCaffery1
  1. 1Screening & Test Evaluation Program (STEP) and Centre for Medical Psychology & Evidence-based Decision-making (CeMPED), School of Public Health, University of Sydney, Sydney, New South Wales, Australia
  2. 2Centre for Medical Psychology & Evidence-based Decision-making (CeMPED), School of Public Health, University of Sydney, Sydney, New South Wales, Australia
  3. 3Screening & Test Evaluation Program (STEP), School of Public Health, University of Sydney, Sydney, New South Wales, Australia
  4. 4School of Public Health, University of Sydney, Sydney, New South Wales, Australia
  5. 5Department of Health Sciences, University of Leicester, Leicester, UK
  6. 6Centre for Medical Psychology & Evidence-based Decision-making (CeMPED), Central Clinical School, University of Sydney, Sydney, New South Wales, Australia
  1. Correspondence to Dr Kirsten McCaffery; kirsten.mccaffery{at}sydney.edu.au

Abstract

Objective To develop, pilot and refine a decision aid (ahead of a randomised trial evaluation) for women around age 50 facing their initial decision about whether to undergo mammography screening.

Design Two-stage mixed-method pilot study including qualitative interviews (n=15) and a randomised comparison using a quantitative survey (n=34).

Setting New South Wales, Australia.

Participants Women aged 43–59 years with no personal history of breast cancer.

Interventions The decision aid provides evidence-based information about important outcomes of mammography screening over 20 years (breast cancer mortality reduction, overdetection and false positives) compared with no screening. The information is presented in a short booklet for women, combining text and visual formats. A control version produced for the purposes of comparison omits the overdetection-related content.

Outcomes Comprehension of key decision aid content and acceptability of the materials.

Results Most women considered the decision aid clear and helpful and would recommend it to others. Nonetheless, the piloting process raised important issues that we tried to address in iterative revisions. Some participants found it hard to understand overdetection and why it is of concern, while there was often confusion about the distinction between overdetection and false positives. In a screening context, encountering balanced information rather than persuasion appears to be contrary to people's expectations, but women appreciated the opportunity to become better informed.

Conclusions The concept of overdetection is complex and new to the public. This study highlights some key challenges for communicating about this issue. It is important to clarify that overdetection differs from false positives in terms of its more serious consequences (overtreatment and associated harms). Screening decision aids also must clearly explain their purpose of facilitating informed choice. A staged approach to development and piloting of decision aids is recommended to further improve understanding of overdetection and support informed decision-making about screening.

  • PUBLIC HEALTH
  • QUALITATIVE RESEARCH
  • PREVENTIVE MEDICINE

This is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/

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