Establishing thresholds for important benefits in screening guidelines

Article type
Authors
Helsingen LM1, Zeng L2, Siemieniuk RAC3, Lytvyn L3, Vandvik PO4, Agoritsas T5, Bretthauer M1, Guyatt G3
1Oslo University Hospital and University of Oslo
2McMaster University and Sichuan University
3McMaster University
4University of Oslo and Lovisenberg Diakonale Hospital
5University Hospitals of Geneva and Faculty of Medicine of Geneva, and McMaster University
Abstract
Background
International standards for clinical practice guidelines require explicit statements regarding how values and preferences influence recommendations. However, no cancer screening guideline has addressed the key question of what magnitude of benefit people would require to undergo screening, given its harms and burdens.

Objective: This article describes the development of a new method for guideline developers to define a threshold for the magnitude of benefit needed to undergo the burdens and harms of screening.

Summary of methods:
The new method was developed and applied in the context of a recent BMJ Rapid Recommendation clinical practice guideline for colorectal cancer (CRC) screening. First, we presented the guideline panel with harms and burdens (derived from a systematic review) associated with the CRC screening tests under consideration. Second, each panel member completed surveys documenting their views of the expected benefits on CRC incidence and mortality that people would require to accept the harms and burdens of screening. Third, the panel discussed the results of the surveys and agreed on thresholds for benefits at which the majority of people would choose screening. During these three steps, the panel had no access to the actual benefits of the screening tests. In step four, the panel was presented with screening test benefits derived from a systematic review of clinical trials and microsimulation modeling. The thresholds derived through steps one to three were applied to these benefits, and directly informed the panel’s recommendations.

Results: The panel inferred that at least half of people in the target population would require a colorectal cancer mortality reduction of 5 per 1000 over a 15-year period to undertake FIT-screening, and a reduction of 10 per 1000 for sigmoidoscopy or colonoscopy. They clarified that a difference in colorectal cancer mortality reduction of 10 or more per 1000 would prompt them to recommend colonoscopy or sigmoidoscopy over FIT, and a difference of 5 or more would prompt recommending FIT every year over FIT every two years and colonoscopy over sigmoidoscopy.

Conclusion:
We present the development and application of a new, four-step method that enables incorporation of explicit and transparent judgments of values and preferences in a screening guideline. Guideline panels should establish their view regarding the magnitude of required benefit, given burdens and harms, before they review screening benefits, and make their recommendations accordingly. Making informed screening decisions requires transparency in values and preferences judgments that our new method greatly facilitates.

Healthcare consumer involvement: Three people with colorectal cancer screening experience took part in the guideline development process, including defining thresholds of the required benefit.