Shared Medical Decision Making in Lung Cancer Screening: Experienced versus Descriptive Risk Formats.

BACKGROUND: Annual lung cancer screening using low-dose computed tomography (LDCT) scans is associated with a survival benefit, but it is also associated with potential harm. Unlike descriptive probability formats, experienced tasks have been shown to decrease perceptions of rare events. The objective of this study was to compare descriptive versus experienced probability formats on patients' knowledge, beliefs, endorsement of screening for heavy smokers, and preference (choice predisposition) to undergo screening.

METHODS: A total of 276 patients attending an outpatient pulmonary practice were randomized to learn about screening using 1 of 3 formats: numbers only, numbers + icon arrays, numbers + a set of slides illustrating LDCT scans of 250 people in random order that displayed the number of normal scans, false-positive lung nodules, cancers found leading to a life saved, and cancers found leading to death despite treatment.

RESULTS: Knowledge differed between the 3 formats (P= 0.001), with participants randomized to the numbers + icon array format having the highest knowledge score. Beliefs were more favorable among participants randomized to the numbers + experienced format compared with the numbers + icon array format (difference between means [95% confidence interval]= 1.6 [0.4-2.8]). Differences in participants' endorsement of screening (P= 0.4) and choice predisposition (P= 0.6) across probability format mirrored those of beliefs but were not statistically significant.

DISCUSSION: Contrary to what we expected, the experienced format increased propensity toward screening compared with the numbers + icon array format, as indicated by more favorable beliefs and nonsignificant trends toward stronger choice predisposition and endorsement. Experienced risk formats may not be a practical approach to improve risk communication for patients deciding whether or not to undergo annual lung cancer screening.