Minimal Clinically Important Differences in Scales Measuring Decision Uncertainty, Distress After a Traumatic Event, Body Image and Health Status Among Women With Breast Cancer Having Surgery

Background: The smallest clinically relevant change (ie, minimal clinically important difference, MCID) for several valuable PROMs for women undergoing breast cancer surgery is unknown. Therefore, this study evaluated the smallest clinically relevant change for decision uncertainty, distress after traumatic events, body image, and health status in women diagnosed with breast cancer considering surgery. Patients and methods: Between August 2020 and October 2022, we included 123 women with breast cancer considering surgical treatment. Women completed the decisional conflict scale (DCS), impact of event scale (IES), body image scale (BIS), and 36-Item Short Form (SF-36) after their first visit, and 4-6 weeks and 6 months after surgery. The MCID was calculated using the anchor-based method. For the MCID to be reliable, it needs to be greater than the minimum detectable change (MDC). Results: The MCID for decision uncertainty (8.6) was smaller than the MDC (22). MCID values were 11 and 12 (MDC 8.4) for improvement in cancer-specific distress (IES), 2.5 and 6.5 (MDC 2.6) for deterioration in body image (BIS) and 27 and 14 (MDC 12) for deterioration in health status (SF-36) at 4 to 6 weeks and 6 months after surgery, respectively. Conclusion: This study successfully determined MCIDs for several PROMs. For IES, BIS, and SF-36 the MCID seems reliable, while the DCS cannot reliably capture a clinically relevant change. The MCID values may be useful when assessing clinically relevant changes over time, interpreting treatment effects, and trial sample size determination.