Minimal Clinically Important Differences to Determine Meaningful Change in the Skin Symptom Assessment (SSA) Questionnaire for the Randomized Controlled Trial of Mepitel Film Versus Standard of Care for the Prevention of Acute and Chronic Dermatitis in Breast Cancer Radiation Treatment.

BACKGROUND

Changes in patient-reported outcomes may be statistically significant, but not necessarily clinically significant. This study determined the minimal clinically important differences (MCIDs) in the Skin Symptom Assessment (SSA) questionnaire for the Mepitel film (MF) versus standard of care (SOC) randomized controlled trial for the prevention of radiation dermatitis (RD) in breast cancer patients. MCIDs are the smallest changes in patient-reported outcome measures (PROMs) that hold meaningful significance for patients and justify a change in clinical management.

METHODS

A secondary analysis was conducted on the MF vs SOC phase III randomized controlled trial (n = 376) aimed at preventing breast cancer radiation dermatitis. Anchor- and distribution-based methods were used to determine MCIDs, with worst CTCAE grade as the anchor. MCIDs were determined between baseline and the 2-week follow-up, as well as between the 2-week follow-up and the 3-, 6-, 12-, and 24-month follow-ups.

RESULTS

MCIDs were determined for total patients, MF patients, and SOC patients. Between baseline and the 2-week follow-up, the MCIDs for deterioration in MF patients ranged from 0.11 (edema) to 0.76 units (erythema). MCIDs for SOC patients ranged from 0.29 (edema) to 1.21 units (pigmentation). The MCIDs for the other time points ranged from 0.12 units (edema) in MF patients to 1.13 units (erythema) in SOC patients. MCIDs at all time-points and in all patient subgroups were closest to 0.5 standard deviation.

CONCLUSION

Determining MCIDs can help HCPs determine when treatments meaningfully improve patient QoL. MCIDs may also guide decisions to introduce alternative or additional treatments.