Sick leave and predictive factors for sick leave at 12 months after breast cancer surgery in the randomized controlled physical activity trial (PhysSURG-B).

Objective: To evaluate sick leave 12 months after breast cancer surgery, to analyze the effect of adjuvant chemotherapy and to identify predictive factors for sick leave, based on a randomized controlled trial of a non-supervised physical activity intervention (PhysSURG-B).

Methods: Sick leave days (for patients age 18-67) were collected from the Swedish Social Insurance Agency, and compared between the intervention and control arm in the trial. A random forest model was used to analyze predictive factors for sick leave, including baseline patient and tumor characteristics as well as patient-reported outcomes measuring quality of life, personality traits, pain, anxiety and depression.