Independent variables
SECONDARY
Observed SDM was assessed from audio-recorded consultations using the Observing Patient Involvement in Decision-Making scale (OPTION12), which aims to assess the extent to which health care professionals involve patients in the decision-making process.The effects of potentially burdensome elements of SDM were analyzed separately. SDM elements were defined using the separate stages of Stiggelbout et al.’s model of SDM (stage 1, “setting the SDM agenda”; stage 2, “informing about the options”; and stage 3, “exploring patient values and preferences”Two trained and blinded assessors independently rated the consultation using both scales (OPTION12 and 4SDM) after training and calibration. The intraclass correlation was strong (>0.80) and the average weighted kappa sufficient was >0.60 for OPTION12 (0.62) and was almost sufficient for 4SDM (0.57).The second independent variable was the intervention condition of the oncologist (i.e., whether the patient consulted a trained or untrained oncologist). The patient communication aid condition was ignored for this secondary analysis, as the observed SDM behavior of oncologists was not shown to be affected by the aid.