Sharing decisions in breast cancer care: Development of the Decision Analysis System for Oncology (DAS-O) to identify shared decision making during treatment consultations.

Abstract

Shared Decision Making (SDM) is widely accepted as the preferred method for reaching treatment decisions in the oncology setting including those about clinical trial participation: however, there is some disagreement between researchers over the components of SDM. Specific standardized coding systems are needed to help overcome this difficulty. The first objective was to describe the development of an oncology specific SDM coding system, the DAS-O. The second objective was to provide reliability and validity data supporting the DAS-O. Consultation data were available from tertiary cancer center out patient oncology clinics in: Australia, New Zealand (ANZ), Switzerland, Germany and Austria (SGA). Patients were women with a confirmed diagnosis of early stage breast cancer. Reliability data were from 18 randomly selected coded transcripts drawn from ANZ and SGA. Concurrent validity data are from 55 (ANZ) consultations. Inter and Intra rater reliability data was evaluated using Kappa correlation statistics and correlation coefficients. Correlation coefficients were used to assess concurrent validity between the DAS-O and two other SDM coding systems, OPTION and DSAT. Inter and Intra rater reliability for the system were high with average Kappas of 0.58 and 0.65 respectively. Correlation coefficients between DAS-O and OPTION was 0.73 and >0.5 for DSAT. We have developed a reliable and valid coding system for identifying and rating the quality of SDM in breast cancer consultations.