Understanding nonresponse and strategies to improve response rates in a randomized controlled trial among breast cancer survivors: the FASTRACS-INSIGHT mixed-methods study

FASTRACS-RCT is a prospective, multisite, randomized, and controlled trial (N=431). It evaluates the effectiveness of the FASTRACS intervention on the return to work for breast cancer survivors (BCSs). A decrease in the rate of response to the intervention was observed during follow-up. This study aimed to identify reasons for nonresponse and evaluate the acceptability of strategies to improve responses through the INSIGHT (Identify Nonresponse and Strategies to Improve Questionnaires' Trustworthiness) intervention, focusing on BCSs' needs and sustainable response strategies.

Needs assessment (1): A statistical analysis identified subgroups at higher risk of nonresponse within the FASTRACS-RCT, and individual interviews explored barriers and facilitators to participation. Intervention development and implementation (2): A brainstorming session was conducted with BCSs from the FASTRACS Intersectoral Strategic Participatory Committee (ISPC) and phone calls were made to interview participants. Evaluation (3): A before-and-after analysis of response rates was conducted.

(1) Nonrespondents were younger than respondents and reported more systemic side effects from breast cancer treatment. Nonresponse was influenced by the breast cancer experience, questionnaire design, and completion context (hospital versus home). (2) Four intervention components were developed: personalized reminder cards with tea bags, printed questionnaires for every participant, a medical appointments booklet with a FASTRACS pen, and reinforcement of phone completion and text reminders. (3) Response rates increased from 54.4% to 74.4% at T3 (p < 0.001) and from 46.2% to 76.7% at T4 (p < 0.001).

The FASTRACS-INSIGHT intervention was developed and implemented, leading to a successful rise in questionnaire completion.

The inclusion of BCSs in the development of the FASTRACS-INSIGHT intervention demonstrates the importance of involving BCSs to develop interventions tailored to their needs.