Reasons for dropout from a randomized controlled trial of individuals undergoing total knee and hip replacement

Purpose: Randomized Controlled Trials (RCT) play a crucial role in evaluating medical and physical activity (PA) interventions. However, patient dropout poses a significant threat to their validity. Various factors may contribute to dropouts in studies involving PAbased interventions, including exercise intervention setup, home-togym distance, motivation, and clinical condition1. Understanding these reasons is fundamental to developing targeted strategies to reduce dropout rates and improve the effectiveness of interventions for the adult population. For these reasons, the aim of the present study was to analyse the reasons for dropout from an RCT based on a PA intervention designed for people after THR and TKR. Methods: A mixed-methods approach was employed to assess and analyse the reasons for dropout from an RCT study using a dedicated questionnaire. The questionnaire included open-ended questions structured based on a list of topics. The main themes of the topic list were the main reason for dropout, other reasons for dropout, what would be the facilitators that would favour participation in the study, and what the participants’ expectations were from participation in the study. Furthermore, closed questions with a 5-point Likert scale were included. A Likert scale question consisted of 9 statements divided into three domains: communication, motivation, and external factors. Results: In Italy, out of the 24 dropouts, 8 (33.3%) were excluded due to comorbidity, 1 (4.2%) due to revision surgery, and 6 (25%) did not undergo surgery after the pre- surgical assessment. In the end, 8 subjects were suitable for answering the questionnaire. In Romania, all 80 subjects enrolled dropped out after the pre-surgical assessment. Of these, 25 were impossible to contact at T0, and 35 did not want to answer the questionnaire. Finally, 20 people (25%) agreed to answer the interview and were included in the analysis. A total of 25 subjects (20 from Romania and 5 from Italy) who dropped out were included in this study. The primary reasons for dropout from this RCT were the inability to access healthcare providers due to distance, fear of hospitals due to COVID-19, and concerns about infection. Additionally, lack of time, medical reasons, negative experiences with medical staff, kinesiophobia, and fatigue emerged as limiting factors. Conclusions: The results lay the groundwork for crafting tailored approaches to diminish attrition rates and amplify the efficacy of interventions tailored to this demographic.