Discussion
SIT, CAD
EVENTS, CAD
Our randomised clinical trial in 212 patients with CAD participating in CR showed that SIT LESS did not induce significantly greater reductions in ST compared to controls, but delivery was feasible and a reduced odds of ST ≥ 9.5 h/day was observed. We also observed improvements of physical activity levels and reductions in the number of prolonged sedentary bouts and cardiovascular risk score from pre- to post-CR, but the change was comparable between groups. Finally, no changes were found regarding quality of life and patients’ competencies for self-management over 12 weeks of follow-up.In the past decade, there has been increasing interest for behavioural change interventions to improve physical activity and reduce sedentary behaviour [SIT LESS was developed to specifically reduce ST in patients with CAD, co-created in close collaboration with end users (patients and nurse specialist) and tailored to the patients’ needs [The observed reductions in ST in both groups could be clinically relevant. Isotemporal substitution analyses show that reducing 30 min of ST is associated with 2% lower risk of mortality and major adverse cardiovascular events [In line with the decrease in ST, the number of prolonged sedentary bouts decreased and time spent during LIPA and MVPA substantially increased from pre- to post-CR, but no additional effect of SIT LESS was found related to these parameters. Data regarding the direct response to vibrotactile feedback were not available, although this information could have been useful for a fidelity check of the activity tracker. Nevertheless, if these acute improvements in physical activity and prolonged sedentary bouts can be maintained after study participation, these changes are likely being accompanied by beneficial long-term health effects [Quality of life did not change across the study period, which is in contrast to previous observations [Strengths of our study include the device-based assessment of ST, co-creation of SIT LESS, a substantive trial for a first test of the SIT LESS intervention, and the low dropout rates supporting the feasibility and acceptability of SIT LESS. Feasibility was also reflected by the high level of adherence to the intervention and activity tracker; the successful implementation at two different centres in clinical practice and the high ratings of patients for participating in the study. Our study also has some limitations. First, due to the nature of the intervention, investigators, nurse specialists and patients were not blinded for the treatment. This may have contributed to contamination bias from the SIT LESS intervention to the control group and a subsequent underestimation of the true difference between SIT LESS and controls. Unfortunately, indicative measures for contamination, e.g. knowledge regarding ST-associated health risks were not collected, so the level of contamination could not be quantified. Second, it remains unknown whether the overall decrease in ST is sustainable over time and how this relates to future clinical endpoints. Therefore, larger, cluster randomised trials with longer-term follow-up are warranted, also including assessment of cost-effectiveness and sufficiently powered to detect improvements in event-free survival of patients with CAD.