A study sample of 49 participants per randomisation arm gave the study a power of 90% to detect a relative 20% decrease in perceived stress/overload levels (from 12 to 10) assuming a two-tailed test, a 5% level of significance, and a standard deviation of ±3 in both groups. Assuming that 20% of participants would not follow the protocol, we included a total of 124 participants. Discrete variables are expressed as counts (percentage) and continuous variables as means and standard deviation (SD). Students T-test were used for between condition comparisons. We also calculated linear regression models to CAL-101 mouse investigate the association of the intervention with the primary and secondary

outcomes. For all analyses we calculated Inhibitors,research,lifescience,medical an intention-to-treat analysis including all Inhibitors,research,lifescience,medical randomised students, and a per-protocol analysis considering only students that followed the instructions in the intervention group. All tests were two-tailed and P values < 0.05 were considered to indicate statistical significance. All analyses were performed using STATA 9.2 (Stata Corp, College Station, TX). Results Characteristics of participants A total of 124 students (68% females) participated and were randomised to the intervention group (n=62) or to a control

group (n=62). The groups were well balanced in terms of age Inhibitors,research,lifescience,medical and gender (Table 1). A total of 46 participants (74%) in the intervention group followed the instructions and posed the two questions aloud; these participants were included in Inhibitors,research,lifescience,medical the per-protocol analysis (Figure 1). Table 1 Baseline characteristics of participants overall and within randomisation groups Stress/overload and performance Overall, the

reported average mean stress/overload (scale 1–20) of participants was 10.9 (SD 1.8), and similar between male and female students (absolute difference Inhibitors,research,lifescience,medical -0.3 (95% CI −1.0, 0.4), p=0.80). Stress/overload levels significantly increased during the resuscitation period as compared to the two periods before and after resuscitation (Figure 2). Figure 2 Overall stress/overload at different time points during the CPR scenario. Median lines are depicted; boxes represent the 25th to 75th many percentile range and whiskers represent 5th and 95th percentiles. There was a significant negative correlation between the overall perceived stress/overload and hands-on time (r=−0.18, p<0.05) indicating that more stress/overload was associated with less hands-on time. No significant correlations were found between stress/overload and time to start CPR and number of leadership statements (data not shown). Impact of intervention on perceived stress Overall, when considering all enrolled 124 students (Intention-to-treat analysis), participants in the intervention group reported significantly smaller amounts of perceived stress/overload compared to the control group (difference of mean perceived stress: -0.6 (95% CI −1.3, -0.1), p=0.04).