Table 4

Generalised estimating equation (GEE) models to explore the effects of stress on the relationship between the non-technical (ANTS) score and the transformed technical score. Model 1 is not adjusted for period effects, while model 2 adjusts for period effects

 Regression coefficient 95% CI p Value Model 1 ANTS score (scenario without stressors) 2.7 −3.5 to 9.0 0.392 ANTS score (scenario with stressors) 12.2 7.7 to 16.8 <0.001 External stressor present (vs no stressor) −448.8 −787.2 to −110.4 0.009 Interaction ANTS score*stress 9.5 1.8 to 17.1 0.015 Intercept (constant) 83.8 −198.6 to 366.1 0.561 Model 2 ANTS score (scenario without stressors) 0.4 −4.9 to 5.6 0.895 ANTS score (scenario with stressors) 10.2 5.9 to 14.5 <0.001 External stressor present (vs no stressor) −474.2 −718.1 to −230.4 <0.001 Interaction ANTS score*stress 9.9 4.2 to 15.5 0.001 Period 48.3 19.4 to 77.1 0.001 Intercept (constant) 119.8 −110.7 to 350.3 0.308
• Interpretation of regression parameters (based on the model with adjustment, analogue considerations apply to the other model): There is no evidence for a relationship between the ANTS score and the transformed technical score in scenarios without external stressors (mean increase of the transformed technical score of 0.4 (–4.9 to 5.6) points per 1-point increase in the ANTS score, p=0.895). In contrast, in scenarios with external stressors, a 1-point increase in the ANTS score is significantly associated with a 10.2 (5.9 to 14.5, p<0.001)-point increase in the transformed technical score (Note that the regression coefficient for the ANTS score in scenarios with stressors is the linear combination between the parameter for the ANTS score in scenarios without stressors and the coefficient for the interaction between the ANTS score and stress). The parameters can also be used to calculate expected scores of the transformed technical score at different ANTS scores, periods and stress levels: For example, at an ANTS score of 40 in the second scenario (second period), with external stressors, we would expect a transformed technical score of (40*10.2)–(1*474.2)+(2*48.3)+119.8=150.2 points. At an ANTS score of 45 in a first scenario without stressors, we would expect a transformed technical score of (45*0.4)–(0*474.2)+(1*48.3)+119.8=186.1 points.

• ANTS, Anaesthetists’ Non-Technical Skills.