Els van Meijel

34 Chapter 2 | Evaluation of the STEPP Discussion In a large mixed-trauma sample, we determined that the Dutch version of the STEPP is reliable and predictive. At the originally recommended cut-off scores, the performance of the STEPP in the study of Winston and colleagues was not replicated; the STEPP appeared to perform only moderately in our sample (Winston et al., 2003). However, adjusting the cut-off scores improved the predictive performance substantially: 82% of the children and 92% of the parents at risk were correctly identified. This high sensitivity supports the use of the STEPP as a screening tool. The high negative predictive values make the STEPP useful to screen out those who are least likely to develop PTSD. Lower positive predictive values are consistent with the results of other studies andmay be a consequence of the low prevalence of PTSD in our sample (11.6% in children, 9.6% in parents) (Nixon et al., 2010; Winston et al., 2003). There are several possible explanations for the deviant performance of the STEPP when using the originally recommended cut-off scores. First, in our study we used different measures and a different time frame than in the study of Winston and colleagues Table 2.2 Performance of the STEPP in predicting PTSD at 3 months, at different cut-off scores Cut-off Sensitivity (95% CI) Specificity (95% CI) PPV (95% CI) NPV (95% CI) Child diagnosis (ADIS-C/P) 2 0.82 (0.57-0.96) 0.28 (0.20-0.36) 0.13 (0.07-0.21) 0.92 (0.79-0.98) 3 0.65 (0.38-0.86) 0.62 (0.53-0.70) 0.18 (0.09-0.30) 0.93 (0.85-0.97) 4 0.41 (0.19-0.67) 0.87 (0.80-0.92) 0.29 (0.13-0.51) 0.92 (0.86-0.96) Child self-report (CRIES) 2 0.87 (0.66-0.97) 0.29 (0.21-0.38) 0.19 (0.12-0.28) 0.92 (0.79-0.98) 3 0.61 (0.39-0.80) 0.62 (0.53-0.71) 0.23 (0.13-0.36) 0.89 (0.81-0.95) 4 0.43 (0.23-0.65) 0.89 (0.82-0.94) 0.43 (0.23-0.65) 0.89 (0.82-0.94) Parent self-report (IES-R) 2 0.92 (0.64-0.99) 0.21 (0.14-0.30) 0.11 (0.06-0.19) 0.96 (0.81-0.99) 3 0.54 (0.25-0.81) 0.57 (0.48-0.66) 0.12 (0.05-0.23) 0.92 (0.84-0.97) 4 0.23 (0.05-0.54) 0.88 (0.81-0.93) 0.17 (0.04-0.41) 0.91 (0.85-0.96) STEPP - Screening Tool for Early Predictors of PTSD, PTSD - Posttraumatic Stress Disorder, AUC - Area Under the Curve, CI - Confidence Interval, PPV - Positive Predictive Value, NPV - Negative Predictive Value, ADIS - Anxiety Disorders Interview Schedule-Child/Parent, CRIES - Children’s Revised Impact of Event Scale, IES-R - Impact of Event Scale-Revised.