Maxime Verhoeven

69 Validation of a prediction model for insufficient response to MTX insufficient response to MTX for this specific patient. Specificity, positive predictive value (PPV), sensitivity and negative predictive values (NPV) were calculated for different cut-off values of these probabilities for insufficient response and are presented in Supplementary Data S1. Our online model can be found in Evidencio using the following link: https://www. evidencio.com/models/show/2191. A patient-specific report presenting the results and model interpretation can be downloaded from Evidencio, Supplementary Data S1. An example is shown in Figure 2, where a patient with DAS28 score= 4.9, HAQ= 0.4, BMI= 22 kg/m 2 , erythrocyte-folate= 720 nmol/L, and current smoking status= yes, has a probability of insufficient response of 71.7%, with corresponding specificity of 86% and PPV of 75%. Figure 2 Example of online platform Evidencio for the implementation of the pre- diction model. Values for each individual patient can be filled out using the buttons and slides. Corresponding probability for insufficient response is automatically calculated using the prediction model. DISCUSSION We externally validated our previously developed prediction model for insufficient response to MTX therapy at 3 and 6 months after treatment initiation in early RA patients including all predictors DAS28 >5.1, HAQ >0.6, ABCB1 rs1045642 genotype, ABCC3 rs4793665 genotype, erythrocyte folate <750 nmol/L, current smoking and BMI >25 kg/m 2 . To enhance clinical applicability and facilitate implementation, the 4