*3.3. Validation of the Predictive Response to Immunotherapy Score (PRIS)*

Linear regression analysis was used to test the predictive value of PRIS on our efficacy index of SLIT [ΔMSS-24 (%)]. Figure 2 shows that overall PRIS significantly predicted ΔMSS-24 (%) (R = 0.622; F (1,97) = 60.810; *p* < 0.001).

**Figure 2.** Correlation analysis revealed a significant direct correlation between the Predictive Response to Immunotherapy Score (PRIS) and ΔMSS-24 (*p* < 0.001).

In addition, regression analysis verified that PRIS significantly predicted ΔMSS-24 (%) in patients treated with a single-allergen SLIT (Mono-SLIT: R = 0.708; F (1.65) = 64.453; *p* < 0.001; Figure 3A) as well as in patients treated with a two-allergen SLIT (MIX-SLIT: R = 0.599; F (1.31) = 16.833; *p* < 0.001; Figure 3B), suggesting that PRIS has the same efficacy in predicting SLIT outcome when one or two allergens are used for SLIT.

Furthermore, regression analysis also showed that PRIS significantly predicted ΔMSS-24 (%) in both patients with only rhinitis (R = 0.660; F (1.48) = 36.313; *p* < 0.001; Figure 3C) and in patients with rhinitis associated with asthma (R = 0.674; F (1.48) = 39.207; *p* < 0.001; Figure 3D), suggesting that PRIS is as effective as in predicting SLIT outcome in both patients with rhinitis and with concomitant asthma. Together these results indicate that PRIS can be used to predict the efficacy of SLIT independent of the number of allergens used with SLIT and the patient's clinical condition.

Finally, in order to check that all parameters that compose the PRIS score contribute to the prediction of the outcome, linear regression analysis was also used to test the association of all individual PRIS components with ΔMSS-24 (%). As shown in Table 4, all PRIS parameters are significant predictors for our outcome, and the parameters' score categories (assumed in the model on an ordinal scale) adequately reflect the difference progression in comparison with the references.

**Figure 3.** Correlation analysis revealed a significant direct correlation between the Predictive Response to Immunotherapy Score (PRIS) and ΔMSS-24 for both patients treated with single-allergen (**A**) and multiple-allergen (**B**) sublingual immunotherapy (SLIT) (*p* < 0.001), and between PRIS and ΔMSS-24 for both patients with only rhinitis (**C**) and with both asthma and rhinitis (**D**) (*p* < 0.001).


**Table 4.** Linear regression models using as predictors all PRIS parameters.
