*3.4. Stratification in Quartiles*

We stratified patients into quartiles to gain insights into the relationship between immunotherapy efficacy and PRIS. Patients were first stratified in quartiles based on ΔMSS (%) to identify patients who had a better clinical response than those with a poor response to SLIT (Table 1). Overall, the vast majority of patients obtained a significant symptom improvement (very high or high) after 12-(72 out of 98 patients; 77.56%) and 24-month SLIT (82 out of 98 patients; 81.64%).

We then stratified patients in quartiles based on PRIS values (PRIS ≥ 80; 80 > PRIS ≥ 60; 60 > PRIS ≥ 40) to identify patients who had more chances to obtain a significant response to SLIT. ANOVA conducted on ΔMSS-24 (%) revealed a significant difference between the

three groups (F (2.97) = 16.32; *p* < 0.001). Post hoc comparisons revealed a significant higher value of ΔMSS-24 (%) for PRIS ≥ 80 (mean ± SD 78.91 ± 8.16) than 80 > PRIS ≥ 60 (post hoc *p* < 0.001; mean ± SD 66.25 ± 18.31) and 60 > PRIS ≥ 40 (post hoc *p* < 0.001; mean ± SD 54.02 ± 15.16) (Figure 4). In addition, ΔMSS-24 (%) for 80 > PRIS ≥ 60 (mean ± SD 66.25 ± 18.31) was significantly higher than 60 > PRIS ≥ 40 (post hoc *p* < 0.001; mean ± SD 54.02 ± 15.16). These results indicate that patients with a higher PRIS value have more chances to obtain a higher ΔMSS-24 (%).

**Figure 4.** Stratification of patients in three groups according to the Predictive Response to Immunotherapy Score (PRIS) results and their ΔMSS-24. A significant difference was found between the three groups (F (2.97) = 16.32; *p* < 0.001).

Finally, we categorized patients by matching quartile stratification based on ΔMSS-24 (%) with quartile stratification based on PRIS. Figure 5 shows that most patients with a PRIS ≥ 80 experienced a very high improvement, whereas patients with 60 > PRIS ≥ 40 mostly experienced a high improvement. Patients with 80 > PRIS ≥ 60 were homogeneously distributed in ΔMSS-24 (%) quartiles. These data strongly suggest that PRIS can effectively predict the clinical response that patients may expect from SLIT.

**Figure 5.** Stratification of patients in three groups according to the Predictive Response to Immunotherapy Score (PRIS) results and their ΔMSS-24. Most patients with a PRIS ≥ 80 experienced a very high improvement, whereas patients with 60 > PRIS ≥ 40 mostly experienced a high improvement. Patients with 80 > PRIS ≥ 60 were homogeneously distributed in ΔMSS-24 (%) quartiles.
