PP and PIM prevalence
The median concomitant medications were 4 (range = 0–16; interquartile range [IQR] = 1–6) at EGFR-TKI treatment initiation. The PP prevalence (≥5 concomitant medications) was 89/232 (38.4%) (Figure 2 ). According to STOPP ver. 2 criteria, 74 (31.9%) older advanced NSCLC patients took at least one medication that was deemed PIM. Of these 74 PIM-STOPP v2(+) patients, 16 (21.6%) violated three or more STOPP ver. 2 criteria checkpoints (Supplementary Table 1 ). According to our criteria, defined in the Materials and Methods section, 66 (28.5%) patients took at least one medication deemed PIM-TKI (Supplementary Table 2 ). PP(+) patients were more likely to take at least one PIM-STOPP v2 (51.7% vs. 19.6%; P < 0.001; odds ratio [OR] = 4.36; 95% confidence interval [CI] = 2.35–8.25) and PIM-TKI (52.3% vs. 14.2%; P < 0.001; OR = 6.56; 95% CI = 3.38–13.15) compared to PP(−) patients.