IL7R and chronic obstructive pulmonary disease: For optimal variable selection, the effect of BMI (t-ratio = −5.75, F-ratio = 33.01, p < 0.0001), lnc-IL7R (t-ratio = −2.07, F-ratio = 4.28, p = 0.042), and SO2 (t-ratio = 2.00, F-ratio = 3.99, p = 0.049) on COPD-E severity were statistically significant, while smoking history (t-ratio = 1.94, F-ratio = 3.75, p = 0.056), PM10 (t-ratio = −1.51, F-ratio = 2.30, p = 0.133), and PM2.5 though exhibiting good effect (F-ratio ≥ 2), were statistically non-significant (Figure 2E,F).