Table 3 Assessment of meta-regression analysis (z-value(P-value))

Specimen

Regulated

Specimen

Regulated

Specimen

Regulated

COPD vs. NCs

6.31(< 0.01)

3.99(< 0.01)

2.73(< 0.01)

2.60(< 0.01)

7.40(< 0.01)

3.77(< 0.01)

AECOPD vs. NCs

4.15(< 0.01)

3.50(< 0.01)

1.95(0.05)

1.88(0.06)

3.74(< 0.01)

3.05(< 0.01)

AECOPD vs. COPD

0.09(0.93)

3.03(< 0.01)

4.53(< 0.01)

2.49(0.01)

4.61(< 0.01)

5.62(< 0.01)