No. of studies | % difference (95% CI) fixed effect | % difference (95% CI) random effect | χ^{2}_{n−1}heterogeneity(p value) | |
---|---|---|---|---|

FVC | 19 | −0.2 (−0.4 to +0.1) | −0.4 (−0.8 to +0.0) | 33.3 (0.015) |

FEV_{1}
| 21 | −0.9 (−1.2 to −0.7) | −1.4 (−1.9 to −1.0) | 42.7 (0.002) |

Mid expiratory flow rate | 19 | −4.8 (−5.4 to −4.3) | −5.0 (−6.6 to −3.3) | 110.7 (0.0000) |

End expiratory flow rate | 9 | −4.3 (−5.3 to −3.3) | −4.3 (−5.5 to −3.1) | 9.5 (0.30) |