Meta-analysis of spirometry parameters
The spirometry parameters were reported in seven articles (13-18). In Knoke study the z score of parameters were reported (16). So, it does not include to meta-analysis. In two studies, spirometry parameters were reported pre- and post-bronchodilator inhalation (13, 18). In five studies, spirometry parameters were reported without bronchodilator inhalation (14-17, 19). The FEV1, FVC and FEV1/FVC were reported in 345 patients. According to random effect modeling in meta-analysis, the mean of FEV1 was 101.72%, 95% CI= (98.72, 104.73), I2=81.7. Forest plot is shown in figure2.
The pooled mean of FVC was 101.31 %, 95% CI= (95.44, 107.18), I2=93.38. Forest plot is shown in figure3. The pooled mean of FEV1/FVC was 96.16 %, 95% CI= (90.47, 101.85), I2=96.86. Forest plot is shown in figure 4. The pooled mean of FEF25-75 was reported in four studies (14, 15, 18, 19). The pooled mean of FEF25-75 was 105.05 %, 95% CI= (101.74, 108.36), I2=26.93. Forest plot is shown in figure5. The mean of DLCO was reported in four studies (13, 15, 17, 18). The pooled mean of DLCO was 105.30 %, 95% CI= (88.12, 122.49), I2=98.10. Forest plot is shown in figure 6. In two studies, FEV1, FVC and FEV1/FVC were reported before and after bronchodilator inhalation (13, 18). Meta- analysis confirmed that there was no significant difference in spirometry parameters before and after bronchodilator inhalation. The SMD for FEV1 was -0.21, 95% CI= (-0.65, 0.23), p value= 0.35, I2=38.3. The SMD for FVC1 was -0.07, 95% CI= (-0.35, 0.21), p value= 0.14, I2=zero. The SMD for FEV1/FVC was -0.29, 95% CI= (-0.58, 0.01), p value= 0.07, I2= zero.