Table 4.
Rate of Change in Lung Function Parameters Values (Ml/Year for Predicted Values) Between Levels of Smoking Recorded (Note Smoking Status Adjudged as the Highest Smoking Level Reported Through the Study Period)
| LFPs | Non-Smoker n=12 | Former Smoker n=41 | Current Smoker n=62 | p-value |
|---|---|---|---|---|
| Forced vital capacity (FVC) | ||||
| Pre-BD (mL) | −50.14 (−245.93, 50.03) | −44.83 (−225.7, 47.3) | −21.46 (−126.45, 170.76) | 0.553 |
| Pre-BD (%) | −1.44 (−4.87, 1.89) | −1.81 (−5.19, 1.62) | 1.51 (−3.17, 7.76) | 0.114 |
| Post-BD (mL) | 9.24 (−214.62, 33.33) | −25.61 (−103.14, 60.33) | −11.3 (−108.7, 120.12) | 0.739 |
| Post-BD (%) | −0.15 (−2.73, 2.01) | 0 (−4.37, 2.06) | 1.27 (−2.61, 5.96) | 0.263 |
| Forced expiratory volume in one second (FEV1) | ||||
| Pre-BD (mL) | −50.06 (−277.39, 26.62) | −12.72 (−98.1, 71.44) | −17.26 (−101.05, 78.55) | 0.837 |
| Pre-BD (%) | −1.77 (−7.76, 1.52) | −1.65 (−4.24, 2.63) | 1.2 (−2.36, 4.4) | 0.196 |
| Post-BD (mL) | −34.52 (−173.94, 21.69) | −43.62 (−126.97, 52.31) | −12.86 (−99.48, 191.6) | 0.704 |
| Post-BD (%) | −0.87 (−5.2, 3.96) | −1.83 (−4.84, 2.72) | 0.92 (−2.92, 6.25) | 0.178 |
| Excessive FEV1 (pre-BD) decline* | 8 (67) | 25 (61) | 32 (52) | 0.486 |
| FEV1/FVC | ||||
| Pre-BD (AV) | 0 (−0.03, 0.01) | 0 (−0.02, 0.01) | −0.01 (−0.03, 0.01) | 0.921 |
| Pre-BD (%) | −1.22 (−4.84, 0.18) | 0 (−2.47, 2.02) | −0.38 (−4.21, 1.83) | 0.828 |
| Post-BD (AV) | −0.01 (−0.02, 0.03) | −0.01 (−0.02, 0.01) | −0.01 (−0.03, 0.02) | 0.796 |
| Post-BD (%) | −0.95 (−3.26, 0.18) | −0.32 (−3, 1.81) | −0.49 (−4.23, 2.52) | 0.981 |
Notes: Data were median (IQR). P-values were obtained via univariate quantile regression for continuous parameters and chi-squared test for categorical parameters. *(Baseline predicted FEV1 – current predicted FEV1) + (0.15 × baseline absolute FEV1).
Abbreviations: AV, absolute value; BD, bronchodilator; LFPs, lung function parameters.