From: Systematic review of the evidence relating FEV1decline to giving up smoking
 |  |  |  |  |  |  | Trend (SE)b |  |  |
---|---|---|---|---|---|---|---|---|---|
Factor | Levels | Study no. | Ref. | Sex | Age range at baseline | Â | Continuing smokers | Quitters | Ex-smokers |
Baseline FEV1 (cL/m3) | 65+, 55-64, 1-54 | 13 | Fletcher et al. [6] | Male | 30-59 | Mean | 10.0 (1.5)*** | 4.0 (8.8) | 4.8 (3.5) |
 |  |  |  |  |  | Diffc | Base | 6.2 (8.9) | 5.1 (3.8) |
Baseline FEV1 (mL) | High, middle, low | 4 | Burchfiel et al. [11] | Male | 45-68 | Mean | -24.8 (1.6)*** | -16.1 (5.3)** | Â |
 |  |  |  |  |  | Diff | Base | -8.8 (5.6) |  |
Baseline FEV1 (mL/m3) | 500+, 1-499 | 45 | Townsend [73] | Male | 35-57 | Mean | 28.1 (8.6)** | 21.2 (15.6) | Â |
 |  |  |  |  |  | Diff | Base | 6.9 (17.8) |  |
Baseline FEV1/FVC (%) | 80+, 70-79, 1-69 | 5 | Burrows et al. [10] | Male | 20-70 | Mean | 27.9 (4.2)*** | Â | -3.4 (5.5) |
 |  |  |  |  |  | Diff | Base |  | 31.3 (6.9)*** |
Obstruction at baseline | None, mild | 13 | Fletcher and Peto [31] | Male | 30-59 | Mean | 24.8 (16.4) | Â | 7.0 (9.4) |
 |  |  |  |  |  | Diff | Base |  | 17.8 (18.9) |
Obstruction at baseline | None, mild | 13 | Fletcher et al. [6] | Male | 30-59 | Mean | 22.1 (11.4) | Â | 4.0 (8.5) |
 |  |  |  |  |  | Diff | Base |  | 18.1 (14.3) |
Doctor visits for LRId | 0-0.24, 0.25-0.49, 0.50-0.99, 1.00-1.49, 1.50+ | 43 | Kanner et al. [70] | Male | 35-60 | Mean | 3.5 (0.8)*** | Â | 2.9 (1.9) |
 |  |  |  |  |  | Diff | Base |  | 0.7 (2.0) |
Respiratory symptoms at baseline | No, Yes | 29 | Sherman et al. [53] | Male | 25-74 | Mean | 4.6 (4.0) | Â | 4.3 (3.1) |
 |  |  |  |  |  | Diff | Base |  | 0.3 (5.1) |
Respiratory symptoms at baseline | No, Yes | 29 | Sherman et al. [53] | Female | 25-74 | Mean | 1.9 (2.4) | Â | -5.9 (5.0) |
 |  |  |  |  |  | Diff | Base |  | 7.8 (5.5) |
Bronchodilator responsiveness | No, Yes | 34 | Vollmer et al. [60] | Both | 25-54 | Mean | 22.0 (30.1) | 46.0 (22.7) | Â |
 |  |  |  |  |  | Diff | Base | -24.0 (37.7) |  |
Bronchodilator responsiveness | No, Yes | 35 | Vollmer et al. [60] | Both | 25-54 | Mean | 10.0 (13.7) | 14.0 (20.0) | Â |
 |  |  |  |  |  | Diff | Base | -4.0 (24.2) |  |
Histamine responsiveness | No, Yes | 32 | Rijcken et al. [5] | Male | 25-54 | Mean | 3.2 (7.9) | Â | 4.5 (9.4) |
 |  |  |  |  |  | Diff | Base |  | -1.3 (12.3) |
Histamine responsiveness | No, Yes | 32 | Rijcken et al. [5] | Female | 25-54 | Mean | 5.8 (8.2) | Â | 5.9 (12.0) |
 |  |  |  |  |  | Diff | Base |  | -0.1 (14.5) |
Occupational exposure | None, low, high | 7 | Sunyer et al. [24] | Male | 20-44 | Mean | 0.8 | Â | -1.1 |
 |  |  |  |  |  | Diff | Base |  | 1.8 |
Occupational exposure | None, low, high | 7 | Sunyer et al. [24] | Female | 20-44 | Mean | 1.2 | Â | 6.2 |
 |  |  |  |  |  | Diff | Base |  | -5.0 |
Exposure to gas and fumes | None, low, high | 7 | Sunyer et al. [24] | Male | 20-44 | Mean | 1.5 | Â | -2.9 |
 |  |  |  |  |  | Diff | Base |  | 4.4 |
Exposure to gas and fumes | None, low, high | 7 | Sunyer et al. [24] | Females | 20-44 | Mean | -3.2 | Â | 5.6 |
 |  |  |  |  |  | Diff | Base |  | -8.9 |
Biological dust exposure | None, low, high | 7 | Sunyer et al. [24] | Males | 20-44 | Mean | 0.2 | Â | 2.5 |
 |  |  |  |  |  | Diff | Base |  | -2.3 |
Biological dust exposure | None, low, high | 7 | Sunyer et al. [24] | Females | 20-44 | Mean | 6.8 | Â | 5.6 |
 |  |  |  |  |  | Diff | Base |  | 1.2 |
Mineral dust exposure | None, low, high | 7 | Sunyer et al. [24] | Males | 20-44 | Mean | 0.0 | Â | 2.3 |
 |  |  |  |  |  | Diff | Base |  | -2.3 |
Mineral dust exposure | None, low, high | 7 | Sunyer et al. [24] | Females | 20-44 | Mean | 2.0 | Â | 6.5 |
 |  |  |  |  |  | Diff | Base |  | -4.5 |