From: Systematic review of the evidence relating FEV1decline to giving up smoking
 |  | Unweighted analysis | Inverse variance-weighted analysis | ||||
---|---|---|---|---|---|---|---|
Factor | Level | Number of betas | Beta (95% CI) | Pvaluea | Number of betas | Beta (95% CI) | Pvaluea |
Sexb | Males | 168 | 35.8 (33.1-38.4) | Base | 150 | 34.6 (32.7-36.5) | Base |
 | Females | 88 | 23.9 (20.2-27.7) | --- | 72 | 28.3 (26.3-30.3) | --- |
 | Both | 39 | 38.2 (32.5-43.9) | NS | 39 | 40.7 (36.2-45.3) | + |
Agec | < 40 | 47 | 13.2 (8.2-18.3) | Base | 39 | 28.7 (25.8-31.5) | Base |
 | 40-49 | 78 | 33.9 (30.0-37.8) | +++ | 68 | 42.8 (39.6-46.1) | +++ |
 | 50-69 | 123 | 37.8 (34.7-41.0) | +++ | 115 | 32.1 (30.1-34.1) | NS |
 | 70+ | 47 | 35.8 (30.7-40.9) | +++ | 39 | 27.9 (25.2-30.6) | NS |
Length of follow-up period | Per year | 295 | -0.16 (-0.57 to 0.25) | NS | 261 | -0.03 (-0.27 to 0.21) | NS |
Continent | North America | 148 | 30.3 (27.5-33.1) | Base | 114 | 29.0 (26.1-32.0) | Base |
 | Europe | 85 | 36.7 (32.9-40.5) | ++ | 85 | 34.8 (31.5-38.1) | ++ |
 | Asia | 28 | 26.3 (19.7-32.8) | NS | 28 | 31.6 (28.2-35.1) | NS |
 | Australasia | 12 | 41.9 (31.6-52.1) | + | 12 | 42.1 (27.5-56.7) | NS |
 | Multicountry | 22 | 34.9 (27.2-42.7) | NS | 22 | 34.3 (30.0-38.6) | NS |
Final follow-up year | < 1980 | 78 | 27.0 (23.3-30.6) | Base | 78 | 25.7 (22.8-28.6) | Base |
 | 1980-1989 | 98 | 42.3 (39.1-45.4) | +++ | 64 | 37.9 (34.8-41.1) | +++ |
 | 1990-1999 | 91 | 26.0 (22.7-29.3) | NS | 91 | 27.6 (25.0-30.3) | NS |
 | 2000+ | 28 | 35.6 (29.3-42.0) | + | 28 | 35.8 (33.1-38.4) | +++ |
Publication year | < 1980 | 26 | 27.1 (20.1-34.1) | Base | 26 | 26.3 (20.5-32.0) | Base |
 | 1980-1989 | 129 | 33.2 (30.2-36.3) | NS | 129 | 35.0 (32.1-37.9) | ++ |
 | 1990-1999 | 99 | 34.2 (30.7-37.6) | NS | 65 | 35.1 (32.5-37.8) | ++ |
 | 2000+ | 41 | 30.0 (24.4-35.5) | NS | 41 | 30.2 (27.9-32.4) | NS |
Population type | General | 266 | 32.5 (30.4-34.6) | Base | 232 | 32.7 (31.4-34.1) | Base |
 | Diseased | 29 | 32.9 (25.8-40.1) | NS | 29 | 28.3 (22.3-34.4) | NS |
Study type | Prospective | 275 | 32.9 (30.8-35.0) | Base | 243 | 32.7 (31.4-34.1) | Base |
 | intervention | 20 | 27.6 (19.2-36.0) | NS | 18 | 28.4 (22.6-34.3) | NS |