Table 1:
Characteristics of participants in the discovery and validation case-control studies
| Characteristic | Discovery Study (NCI-MD) | Validation Study (WSU) | ||||
|---|---|---|---|---|---|---|
| P | P | |||||
| Age, years mean (range) | 64 (42–88) | 66 (43–86) | <0.001* | 63.6 (36–89) | 62.5 (46–87) | ns* |
| Gender, N (%) | ||||||
| Male | 177 (56%) | 346 (68%) | 177 (44%) | 177 (44%) | ||
| Female | 139 (44%) | 163 (32%) | 222 (56%) | 223 (56%) | ||
| Missing | 0 (0%) | 0 (0%) | <0.001† | 0 (0%) | 0 (0%) | ns† |
| Body Mass Index (kg/m2) N (%) | ||||||
| Underweight (<18.5) | 22 (7%) | 2 (<0.5%) | 38 (9.5%) | 3 (<1%) | ||
| Healthy (18.5–25) | 121 (38%) | 89 (18%) | 170 (42.5%) | 136 (34%) | ||
| Over-weight (25–30) | 105 (33%) | 180 (35%) | 110 (28%) | 131 (33%) | ||
| Obese (>30) | 68 (22%) | 238 (46.5%) | 81 (20.5%) | 130 (32.5%) | ||
| Missing | 0 (0%) | 0 (0%) | <0.001† | 0 (0%) | 0 (0%) | <0.001† |
| Smoking Status, N (%) | ||||||
| Never | 24 (8%) | 173 (34%) | 26 (6.5%) | 26 (6.5%) | ||
| Former | 114 (36%) | 244 (48%) | 159 (40%) | 123 (31%) | ||
| Current | 178 (56%) | 92 (18%) | 214 (53.5%) | 251 (62.5%) | ||
| Missing | 0 (0%) | 0 (0%) | <0.001† | 0 (0%) | 0 (0%) | 0.023† |
| Pack-years, mean ± SD (ever and never smokers only) | 39.19 ± 29.09 | 22.76 ± 18.36 | <0.001* | 36.64 ± 27.61 | 26.68 ± 20.33 | <0.001* |
| Menthol Cigarette Usage, N (%) | ||||||
| Menthol | 177 (60%) | 175 (52%) | 159 (42%) | 319 (85%) | ||
| Non- menthol | 96 (33%) | 125 (37%) | 29 (8%) | 54 (14%) | ||
| Both | 19 (7%) | 36 (11%) | - | - | ||
| Missing | 0 (0%) | 0 (0%) | 0.046† | 185 (50%) | 1 (<1%) | <0.001† |
| Filtered Cigarette Usage, Na (%) | ||||||
| Filtered | 248 (85%) | 285 (85%) | - | - | ||
| Non-filtered | 27 (9%) | 24 (7%) | - | - | ||
| Both | 17 (6%) | 27 (8%) | - | - | ||
| Missing | 0 (0%) | 0 (0%) | ns† | - | - | |
| History of emphysema, bronchitis, asthma, TB, N (%) | ||||||
| No | 184 (58%) | 398 (78%) | - | - | ||
| Yes | 132 (42%) | 111 (22%) | - | - | ||
| Missing | 0 (0%) | 0 (0%) | - | - | ||
| Stage, N (%) | ||||||
| I | 102 (32%) | - | 68 (17%) | - | ||
| II | 34 (11%) | - | 48 (12%) | - | ||
| III | 71 (23%) | - | 101 (25.5%) | - | ||
| IV | 62 (20%) | - | 168 (42%) | - | ||
| Missing | 47 (14%) | - | 14 (3.5%) | - | ||
| Histology, N (%) | ||||||
| Adenocarcinoma | 141 (45%) | - | 240 (60%) | - | ||
| Squamous | 90 (28%) | - | 108 (27%) | - | ||
| Other | 72 (23%) | - | 47 (12%) | |||
| Missing | 13 (4%) | 4 (<1%) | ||||
*
Statistically significant differences between cases and controls were determined using independent sample t-tests
†
Statistically significant differences between cases and controls were determined using chi-squared tests