Table I.
Demographic characteristics of study participants
| NCI-MD case–case study (%), n = 305 | NCI-MD case-control (%), n = 227 | Norwegian case-only study (%), n = 282 | P-value | |
| Age | ||||
| Overall mean (SD) | 64.5 (9) | 65.9 (10) | 66.2 (10) | 0.11 |
| Mean (SD) for women | 64.8 (9) | 65.8 (10) | 64.6 (10) | 0.71 |
| Mean (SD) for men | 64.4 (9) | 66.0 (10) | 67.2 (10) | 0.03 |
| Gender (%) | ||||
| Male | 205 (67) | 151 (67) | 178 (63) | |
| Female | 100 (33) | 76 (33) | 104 (37) | 0.55 |
| Race (%) | ||||
| Caucasian | 235 (77) | 175 (77) | 282 (100) | |
| Males | 157 (67) | 116 (66) | 178 (63) | |
| Females | 78 (33) | 59 (34) | 104 (37) | |
| African–American | 70 (23) | 52 (23) | 0 (0) | |
| Males | 48 (69) | 35 (67) | 0 (0) | |
| Females | 22 (31) | 17 (33) | 0 (0) | <0.001 |
| Smoking history (%)a | ||||
| Never-smoker | 9 (3) | 13 (6) | 19 (7) | |
| Former-smoker | 121 (40) | 109 (48) | 87 (31) | |
| Current-smoker | 175 (57) | 105 (46) | 166 (59) | 0.001 |
| Mean pack-years + SD | 60.2 (31) | 53.9 (27) | 32.5 (18.3) | <0.001 |
| Tumor stage (%)b | ||||
| Stage I | 188 (62) | 66 (29) | 165 (58) | |
| Stage II | 56 (18) | 23 (10) | 59 (21) | |
| Stage III | 51 (17) | 38 (17) | 41 (15) | |
| Stage IV | 5 (2) | 32 (14) | 3 (1) | <0.001 |
Values given in bold are statistically significant.
a
Ten cases (3%) from the Norwegian case-only study were missing data on smoking status.
b
Five cases (1%) from the NCI-MD case–case study; 68 (30%) cases from the NCI-MD case–control study and 14 cases (5%) from the Norwegian case-only study were missing data on tumor stage.