Table 3. Differences in characteristics and spirometric measures according to serum Fe level in male subjects.
| Fe <54 µg/dL n = 60 | Fe ≥54 µg/dL n = 1440 | P | |
| age, years | 64.1 (10.0) | 62.8 (10.4) | 0.354 |
| BMI, kg/m2 | 23.1 (3.0) | 23.5 (3.0) | 0.360 |
| percentage of current and past smokers, % | 56.7 | 66.9 | 0.105 |
| Brinkman index overall, cigarette×year | 365.2 (474.8) | 444.5 (496.4) | 0.273 |
| Brinkman index in current and past smokers, cigarette×year | 778.0 (395.1) | 738.7 (438.3) | 0.672 |
| haemoglobin, g/dL | 13.6 (1.9) | 14.7 (1.2) | <0.0001 |
| uric acid, mg/dL | 5.6 (1.4) | 5.8 (1.3) | 0.192 |
| homocysteine, µM | 11.6 (3.5) | 12.6 (7.0) | 0.254 |
| FVC %predicted | 97.5 (13.9) | 97.3 (14.9) | 0.911 |
| FEV1%predicted | 93.3 (17.7) | 95.7 (17.5) | 0.312 |
| FEV1/FVC, % | 74.7 (8.0) | 77.1 (8.9) | 0.038 |
Data are mean values (SD). Data for sFe, haemoglobin, uric acid and homocysteine levels, and for Brinkman index were not available for 2, 2, 2, 29 and 266 of the 1502 male subjects, respectively. Eight subjects in the normal sFe group and three subjects in the low sFe group were receiving anti-anaemia therapy (chi-square test: P = 0.266). Nine subjects in the normal sFe group and two subjects in the low sFe group were receiving respiratory therapy (chi-square test: P = 0.729). Information on diagnoses and medications was not available.
BMI, body mass index; FVC, forced vital capacity; FEV1, forced expiratory volume in 1 s.