Baseline characteristics by tertiles (T) of skin autofluorescence (n=4111)
| T1, 1.0–1.8 AU | T2, 1.9–2.1 AU | T3, 2.2–4.6 AU | p-value | |
| Subjects | 1480 | 1345 | 1286 | |
| Age years | 56.8±4.3 | 57.5±4.1 | 58.4±4.3 | <0.001 |
| Females | 55.5% | 53.6% | 50.7% | 0.011 |
| Height cm | 171.8±9.9 | 171.7±9.6 | 170.9±9.7 | 0.020 |
| Weight kg | 79.9±15.7 | 80.1±15.4 | 80.9±16.9 | 0.087 |
| Smoking | ||||
| Current | 9.7% | 15.9% | 26.1% | <0.001 |
| Former | 38.5% | 41.0% | 41.0% | |
| Never | 51.8% | 43.0% | 32.9% | |
| eGFR mL·min−1·1.73 m−2 | 82.9±15.3 | 82.7±14.3 | 82.7±16.6 | 0.643 |
| Diabetes | 5.4% | 6.5% | 13.3% | <0.001 |
| COPD | 1.5% | 1.6% | 3.3% | 0.009 |
| HbA1c mmol·mol−1 geometric mean | 35.9 | 36.0 | 37.5 | <0.001 |
| Plasma glucose mmol·L−1 geometric mean | 5.38 | 5.43 | 5.58 | <0.001 |
| CRP mmol·L−1 geometric mean | 1.3 | 1.4 | 1.6 | <0.001 |
| FEV1 L | 3.25±0.76 | 3.21±0.80 | 3.06±0.76 | <0.001 |
| FEV1 % predicted | 94.9±11.6 | 94.2±12.4 | 92.2±12.9 | <0.001 |
| FVC L | 4.13±0.99 | 4.09±1.0 | 3.94±0.94 | <0.001 |
| FVC % predicted | 97.7±12.7 | 96.6±14.1 | 93.6±14.7 | <0.001 |
| FEV1/FVC | 0.790±0.06 | 0.785±0.06 | 0.779±0.07 | <0.001 |
| DLCO % predicted | 90.9±12.6 | 89.8±13.6 | 86.9±14.6 | <0.001 |
| DLCO/VA % predicted | 97.0±13.5 | 96.1±14.1 | 94.6±15.8 | <0.001 |
| R5 % predicted | 106.9 (93.3–125.6) | 107.7 (92.1–127.8) | 108.6 (93.3–127.3) | 0.312 |
| R20 % predicted | 128.6±31.3 | 128.5±31.1 | 128.2±31.2 | 0.766 |
| R5−R20 % predicted | 54.9 (24.0–91.9) | 55.9 (23.1–93.4) | 63.3 (29.4–99.9) | 0.667 |
| X5 % predicted | 87.2 (68.1–108.9) | 88.1 (68.5–110.0) | 89.6 (71.1–114.6) | 0.001 |
| AX % predicted | 60.6 (38.3–97.0) | 61.8 (39.5–101.6) | 65.2 (39.7–112.6) | 0.348 |
| fres % predicted | 79.2 (68.8–95.1) | 80.4 (69.3–95.9) | 82.3 (68.9–98.6) | <0.001 |
Data are presented as mean±sd or median (interquartile range), unless otherwise stated. Diffusing capacity parameters: % predicted values calculated for 3889 subjects (T1, n=1408; T2, n=1273; T3, n=1208). Impulse oscillometry parameters: % predicted values presented for 3970 subjects (T1, n=1433; T2, n=1298; T3, n=1239). p-value: ANOVA or Chi-squared for test of linearity for continuous and categorical variables, respectively. Mean values of X5 in T1–T3 of SAF are: T1, −0.089 kPa·L−1·s; T2, −0.092 kPa·L−1·s; T3, −0.097 kPa·L−1·s. Higher % predicted values of impulse oscillometry measures reflect an impairment in lung function. eGFR: estimated glomerular filtration rate; HbA1c: glycated haemoglobin; CRP: C-reactive protein; FEV1: forced expiratory volume in 1 s; FVC: forced vital capacity; DLCO: diffusing capacity of the lung for carbon monoxide; VA: alveolar volume; R5: resistance measured at 5 Hz; R20: resistance measured at 20 Hz; X5 reactance measured at 5 Hz; AX: area of reactance; fres: resonant frequency.