Table 1.
Clinical and Biological Variables by Quartile of Pulmonary Surfactant Protein B
| Variable | Q1 (n=873) | Q2 (n=773) | Q3 (n=825) | Q4 (n=823) | p trend |
|---|---|---|---|---|---|
| SP-B, ng/mL | <1.0 | 1.0 – 2.6 | 2.67 – 7.57 | 7.63 – 829.72 | |
| Age, years | 39 [33, 47] | 43 [36, 51] | 45 [37, 54] | 47 [40, 54] | <0.0001 |
| Men | 341 (39%) | 331 (43%) | 402 (49%) | 381 (46%) | 0.000 |
| Black | 345 (40%) | 362 (47%) | 464 (56%) | 525 (64%) | <0.0001 |
| White | 294 (34%) | 237 (31%) | 251 (30%) | 192 (23%) | <0.0001 |
| Hispanic | 209 (24%) | 148 (19%) | 99 (12%) | 98 (12%) | <0.0001 |
| Hypertension | 212 (25%) | 212 (28%) | 323 (40%) | 355 (44%) | <0.0001 |
| Diabetes | 81 (9%) | 100 (13%) | 104 (13%) | 101 (12%) | 0.072 |
| Metabolic Syndrome | 225 (29%) | 255 (33%) | 293 (36%) | 300 (36%) | 0.001 |
| Hypercholesterolemia | 80 (9%) | 95 (12%) | 125 (15%) | 131 (16%) | <0.0001 |
| Low HDL | 356 (41%) | 316 (41%) | 336 (41%) | 359 (44%) | 0.273 |
| Current Smokers | 94 (11%) | 117 (15%) | 264 (32%) | 486 (59%) | <0.0001 |
| Former Smokers | 137 (16%) | 153 (20%) | 172 (21%) | 94 (12%) | 0.056 |
| Never Smokers | 641 (73%) | 502 (65%) | 389 (47%) | 240 (29%) | <0.0001 |
| Pack-Years (current smokers) | 2.9 [0.7, 8.0] | 6.9 [1.7, 19.8] | 13.1 [5.3, 24.0] | 17.5 [8.0, 29.0] | <0.0001 |
SP-B=Pulmonary Surfactant Protein B
Levels of continuous variables are reported as median [IQR] and categorical variables as percentages.