Table 2.
Distribution of Pro-SFTPB by Selected Study Variables
| Variable | No. of Participants | Mean | SD | Median | IQR | Range | P* |
|---|---|---|---|---|---|---|---|
| Pro-SFTPB (ng/mL) | 2,485 | 45.32 | 44.64 | 31.93 | 16.92-56.26 | 1.15-426.86 | N/A |
| Log-proSFTPB | 2,485 | 3.49 | 0.83 | 3.49 | 2.89-4.05 | 0.77-6.06 | N/A |
| Age, years | .219† | ||||||
| 50-54 | 270 | 46.26 | 47.19 | 33.27 | 16.21-57.36 | 1.15-324.35 | |
| 55-59 | 491 | 45.34 | 44.13 | 33.11 | 17.28-57.67 | 2.56-426.86 | |
| 60-64 | 791 | 42.82 | 42.81 | 29.82 | 16.26-53.85 | 1.42-330.24 | |
| 65-69 | 642 | 44.10 | 43.05 | 30.18 | 16.72-54.64 | 2.85-344.38 | |
| ≥ 70 | 291 | 53.93 | 50.30 | 37.98 | 19.12-66.82 | 4.29-294.48 | |
| Sex | .0794 | ||||||
| Male | 1,377 | 46.73 | 45.54 | 33.24 | 17.59-58.35 | 1.42-426.86 | |
| Female | 1,108 | 43.58 | 43.47 | 30.02 | 16.31-53.45 | 1.15-344.38 | |
| BMI, kg/m2 | .001† | ||||||
| Underweight (< 18.5) | 27 | 37.28 | 24.57 | 28.76 | 18.95-55.37 | 7.45-98.90 | |
| Normal (18.5-24.9) | 919 | 47.70 | 46.39 | 33.70 | 18.63-57.67 | 1.15-426.86 | |
| Overweight (25-29.9) | 1,123 | 45.53 | 45.17 | 31.64 | 16.01-58.68 | 2.18-372.25 | |
| Obese (≥ 30) | 416 | 40.03 | 39.62 | 28.32 | 15.87-48.71 | 1.42-282.03 | |
| Personal history of cancer | .4399 | ||||||
| No | 2,321 | 45.14 | 44.75 | 31.65 | 16.88-55.85 | 1.15-426.86 | |
| Yes | 156 | 47.95 | 43.88 | 34.90 | 18.58-59.51 | 2.18-282.03 | |
| Family history of cancer | .2389 | ||||||
| No | 1,625 | 45.90 | 45.13 | 32.08 | 17.29-56.94 | 1.42-426.86 | |
| Yes | 819 | 43.71 | 42.59 | 30.85 | 16.21-55.79 | 1.15-330.24 | |
| Pneumonia | .0651 | ||||||
| No | 1,813 | 44.29 | 43.32 | 31.79 | 16.88-55.40 | 1.42-426.86 | |
| Yes | 665 | 48.22 | 48.15 | 31.73 | 16.96-58.71 | 1.15-324.35 | |
| Emphysema | .0984 | ||||||
| No | 2,315 | 44.82 | 43.73 | 31.71 | 16.94-55.80 | 1.15-426.86 | |
| Yes | 160 | 51.97 | 53.19 | 36.25 | 15.38-64.30 | 3.14-328.88 | |
| Smoking status | < .001 | ||||||
| Former smoker | 938 | 35.51 | 42.42 | 21.26 | 12.13-40.81 | 1.15-426.86 | |
| Current smoker | 1,547 | 51.28 | 44.92 | 38.48 | 21.77-63.99 | 2.18-344.38 | |
| Race/ethnicity | .396† | ||||||
| White | 2,410 | 45.50 | 44.95 | 31.96 | 16.93-56.33 | 1.15-426.86 | |
| Asian | 29 | 40.28 | 34.98 | 33.30 | 15.62-50.70 | 5.04-160.48 | |
| Aboriginal | 8 | 35.19 | 26.60 | 30.89 | 17.19-47.46 | 3.92-86.55 | |
| Black or African Canadian | 13 | 45.89 | 45.79 | 27.05 | 18.63-64.41 | 5.90-172.51 | |
| Other | 15 | 33.53 | 23.13 | 30.94 | 11.95-41.49 | 6.15-78.02 | |
| Education | < .001† | ||||||
| 8th grade or less | 74 | 56.22 | 42.43 | 47.60 | 23.77-75.39 | 7.22-241.07 | |
| 9th to 11th grade | 326 | 53.33 | 51.04 | 38.23 | 18.48-67.05 | 1.15-372.25 | |
| High school graduate | 649 | 42.99 | 43.20 | 29.96 | 16.68-52.69 | 1.42-344.38 | |
| Technical/vocational school | 264 | 48.74 | 48.06 | 33.62 | 17.46-64.93 | 2.15-330.24 | |
| Associate's degree/some college | 475 | 43.66 | 39.07 | 32.03 | 16.68-57.59 | 2.39-274.28 | |
| Bachelor's degree | 426 | 42.99 | 46.71 | 28.99 | 15.65-51.78 | 4.15-426.86 | |
| Advanced degree | 271 | 41.57 | 41.32 | 26.62 | 16.54-52.06 | 2.18-235.45 |
Abbreviations: IQR, interquartile range; N/A, not applicable; pro-SFTPB, pro–surfactant protein B; SD, standard deviation.
*
P values are for Satterthwaite's unequal variance t test, unless otherwise marked.
†
Nonparametric test.