Table 1.
Characteristics of study participants, NHANES 2007–2012
| Characteristics | PRISm (n = 671) |
Normal spirometry (n = 7653) |
p-Value (PRISm vs Normal spirometry) |
Obstructive spirometry (n = 1232) |
p-Value (PRISm vs Obstructive spirometry) |
|---|---|---|---|---|---|
| Demographics | |||||
| Age group | < 0.0001 | < 0.0001 | |||
| < 30 y | 109 (16.24) | 2060 (26.92) | 71 (5.76) | ||
| 30–39 y | 96 (14.31) | 1535 (20.06) | 111 (9.01) | ||
| 40–49 y | 120 (17.88) | 1460 (19.08) | 181 (14.69) | ||
| 50–59 y | 149 (22.21) | 1142 (14.92) | 272 (22.08) | ||
| 60–69 y | 137 (20.42) | 971 (12.69) | 330 (26.79) | ||
| 70–79 y | 60 (8.94) | 485 (6.34) | 267 (21.67) | ||
| Sex | 0.6542 | < 0.0001 | |||
| Female | 333 (49.63) | 3867 (50.53) | 431 (34.98) | ||
| Male | 338 (50.37) | 3786 (49.47) | 801 (65.02) | ||
| Race/ethnicity | < 0.0001 | < 0.0001 | |||
| Non-Hispanic White | 107 (15.95) | 1777 (23.22) | 115 (9.33) | ||
| Non-Hispanic Black | 318 (47.39) | 3796 (49.60) | 821 (66.64) | ||
| Mexican American | 246 (36.66) | 2080 (27.18) | 296 (24.03) | ||
| BMI (kg/m2) | < 0.0001 | < 0.0001 | |||
| < 18.5 (underweight) | 20 (2.99) | 96 (1.26) | 30 (2.44) | ||
| 18.5–24.9 (normal weight) | 110 (16.44) | 2089 (27.31) | 412 (33.50) | ||
| 25–29.9 (overweight) | 158 (23.62) | 2556 (33.42) | 445 (36.18) | ||
| ≥ 30 (obese) | 381 (56.95) | 2907 (38.01) | 343 (27.89) | ||
| Missing | 2 | 5 | 2 | ||
| Educational level | < 0.0001 | 0.8612 | |||
| Primary school and less | 65 (10.19) | 637 (8.93) | 123 (10.12) | ||
| Middle and high school | 299 (46.87) | 2712 (38.01) | 555 (45.64) | ||
| College and higher | 274 (42.95) | 3786 (53.06) | 538 (44.24) | ||
| Missing | 33 | 518 | 16 | ||
| PIR | < 0.0001 | 0.0024 | |||
| < 1.85 | 340 (53.71) | 3144 (44.55) | 530 (46.21) | ||
| ≥ 1.85 | 293 (46.29) | 3914 (55.45) | 617 (53.79) | ||
| Missing | 38 | 595 | 85 | ||
| Health insurance coverage | 0.1441 | 0.0085 | |||
| No | 173 (25.82) | 2176 (28.47) | 253 (20.55) | ||
| Yes | 497 (74.18) | 5467 (71.53) | 978 (79.45) | ||
| Missing | 1 | 10 | 1 | ||
| Sedentary activity | 0.0131 | 0.0357 | |||
| < 3 h | 120 (17.91) | 1584 (20.72) | 217 (17.66) | ||
| 3-6 h | 231 (34.48) | 2861 (37.43) | 494 (40.20) | ||
| ≥ 6 h | 319 (47.61) | 3198 (41.84) | 518 (42.15) | ||
| Missing | 1 | 10 | 3 | ||
| Exposure history | |||||
| Smoking status | < 0.0001 | < 0.0001 | |||
| Never smoker | 303 (47.49) | 4143 (58.09) | 339 (27.88) | ||
| Former smoker | 160 (25.08) | 1470 (20.61) | 395 (32.48) | ||
| Current smoker | 175 (27.43) | 1519 (21.30) | 482 (39.64) | ||
| Missing | 33 | 521 | 16 | ||
| Smoking exposure (pack-years) | < 0.0001 | < 0.0001 | |||
| 0 | 303 (48.79) | 4143 (59.59) | 339 (28.80) | ||
| < 10 | 105 (16.91) | 1571 (22.60) | 229 (19.46) | ||
| ≥ 10 | 213 (34.30) | 1238 (17.81) | 609 (51.74) | ||
| Median (IQR) | 16.9 (28.03) | 7.6 (16.8) | 22 (34) | ||
| Missing | 50 | 701 | 55 | ||
| Passive smoking | 0.8658 | 0.9268 | |||
| No | 204 (84.30) | 2941 (83.88) | 363 (84.03) | ||
| Yes | 38 (15.70) | 565 (16.12) | 69 (15.97) | ||
| Missing | 429 | 4147 | 800 | ||
| Smokers living in the home | < 0.0001 | 0.0622 | |||
| 0 | 158 (47.88) | 2541 (66.92) | 251 (39.97) | ||
| 1–2 | 153 (46.36) | 1102 (29.02) | 337 (53.66) | ||
| ≥ 3 | 19 (5.76) | 154 (4.06) | 40 (6.37) | ||
| Missing | 341 | 3856 | 604 | ||
| Mineral dusts | 0.1995 | 0.0033 | |||
| No | 419 (65.78) | 4991 (68.25) | 711 (58.76) | ||
| Yes | 218 (34.22) | 2322 (31.75) | 499 (41.24) | ||
| Missing | 34 | 340 | 22 | ||
| Organic dusts | 0.4042 | 0.0410 | |||
| No | 483 (75.82) | 5657 (77.27) | 868 (71.38) | ||
| Yes | 154 (24.18) | 1664 (22.73) | 348 (28.62) | ||
| Missing | 34 | 332 | 16 | ||
| Fumes from machinery or engines | 0.4509 | < 0.0001 | |||
| No | 487 (76.33) | 5492 (74.99) | 780 (64.09) | ||
| Yes | 151 (23.67) | 1832 (25.01) | 437 (35.91) | ||
| Missing | 33 | 329 | 15 | ||
| Any other gases, vapors or fumes | 0.4071 | 0.0034 | |||
| No | 426 (66.77) | 5007 (68.36) | 728 (59.82) | ||
| Yes | 212 (33.23) | 2317 (31.64) | 489 (40.18) | ||
| Missing | 33 | 329 | 15 | ||
| Medical history/Comorbidities | |||||
| Emphysema, bronchitis or asthma during childhood | 0.0013 | 0.1292 | |||
| No | 475 (70.79) | 5842 (76.34) | 912 (74.03) | ||
| Yes | 196 (29.21) | 1811 (23.66) | 320 (25.97) | ||
| Emphysema | 0.0004 | 0.0012 | |||
| No | 628 (98.28) | 7097 (99.45) | 1153 (95.29) | ||
| Yes | 11 (1.72) | 39 (0.55) | 57 (4.71) | ||
| Missing | 32 | 517 | 22 | ||
| Chronic bronchitis | < 0.0001 | 0.4515 | |||
| No | 586 (91.85) | 6864 (96.24) | 1096 (90.80) | ||
| Yes | 52 (8.15) | 268 (3.76) | 111 (9.20) | ||
| Missing | 33 | 521 | 25 | ||
| Asthma | < 0.0001 | 0.0684 | |||
| No | 548 (81.67) | 6735 (88.07) | 961 (78.13) | ||
| Yes | 123 (18.33) | 912 (11.93) | 269 (21.87) | ||
| Missing | 0 | 6 | 2 | ||
| Close relative had asthma | 0.0578 | 0.0826 | |||
| No | 506 (76.67) | 6019 (79.77) | 962 (80.10) | ||
| Yes | 154 (23.33) | 1526 (20.23) | 239 (19.90) | ||
| Missing | 11 | 108 | 31 | ||
| Hypertension | < 0.0001 | 0.5455 | |||
| No | 394 (58.98) | 5638 (73.73) | 709 (57.55) | ||
| Yes | 274 (41.02) | 2009 (26.27) | 523 (42.45) | ||
| Missing | 3 | 6 | 0 | ||
| Coronary heart disease | < 0.0001 | 0.3840 | |||
| No | 602 (94.80) | 7008 (98.29) | 1135 (93.80) | ||
| Yes | 33 (5.20) | 122 (1.71) | 75 (6.20) | ||
| Missing | 36 | 523 | 22 | ||
| Heart failure | < 0.0001 | 0.7058 | |||
| No | 608 (95.75) | 7052 (98.91) | 1152 (95.36) | ||
| Yes | 27 (4.25) | 78 (1.09) | 56 (4.64) | ||
| Missing | 36 | 523 | 24 | ||
| Stroke | < 0.0001 | 0.6390 | |||
| No | 613 (95.93) | 7015 (98.40) | 1157 (95.46) | ||
| Yes | 26 (4.07) | 114 (1.60) | 55 (4.54) | ||
| Missing | 32 | 524 | 20 | ||
| Diabetes | < 0.0001 | 0.0004 | |||
| No | 527 (80.34) | 6905 (91.77) | 1044 (86.57) | ||
| Yes | 129 (19.66) | 619 (8.23) | 162 (13.43) | ||
| Missing | 15 | 129 | 26 | ||
| Symptoms (≥ 40 y) | |||||
| Chronic cough | 0.0017 | 0.0316 | |||
| No | 410 (87.98) | 3737 (92.20) | 879 (83.71) | ||
| Yes | 56 (12.02) | 316 (7.80) | 171 (16.29) | ||
| Missing | 205 | 3600 | 182 | ||
| Coughing phlegm | 0.0014 | 0.0049 | |||
| No | 420 (90.13) | 3811 (93.96) | 890 (84.76) | ||
| Yes | 46 (9.87) | 245 (6.04) | 160 (15.24) | ||
| Missing | 205 | 3597 | 182 | ||
| Wheezing | < 0.0001 | 0.0117 | |||
| No | 535 (79.73) | 6851 (89.61) | 919 (74.59) | ||
| Yes | 136 (20.27) | 794 (10.39) | 313 (25.41) | ||
| Shortness of breath | < 0.0001 | 0.0619 | |||
| No | 256 (54.94) | 2984 (73.61) | 630 (60.06) | ||
| Yes | 210 (45.06) | 1070 (26.39) | 419 (39.94) | ||
| Missing | 205 | 3599 | 183 | ||
| Lung function | |||||
| FEV1% predicted | 72.80 ± 6.68 | 100.69 ± 11.39 | < 0.0001 | 80.02 ± 17.68 | < 0.0001 |
| FVC % predicted | 77.07 ± 14.42 | 104.31 ± 17.87 | < 0.0001 | 102.58 ± 21.49 | < 0.0001 |
| FEV1/FVC | 0.78 ± 0.06 | 0.81 ± 0.06 | < 0.0001 | 0.63 ± 0.07 | < 0.0001 |
| Serum heavy metals (μg/L) | |||||
| Cadmium | 0.65 ± 0.74 | 0.47 ± 0.54 | < 0.0001 | 0.84 ± 0.93 | < 0.0001 |
| Lead | 1.62 ± 1.81 | 1.51 ± 1.87 | 0.0003 | 2.12 ± 1.50 | < 0.0001 |
| Mercury | 1.39 ± 2.16 | 1.37 ± 2.04 | 0.1294 | 1.33 ± 1.83 | 0.5378 |
Results are shown as N (%) for binary variables, and as mean ± standard deviation (SD) for continuous variables. BMI, body mass index; PIR: poverty income ratio; FEV1, forced expiratory volume in 1 s; FVC, forced vital capacity; PRISm, preserved ratio impaired spirometry; NHANES, National Health and Nutrition Examination Survey