NHANES 1999–2010 sample characteristics (N=6472)
| Variables | Total N (%) | Cotinine levels N (%) | Cotinine level-confirmed smoking status N (%) | |||||
|---|---|---|---|---|---|---|---|---|
| High cotinine 1878 (29.0) | Medium cotinine 1759 (27.2) | Low cotinine 2835 (43.8) | Current smokers 1794 (27.4) | Former smokers 1681 (25.0) | Secondhand smokers 1158 (17.8) | Non-smokers 1839 (29.8) | ||
| Gender | ||||||||
| Male | 3352 (50.0) | 1092 (31.4)* | 953 (30.0)* | 1307 (38.6) | 1045 (30.4)† | 938 (25.7)† | 604 (19.2)† | 765 (24.8) |
| Female (reference) | 3120 (50.0) | 786 (25.2) | 806 (24.5) | 1528 (50.3) | 749 (24.5) | 743 (24.3) | 554 (16.3) | 1074 (34.8) |
| Race/ethnicity | ||||||||
| White (reference) | 3495 (74.6) | 952 (27.0) | 924 (26.8) | 1619 (46.2) | 926 (26.5) | 1098 (27.9) | 507 (15.7) | 964 (29.9) |
| Black | 1094 (9.0) | 441 (40.5)* | 392 (35.0)* | 261 (24.5) | 418 (38.3)† | 161 (11.6)† | 317 (30.5)† | 198 (19.6) |
| Hispanic | 1238 (7.6) | 299 (24.7) | 267 (22.1)* | 672 (53.2) | 271 (22.7)† | 293 (19.9)† | 196 (17.4) | 478 (39.9) |
| Other Hispanic | 399 (4.0) | 106 (27.7) | 111 (27.3) | 182 (45.0) | 103 (26.8) | 78 (17.1)† | 90 (24.0) | 128 (32.1) |
| Other | 246 (4.8) | 80 (32.0) | 65 (27.8) | 101 (40.2) | 76 (30.3) | 51 (18.9) | 48 (21.4) | 71 (29.5) |
| Alcohol consumption (drinks per day) | ||||||||
| ≤1 (reference) | 2316 (35.3) | 334 (13.9) | 593 (25.3) | 1389 (60.8) | 314 (13.3) | 674 (27.6) | 390 (16.5) | 938 (42.6) |
| 2–3 | 2658 (43.4) | 784 (28.0)* | 772 (28.7)* | 1102 (43.2) | 739 (26.9)† | 747 (26.9)† | 500 (18.6)† | 672 (27.7) |
| 4–5 | 741 (11.2) | 354 (49.0)* | 201 (28.7)* | 186 (22.3) | 341 (47.7)† | 135 (17.8)† | 143 (19.9)† | 122 (14.6) |
| ≥6 | 757 (10.1) | 406 (56.7)* | 193 (25.9)* | 158 (17.4) | 400 (56.6)† | 125 (15.7)† | 125 (16.3)† | 107 (11.4) |
| Physical activity | ||||||||
| Active (reference) | 3834 (65.6) | 911 (23.5) | 1096 (28.0) | 1827 (48.5) | 866 (22.6) | 1048 (25.9) | 733 (18.8) | 1187 (32.7) |
| Non-active | 2638 (34.4) | 967 (37.5)* | 663 (25.8) | 1008 (36.7) | 928 (36.7)† | 633 (23.3)† | 425 (15.8) | 652 (24.2) |
| CRP | ||||||||
| <0.5 (reference) | 4997 (79.5) | 1429 (27.9) | 1354 (27.1) | 2214 (45.0) | 1366 (27.3) | 1268 (24.1) | 912 (17.9) | 1451 (30.7) |
| ≥0.5 | 1475 (20.5) | 449 (29.7) | 405 (27.7 | 621 (42.6) | 428 (28.0) | 413 (28.3)† | 246 (17.4) | 388 (26.2) |
| Federal poverty level | ||||||||
| <200% | 2494 (27.1) | 1042 (42.8)* | 654 (28.4)* | 798 (28.8) | 1006 (41.9) | 495 (17.4) | 459 (20.2) | 534 (20.5) |
| ≥200% (reference) | 3978 (72.9) | 836 (22.9) | 1105 (26.8) | 2037 (50.3) | 788 (22.1)† | 1186 (27.8) | 699 (16.9)† | 1305 (33.2) |
| Education | ||||||||
| Less than high school | 1507 (14.4) | 632 (47.4)* | 385 (26.8)* | 490 (25.8) | 593 (45.2)† | 352 (20.2)† | 262 (18.2)† | 300 (16.4) |
| High School | 1489 (22.7) | 549 (39.4)* | 435 (30.0)* | 505 (30.6) | 529 (38.5)† | 344 (21.8)† | 286 (19.4)† | 330 (20.3) |
| More than high school (reference) | 3476 (62.9) | 697 (19.9) | 939 (26.3) | 1840 (53.7) | 672 (19.4) | 985 (27.2) | 610 (17.1) | 1209 (36.3) |
| Year of survey cycle | ||||||||
| 1999–2000 | 653 (3.2) | 193 (29.9) | 229 (36.6)* | 231 (33.5) | 186 (30.3)† | 176 (27.5)† | 142 (22.3)† | 149 (19.9) |
| 2001–2002 | 1148 (5.9) | 350 (31.9)* | 311 (27.9)* | 487 (40.1) | 339 (31.5)† | 309 (25.0)† | 204 (18.9)† | 296 (24.6) |
| 2003–2004 | 979 (20.7) | 290 (30.0)* | 299 (31.0)* | 390 (39.0) | 275 (29.1)† | 265 (24.4)† | 192 (20.6)† | 247 (25.9) |
| 2005–2006 | 1047 (23.0) | 305 (30.6)* | 308 (28.3)* | 434 (41.1) | 287 (29.3)† | 273 (25.6)† | 203 (18.0)† | 284 (27.0) |
| 2007–2008 | 1236 (23.3) | 377 (28.6)* | 318 (28.5)* | 541 (42.9) | 361 (28.0)† | 308 (23.8) | 211 (18.5)† | 356 (29.7) |
| 2009–2010 (reference) | 1409 (24.0) | 363 (23.3) | 294 (20.3) | 752 (56.4) | 346 (22.3) | 350 (25.7) | 206 (13.5) | 507 (38.4) |
| Variables | Unadjusted mean+SE | |||||||
|---|---|---|---|---|---|---|---|---|
| High cotinine | Medium cotinine | Low cotinine | Current smokers | Former smokers | Secondhand smokers | Non-smokers | ||
| Age (years) | 45 (0.3) | 40 (0.4)* | 43 (0.6)* | 48 (0.5) | 40 (0.4)† | 53 (0.5)† | 40 (0.5)† | 45 (0.5) |
| BMI (kg/m2) | 28 (0.1) | 26.6 (0.1) | 28.2 (0.1)* | 27.4 (0.2) | 26.5 (0.1)† | 28.0 (0.2)† | 28. 3(0.2)† | 27.2 (0.2) |
| HOMA-IR (mg/iU) | 2.9 (0.1) | 1.9 (0.1) | 2.3 (0.1)* | 2.1 (0.1) | 1.9 (0.1) | 2.3 (0.1)† | 2.3 (0.1)† | 2.0 (0.1) |
| HbA1c (%) | 5.4 (0.01) | 5.3 (0.01) | 5.3 (0.02) | 5.4 (0.01) | 5.3 (0.01) | 5.4 (0.02)† | 5.3 (0.02) | 5.3 (0.01) |
| FPG (mg/dL) | 99.2 (0.3) | 97.2 (0.4) | 98.8 (0.4) | 98.2 (0.4) | 96.9 (0.4) | 100.9 (0.6)† | 98.3 (0.5)† | 96.8 (0.4) |
*Statistically significant at p<0.05 compared with low cotinine.
†Statistically significant at p<0.05 compared with non-smokers.
BMI, body mass index; FPG, fasting plasma glucose; HbA1c, hemoglobin A1c; HOMA-IR, Homeostasis Model Assessment.