Table 1.
Baseline characteristics among shiftworkers compared with nonshiftworkers*
| Characteristics | Nonshiftworkers, mean (SD) | Shiftworkers, mean (SD) | P |
|---|---|---|---|
| No. | 1784 | 233 | |
| Age, y | 51.4 (6.7) | 50.4 (6.8) | .03 |
| Height, cm | 174.8 (7.8) | 175.1 (7.3) | .49 |
| Weight, kg | 88.5 (18.7) | 89.7 (17.9) | .34 |
| BMI, kg/m2 | 28.9 (5.4) | 29.2 (5.3) | .41 |
| Average sleep duration, h | 6.7 (1.2) | 6.2 (1.5) | <.001 |
| Hours worked last week, h | 44.3 (12.9) | 47.3 (16.2) | .02 |
| Total PSA, ng/mL | 1.2 (1.3) | 1.3 (2.1) | .32 |
| No. (%) | No. (%) | ||
| Marital status | |||
| Married | 1286 (72.1) | 138 (60.0) | <.001 |
| Widowed | 20 (1.1) | 5 (2.1) | |
| Divorced | 188 (10.5) | 37 (16.0) | |
| Separated | 51 (2.9) | 12 (5.2) | |
| Never married | 113 (6.3) | 27 (11.7) | |
| Living with partner | 125 (7.0) | 12 (5.2) | |
| Race ethnicity | |||
| White | 834 (46.8) | 80 (34.3) | <.001 |
| Black | 317 (17.8) | 69 (29.6) | |
| Hispanic | 552 (30.9) | 71 (30.5) | |
| Other | 81 (4.5) | 13 (5.6) | |
| Education | |||
| Less than 9th grade | 226 (12.7) | 31 (13.3) | .002 |
| 9th–11th grade | 235 (13.2) | 35 (15.0) | |
| High school graduate | 403 (22.6) | 65 (27.9) | |
| Some college | 449 (25.2) | 68 (29.2) | |
| College graduate | 470 (26.4) | 34 (14.6) | |
| Annual household income | |||
| <$20 000 | 204 (14.9) | 43 (21.7) | .02 |
| $20 001–55 000 | 575 (41.9) | 90 (45.5) | |
| $55 001–75 000 | 237 (17.3) | 32 (16.2) | |
| >$75 000 | 356 (26.0) | 33 (16.7) | |
| Ever smokers | 927 (52.0) | 120 (51.5) | .57 |
| Covered by health insurance | 1346 (75.5) | 153 (65.6) | <.001 |
| Have ≥12 alcoholic drinks/yr | 1416 (84.9) | 173 (83.2) | .52 |
* Continuous variables were analyzed using two-sided t-tests and categorical variables were analyzed using χ2 tests. BMI = body mass index; PSA = prostate-specific antigen; SD = standard deviation.