Table 1.
Baseline clinical characteristics of the study population (N = 1,495).
| Variable | Mean (SD)/Number (%) |
|---|---|
| Age (years)1 | 46.8 (2.5) |
| Race1 | |
| Caucasian | 643 (43.2%) |
| African America | 449 (30.1%) |
| Japanese | 155 (10.4%) |
| Chinese | 145 (9.7%) |
| Hispanic | 98 (6.6%) |
| Body Mass Index (kg/m2)1 | 28.2 (7.4) |
| Study site1 | |
| Oakland, CA | 231 (15.5%) |
| Los Angeles, CA | 230 (15.4%) |
| Detroit, MI | 250 (16.7%) |
| Boston, MA | 236 (15.8%) |
| Chicago, IL | 219 (14.7%) |
| Pittsburgh, PA | 177 (11.9%) |
| Newark, NJ | 151 (10.1%) |
| Abdominal cramps1 | 856 (57.7%) |
| Current smoking1 | 236 (15.9%) |
| Depression | 325 (21.7%) |
| Sleep problems1 | 435 (29.3%) |
| Short Form-36 bodily pain (0-100 with higher number = more pain) | 28.7 (22.1) |
| Short Form-36 bodily pain magnitude | 27.6 (24.4) |
| Short Form-36 bodily pain interference | 17.1 (23.1) |
Abbreviations: SD, standard deviation
1
Due to missing data, N = 1494 for age, BMI and study site; N = 1490 for race; N = 1486 for sleeping problems; N = 1485 for smoking status; N = 1483 for abdominal cramps