Unweighted and weighted distributions of baseline demographic and clinical variables of study participants (n = 3068), Johnston County Osteoarthritis Project, 1991–199718.
| Variable | Categories | Unweighted | Weighted | ||
|---|---|---|---|---|---|
| Count | % | %* | 95% CI | ||
| Age group, yrs | 45–54 | 1008 | 32.9 | 33.8 | 31.9, 35.6 |
| 55–64 | 885 | 28.8 | 27.1 | 25.8, 28.4 | |
| 65–74 | 794 | 25.9 | 26.5 | 25.1, 28.0 | |
| 75+ | 381 | 12.4 | 12.6 | 11.4, 13.8 | |
| Sex | Men | 1162 | 37.9 | 42.6 | 41.2, 44.0 |
| Women | 1906 | 62.1 | 57.4 | 56.0, 58.8 | |
| Race/ethnicity | Caucasian | 2069 | 67.4 | 81.5 | 79.4, 83.5 |
| African-American | 999 | 32.6 | 18.5 | 16.5, 20.6 | |
| Body mass index kg/m2† | < 18.5 (underweight) | 35 | 1.2 | 1.1 | 0.8, 1.3 |
| 18.5–24.9 (normal) | 749 | 24.5 | 25.1 | 23.9, 26.4 | |
| 25.0–29.9 (overweight) | 1160 | 38.0 | 39.5 | 38.1, 40.9 | |
| ≥ 30 (obese) | 1112 | 36.4 | 34.3 | 32.9, 35.8 | |