Descriptive characteristics of the cohort and associations between selected environmental and perinatal factors and rheumatoid factor positivity
| RF positive | RF negative | Univariate OR (95% CI) | p Value | |
|---|---|---|---|---|
| *Other includes Hispanic (77.8%), African-American (6.7%), Asian (2.2%), American Indian (0.7%) and biracial (12.6%). | ||||
| †Data on exclusive breast feeding duration were missing for 76 children. | ||||
| ‡Data on smoking during pregnancy were missing for 58 children. | ||||
| HLA, human leucocyte antigen; RF, rheumatoid factor. | ||||
| Race/ethnicity | ||||
| Non-Hispanic white | 20 (87.0%) | 496 (79.0%) | ||
| Other* | 3 (13.0%) | 132 (21.0%) | 0.56 (0.17 to 1.93) | 0.360 |
| Maternal education level (years) | ||||
| ⩽12 | 4 (17.4%) | 137 (21.8%) | ||
| >12 | 19 (82.6%) | 491 (78.2%) | 1.32 (0.44 to 3.95) | 0.614 |
| Sex | ||||
| Male | 16 (69.6%) | 336 (53.5%) | ||
| Female | 7 (30.4%) | 292 (46.5%) | 0.50 (0.20 to 1.24) | 0.136 |
| HLA genotype | ||||
| DR4 – | 9 (39.1%) | 181 (28.7%) | ||
| DR4 + | 14 (60.9%) | 448 (71.3%) | 0.63 (0.27 to 1.47) | 0.281 |
| Family history of type 1 diabetes | ||||
| No | 11 (47.8%) | 377 (60.0%) | ||
| Yes | 12 (52.2%) | 251 (40.0%) | 1.63 (0.71 to 3.77) | 0.246 |
| Age in years, mean (SD) | 5.33 (2.55) | 6.43 (2.60) | 0.83 (0.69 to 0.99) | 0.046 |
| BMI z score, mean (SD) | –0.02 (1.13) | 0.19 (1.00) | 0.081 (0.52 to 1.25) | 0.336 |
| Age at introduction of cereals | ||||
| 4–6 months | 13 (56.5%) | 320 (51%) | ||
| Other | 10 (43.5%) | 308 (49%) | 0.80 (0.35 to 1.85) | 0.600 |
| Breast feeding duration (months) | ||||
| 0–3 | 12 (47.8%) | 231 (36.8%) | ||
| >3 | 11 (52.2%) | 397 (63.2%) | 0.64 (0.28 to 1.46) | 0.286 |
| Exclusive breast feeding duration† (months) | ||||
| 0–3 | 17 (80.9%) | 439 (79.2%) | ||
| >3 | 4 (19.0%) | 115 (20.8%) | 0.90 (0.30 to 2.72) | 0.849 |
| Current parental smoking status | ||||
| No | 17 (73.9%) | 485 (77.1%) | ||
| Yes | 6 (26.1%) | 144 (22.9%) | 1.19 (0.46 to 3.07) | 0.724 |
| Exposure to cigarette smoking by care giver/relative/friend | ||||
| No | 19 (82.6%) | 543 (86.5%) | ||
| Yes | 4 (17.4%) | 85 (13.5%) | 1.35 (0.45 to 4.05) | 0.598 |
| Maternal smoking during pregnancy‡ | ||||
| No | 20 (90.9%) | 522 (91.4%) | ||
| Yes | 2 (9.1%) | 49 (8.6%) | 1.07 (0.24 to 4.69) | 0.933 |