Table 1.
Risk of JIA and non-chronic arthritis according to early feeding and family history. P-values from logistic regression. Classification according to ILAR criteria. The number (n) and proportion (%) of patients in each category
| Controls | Non-chronic arthritis | JIA | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Univariate analysisa vs controls | Univariate analysis vs controls | Adjusted for potential confounding factorsb | ||||||||
| (n = 10,883) | (n = 111) | OR (95% CI) | p | (n = 32) | OR (95% CI) | p | aOR (95% CI) | p | ||
| Duration of exclusive breastfeeding | ||||||||||
| Mean (SD) months | 4.5 (1.9) | 4.6 (1.9) | 3.6 (1,6) | |||||||
| Median (Range) months | 4 (1 - 9) | 4 (1 - 9) | 1.0 (0.9-1.1) | 0.879 | 4 (1 - 7) | 1.3 (1.1-1.6) | 0.004 | 1.3 (1.1-1.6) | 0.008 | |
| Mean (SD) daysc | 126 (60) | 135 (61) | 109 (55) | 1.0 (1.0-1.0) | 0.005 | 1.0 (1.0-1.0) | 0.009 | |||
| Exclusive breastfeeding <4 months (n) | 5351 (52.3%) | 61 (51%) | 1.3 (0.9-2.1) | 0.220 | 22 (73%) | 2.5 (1.2-5.6) | 0.026 | 2.5 (1.2-5.6) | 0.029 | |
| Duration of total breastfeeding | ||||||||||
| Mean (SD) months | 7.1 (2.4) | 7.2 (2.4) | 5.7 (2.8) | |||||||
| Median (Range) months | 8 (1 - 9) | 8 (1 - 9) | 0.99 (0.9-1.1) | 0.940 | 6 (1 - 9) | 1.2 (1.1-1.4) | <0.001 | 1.2 (1.1-1.3) | <0.001 | |
| Mean (SD) daysd | 219 (82) | 225 (90) | 0.97 (0.9-1.1) | 0.982 | 166 (100) | 1.0 (1.0-1.0) | <0.001 | 1.0 (1.0-1.0) | <0.001 | |
| Total breastfeeding <4 months (n) | 1694(16%) | 19 (18%) | 1.1 (0.7-1.8) | 0.715 | 11 (36%) | 2.8 (1.3-5.8) | 0.006 | 2.8 (1.3-5.7) | 0.009 | |
| Total breastfeeding <6 months (n) | 3166 (31%) | 33 (31%) | 1.0 (0.7-1.5) | 0.981 | 19 (61%) | 3.6 (1.7-7.4) | <0.001 | 3.5 (1.6-6.2) | <0.001 | |
| Introduction of cow’s milk formula | ||||||||||
| Mean (SD) months | 4.8 (2.5) | 4.9 (2.7) | 1.0 (0.9-1.1) | 0.770 | 3.9 (2.2) | 1.2 (1.0-1.3) | 0.052 | 1.0 (1.0-1.3) | 0.055 | |
| Median (Range) months | 5 (1 - 9) | 6 (1 - 9) | 4 (1 - 9) | |||||||
| Introduction of gluten | ||||||||||
| Mean (SD) months | 6.0 (1.39) | 5.9 (1.4) | 1.0 (0.9-1.2) | 0.563 | 5.8 (1.27) | 1.1 (0.9-1.4) | 0.483 | No analysis performed | ||
| Median (Range) months | 6 (1 - 9) | 6 (3 - 9) | 6 (4 - 8) | |||||||
| Family history / Heredity for JIA/RA | ||||||||||
| Mother with RA (n) | 100 (1%) | 1 (1%) | 0.9 (0.3-6.7) | 0.941 | 1 (3%) | 3.5 (0.5-2.6) | 0.223 | No analysis performed | ||
| Father with RA (n) | 31 (0%) | 0 (0%) | 0 | 1.000 | 0 (0%) | 0 | 1.000 | No analysis performed | ||
| Siblings with JIA/RA (n) | 0 (0%) | 0 (0%) | 0 | 1.000 | 0 (0%) | 0 | 1.000 | No analysis performed | ||
| 2nd degree family member with RA (n) | 940 (9%) | 16 (14%) | 1.7 (0.98-2.8) | 0.06 | 3 (9%) | 1.7 (0.98-2.8) | 0.910 | No analysis performed | ||
| Category at Onset (ILAR) (n) | ||||||||||
| Oligoarticulara | 14 (44%) | |||||||||
| Polyarticulare | 4 (13%) | |||||||||
| Enthesitis-related arthritis | 2 (6%) | |||||||||
| Psoriatic arthritis | 3 (9%) | |||||||||
| Systemic | 4 (13%) | |||||||||
| Unclassifiable | 5 (16%) | |||||||||
a Patients with oligoarticular disease, not possible to classify as extended or persistent because of missing data
b Potential confounding factors were heredity for rheumatism (JIA or RA in first- and second-degree relatives), parity, mode of delivery, preterm birth, infections during the first year of life, introduction of formula, the parents’ level of education, smoking and age as well as country of birth
cData from diary: Control (n = 8913); Non-chronic arthritis (n = 79); JIA (n = 29)
d Data from diary: Control (n = 9732); Non-chronic arthritis (n = 105); JIA (n = 31)
e Patients with polyarticular disease, not possible to classify as RF positive or negative because of missing data