Associations of childhood socioeconomic factors with rheumatoid arthritis (RA)
| Non-cases* (N=48 919) | Cases (N=424) | OR (95% CI)† | ||
|---|---|---|---|---|
| Socioeconomic factors | N (%) | N (%) | Age-adjusted | Age and race-adjusted |
| Household education (highest) | ||||
| Graduate/professional degree | 5136 (11) | 30 (7) | Ref | Ref |
| College graduate (BA) | 7999 (16) | 56 (13) | 1.2 (0.76 to 1.8) | 1.2 (0.75 to 1.8) |
| Some college/technical degree | 9196 (19) | 67 (16) | 1.2 (0.77 to 1.8) | 1.2 (0.76 to 1.9) |
| High-school graduate | 17 289 (36) | 158 (38) | 1.5 (1.0 to 2.2) | 1.5 (1.0 to 2.2) |
| Less than high school | 8739 (18) | 108 (26) | 1.8 (1.2 to 2.7) | 1.7 (1.1 to 2.5) |
| Missing | 560 | 5 | ||
| Relative income | ||||
| Well off | 3143 (6) | 24 (6) | ||
| Middle income | 29 342 (60) | 222 (52) | Ref | Ref |
| Low income | 12 524 (26) | 136 (32) | 1.3 (1.1 to 1.6)‡ | 1.3 (1.0 to 1.5) |
| Poor | 3793 (8) | 41 (10) | ||
| Missing | 117 | 1 | ||
| Food insecurity | ||||
| No | 44 402 (91) | 366 (86) | Ref | Ref |
| Yes | 4483 (9) | 58 (14) | 1.6 (1.2 to 2.1) | 1.5 (1.1 to 2.0) |
| Missing | 34 | 0 | ||
| Maternal age, years | ||||
| ≥35 | 8640 (18) | 87 (21) | 1.3 (1.1 to 2.6) | 1.3 (1.0 to 1.7) |
| 20–34 | 36 690 (77) | 291 (71) | Ref | Ref |
| <20 | 2250 (5) | 33 (8) | 1.8 (1.3 to 2.6) | 1.7 (1.2 to 2.5) |
| Missing | 1339 | 13 | ||
| Paternal age, years | ||||
| ≥35 | 15 158 (33) | 137 (35) | 1.2 (0.94 to 1.5) | 1.2 (0.93 to 1.4) |
| 24–34 | 25 414 (56) | 202 (52) | Ref | Ref |
| <24 | 4965 (11) | 51 (13) | 1.3 (0.96 to 1.8) | 1.3 (0.93 to 1.7) |
| Missing | 3382 | 34 | ||
| Single parent household | ||||
| No | 44 228 (90) | 380 (90) | Ref | Ref |
| Yes | 4680 (10) | 44 (10) | 1.2 (0.84 to 1.6) | 1.1 (0.80 to 1.5) |
| Missing | 11 | 0 | ||
| Number of early life SES factors$ | ||||
| None | 17 300 (37) | 113 (28) | Ref | Ref |
| 1 | 15 858 (34) | 124 (31) | 1.1 (0.88 to 1.5) | 1.1 (0.87 to 1.5) |
| 2 | 10 389 (22) | 126 (31) | 1.7 (1.3 to 2.2) | 1.6 (1.2 to 2.1) |
| 3 | 3147 (7) | 36 (9) | 1.6 (1.1 to 2.4) | 1.5 (1.0 to 2.2) |
| 4 | 257 (1) | 6 (2) | 3.3 (1.4 to 7.5) | 3.0 (1.3 to 7.0) |
| Missing | 1968 | 19 | ||
↵* Excluding other possible and unlikely cases with self-reported RA; In non-cases, the percentage missing ranged from <0.5% for most variables to 2.7% missing maternal age and 7% missing paternal age; 4% were missing on the summary SES score, which was similar for cases. Percentages shown in the table reflect unadjusted comparisons excluding missing data.
↵† Logistic regression models adjusted for age, or age and race/ethnicity (non-Hispanic white, Hispanic, black, other), excluding missing data.
↵‡ No difference low income versus poor, so groups were combined to compare low income/poor versus middle income/well-off.
↵$ Summary score: one or more early life factors (≤high-school household education, low/poor relative household income, young maternal age, food insecurity); p for trend <0.0001 for both models shown.
SES, socioeconomic status.