Predictors of seropositive (RF+ or ACPA+) inflammatory polyarthritis
| Model 1 (All, n=107/25336) | Model 2 (Women, n=74/13821) | |||||||
|---|---|---|---|---|---|---|---|---|
| Age and gender adjusted | Multivariable* | Age adjusted | Multivariable* | |||||
| Risk factor | HR (95% CI) | p Value | HR (95% CI) | p Value | HR (95% CI) | p Value | HR (95% CI) | p Value |
| Pack-years of smoking (every 10 pack-years) | 1.24 (1.11 to 1.38) | <0.001 | 1.24 (1.10 to 1.41) | 0.001 | 1.17 (0.98 to 1.40) | 0.08 | Not included | |
| Smoking status | ||||||||
| Never smokers | 1 (ref) | Not included | 1 (ref) | 1 (ref) | ||||
| Men, current smokers | 4.64(1.53 to 14.06) | 0.02 | ||||||
| Men, ex-smokers | 2.20 (0.80 to 6.03) | |||||||
| Women, current smokers | 1.61 (0.87 to 3.01) | 0.12 | 1.61 (0.86 to 3.00) | 1.66 (0.88 to 3.13) | ||||
| Women, ex-smokers | 0.77 (0.44 to 1.33) | 0.77 (0.44 to 1.33) | 0.12 | 0.78 (0.44 to 1.39) | 0.12 | |||
| Alcohol (every 7 units/ week) | 0.83 (0.69 to 0.98) | 0.03 | 0.86 (0.73 to 1.01) | 0.07 | 0.67 (0.48 to 0.95) | 0.02 | 0.78 (0.57 to 1.08) | 0.13 |
| BMI† | ||||||||
| Normal or underweight (BMI<25) | 1 (ref) | Not included | 1 (ref) | Not included | ||||
| Overweight (BMI 25 to < 30) | 0.73 (0.48 to 1.13) | 0.74 (0.43 to 1.25) | ||||||
| Obese (BMI>30) | 1.05 (0.61 to 1.79) | 0.27 | 1.18 (0.64 to 2.17) | 0.31 | ||||
| Social class | ||||||||
| Manual worker | 1 (ref) | 1 (ref) | 1 (ref) | 1 (ref) | ||||
| Technical/skilled/managerial | 0.63 (0.42 to 0.92) | 0.61 (0.41 to 0.92) | 0.48 (0.30 to 0.76) | 0.47 (0.29 to 0.77) | ||||
| Professional | 0.21 (0.05 to 0.87) | 0.01 | 0.24 (0.06 to 0.97) | 0.02 | 0.28 (0.07 to 1.15) | 0.003 | 0.32 (0.08 to 1.35) | 0.01 |
| Education | ||||||||
| No degree | 1 (ref) | Not included | 1 (ref) | Not included | ||||
| Degree | 0.36 (0.15 to 0.89) | 0.03 | 0.11 (0.01 to 0.81) | 0.03 | ||||
| Diabetes mellitus | 2.99 (1.26 to 7.08) | 0.01 | 1.99 (0.69 to 5.74) | 0.20 | 4.95(1.93 to 12.72) | 0.001 | 5.20 (2.00 to 13.52) | 0.01 |
| Parity | ||||||||
| None | 1 (ref) | 1 (ref) | ||||||
| 1 | 1.56 (0.51 to 4.78) | 1.50 (0.49 to 4.56) | ||||||
| ≥2 | 2.36 (0.96 to 5.81) | 0.11 | 2.43 (0.99 to 6.00) | 0.09 | ||||
| Breast feeding (every 52 weeks) | 0.77 (0.53 to 1.14)‡ | 0.19 | 0.66 (0.41 to 1.05)‡ | 0.08 | ||||
*Adjusted for all other variables in model.
†BMI was a significant predictor of seronegative inflammatory polyarthritis. Age- and gender-adjusted HR (95% CI) for being overweight=2.23 (1.22 to 4.08) and for being obese=2.75 (1.39 to 5.46) (whole cohort). For women, age-adjusted HR (95% CI) for being overweight=2.65 (1.29 to 5.46) and for being obese=3.66 (1.68 to 7.98).
‡For all women, including nulliparous.
ACPA+, anti-citrullinated peptide antibody positive; BMI, body mass index; RF+, Rheumatoid factor positive.