Asthma and elevation of anti-citrullinated protein antibodies prior to the onset of rheumatoid arthritis

Table 3 Odds ratios for incident RA by elevated or normal levels of pre-RA ACPA using conditional logistic regression in the Nurses’ Health Studies

	OR (95%CI) adjusted for matching factors^a	Multivariable^b OR (95%CI)
Pre-RA ACPA+ RA n = 96 outcomes from total n = 382
No asthma	1.00 (Ref)	1.00 (Ref)
Asthma	3.70 (1.70, 8.05)	3.57 (1.58, 8.04)
Pre-RA ACPA− RA n = 188 outcomes from total n = 751
No asthma	1.00 (Ref)	1.00 (Ref)
Asthma	0.93 (0.50, 1.72)	0.87 (0.46, 1.61)
p for heterogeneity	0.006	0.004

ACPA anti-citrullinated protein antibodies, CI confidence interval, OR odds ratio, RA rheumatoid arthritis
^aCases and controls were matched by age at index date, time from blood draw to index date, cohort, calendar year, fasting status, menopausal status, and postmenopausal hormone use
^bAdditionally adjusted for smoking (continuous pack-years), parental passive smoking (yes/no), ever lived with smoker (yes/no), and body mass index (continuous, kg/m²)

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