Table 4.

Associations between preceding respiratory tract diseases (at least two years before index date) and incident RA, stratified by smoking status

Respiratory tract disease	Adjusted* Odds Ratio for RA (95% CI)
	Nonsmokers (n=1,606)	Ever smokers (n=1,358)
Any respiratory tract disease	1.02 (0.77,1.34)	1.10 (0.84,1.45)
Acute upper	0.97 (0.69,1.36)	1.21 (0.86,1.70)
Acute sinusitis	1.35 (0.74,2.44)	1.51 (0.88,2.60)
Acute pharyngitis	0.87 (0.56,1.36)	1.42 (0.90,2.22)
Chronic upper	1.01 (0.69,1.47)	1.06 (0.71,1.59)
Chronic sinusitis	1.86 (1.05, 3.29)	1.82 (0.98,3.38)
Chronic rhinitis/pharyngitis	1.71 (0.79,3.72)	1.10 (0.38,3.19)
Acute lower	1.20 (0.75,1.93)	1.46 (0.94,2.27)
Pneumonia	1.07 (0.57,2.03)	1.30 (0.74,2.28)
Chronic lower	1.18 (0.81,1.73)	1.31 (0.89,1.91)
Asthma	1.23 (0.82,1.84)	1.28 (0.83,1.98)
COPD	1.53 (0.77,3.04)	1.46 (0.88,2.44)

BMI = body mass index, CI = confidence interval, COPD = chronic obstructive pulmonary disease, RA = rheumatoid arthritis

^*Respiratory codes at least two years before index date of RA or matched date. Reference group was individuals with no respiratory tract disease codes of any kind prior to index date. Adjusting for age, sex, EHR history, enrollment year, race/ethnicity, education, BMI. The ever smoker analysis was additionally adjusted for smoking status (past/current) and pack-years. Bold values are statistically significant.