Table 1.

Characteristics of the 84 incident RA-ILD cases and their 233 RA non-ILD controls. These characteristics were collected at the time of the earliest BRASS study visit.

RA-ILD cases, n = 84RA controls, n = 233P
Years to index/matched date, median (IQR)1.5 (0.6–2.5)1.9 (1.6–5.6)0.84a
Age, yrs, mean (SD)67 (10)66 (11)0.41a
Female sex65 (77)186 (80)0.64a
RA duration, yrs, mean (SD)b20 (12)20 (11)0.99a
RF-positive73 (87)195 (84)0.48a
CCP-positive70 (83)190 (82)0.71
White, non-Hispanic76 (90)219 (94)0.28
Education, below college30 (36)98 (42)0.31
Joint erosions49 (58)144 (62)0.58
Rheumatoid nodules42 (50)80 (34)0.01
BMI, kg/m20.18
    < 204 (5)16 (7)
    20 to < 2520 (23)77 (33)
    25 to < 3032 (38)87 (37)
    ≥ 3028 (33)53 (23)
Smoking status0.03
    Never33 (39)124 (53)
    Past43 (51)100 (43)
    Current8 (10)9 (4)
Smoking, pack-yrs< 0.001
    Never smoker36 (43)126 (54)
    1–97 (8)45 (19)
    10–1911 (13)28 (12)
    20–297 (8)21 (9)
    ≥ 3023 (27)13 (6)
CRP, mg/L0.006
    Normal (< 3)33 (39)136 (58)
    Low-positive (3 to < 10)31 (37)67 (29)
    High-positive (≥ 10)20 (24)30 (13)
DAS28-CRP< 0.001
    Remission (< 2.6)27 (32)104 (45)
    Low (2.6 to < 3.2)4 (5)39 (17)
    Moderate (3.2 to < 5.1)37 (44)70 (30)
    High (≥ 5.1)16 (19)20 (9)
MDHAQ Score< 0.001
    0 to < 0.215 (18)64 (27)
    0.2 < 1.037 (44)127 (55)
    ≥ 1.032 (38)42 (18)
bDMARD use0.03
    Never29 (35)76 (33)
    Past19 (23)27 (12)
    Current36 (43)130 (56)
Methotrexate use0.03
    Never18 (21)24 (10)
    Past32 (38)93 (40)
    Current34 (41)116 (50)
Prednisone use0.007
    Never5 (6)31 (13)
    Past42 (50)140 (60)
    Current37 (44)62 (27)
  • Values are n (%) unless otherwise indicated.

  • a Matched factor.

  • b Range was 1–46 years for cases and 2–47 years for controls. Median (IQR) was 20 (10–31) for cases and 18 (11–29) for controls. bDMARD: biological disease-modifying antirheumatic drug; BRASS: Brigham Rheumatoid Arthritis Sequential Study; CCP: citrullinated peptide antibody; CRP: C-reactive protein; DAS28: Disease Activity Score in 28 joints; ILD: interstitial lung disease; MDHAQ: multidimensional Health Assessment Questionnaire; RA: rheumatoid arthritis; RF: rheumatoid factor.