Table 1 Population characteristics at baseline and comparison between cases (patients with DFR status) and their paired controls

 Years of age^a

38.3 (27.2–48.3)

39 (25.5–44.2)

36.3 (27.9–46.6)

0.656

 Female sex^b

183 (87.6)

18 (78.3)

36 (78.3)

1

 Years of formal education^a

12 (9–15)

12 (9–15)

11.5 (9–14)

0.5

 Medium-low SE status^b

188 (90)

20 (87)

39 (84.8)

1

 Months of disease duration^a

5.1 (3–6.8)

5.2 (2.5–7)

4.9 (2.9–7.1)

0.775

 RF (positive titers)^b

173 (82.8)

13 (56.5)

33 (71.7)

0.280

 ACPA (positive titers)^b

172 (82.3)

11 (47.8)

28 (60.9)

0.318

 Erosions^b

21 (10.1)

1 (4.3)

5 (10.9)

0.656

 DAS28^a

5.8 (4.6–6.8)

5.3 (4.5–6.4)

5.6 (4.2–6.5)

0.990

 Swollen joint count^a

13 (8–18)

10 (6–16)

11.5 (7.8–18)

0.389

 Tender joint count^a

13 (7–18)

12 (6–18)

12 (7–16)

0.784

 ESR, mm/H^a

21 (10–39)

18 (13–31)

19 (7.5–35.3)

0.731

 CRP, mg/dL^a

0.7 (0.2–2.5)

0.3 (0.1–1.5)

0.6 (0.2–2.4)

0.074

 HAQ score (0–3)^a

1.4 (0.9–2)

1.3 (0.8–1.8)

1.1 (0.4–1.8)

0.342

 SF36 physical-component score (0–100)^a

35 (23.5–54.2)

30.7 (22.3–51.3)

44.7 (27.3–66.6)

0.044

 SF36 mental-component score (0–100)^a

44.6 (29.7–59.4)

39.5 (28.8–66)

51.7 (37.3–68)

0.208

 Patient-overall disease-VAS^a

51 (28.5–74)

44 (18.5–68)

44.5 (23.8–73.8)

0.593

 With corticosteroids^b

109 (52.2)

9 (39.1)

18 (39.1)

1

 With DMARDs^b

209 (100)

23 (100)

46 (100)

NA

 DMARDs/patient

2 (1–2)

2 (1–2)

2 (1–2)

0.265