| | Author and year | Country | Sample size (% women/% men) | Age in years (mean or Min–Max) | DAS-28 (mean) | Duration of disease (mean or Min–Max) | | Cases | Controls | Cases | Controls |
| | García-González et al., 2015 [27] | Mexico | 10 (90/10) A, 19 (84/16) I | 41 (90/10) | 48 A, 48.5 I | 38.0 | 4.3 A, 2.1 I | 7.0 y A, 2.0 y I | | Thiele et al., 2015 [18] | USA | 1720 (9.1/90.9) | 80 (NS) | 63.4 | NS | 3.9 | 12.4 y | | Datta et al., 2014 [16] | India | 36 (77.7/22.3) | NS | 40 | NS | 5.6 | 11 m–24 y | | Nakajima et al., 2014 [17] | Japan | 152 (67.7/32.3) | 80 (42.5/57.5) | 63.1 | 59.2 | 3.5 | 14.3 y | | Nzeusseu Toukap et al., 2014 [19] | Belgium | 33 URA (NS), 33 TRA (NS) | 39 (NS) | NS | NS | 4.8 URA, 4.9 TRA | NS | | Veselinovic et al., 2014 [28] | Serbia | 52 (63.5/36.5) | 30 (63.2/36.8) | 52.4 | 54.2 | 3.6 | 5.7 y | | Wang et al., 2014 [35] | China | 100 (62/38) | 50 (68/32) | 55.7 | 52.5 | 5.3 | 7.0 y | | Jacobson et al., 2012 [26] | Australia | 35 (62.9/37.1) | 39 (61.5/38.5) | 62.9 | 62.8 | NS | NS | | Kundu et al., 2012 [33] | India | 25 (80/20) | 10 (80/20) | 40.0 | 26.5 | 5.7 | 11 m–25 y | | Kwaśny-Krochin et al., 2012 [29] | Poland | 46 (85/15) | 50 (86/14) | 57.0 | 56.0 | 5.2 | 8.1 y | | Mishra et al., 2012 [42] | India | 36 (61.1/38.9) | 36 (69.4/30.6) | 49.7 | 49.6 | NS | NS | | Stamp et al., 2012 [20] | New Zealand | 77 (71.4/28.6) | 120 (NS) | 54.7 | NS | 3.8 | NS | | Staroń et al., 2012 [21] | Poland | 25 (84/16) | 35 (NS) | NS | NS | NS | NS | | Alver et al., 2011 [31] | Turkey | 52 (76.9/23.1) | 42 (73.8/26.2) | 49.2 | 48.5 | NS | NS | | Aryaeian et al., 2011 [34] | Iran | 59 (64.4/35.6) | 59 (64.4/35.6) | 41.9 |
39.1 | NS | 8.2 y | | Ediz et al., 2011 [25] | Turkey | 25 (72/28) ACPA (+) | 24 (76/24) ACPA (−) | 54.4 | 56.2 | 4.1 ACPA (+), 3.4 ACPA (−) | 9.6 y ACPA (+), 8.1 y ACPA (−) | | Hassan et al., 2011 [10] | Egypt | 30 (100) | 30 (100) | 35.8 | 32.3 | 4.0 | 6.5 y | | Karaman et al., 2011 [30] | Turkey | 43 (74.4/25.6) | 30 (56.7/43.3) | 39.8 | 37.2 | NS | 4.2 y | | Desai et al., 2010 [22] | India | 40 (50/50) | 40 (NS) | 40–60 | 40–60 | NS | NS | | Rho et al., 2010 [23] | USA | 169 (NS) | 92 (NS) | >18 | >18 | NS | NS | | Shah et al., 2011 [32] | India | 30 (83.3/16.7) | 30 (90/10) | 24.2 | 26.7 | 4.5 | 5.0 y | | Tetik et al., 2010 [24] | Turkey | 20 (NS) | 20 (NS) | 48 | 25 | NS | 11 y |
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