Table 1 The characteristics of RA patients according to the serum klotho concentration
Characteristics | Total | Serum klotho | ||||
|---|---|---|---|---|---|---|
Q1 | Q2 | Q3 | Q4 | p value | ||
N = 841 | N = 211 | N = 209 | N = 210 | N = 211 | ||
Gender (%) | Â | Â | Â | Â | Â | 0.024 |
 Male | 354 (42.09) | 97 (45.97) | 95 (45.45) | 92 (43.81) | 70 (33.18) |  |
 Female | 487 (57.91) | 114 (54.03) | 114 (54.55) | 118 (56.19) | 141 (66.82) |  |
Age, years (%) | Â | Â | Â | Â | Â | 0.358 |
  < 60 | 355 (42.21) | 86 (40.76) | 86 (41.15) | 83 (39.52) | 100 (47.39) |  |
  ≥ 60 | 486 (57.79) | 125 (59.24) | 123 (58.85) | 127 (60.48) | 111 (52.61) |  |
Race (%) | Â | Â | Â | Â | Â | 0.170 |
 Non-Hispanic White | 332 (39.48) | 82 (38.86) | 92 (44.02) | 92 (43.81) | 66 (31.28) |  |
 Non-Hispanic Black | 251 (29.84) | 64 (30.33) | 56 (26.79) | 53 (25.24) | 78 (36.97) |  |
 Mexican American | 128 (15.22) | 31 (14.69) | 34 (16.27) | 31 (14.76) | 32 (15.17) |  |
 Others | 130 (15.46) | 34 (16.11) | 27 (12.92) | 34 (16.19) | 35 (16.59) |  |
Education level (%) | Â | Â | Â | Â | Â | 0.092 |
 Less than 9th grade | 130 (15.46) | 34 (16.11) | 30 (14.35) | 30 (14.29) | 36 (17.06) |  |
 9–11th grade | 155 (18.43) | 52 (24.64) | 37 (17.70) | 29 (13.81) | 37 (17.54) |  |
 High school graduate | 189 (22.47) | 41 (19.43) | 50 (23.92) | 60 (28.57) | 38 (18.01) |  |
 Some college or AA degree | 265 (31.51) | 64 (30.33) | 66 (31.58) | 69 (32.86) | 66 (31.28) |  |
 College graduate or above | 102 (12.13) | 20 (9.48) | 26 (12.44) | 22 (10.48) | 34 (16.11) |  |
Marital status (%) | Â | Â | Â | Â | Â | 0.044 |
 Married or living with partner | 480 (57.07) | 120 (56.87) | 134 (64.11) | 124 (59.05) | 102 (48.34) |  |
 Widowed, divorced, or separated | 293 (34.84) | 73 (34.60) | 60 (28.71) | 74 (35.24) | 86 (40.76) |  |
 Never married | 68 (8.09) | 18 (8.53) | 15 (7.18) | 12 (5.71) | 23 (10.90) |  |
Family poverty income ratio (%) | Â | Â | Â | Â | Â | 0.526 |
 0.00–1.00 | 239 (28.42) | 63 (29.86) | 57 (27.27) | 60 (28.57) | 59 (27.96) |  |
 1.00–3.00 | 375 (44.59) | 103 (48.82) | 90 (43.06) | 88 (41.90) | 94 (44.55) |  |
  ≥ 3.00 | 227 (26.99) | 45 (21.33) | 62 (29.67) | 62 (29.52) | 58 (27.49) |  |
BMI, kg/m2 (%) | Â | Â | Â | Â | Â | 0.422 |
  < 25.0 | 158 (18.79) | 37 (17.54) | 40 (19.14) | 39 (18.57) | 42 (19.91) |  |
 25.0–30.0 | 238 (28.30) | 58 (27.49) | 66 (31.58) | 66 (31.43) | 48 (22.75) |  |
  ≥ 30.0 | 445 (52.91) | 116 (54.98) | 103 (49.28) | 105 (50.00) | 121 (57.35) |  |
Ever drinking (%) | Â | Â | Â | Â | Â | 0.054 |
 Yes | 566 (67.30) | 153 (72.51) | 142 (67.94) | 144 (68.57) | 127 (60.19) |  |
 No | 275 (32.70) | 58 (27.49) | 67 (32.06) | 66 (31.43) | 84 (39.81) |  |
Cotinine, ng/ml | 0.07 (0.02,92.10) | 0.13 (0.02,129.00) | 0.09 (0.02,163.00) | 0.07 (0.02,19.30) | 0.05 (0.02,1.06) | 0.303 |
Hypertension (%) | Â | Â | Â | Â | Â | 0.714 |
 Yes | 541 (64.33) | 142 (67.30) | 131 (62.68) | 136 (64.76) | 132 (62.56) |  |
 No | 300 (35.67) | 69 (32.70) | 78 (37.32) | 74 (35.24) | 79 (37.44) |  |
Diabetes (%) | Â | Â | Â | Â | Â | 0.661 |
 Yes | 239 (28.42) | 54 (25.59) | 58 (27.75) | 62 (29.52) | 65 (30.81) |  |
 No | 602 (71.58) | 157 (74.41) | 151 (72.25) | 148 (70.48) | 146 (69.19) |  |
eGFR, mL/(min × 1.73 m2) (%) |  |  |  |  |  | 0.013 |
  < 60.0 | 119 (14.15) | 43 (20.38) | 29 (13.88) | 27 (12.86) | 20 (9.48) |  |
  ≥ 60.0 | 722 (85.85) | 168 (79.62) | 180 (86.12) | 183 (87.14) | 191 (90.52) |  |
Physical activity, MET time/week (%) | Â | Â | Â | Â | Â | 0.976 |
  < 600 | 446 (53.03) | 114 (54.03) | 106 (50.72) | 113 (53.81) | 113 (53.55) |  |
 600–1200 | 87 (10.34) | 22 (10.43) | 20 (9.57) | 23 (10.95) | 22 (10.43) |  |
  ≥ 1200 | 308 (36.63) | 75 (35.55) | 83 (39.71) | 74 (35.24) | 76 (36.02) |  |
25-hydroxyvitamin D, nmol/L (%) | Â | Â | Â | Â | Â | 0.780 |
  < 50.0 | 271 (32.22) | 148 (70.14) | 142 (67.94) | 142 (67.62) | 138 (65.40) |  |
  ≥ 50.0 | 570 (67.78) | 63 (29.86) | 67 (32.06) | 68 (32.38) | 73 (34.60) |  |
NHANES cycles (%) | Â | Â | Â | Â | Â | 0.006 |
 2007–2008 | 199 (23.67) | 55 (26.07) | 42 (20.10) | 53 (25.24) | 49 (23.22) |  |
 2009–2010 | 180 (21.40) | 51 (24.17) | 54 (25.84) | 38 (18.10) | 37 (17.54) |  |
 2011–2012 | 143 (17.00) | 24 (11.37) | 33 (15.79) | 47 (22.38) | 39 (18.48) |  |
 2013–2014 | 146 (17.36) | 26 (12.32) | 38 (18.18) | 43 (20.48) | 39 (18.48) |  |
 2015–2016 | 173 (20.57) | 55 (26.07) | 42 (20.10) | 29 (13.81) | 47 (22.27) |  |