Table 1. Baseline characteristics of included trials.
| First author | Year | Study design | Race | Age | Female | Male | Follow-up | Collection | Case | Control | Selenium concentration | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Case | Control | |||||||||||
| Massimo Casaril | 1994 | case-control | Caucasian | 21–74 | 6 | 17 | NA | Serum | 23 | 19 | 78.35 ± 19.78 ng/ml | 96.09 ± 22.03 ng/ml |
| TE-HSIEN LIN | 1998 | case-control | Asian | 21–82 | NA | NA | NA | blood | 51 | 19 | 106 ± 17.7 μg/l | 126.4 ± 10.1 μg/l |
| Ming-Whei Yu | 1999 | cohort | Asian | 30–65 | NA | NA | 4 | blood | 69 | 138 | 131.6 ± 30.9 μg/l | 150.2 ± 35.2 μg/l |
| Wang Chin-Thin1 | 2002 | case-control | Asian | 42–69 | NA | 51 | 2 | blood | 51 | 50 | 0.18 ± 0.02 μg/ml | 0.28 ± 0.06 μg/ml |
| CHING-CHIANG Lin | 2006 | case-control | Asian | 35–61 | 9 | 9 | NA | Serum | 18 | 50 | 108.5 ± 21.8 μg/l | 129 ± 21.5 μg/l |
| In-Wook Kim | 2012 | case-control | Asian | 40–59 | 7 | 23 | NA | Serum | 30 | 120 | 67.47 ± 14.3 μg/l | 108.38 ± 29.5 μg/l |
| Dominik Bettinger | 2013 | case-control | Caucasian | NA | NA | 10 | NA | blood | 10 | 10 | 85 ± 11.5 μg/l | 117.5 ± 15.7 μg/l |
| David J Hughes | 2016 | cohort | Caucasian | 25–70 | NA | NA | 4 | blood | 107 | 108 | 74.127 ± 19.29 μg/l | 87.309 ± 18.582 μg/l |
| Lori C.Sakoda | 2005 | cohort | Asian | NA | 12 | 154 | 8 | toenial | 166 | 394 | 3.1 ± 0.333 ppm | 3.5 ± 0.45 ppm |
NA, not available.