From: Advantages of the nested case-control design in diagnostic research
 | Full study population | Nested case-control samples for different case-control ratios | |||||
---|---|---|---|---|---|---|---|
 | DVT + | DVT- | Cases | Controls | |||
Test results | n = 289 | n = 1006 | n = 289 | 1:1 n = 289 | 1:2 n = 578 | 1:3 n = 867 | 1:4 n = 1156 |
D-dimer test abnormal | 271 (94) | 621 (62) | 271 (94) | 178 (61) | 357 (62) | 535 (62) | 713 (62) |
Calf difference, cm* | 3.2 (1.7) | 2.1 (1.6) | 3.2 (1.7) | 2.1 (1.6) | 2.1 (1.6) | 2.1 (1.6) | 2.1 (1.6) |
Age, years* | 61.9 (16.8) | 59.4 (17.7) | 61.9 (16.8) | 59.4 (17.8) | 59.5 (17.8) | 59.4 (17.8) | 59.4 (17.7) |
Male gender | 137 (47) | 330 (33) | 137 (47) | 94 (33) | 190 (33) | 282 (33) | 380 (33) |