差异脂质ROC曲线分析
ROC曲线（receiver operating characteristic），亦名受试者工作特征曲线或感受性曲线，是根据一系列不同的二分类方式（分界值或决定阈），以真阳性率（灵敏度）为纵坐标，假阳性率（1-特异度）为横坐标绘制的曲线。脂质组学数据分析获得差异脂质后，采用ROC曲线来评价并筛选潜在的生物标记物，所使用的分析软件为R(v3.2.1)。
ROC曲线下面积（Area Under Curve，AUC）被用来评估生物标记物对于预测事件发生的灵敏度和特异性，每个脂质的灵敏度和特异性由ROC曲线的最佳阈值决定[1]。AUC值在0.5~1.0之间，AUC值越接近于1，预测的准确性越高。通常来说，AUC值在 0.5～0.7时预测准确性较低，AUC值在0.7～0.9时有一定预测准确性，AUC值在0.9以上时有较高预测准确性，当AUC值 = 0.5时，该生物标记物对于预测事件发生完全不起作用，无预测价值[2]。
本实验中所得差异脂质的AUC值见下表：
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| AUC | Ci1 | Ci2 | specificity | sensitivity | threshold | fold change | |
|---|---|---|---|---|---|---|---|
| BisMePA(18:3e_18:1) | 1 | 1 | 1 | 1 | 1 | 5.248192 | 0.38818 |
| BisMePA(18:2e_18:2) | 1 | 1 | 1 | 1 | 1 | 4.5246005 | 0.2473 |
| ChE(18:2) | 1 | 1 | 1 | 1 | 1 | 90.631375 | 0.80289 |
| ChE(20:4) | 0.944 | 0.833 | 1 | 1 | 0.833 | 37.565995 | 0.27194 |
| DG(32:0e) | 1 | 1 | 1 | 1 | 1 | 11.166361 | 0.35813 |
| DG(32:1e) | 1 | 1 | 1 | 1 | 1 | 5.73981 | 0.17156 |
| DG(34:0e) | 1 | 1 | 1 | 1 | 1 | 3.3333975 | 0.33639 |
| DG(34:3e) | 1 | 1 | 1 | 1 | 1 | 11.1278065 | 0.32582 |
| DG(34:4e) | 1 | 1 | 1 | 1 | 1 | 5.9070885 | 0.13613 |
| DG(18:2_18:2) | 1 | 1 | 1 | 1 | 1 | 3.5731575 | 1.211 |
| LPC(16:0) | 0.958 | 0.667 | 1 | 1 | 0.833 | 61.53389 | 0.11898 |
| LPC(18:1) | 1 | 1 | 1 | 1 | 1 | 100.20851 | 0.70883 |
| LPC(18:2) | 0.917 | 0.667 | 1 | 0.667 | 1 | 213.8275 | 0.065153 |
| MePC(28:1) | 1 | 1 | 1 | 1 | 1 | 4.058072 | 0.55826 |
| MePC(31:0e) | 1 | 1 | 1 | 1 | 1 | 45.4504 | 0.55728 |
| MePC(31:3) | 1 | 1 | 1 | 1 | 1 | 4.070992 | 0.66871 |
| MePC(32:1) | 1 | 1 | 1 | 1 | 1 | 8.2557295 | 0.78007 |
| MePC(32:2) | 1 | 1 | 1 | 1 | 1 | 29.67806 | 0.70694 |
| MePC(33:0e) | 1 | 1 | 1 | 1 | 1 | 10.8288645 | 0.55245 |
| MePC(33:2) | 1 | 1 | 1 | 1 | 1 | 42.48402 | 0.34586 |
| MePC(34:5) | 1 | 1 | 1 | 1 | 1 | 13.89611 | 0.57991 |
| MePC(34:6) | 1 | 1 | 1 | 1 | 1 | 19.247405 | 0.58481 |
| MePC(35:0) | 1 | 1 | 1 | 1 | 1 | 205.60935 | 0.43674 |
| MePC(35:1) | 0.972 | 0.833 | 1 | 1 | 0.833 | 364.2973 | 0.11973 |
| MePC(35:1e) | 1 | 1 | 1 | 1 | 1 | 32.68277 | 0.14387 |
| MePC(35:2) | 1 | 1 | 1 | 1 | 1 | 52.04319 | 0.56018 |
| MePC(35:3) | 1 | 1 | 1 | 1 | 1 | 27.054665 | 0.54129 |
| PC(8:0e_8:0) | 0.889 | 0.679 | 1 | 1 | 0.833 | 61.60269 | 0.29252 |
| PC(30:0) | 1 | 1 | 1 | 1 | 1 | 9.282053 | 0.41409 |
| PC(18:2_13:0) | 1 | 1 | 1 | 1 | 1 | 4.0370455 | 0.33495 |
| PC(32:0) | 1 | 1 | 1 | 1 | 1 | 63.177295 | 0.14914 |
| PC(32:0e) | 1 | 1 | 1 | 1 | 1 | 16.670905 | 0.48331 |
| PC(32:1) | 1 | 1 | 1 | 1 | 1 | 27.83274 | 0.70451 |
| PC(33:1) | 1 | 1 | 1 | 1 | 1 | 7.873963 | 0.58169 |
| PC(15:0_18:2) | 1 | 1 | 1 | 1 | 1 | 13.6911615 | 0.60104 |
| PC(33:3) | 1 | 1 | 1 | 1 | 1 | 2.5426215 | 0.62425 |
| PC(34:0) | 1 | 1 | 1 | 1 | 1 | 21.163045 | 0.56844 |
| PC(16:0_18:1) | 1 | 1 | 1 | 1 | 1 | 28.30705 | 0.21726 |
| PC(34:1) | 1 | 1 | 1 | 1 | 1 | 573.8302 | 0.4508 |
| PC(34:2) | 1 | 1 | 1 | 1 | 1 | 1169.3601 | 0.57078 |
| PC(34:2e) | 1 | 1 | 1 | 1 | 1 | 29.312575 | 0.54328 |
| PC(34:3) | 1 | 1 | 1 | 1 | 1 | 18.13868 | 0.48771 |
| PC(34:4) | 1 | 1 | 1 | 1 | 1 | 4.8360505 | 0.4746 |
| PC(35:2) | 1 | 1 | 1 | 1 | 1 | 52.88029 | 0.54855 |
| PC(35:4) | 1 | 1 | 1 | 1 | 1 | 8.2149555 | 0.51385 |
| PC(18:0_18:1) | 1 | 1 | 1 | 1 | 1 | 16.487295 | 0.69597 |
| PC(36:1) | 1 | 1 | 1 | 1 | 1 | 184.9917 | 0.44969 |
| PC(18:0_18:2) | 0.903 | 0.621 | 1 | 0.833 | 1 | 47.01595 | 0.60102 |
| PC(36:2) | 1 | 1 | 1 | 1 | 1 | 1024.4015 | 0.27191 |
| PC(36:2e) | 1 | 1 | 1 | 1 | 1 | 10.7088265 | 0.3567 |
| PC(16:0_20:3) | 1 | 1 | 1 | 1 | 1 | 32.49061 | 0.45621 |
| PC(36:4) | 1 | 1 | 1 | 1 | 1 | 551.68315 | 0.47264 |
| PC(18:4_18:0) | 0.833 | 0.5 | 1 | 1 | 0.833 | 27.307365 | 0.63234 |
| PC(19:1_18:1) | 1 | 1 | 1 | 1 | 1 | 7.275707 | 0.39624 |
| PC(38:1e) | 1 | 1 | 1 | 1 | 1 | 20.65446 | 0.44559 |
| PC(38:2) | 1 | 1 | 1 | 1 | 1 | 24.457995 | 0.49208 |
| PC(18:0_20:3) | 1 | 1 | 1 | 1 | 1 | 18.5598 | 0.40172 |
| PC(38:4) | 1 | 1 | 1 | 1 | 1 | 17.990615 | 0.3667 |
| PC(38:4e) | 1 | 1 | 1 | 1 | 1 | 29.74714 | 0.69416 |
| PC(38:5) | 1 | 1 | 1 | 1 | 1 | 98.08908 | 0.57284 |
| PC(18:0_20:5) | 1 | 1 | 1 | 1 | 1 | 4.594508 | 0.66608 |
| PC(38:6) | 1 | 1 | 1 | 1 | 1 | 28.94691 | 0.71644 |
| PC(40:4) | 1 | 1 | 1 | 1 | 1 | 18.92658 | 0.64141 |
| PC(40:5) | 0.944 | 0.756 | 1 | 1 | 0.833 | 10.318332 | 0.65251 |
| PC(40:6) | 0.847 | 0.617 | 1 | 0.667 | 1 | 120.3527 | 0.57219 |
| PE(18:0_18:1) | 1 | 1 | 1 | 1 | 1 | 8.1655775 | 0.6397 |
| SM(d32:1) | 1 | 1 | 1 | 1 | 1 | 24.66403 | 0.42044 |
| SM(d33:1) | 1 | 1 | 1 | 1 | 1 | 27.471355 | 0.63152 |
| SM(d34:0) | 1 | 1 | 1 | 1 | 1 | 24.169985 | 0.75919 |
| SM(d34:1) | 1 | 1 | 1 | 1 | 1 | 366.5325 | 0.59552 |
| SM(d18:1_16:0) | 1 | 1 | 1 | 1 | 1 | 334.9346 | 0.52004 |
| SM(d34:2) | 1 | 1 | 1 | 1 | 1 | 64.34811 | 0.20676 |
| SM(d36:1) | 0.889 | 0.617 | 1 | 1 | 0.667 | 44.930655 | 0.099253 |
| SM(d38:1) | 1 | 1 | 1 | 1 | 1 | 64.628235 | 0.013495 |
| SM(d39:1) | 1 | 1 | 1 | 1 | 1 | 18.713125 | 0.027478 |
| SM(d18:1_22:0) | 1 | 1 | 1 | 1 | 1 | 192.3739 | 0.015109 |
| SM(d18:2_22:2) | 1 | 1 | 1 | 1 | 1 | 7.581332 | 0.021276 |
| SM(d18:1_23:1) | 1 | 1 | 1 | 1 | 1 | 22.718415 | 0.038914 |
| SM(d18:1_24:0) | 1 | 1 | 1 | 1 | 1 | 149.5518 | 0.03942 |
| SM(d18:1_24:1) | 0.861 | 0.534 | 1 | 0.667 | 1 | 200.0129 | 0.031883 |
| SM(d18:1_24:3) | 1 | 1 | 1 | 1 | 1 | 28.37225 | 0.14204 |
| SM(d44:4) | 1 | 1 | 1 | 1 | 1 | 16.771165 | 0.13328 |
| TG(12:1e_10:1_14:1) | 1 | 1 | 1 | 1 | 1 | 4.4703795 | 0.03109 |
| TG(12:0e_6:0_19:0) | 0.958 | 0.756 | 1 | 1 | 0.833 | 30.789945 | 0.40771 |
| TG(20:0e_8:0_9:0) | 1 | 1 | 1 | 1 | 1 | 2.2572836 | 0.21237 |
| TG(16:0_12:0_14:0) | 1 | 1 | 1 | 1 | 1 | 2.16437905 | 0.12599 |
| TG(16:0_14:0_14:0) | 1 | 1 | 1 | 1 | 1 | 3.15490055 | 0.12066 |
| TG(18:1_12:0_14:0) | 1 | 1 | 1 | 1 | 1 | 5.30853255 | 0.19271 |
| TG(16:0_10:1_18:1) | 1 | 1 | 1 | 1 | 1 | 3.7514757 | 0.10974 |
| TG(16:0_14:0_16:0) | 1 | 1 | 1 | 1 | 1 | 6.2244101 | 0.33169 |
| TG(16:0_13:0_18:1) | 1 | 1 | 1 | 1 | 1 | 3.7181458 | 0.72585 |
| TG(15:0_14:0_18:2) | 1 | 1 | 1 | 1 | 1 | 2.59225325 | 0.13303 |
| TG(16:1_14:0_18:1) | 1 | 1 | 1 | 1 | 1 | 2.51414 | 0.70494 |
| TG(16:0_14:0_18:3) | 1 | 1 | 1 | 1 | 1 | 2.963121 | 0.5268 |
| TG(16:0_16:0_17:0) | 1 | 1 | 1 | 1 | 1 | 5.94217075 | 0.26791 |
| TG(16:0_16:0_18:1) | 1 | 1 | 1 | 1 | 1 | 6.897628 | 0.37487 |
| TG(18:0_14:0_18:1) | 1 | 1 | 1 | 1 | 1 | 232.99425 | 0.22722 |
| TG(14:0_18:2_18:3) | 1 | 1 | 1 | 1 | 1 | 6.3501925 | 0.12216 |
| TG(12:0_18:2_20:4) | 1 | 1 | 1 | 1 | 1 | 2.7458785 | 0.21107 |
| TG(16:0_17:1_18:1) | 1 | 1 | 1 | 1 | 1 | 4.2542165 | 0.2272 |
| TG(18:0_16:0_18:0) | 1 | 1 | 1 | 1 | 1 | 2.6673375 | 0.18594 |
| TG(18:0_16:0_18:1) | 1 | 1 | 1 | 1 | 1 | 11.0161255 | 0.17251 |
| TG(16:0_18:1_18:2) | 1 | 1 | 1 | 1 | 1 | 27.28646 | 0.25908 |
| TG(18:0_16:0_18:3) | 1 | 1 | 1 | 1 | 1 | 3.6343015 | 0.31822 |
| TG(16:0_18:1_18:3) | 1 | 1 | 1 | 1 | 1 | 28.381775 | 0.61284 |
| TG(16:1_18:2_18:2) | 1 | 1 | 1 | 1 | 1 | 19.15572 | 0.5982 |
| TG(16:1_18:2_18:3) | 1 | 1 | 1 | 1 | 1 | 4.580508 | 0.15816 |
| TG(18:4_16:1_18:1) | 1 | 1 | 1 | 1 | 1 | 7.778886 | 0.52039 |
| TG(18:4_16:1_18:2) | 1 | 1 | 1 | 1 | 1 | 5.2684335 | 0.21281 |
| TG(18:4_16:0_18:4) | 1 | 1 | 1 | 1 | 1 | 2.5842051 | 0.15333 |
| TG(17:0_18:1_18:2) | 1 | 1 | 1 | 1 | 1 | 42.903785 | 0.21676 |
| TG(18:1_17:1_18:2) | 1 | 1 | 1 | 1 | 1 | 28.64727 | 0.22944 |
| TG(15:0_18:1_20:4) | 1 | 1 | 1 | 1 | 1 | 4.2506075 | 0.3626 |
| TG(18:0_18:0_18:1) | 1 | 1 | 1 | 1 | 1 | 4.416687 | 0.39431 |
| TG(18:0_18:1_18:1) | 1 | 1 | 1 | 1 | 1 | 161.58639 | 0.46394 |
| TG(18:0_16:0_20:4) | 1 | 1 | 1 | 1 | 1 | 10.749031 | 0.14624 |
| TG(18:1_18:2_18:2) | 1 | 1 | 1 | 1 | 1 | 12.771215 | 0.3874 |
| TG(18:1_18:2_18:3) | 1 | 1 | 1 | 1 | 1 | 16.86847 | 0.54332 |
| TG(16:0_16:0_22:6) | 1 | 1 | 1 | 1 | 1 | 4.1250885 | 0.42921 |
| TG(16:1_18:2_20:5) | 1 | 1 | 1 | 1 | 1 | 20.420275 | 0.32609 |
| TG(18:4_18:2_18:3) | 1 | 1 | 1 | 1 | 1 | 3.867137 | 0.13932 |
| TG(19:1_18:1_18:1) | 1 | 1 | 1 | 1 | 1 | 3.33269 | 1.9469 |
| TG(19:1_18:1_18:2) | 1 | 1 | 1 | 1 | 1 | 4.5701675 | 1.6501 |
| TG(16:0_18:1_22:0) | 1 | 1 | 1 | 1 | 1 | 5.493698 | 1.7423 |
| TG(20:0_18:1_18:2) | 1 | 1 | 1 | 1 | 1 | 22.4786 | 1.9464 |
| TG(20:1_18:1_18:2) | 1 | 1 | 1 | 1 | 1 | 23.349765 | 1.3199 |
| TG(18:0_18:1_20:3) | 1 | 1 | 1 | 1 | 1 | 14.191465 | 1.2062 |
| TG(18:0_18:0_20:4) | 1 | 1 | 1 | 1 | 1 | 4.407997 | 0.71505 |
| TG(18:1_18:2_20:3) | 1 | 1 | 1 | 1 | 1 | 95.26307 | 0.36496 |
| TG(18:3_18:2_20:4) | 1 | 1 | 1 | 1 | 1 | 12.279625 | 0.72476 |
| TG(20:5_18:2_20:4) | 1 | 1 | 1 | 1 | 1 | 5.315382 | 0.39294 |
| TG(18:1_18:1_22:0) | 1 | 1 | 1 | 1 | 1 | 6.1465205 | 1.1536 |
| TG(18:1_18:2_22:0) | 0.944 | 0.79 | 1 | 1 | 0.833 | 5.334492 | 0.75487 |
| TG(18:1_18:2_22:5) | 1 | 1 | 1 | 1 | 1 | 3.8133195 | 0.63831 |
| Cer(d18:1_24:0) | 0.917 | 0.692 | 1 | 1 | 0.833 | 14.90517 | 0.88894 |
| MGDG(36:1e) | 0.833 | 0.5 | 1 | 1 | 0.833 | 10.63481 | 1.1492 |
| MGDG(38:2e) | 1 | 1 | 1 | 1 | 1 | 11.570184 | 0.8028 |
| MGMG(30:0) | 1 | 1 | 1 | 1 | 1 | 42.2344 | 0.78713 |
| MGMG(36:1) | 0.833 | 0.667 | 1 | 1 | 0.833 | 10.631431 | 1.6925 |
| MGMG(38:1) | 1 | 1 | 1 | 1 | 1 | 16.90753 | 1.7067 |
| MGMG(38:2) | 1 | 1 | 1 | 1 | 1 | 11.564069 | 1.6925 |
| PC(16:0_18:2) | 1 | 1 | 1 | 1 | 1 | 138.5929 | 0.75053 |
| SM(d40:2) | 0.833 | 0.5 | 1 | 1 | 0.833 | 10.63481 | 0.8949 |
注：Name，脂质名称；AUC，ROC曲线下的面积；Ci1，95% CI下限；Ci2，95% CI上限；specificity，特异性值；sensitivity，敏感性值；threshold，鉴别阈值