AUC (area under the curve) calculation

MRM95 · Posted 10-20-2023 09:52 AM

Hello SAS users

I'm having trouble estimating AUC on my data.

I have the following data (dummy example below):

data original_data2;
input ID rho Time Sp02;
datalines;
1 1 0 17
1 1 0 0
1 1 0.026 39.5
1 1 0.031 30.4
1 1 0.04 29.2
1 1 0.051 17.8
1 1 0.092 30.3
1 1 0.176 71.5
1 1 0.342 251
1 1 0.508 291
1 1 1.015 360
1 1 2.015 359
1 1 3.014 617
1 1 4.01 502
1 1 5.014 693
1 1 6.016 672
1 1 7.019 529
1 1 8.02 492
1 1 9.017 590
1 1 10.013 490
1 1 11.014 548
1 1 12.013 443
1 1 13.013 449
1 2 14.013 422
1 2 30.012 295
1 2 58.019 268
1 2 120.943 214
1 2 211.019 185
1 2 242.995 125
1 2 272.994 137
1 2 305.993 156
1 2 334.998 135
1 2 366.027 160
1 2 393.053 127
1 2 424.996 131
1 2 456.99 139
1 2 484.996 120
1 2 515.981 115
1 2 544.015 114
1 2 578.994 133
1 2 608.986 120
1 2 638.001 116
1 2 658.993 122
1 2 695.088 136
1 2 726.001 132
1 2 726.03 237
1 2 726.051 183
1 2 726.092 151
1 2 726.176 155
1 2 726.342 181
1 2 727.015 118
1 2 728.014 72.8
1 2 729.012 54.6
1 2 730.021 48.1
2 1 0 15
2 1 0 0
2 1 0.021 27.1
2 1 0.033 74.9
2 1 0.052 142
2 1 0.094 191
2 1 0.18 197
2 1 0.346 242
2 1 0.51 350
2 1 1.015 442
2 1 2.015 555
2 1 3.01 593
2 1 4.013 540
2 1 5.016 425
2 1 6.016 460
2 1 7.02 610
2 1 9 514
2 1 10.001 466
2 1 11.007 503
2 1 12.014 415
2 1 13.024 458
2 1 14.017 448
2 1 28.035 44.7
2 1 56.02 366
2 1 88.033 278
2 2 120.026 247
2 2 215.973 228
2 2 246.013 186
2 2 276.978 251
2 2 306.206 210
2 2 334.98 190
2 2 365.073 183
2 2 393.094 179
2 2 425.052 217
2 2 456.056 180
2 2 484.043 290
2 2 522.051 317
2 2 550.059 201
2 2 582.078 339
2 2 600.007 203
2 2 600.045 256
2 2 600.068 266
2 2 600.108 183
2 2 600.191 186
2 2 600.358 146
2 2 601.181 81.2
2 2 602.106 65
2 2 603.073 31.5
2 2 604.075 23.2
;
run;

With this data, how can I estimate the AUC (per ID) of when the variable Sp02 goes below 90.

Does anyone know how to do this? I've found some very helpful guidance from @PGStats on this topic in other posts (https://communities.sas.com/t5/Statistical-Procedures/Area-under-the-curve-calculation/td-p/273882), but still can't figure out this issue specifically.

Any help will be greatly appreciated, thank you!