Propensity score adjusted and matched outcomes
A total of 524520 medical records were screened, including 20165 patients with planned extubation. Finally, 801 patients with moderate and severe hypoxemia when mechanical ventilation weaning was included (100 < PaO2/FiO2 ≤ 300 mmHg), and 358 patients received HFNC therapy after extubation in the treatment group. There were 233 patients remained in the treatment group with median oxygenation index 209[164,253] mmHg after PSM. There were no significant differences in age, sex, BMI, SPAS-II score, comorbidities, duration of mechanical ventilation or physiological parameters before weaning between the 2 groups (all P > 0.05).
There were no significant differences in the 28-day reintubation rate (4.29% vs. 5.15%, P = 0.827) or 28-day mortality (4.29% vs. 5.15%, P = 0.827) between the two groups. The 48-hour reintubation rate in the treatment group was lower than that in the control group (8.58% vs. 15.88%, P = 0.024).
There were 315 patients with severe hypoxemia (100 < PaO2/FiO2 ≤ 200 mmHg) before extubation, and 190 patients remained in the treatment group with median oxygenation index 166[157,180] mmHg after PSM. There were no significant differences in the 48-hour reintubation rate, 28-day reintubation rate or 28-day mortality between the 2 groups (all P > 0.05).
There were 486 patients with moderate hypoxemia (200 < PaO2/FiO2 ≤ 300 mmHg) before extubation, and 304 patients remained in the treatment group with median oxygenation index 238[214,267] mmHg after PSM. There were no significant differences in the 48-hour reintubation rate, 28-day reintubation rate or 28-day mortality between the 2 groups (all P > 0.05).
Both the length of stay in the ICU and in the hospital in the treatment group were longer than those in the control group (6.36 vs. 4.72 days, P < 0.001 and 12.62 vs. 10.93 days, P = 0.001). The duration before reintubation in the treatment group was longer than that in the control group (73.28 vs. 21.52 hours, P = 0.001). (Table 1 and Fig. 1)
The 28-day mortality of patients with reintubation 48 hours after extubation was not higher than that within 48 hours in either the treatment group or the control group (23.08% vs. 10.00%, P = 0.206 and 19.23% vs. 12.73%, P = 0.509). (Table 2)
Features and predictors of HFNC failure
The important features predicting weaning failure were PaO2, duration before extubation, heart rate, BMI, age, mean blood pressure, pH, SAPS-II, SpO2, tidal volume and respiratory rate (Fig. 2). Thus HR/PaO2 and HR/SpO2 were calculated manually based on the above important features. There was a significant difference of HR/SpO2 at 4 hours after extubation between patients weaning failed and successfully (1.00 vs. 0.92, P < 0.05), and no significant difference of ROX index at the same time (7.38 vs. 7.29, P>0.05). HR/SpO2 increased more than 10% compared to baseline data in patients with failed HFNC treatment at 24 hours after extubation (1.06 vs.0.93, P < 0.05) while there was no significant change in the ROX index at the same time (6.54 vs. 8.61, P>0.05). (Table 3 and Fig. 3–4)
According to values at 4 hours before extubation, the AUCs of HR/PaO2 and HR/SpO2 were 0.640 and 0.618 for predicting 48-hour reintubation, respectively, which were larger than that of RSBI (AUC = 0.541) and ROX index (AUC = 0.551). According to values at 4 hours after extubation, the AUC of HR/SpO2 were 0.657 for predicting 48-hour reintubation, which were larger than that of ROX index (AUC = 0.583). The specificity reached 93% when the cut-off point of HR/SpO2 was 1.20 at 4 hours after extubation. (Table 4 and Fig. 5)
Table 1
The baseline data and prognosis of patients with hypoxemia of different severities in the two groups after PSM
| 1002/FiO2 ≤ 300 n = 801 | 1002/FiO2 ≤ 200 n = 315 | 2002/FiO2 ≤ 300 n = 486 |
| After PSM n = 466 | Treatment group n = 233 | Control group n = 233 | P value | After PSM n = 190 | Treatment group n = 95 | Control group n = 95 | P value | After PSM l n = 304 | Treatment group n = 152 | Control group n = 152 | P |
Age, median [Q1, Q3] | 69.38[61.00, 77.59] | 68.74[59.90, 77.81] | 69.80[61.48, 76.32] | 0.850 | 70.06[60.32, 78.09] | 69.91[60.55, 77.58] | 70.80[59.47, 78.50] | 0.638 | 68.09[59.57, 75.49] | 66.79[58.59, 75.85] | 68.71[60.21, 75.22] | 0.391 |
Male, n (%) | 322(69.10) | 158(67.81) | 164(70.39) | 0.616 | 126(66.32) | 62(65.26) | 64(67.37) | 0.878 | 195(64.14) | 92(60.53) | 103(67.76) | 0.232 |
BMI, mean (SD) | 31.93(6.56) | 32.04(6.60) | 31.81(6.53) | 0.708 | 33.85(6.47) | 33.38(6.34) | 34.34(6.61) | 0.322 | 31.51(7.33) | 31.09(6.93) | 31.94(7.72) | 0.330 |
Baseline disease |
Hypertension, n (%) | 316(67.81) | 157(67.38) | 159(68.24) | 0.921 | 123(64.74) | 59(62.11) | 64(67.37) | 0.544 | 188(61.84) | 92(60.53) | 96(63.16) | 0.723 |
Diabetes mellitus, n (%) | 88(18.88) | 47(20.17) | 41(17.60) | 0.554 | 30(15.79) | 15(15.79) | 15(15.79) | 1.000 | 57(18.75) | 32(21.05) | 25(16.45) | 0.378 |
COPD, n (%) | 52(11.16) | 29(12.45) | 23(9.87) | 0.462 | 17(8.95) | 12(12.63) | 5(5.26) | 0.127 | 35(11.51) | 18(11.84) | 17(11.18) | 1.000 |
Congestive heart failure, n (%) | 133(28.54) | 62(26.61) | 71(30.47) | 0.412 | 51(26.84) | 20(21.05) | 31(32.63) | 0.102 | 79(25.99) | 39(25.66) | 40(26.32) | 1.000 |
Myocardial infarction, n (%) | 54(11.59) | 28(12.02) | 26(11.16) | 0.885 | 25(13.16) | 11(11.58) | 14(14.74) | 0.668 | 36(11.84) | 19(12.50) | 17(11.18) | 0.859 |
Chronic kidney disease, n (%) | 96(20.60) | 51(21.89) | 45(19.31) | 0.567 | 35(18.42) | 15(15.79) | 20(21.05) | 0.454 | 60(19.74) | 33(21.71) | 27(17.76) | 0.471 |
Leukaemia, n (%) | 3(0.64) | 1(0.43) | 2(0.86) | 1.000 | 6(3.16) | 2(2.11) | 4(4.21) | 0.682 | 3(0.99) | 1(0.66) | 2(1.32) | 1.000 |
Strokes, n (%) | 20(4.29) | 11(4.72) | 9(3.86) | 0.819 | 5(2.63) | 2(2.11) | 3(3.16) | 1.000 | 20(6.58) | 13(8.55) | 7(4.61) | 0.247 |
Cancer, n (%) | 48(10.30) | 25(10.73) | 23(9.87) | 0.879 | 25(13.16) | 16(16.84) | 9(9.47) | 0.198 | 33(10.86) | 15(9.87) | 18(11.84) | 0.712 |
Liver disease, n (%) | 32(6.87) | 14(6.01) | 18(7.73) | 0.583 | 12(6.32) | 9(9.47) | 3(3.16) | 0.136 | 32(10.53) | 20(13.16) | 12(7.89) | 0.191 |
SAPS-II at admission, mean (SD) | 42.99(12.44) | 43.00(12.96) | 42.97(11.92) | 0.979 | 43.17(13.09) | 43.42(13.60) | 42.93(12.62) | 0.795 | 42.61(12.97) | 43.12(13.54) | 42.09(12.39) | 0.491 |
Duration before extubation, median [Q1,Q3], hours | 20.77[6.89, 65.71] | 22.00[7.32, 73.27] | 19.50[6.12, 48.85] | 0.136 | 21.73[6.68, 57.68] | 24.00[6.73, 68.37] | 20.47[6.76, 47.30] | 0.304 | 19.78[6.91, 81.10] | 21.99[7.24, 108.54] | 18.08[6.35, 46.92] | 0.133 |
Physiological variables before extubation 4 hours |
Heart rate, mean (SD) | 83.15(13.84) | 83.74(13.97) | 82.55(13.72) | 0.354 | 82.93(13.39) | 82.72(12.30) | 83.14(14.47) | 0.832 | 83.94(13.47) | 84.72(14.41) | 83.17(12.47) | 0.316 |
Respiratory rate, mean (SD) | 18.99(3.95) | 19.07(3.90) | 18.91(4.00) | 0.669 | 19.37(3.97) | 19.40(4.06) | 19.35(3.90) | 0.938 | 18.81(3.97) | 18.90(4.09) | 18.73(3.86) | 0.701 |
Tidal volume, mean (SD) | 487.80(125.50) | 493.81(127.26) | 481.81(123.75) | 0.337 | 504.61(134.40) | 521.13(139.12) | 487.07(127.73) | 0.101 | 487.71(122.32) | 487.63(124.30) | 487.79(120.82) | 0.991 |
MBP, mean (SD) | 77.51(11.00) | 77.80(11.62) | 77.22(10.35) | 0.570 | 77.91(10.51) | 78.35(10.40) | 77.46(10.65) | 0.562 | 78.46(12.22) | 78.83(13.21) | 78.08(11.16) | 0.591 |
pH, mean (SD) | 7.40(0.05) | 7.40(0.05) | 7.39(0.05) | 0.366 | 7.40(0.06) | 7.40(0.06) | 7.40(0.05) | 0.358 | 7.39(0.05) | 7.39(0.05) | 7.39(0.05) | 0.812 |
PaO2, median [Q1, Q3] | 100.00[84.00, 115.00] | 97.75[83.00, 114.00] | 101.50[86.00, 118.00] | 0.208 | 84.42[76.25, 95.00] | 84.50[78.75, 95.00] | 84.33[76.00, 95.25] | 0.924 | 109.00[98.88, 125.63] | 107.00[95.38, 122.56] | 110[100.50, 130.63] | 0.340 |
PaCO2, mean (SD) | 41.01(6.96) | 40.75(6.57) | 41.26(7.34) | 0.433 | 40.70[6.56] | 40.61[6.12] | 40.79[7.01] | 0.852 | 41.08(6.65) | 40.78(6.98) | 41.37(6.32) | 0.441 |
SpO2, median [Q1, Q3] | 97.50[95.83, 98.75] | 97.25[95.80, 98.75] | 97.50[96.00, 99.00] | 0.397 | 96.06[94.68, 97.79] | 95.75[94.50, 97.52] | 96.50[94.90, 98.20] | 0.152 | 98.00[96.67, 99.25] | 97.75[96.75, 99.16] | 98.25[96.50, 99.25] | 0.412 |
PaO2/FiO2, median [Q1,Q3] | 211.79[171.42, 253.23] | 209.00[164.00, 253.62] | 213.00[179.33, 253.06] | 0.253 | 169.46[155.08, 182.83] | 166.67[157.44, 180.60] | 171.33[153.44, 187.56] | 0.283 | 242.00[217.50, 270.23] | 238.46[214.00, 267.34] | 248.04[222.00, 273.98] | 0.209 |
Reintubation 48 hours, n (%) | 57(12.23) | 20(8.58) | 37(15.88) | 0.024 | 24(12.63) | 8(8.42) | 16(16.84) | 0.126 | 37(12.17) | 15(9.87) | 22(14.47) | 0.293 |
Reintubation 28 days, n (%) | 97(20.82) | 46(19.74) | 51(21.89) | 0.648 | 39(20.53) | 16(16.84) | 23(24.21) | 0.281 | 67(22.04) | 38(25.00) | 29(19.08) | 0.268 |
Mortality 28 days, n (%) | 22(4.72) | 10(4.29) | 12(5.15) | 0.827 | 7(3.68) | 3(3.16) | 4(4.21) | 1.000 | 21(6.91) | 12(7.89) | 9(5.92) | 0.651 |
Duration before reintubation, median [Q1, Q3], hours | 28.65[11.57, 90.78] | 73.28[21.63, 124.15] | 21.52[8.84, 56.85] | 0.001 | 25.03[9.04, 113.43] | 52.22[5.96, 163.10] | 21.72[10.88, 66.22] | 0.424 | 38.55[12.12, 111.62] | 73.66[27.39, 133.14] | 19.70[4.62, 40.63] | 0.001 |
LOS in hospital, median [Q1, Q3] | 11.54[7.18, 17.75] | 12.62[7.65, 20.61] | 10.93[6.83, 15.82] | 0.001 | 11.87[7.65, 16.61] | 12.80[7.79, 19.23] | 11.28[7.48, 15.43] | 0.102 | 12.01[7.02, 19.90] | 14.59[8.68, 25.02] | 10.12[6.22, 16.72] | < 0.001 |
LOS in ICU, median [Q1, Q3] | 5.55[3.09, 11.14] | 6.36[3.85, 13.59] | 4.72[2.27, 9.70] | < 0.001 | 5.39[3.10, 10.93] | 6.22[3.82, 12.69] | 4.80[2.30, 9.39] | 0.026 | 6.19[3.12, 13.14] | 7.43[4.19, 15.89] | 4.25[2.23, 9.47] | < 0.001 |
Table 2
The baseline data and prognosis of patients who received reintubation within 48 hours of and 48 hours after extubation in the two groups
| Treatment group n = 358 | Control group n = 443 |
| All reintubations n = 79 | Within 48 h n = 40 | 48 h after n = 39 | P value | All reintubations n = 81 | Within 48 h n = 55 | 48 h after n = 26 | P value |
Age, median[Q1, Q3] | 67.68[57.02, 78.00] | 64.47[49.57, 77.97] | 68.83[62.52, 77.59] | 0.202 | 71.82[62.27, 78.93] | 71.52[60.69, 78.69] | 73.40[64.81, 78.74] | 0.485 |
Male, n (%) | 59(74.68) | 31(77.50) | 28(71.79) | 0.746 | 48(59.26) | 29(52.73) | 19(73.08) | 0.134 |
BMI, mean (SD) | 29.65(5.87) | 28.99(5.72) | 30.38(6.02) | 0.314 | 32.60(9.00) | 31.12(8.34) | 35.67(9.71) | 0.051 |
Baseline disease |
Hypertension, n (%) | 41(51.90) | 18(45.00) | 23(58.97) | 0.309 | 54(66.67) | 33(60.00) | 21(80.77) | 0.110 |
Diabetes mellitus, n (%) | 12(15.19) | 7(17.50) | 5(12.82) | 0.790 | 13(16.05) | 7(12.73) | 6(23.08) | 0.331 |
COPD, n (%) | 5(6.33) | 3(7.50) | 2(5.13) | 1.000 | 9(11.11) | 5(9.09) | 4(15.38) | 0.458 |
Congestive heart failure, n (%) | 23(29.11) | 10(25.00) | 13(33.33) | 0.570 | 29(35.80) | 17(30.91) | 12(46.15) | 0.277 |
Myocardial infarction, n (%) | 6(7.59) | 4(10.00) | 2(5.13) | 0.675 | 14(17.28) | 9(16.36) | 5(19.23) | 0.760 |
Chronic kidney disease, n (%) | 17(21.52) | 5(12.50) | 12(30.77) | 0.089 | 21(25.93) | 10(18.18) | 11(42.31) | 0.041 |
Leukaemia, n (%) | 1(1.27) | 0 | 1(2.56) | 0.494 | 2(2.47) | 1(1.82) | 1(3.85) | 0.542 |
Strokes, n (%) | 8(10.13) | 1(2.50) | 7(17.95) | 0.029 | 6(7.41) | 4(7.27) | 2(7.69) | 1.000 |
Cancer, n (%) | 10(12.66) | 6(15.00) | 4(10.26) | 0.737 | 16(19.75) | 9(16.36) | 7(26.92) | 0.415 |
Liver disease, n (%) | 12(15.19) | 7(17.50) | 5(12.82) | 0.790 | 14(17.28) | 8(14.55) | 6(23.08) | 0.360 |
SAPS-II at admission, mean (SD) | 44.32(13.08) | 43.30(10.86) | 45.36(15.09) | 0.490 | 47.20(13.72) | 46.73(13.48) | 48.19(14.45) | 0.665 |
Duration before extubation, median [Q1,Q3], hours | 61.50[20.33, 125.27] | 53.92[15.14, 110.82] | 67.35[22.86, 138.07] | 0.364 | 38.90[20.25, 131.67] | 40.83[23.53, 128.29] | 28.46[17.63, 127.40] | 0.413 |
Physiological variables before extubation 4 hours |
Heart rate, mean (SD) | 87.28(15.55) | 89.67(16.07) | 84.84(14.80) | 0.168 | 86.00(16.39) | 87.03(14.03) | 83.81(20.67) | 0.476 |
Respiratory rate, mean (SD) | 19.10(4.67) | 19.41(4.09) | 18.78(5.23) | 0.556 | 19.73(4.17) | 19.70(4.42) | 19.79(3.64) | 0.920 |
Tidal volume, mean (SD) | 534.45(132.46) | 527.92(146.70) | 539.43(122.28) | 0.734 | 454.31(111.36) | 448.81(112.36) | 466.35(110.87) | 0.553 |
MBP, mean (SD) | 79.62(12.93) | 81.10(13.91) | 78.10(11.82) | 0.304 | 77.45(10.11) | 77.61(10.55) | 77.13(9.31) | 0.836 |
pH, mean (SD) | 7.41(0.07) | 7.39(0.07) | 7.42(0.06) | 0.068 | 7.39(0.05) | 7.39(0.06) | 7.38(0.05) | 0.831 |
PaO2, median [Q1, Q3] | 91.00[82.00, 107.00] | 89.25[83.50, 104.62] | 95.50[81.17, 110.50] | 0.444 | 96.00[87.00, 108.00] | 95.00[85.75, 106.25] | 98.25[89.54, 115.00] | 0.347 |
PaCO2, mean (SD) | 39.76(6.76) | 39.52(6.60) | 40.01(6.99) | 0.751 | 44.79(10.47) | 45.58(11.74) | 43.10(7.01) | 0.240 |
SpO2, median [Q1, Q3] | 97.00[95.54, 98.69] | 96.50[95.00, 98.29] | 97.25[96.38, 98.88] | 0.088 | 97.25[95.50, 98.60] | 97.80[95.75, 98.78] | 96.50[95.56, 97.93] | 0.172 |
PaO2/FiO2, median [Q1,Q3] | 209.00[175.50, 248.62] | 208.00[170.00, 229.86] | 217.50[189.75, 254.30] | 0.233 | 220.00[187.50, 252.52] | 213.00[186.50, 254.32] | 221.88[192.12, 249.65] | 0.712 |
Mortality 28 days, n (%) | 13(16.46) | 4(10.00) | 9(23.08) | 0.206 | 12(14.81) | 7(12.73) | 5(19.23) | 0.509 |
Table 3
Changes in physiological parameters in patients with successful or failed weaning in the HFNC treatment group
| Failed n = 40 | Successful n = 318 |
| 4 hours before extubation | 4 hours after extubation | 8–12 hours later | 20–24 hours later | 36–40 hours | 4 hours before reintubation | 4 hours before extubation | 4 hours after extubation | 8–12 hours later | 20–24 hours later | 36–40 hours |
Heart rate, mean (SD) | †89.67(16.07) | †94.62 (17.57) | †94.26 (18.59) | *†99.78 (14.64) | *†115.05 (9.92) | *99.18 (18.88) | 83.01(13.42) | *87.65 (14.48) | *87.93 (14.79) | *85.33 (14.28) | 85.01 (14.56) |
Respiratory rate, mean (SD) | 19.41(4.09) | *†22.83 (4.29) | *22.64 (5.31) | *†24.40 (5.69) | 26.88 (8.09) | *24.47 (4.81) | 19.31(4.29) | *21.21 (4.75) | *21.29 (4.80) | *21.00 (4.58) | *21.02 (4.91) |
Tidal volume, mean (SD) | 527.92(146.70) | - | - | - | - | - | 504.81(126.12) | - | 515.93 (132.49) | - | - |
MBP, mean (SD) | 81.10(13.91) | 80.82 (15.61) | 83.41 (14.24) | 81.46 (14.29) | 81.91 (12.14) | *83.97 (14.58) | 78.34(11.79) | 79.95 (12.62) | 79.32 (14.04) | 79.18 (12.32) | 78.93 (11.57) |
pH, mean (SD) | 7.39(0.07) | 7.37 (0.12) | 7.40 (0.08) | 7.36 (0.10) | 7.42 (0.08) | 7.38 (0.10) | 7.40(0.06) | 7.41 (0.07) | 7.42 (0.06) | *7.43 (0.06) | *7.45 (0.06) |
PaO2, median [Q1, Q3] | 89.25[83.50, 104.62] | 91.50 [74.38,119.00] | *75.50 [64.50,95.00] | *81.00 [72.50,82.75] | 75.50 [68.75,82.25] | *76.75 [66.75,98.50] | 92.50[80.00, 110.00] | *83.00 [71.00,99.00] | *81.00 [71.00,97.00] | *78.00 [69.50,87.00] | *79.00 [68.75,104.50] |
PaCO2, mean (SD) | 39.52(6.60) | 41.78 (7.62) | 39.61 (6.56) | 39.00 (9.94) | 47.50 (4.95) | 40.09 (9.12) | 40.00(6.83) | 39.65 (7.36) | *37.82 (6.83) | *37.72 (8.68) | 37.76 (8.35) |
SpO2, median [Q1, Q3] | 96.50[95.00, 98.29] | *95.12 [93.94,95.88] | *95.38 [93.44,96.43] | *94.25 [93.66,95.62] | 95.00 [94.50,96.25] | *93.27 [91.69,95.29] | 97.00[95.00, 98.50] | *95.00 [93.75,96.59] | *95.00 [93.50,96.50] | *95.00 [93.75,96.50] | *95.25 [93.55,96.94] |
PaO2/FiO2, median [Q1,Q3] | 208.00[170.00, 229.88] | *151.61 [133.75,171.50] | *129.00 [100.83,130.00] | *95.30 [85.99,111.55] | *†75.50 [68.75,82.25] | *98.84 [79.38,147.03] | 201.29[163.20, 238.35] | *137.75 [102.12,175.50] | *126.08 [100.08,171.39] | *126.00 [90.31,171.00] | *133.53 [110.00,171.08] |
ROX Index | †8.61 [7.57,9.45] | 7.38 [5.27,9.49] | 6.95 [5.25,8.75] | 6.54 [4.82,9.33] | 5.32 [3.93, 8.12] | *3.54 (0.43) | 11.63 [9.22,13.51] | *7.29 [6.33,8.62] | *7.97 [7.08,9.01] | 7.51 [6.97,8.06] | 12.24 [9.55,14.94] |
RSBI | 40.35[30.71, 54.80] | - | - | - | - | *49.88 [40.31,55.09] | 39.22[29.87, 50.51] | - | - | - | - |
HR/PaO2 | †0.97(0.22) | 1.05 (0.37) | 1.17 (0.34) | *1.25 (0.27) | 1.64 (0.49) | *1.25 (0.45) | 0.89(0.27) | *1.07 (0.33) | *1.05 (0.32) | *1.13 (0.58) | *1.09 (0.35) |
HR/SpO2 | †0.93(0.16) | †1.00 (0.19) | 0.99 (0.19) | *†1.06 (0.16) | *†1.22 (0.10) | *1.06 (0.20) | 0.86(0.14) | *0.92 (0.15) | *0.93 (0.16) | *0.90 (0.15) | *0.89 (0.15) |
† P < 0.05 vs value of patients with successful weaning, * P < 0.05 vs value at baseline |
Table 4
Predicting power of HFNC failure by HR/PaO2, HR/SpO2, RSBI and the ROX index at 4 hours before and after extubation
| AUC(95% CI) | P | Cutoff value | Youden Index | Sensitivity | Specificity | PPV | NPV |
4 hours before extubation |
HR/PaO2 | 0.640 [0.584, 0.694] | P < 0.01 | 0.829 | 0.263 | 0.733 | 0.530 | 0.159 | 0.943 |
HR/SpO2 | 0.618 [0.551, 0.683] | P < 0.01 | 0.830 | 0.215 | 0.733 | 0.481 | 0.146 | 0.937 |
RSBI | 0.541 [0.467, 0.607] | P < 0.01 | 48.4 | 0.120 | 0.413 | 0.707 | 0.146 | 0.909 |
ROX index | 0.551 [0.488, 0.610] | P < 0.01 | 0.107 | 0.168 | 0.640 | 0.528 | 0.141 | 0.924 |
4 hours after extubation |
HR/SpO2 | 0.657 [0.571, 0.724] | P < 0.01 | 1.203 | 0.330 | 0.400 | 0.930 | 0.462 | 0.911 |
ROX index | 0.583 [0.519, 0.629] | P < 0.01 | 6.376 | 0.020 | 0.800 | 0.220 | 0.133 | 0.880 |