| COPD non-depressed (CN) (n = 51) | COPD depressed (CD) (n = 27) | Estimated difference | ANCOVA p value |
---|---|---|---|---|
Plasma concentrations (μmol/L) | ||||
 Tryptophan | 35.76 [33.64, 37.89] | 35.24 [31.77, 38.71] | − 0.26 [− 2.79, 2.27] | 0.783 |
 Tryptophan corrected for large neutral amino acids |  |  | 1.07 [− 3.39, 5.53] | 0.656 |
 Tyrosine | 54.23 [50.65, 57.80] | 47.11 [43.14, 51.08] | − 8.13 [− 13.63, − 2.63] | 0.005 |
 Tyrosine corrected for large neutral amino acids |  |  | − 5.58 [− 10.99, − 0.17] | 0.048 |
 Phenylalanine | 48.54 [45.71, 51.38] | 43.40 [40.55, 47.57] | − 5.75 [− 9.86, − 1.64] | 0.008 |
 Leucine | 110.50 [98.87, 122.10] | 95.95 [79.09, 106.70] | − 18.77 [− 34.54, − 2.99] | 0.031 |
 Isoleucine | 65.79 [58.34, 73.23] | 53.83 [41.92, 63.58] | − 15.11 [− 24.20, − 6.02] | 0.003 |
 Valine | 177.60 [162.70, 192.40] | 163.30 [137.20, 177.70] | − 20.67 [− 42.12, 0.80] | 0.090 |
 Sum branched chain amino acids | 332.40 [306.40, 358.40] | 294.70 [243.10, 327.90] | − 49.57 [− 86.83, − 12.32] | 0.016 |
 Sum large neutral amino acids | 435.20 [406.50, 463.90] | 385.20 [322.20, 430.30] | − 63.42 [− 104.03, − 22.79] | 0.005 |
Whole body production rates (μmol/h) | ||||
 Phenylalanine | 3507.33 [3250.40, 3764.27] | 4022.20 [3522.65, 4521.75] | 271.60 [− 286.95, 830.06] | 0.214 |
 Tyrosine | 3188.99 [2894.67, 3483.31] | 3618.15 [3059.27, 4177.04] | 107.01 [− 514.88, 728.98] | 0.581 |
 Tryptophan | 1175.83 [1026.55, 1325.11] | 1326.93 [1088.30, 1565.57] | 114.50 [− 145.50, 374.50] | 0.382 |
 Isoleucine | 3673.94 [3094.86, 4253.01] | 3989.06 [3155.51, 4822.61] | 362.20 [− 623.90, 1348.00] | 0.465 |
 Valine | 11,119.21 [9712.82, 12,525.61] | 11,880.31 [9962.54, 11,602.38] | 276.61 [− 1423.95, 1976.60] | 0.570 |
 Leucine | 9782.64 [8789.57, 10,775.71] | 10,352.46 [9102.55, 12,188.00] | − 3.91 [− 1384.21, 1376.47] | 0.811 |
 Phenylalanine to tyrosine (net protein breakdown) | 216.80 [179.40, 235.00] | 267.50 [200.50, 287.20] | 34.51 [− 7.93, 76.96] | 0.104 |
 Branched chain amino acids | 24,783.00 [21684.00, 27,881.00] | 26,808.00 [20235.00, 31,134.00] | 1354.79 [− 2141.15, 4851.15] | 0.315 |
Clearance rates (L h−1) | ||||
 Leucine | 1.98 [1.79, 2.18] | 2.24 [1.78, 2.64] | 0.34 [0.08, 0.60] | 0.013 |
 Valine | 1.35 [1.24, 1.47] | 1.47 [1.18, 1.76] | 0.18 [0.004, 0.36] | 0.071 |
 Isoleucine | 1.30 [1.09, 1.50] | 1.51 [1.00, 1.74] | 0.33 [− 0.08, 0.74] | 0.133 |
 Phenylalanine | 1.55 [1.46, 1.64] | 1.88 [1.51, 2.18] | 0.30 [0.11, 0.49] | 0.003 |
 Tryptophan | 0.72 [0.65, 0.80] | 0.77 [0.62, 0.95] | 0.06 [− 0.08, 0.21] | 0.371 |