Table 1 Demographics, clinical characteristics, and comorbidities of the non-depressed and depressed COPD groups
|  | COPD non-depressed (CN) (n = 51) | COPD depressed (CD) (n = 27) | Estimated difference | Unpaired t-test p value |
|---|---|---|---|---|
Demographics | ||||
 Age (years) | 64.72 [63.16, 66.28] | 64.04 [57.90, 69.64] | − 0.68 [− 3.60, 2.24] | 0.643 |
 Sex (male/female) | 26/25 | 13/14 |  | > 0.999 |
 Level of education (score) | 2.19 [1.56, 2.81] | 2.00 [1.39, 2.62] | − 0.19 [− 1.15, 0.78] | 0.698 |
General characteristics | ||||
 Body weight (kg) | 79.03 [73.15, 85.38] | 83.96 [74.03, 95.23] | 5.76 [− 4.93, 16.45] | 0.384 |
 Height (m) | 1.67 [1.64, 1.70] | 1.66 [1.63, 1.69] | − 0.01 [− 0.05, 0.03] | 0.667 |
 Body Mass Index (kg/m2) | 29.08 [27.30, 30.85] | 31.65 [28.40, 34.90] | 2.574 [− 0.75, 5.90] | 0.128 |
COPD parameters | ||||
 FEV1 (% of predicted) | 43.86 [38.94, 48.79] | 44.59 [37.13, 52.06] | − 1.66 [− 9.01, 5.69] | 0.911 |
 GOLD stage (I/II/III/IV) | 5/15/17/14 | 2/7/11/7 |  | 0.765 |
 Years of COPD related symptom (yr) | 11.81 [8.74, 14.88] | 10.21 [7.18, 13.24] | − 1.51 [− 51.87, 48.86] | 0.644 |
 No. of hospitalizations past year for exacerbation | 0.24 [0.07, 0.42] | 0.42 [0.12, 0.73] | 0.26 [− 0.06, 0.57] | 0.267 |
 No. of exacerbations in the past year | 0.57 [0.25, 0.89] | 1.00 [0.29, 1.71] | 0.56 [− 0.12, 1.24] | 0.203 |
 O2 use (no/yes) | 30/21 | 11/16 |  | 0.157 |
 mMRC dyspnea grade | 2.20 [1.92, 2.49] | 2.48 [2.14, 2.82] | 0.32 [− 0.15, 0.79] | 0.238 |
 CAT score | 16.71 [13.48, 19.94] | 25.27 [21.16, 29.38] | 9.04 [3.47, 14.61] | 0.003 |
 Current smoker (yes/no) | 29/21 | 18/8 |  | 0.456 |
 Years smoking | 34.57 [30.00, 40.00] | 34.50 [30.00, 40.00] | 1.57 [− 3.76, 6.91] | 0.619 |
 Smoke pack years | 46.31 [32.00, 45.00] | 48.96 [25.00, 66.00] | 1.74 [− 13.19, 16.65] | 0.716 |
Vitals | ||||
 Heart rate (bpm) | 70.90 [66.00, 73.00] | 75.48 [67.00, 83.00] | 5.02 [− 0.44, 10.47] | 0.090 |
 Systolic BP (mmHg) | 137.20 [127.00, 141.00] | 130.20 [117.00, 142.00] | − 8.81 [− 16.79, − 0.84] | 0.085 |
 Diastolic BP (mmHg) | 78.41 [76.00, 82.00] | 77.33 [71.00, 83.00] | − 1.78 [− 5.83, 2.28] | 0.594 |
 Temperature (°C) | 36.52 [36.40, 36.67] | 36.57 [36.17, 36.94] | 0.07 [− 0.13, 0.26] | 0.589 |
 O2 saturation (%) | 95.31 [94.00, 97.00] | 94.81 [94.00, 97.00] | − 0.46 [− 2.014, 1.10] | 0.155 |
Comorbidities | ||||
 Charlson comorbidity index (score) | 1.80 [1.52, 2.09] | 1.93 [1.58, 2.27] | 0.30 [− 0.07, 0.67] | 0.446 |
 Cardiovascular disease (yes/no) | 32/19 | 20/7 |  | 0.449 |
 Diabetes (yes/no) | 12/39 | 6/21 |  | > 0.999 |
 Glucose intolerance (yes/no) | 5/46 | 2/25 |  | > 0.999 |
 Obstructive sleep apnea (yes/no) | 19/32 | 15/12 |  | 0.153 |
 Sleep disordered breathing (yes/no) | 7/44 | 12/15 |  | 0.005 |
 Osteoporosis (yes/no) | 3/48 | 1/25 |  | > 0.999 |
 Other neurological disorders (yes/no) | 6/45 | 5/22 |  | 0.499 |
 Cognitive deficit (yes/no) | 3/48 | 2/25 |  | > 0.999 |
 Psychological issues (yes/no) | 21/30 | 13/14 |  | 0.634 |
 Dementia (yes/no) | 2/49 | 0/27 |  | 0.542 |
Medications | ||||
 Antianxiety or antidepressant agent (yes/no) | 24/27 | 16/11 |  | 0.474 |
 Anxiolytic agent (yes/no) | 7/44 | 4/23 |  | > 0.999 |
 Antidepressant (yes/no) | 23/28 | 15/12 |  | 0.477 |
  SSRI (yes/no) | 16/35 | 9/18 |  | > 0.999 |
  SNRI (yes/no) | 10/41 | 3/24 |  | 0.525 |
 Antipsychotic (yes/no) | 5/45 | 4/23 |  | 0.712 |