Table 1.
Baseline clinical characteristics of patients with and without EFL
| Clinical characteristics | EFL, n=55 | Non−EFL, n=92 | P-value |
|---|---|---|---|
| Sex (% male) | 67 | 65 | 0.80 |
| Age (years) | 66 (64–68) | 66 (64–67) | 0.73 |
| Current smokers (%) | 38 | 20 | 0.015 |
| Smoking (pack-years) | 45 (29–59) | 47 (35–67) | 0.23 |
| ICS (%) | 80 | 78 | 0.80 |
| LABA (%) | 82 | 83 | 0.90 |
| LAMA (%) | 75 | 78 | 0.61 |
| 12-month exacerbation prior to study entry (number/year) | 1.9 (1.5–2.3) | 1.6 (1.2–2.0) | 0.10 |
| Pre-BD FEV1% predicted | 42 (37–46) | 59 (54–63) | <0.0001 |
| Pre-BD FEV1/FVC (%) | 38 (33–45) | 47 (40–57) | <0.0001 |
| Post-BD FEV1% predicted | 47 (43–52) | 64 (60–68) | <0.0001 |
| Post-BD FEV1/FVC (%) | 39 (34–45) | 48 (41–56) | <0.0001 |
| SGRQ activity | 68 (59–92) | 67 (37–83) | 0.049 |
| SGRQ impact | 35 (29–42) | 32 (27–36) | 0.33 |
| SGRQ symptoms | 67 (52–81) | 57 (35–71) | 0.008 |
| SGRQ total | 53 (29–67) | 45 (21–61) | 0.12 |
| CAT score | 21 (15–26) | 17 (11–25) | 0.07 |
| VAS dyspnea score | 44 (21–63) | 38 (18–59) | 0.44 |
| 6MWD (min) | 343 (324–363) | 393 (371–415) | 0.002 |
| DLCO% predicted | 54 (49–60) | 59 (55–64) | 0.14 |
| KCO% predicted | 76 (57–91) | 69 (55–95) | 0.49 |
| VA% predicted | 72 (69–87) | 82 (71–88) | 0.06 |
| TLC% predicted | 113 (108–117) | 105 (101–109) | 0.015 |
| RV% predicted | 166 (128–187) | 121 (101–153) | <0.0001 |
| RV/TLC (%) | 61 (55–67) | 47 (39–55) | <0.0001 |
| FRC% predicted | 144 (134–154) | 122 (115–129) | 0.0003 |
| R5 (kPa/L/s) | 0.77 (0.66–0.93) | 0.49 (0.42–0.59) | <0.0001 |
| R20 (kPa/L/s) | 0.38 (0.32–0.42) | 0.34 (0.30–0.41) | 0.040 |
| R5–R20 (kPa/L/s) | 0.41 (0.38–0.45) | 0.15 (0.13–0.17) | <0.0001 |
| R5insp–R20insp (kPa/L/s) | 0.25 (0.19–0.35) | 0.10 (0.05–0.18) | <0.0001 |
| X5 (kPa/L/s) | −0.53 (−0.59 to −0.43) | −0.22 (−31 to −0.15) | <0.0001 |
| ΔX5 (kPa/L/s) | 0.51 (0.42–0.77) | 0.05 (0.00–0.19) | <0.0001 |
| AX (kPa/L) | 5.49 (4.43–6.81) | 1.78 (1.07–2.88) | <0.0001 |
| Fres (Hz) | 30.6 (27.3–34.3) | 22.9 (20.0–25.2) | <0.0001 |
| R5exp (kPa/L/s) | 0.79 (0.68–0.94) | 0.52 (0.46–0.63) | <0.0001 |
| R5insp (kPa/L/s) | 0.64 (0.56–0.76) | 0.44 (0.38–0.54) | <0.0001 |
| X5exp (kPa/L/s) | −0.78 (−1.02 to −0.70) | −0.23 (−0.40 to −0.16) | <0.0001 |
| X5insp (kPa/L/s) | −0.26 (−0.34 to −0.19) | −0.19 (−0.23 to −0.14) | <0.0001 |
Note: Data are presented as mean (95% CI), median (interquartile range), and percentages as appropriate.
Abbreviations: EFL, expiratory flow limitation; ICS, inhaled corticosteroid; LABA, long-acting beta agonist; LAMA, long-acting muscarinic antagonist; BD, bronchodilator; FEV1, forced expired volume in 1 second; FVC, forced vital capacity; SGRQ, St George’s Respiratory Questionnaire; CAT, COPD Assessment Test; VAS, visual analog scale (dyspnea); 6MWD, 6-minute walk distance; DLCO, diffusing capacity of the lungs for carbon monoxide; KCO, carbon monoxide transfer coefficient; VA, alveolar volume; TLC, total lung capacity; RV, residual volume; FRC, functional residual capacity; R5, total resistance; R20, central resistance; R5–R20, peripheral resistance; R5insp–R20insp, peripheral resistance during inspiration; X5, total reactance; ΔX5, difference in total reactance between inspiration and expiration; AX, reactance area; Fres, resonance frequency; R5exp, total expiratory resistance; R5insp, total inspiratory resistance; X5exp, total expiratory reactance; X5insp, total inspiratory reactance; CI, confidence interval.