Baseline characteristics in different expiratory flow limitation (EFL)# groups (n=69)¶
| EFLNone | EFLIntermediate | EFLHigh | ANOVA p-value | |
| Patients (n) | 24 | 12 | 33 | |
| Age (years) | 64.9 (61.6–68.2) | 63.6 (58.8–68.3) | 65.9 (63.3–68.5) | 0.64 |
| Male (%) | 58.3 | 66.7 | 51.5 | 0.79 |
| BMI (kg·m−2) | 25.8 (23.9–27.8) | 27.93 (24.3–31.5) | 30.2 (28.2–32.2)** | 0.01 |
| FFMI+ | 17.44 (12.20–24.89) | 17.50 (5.52–22.90) | 18.05 (13.22–31.65) | 0.56 |
| Current smoking (%) | 50.0 | 58.3 | 30.3 | 0.15 |
| Smoking pack-years | 36.9 (30.6–43.2) | 42.3 (42.6–62.0) | 45.7 (37.8–53.6) | 0.06 |
| Exacerbation in previous 12 months+ | 1.0 (0.0–4.0) | 1.0 (0.0–3.0) | 0.0 (0.0–4.0) | 0.06 |
| ICS use (%) | 75.0 | 58.3 | 81.8 | 0.27 |
| mMRC+ | 4.0 (2.0–4.0) | 4.0 (2.0–4.0) | 4.0 (2.0–4.0) | 0.22 |
| CAT+ | 20.0 (15.0–31.0) | 22.50 (15.0–30.0) | 21.0 (15.0–32.0) | 0.47 |
| SGRQ total | 48.0 (42.1–53.9) | 55.8 (46.0–65.7) | 57.7 (52.5–62.9)* | 0.05 |
| SGRQ symptoms | 66.9 (60.1–73.6) | 69.7 (15.6–81.8) | 66.1 (60.7–71.6) | 0.80 |
| SGRQ activity | 65.8 (59.5–72.1) | 68.6 (56.1–81.1) | 77.1 (70.6–83.6)* | 0.05 |
| SGRQ impact | 31.1 (24.0–38.2) | 43.3 (33.0–53.6) | 43.4 (37.1–49.8)* | 0.02 |
| Chronic bronchitis (%) | 83.3 | 66.7 | 75.8 | 0.53 |
| 6-min walk distance (m)+ | 368.5 (160.0–516.0) | 336.5 (240.0–534.0) | 338.0 (112.0–436.0) | 0.58 |
| Post-BD FEV1 (% pred) | 76.3 (71.5–81.1) | 66.6 (56.5–76.6) | 56.8 (51.1–62.5)** | <0.01 |
| Post-BD FEV1 (L) | 2.1 (1.8–2.3) | 1.7 (1.5–2.0) | 1.5 (1.3–1.6)** | <0.01 |
| Post-BD FVC (% pred) | 106.2 (100.5–112.0) | 96.8 (85.2–108.3) | 96.6 (90.9–102.3) | 0.06 |
| Post-BD FVC (L) | 3.6 (3.2–4.0) | 3.2 (2.7–3.6) | 3.1 (2.8–3.4) | 0.08 |
| FEV1 reversibility (%) | 8.9 (5.1–12.4) | 10.7 (4.0–17.4) | 12.6 (8.0–17.3) | 0.72 |
| FEV1 reversibility (mL) | 146.2 (81.82–210.5) | 155.0 (33.1–276.9) | 136.1 (95.1–177.0) | 0.92 |
| Post-BD FEV1/FVC ratio (%) | 57.8 (54.4–61.3) | 55.8 (49.7–62.0) | 47.5 (43.3–51.7)** | <0.01 |
| Fibrinogen (g·L−1)+ | 3.21 (2.20–4.60) | 3.29 (0.00–4.30) | 3.42 (0.00–4.60) | 0.41 |
| IgE (kIU·L−1)+ | 48.50 (0.00–1297.00) | 65.00 (7.00–837.00) | 66.00 (3.00–858.00) | 0.64 |
| Neutrophil–lymphocyte ratio+ | 2.00 (0.92–4.98) | 1.84 (1.13–3.04) | 2.26 (0.99–6.79) | 0.46 |
| R5 (kPa·L−1·s−1)+ | 0.45 (0.21–0.74) | 0.65 (0.48–1.02)§§ | 0.69 (0.44–1.02)** | <0.01 |
| R20 (kPa·L−1·s−1) | 0.36 (0.33–0.39) | 0.40 (0.32–0.48) | 0.39 (0.36–0.42) | 0.41 |
| R5–R20 (kPa·L−1·s−1) | 0.08 (0.06–0.11) | 0.21 (0.15–0.27)§§ | 0.33 (0.29–0.36)**,ƒƒ | <0.01 |
| AX+ | 0.95 (0.13–3.71) | 2.38 (0.94–6.38)§ | 8.43 (1.91–8.52)**,ƒ | <0.01 |
| X5 (kPa·L−1·s−1)+ | −0.15 (−0.34 (−0.07)) | −0.28 (−0.46– −0.21)§ | −0.41 (−0.92– −0.23)** | <0.01 |
| ΔX5 (kPa·L−1·s−1)+ | 0.03 (−0.05–0.08) | 0.20 (0.15–0.27)§ | 0.54 (0.29–1.48)**,ƒƒ | <0.01 |
| TLC (L)+ | 5.90 (4.29–9.14) | 6.09 (4.53–9.47) | 6.00 (3.75–8.60) | 0.90 |
| TLC (% pred)+ | 101.50 (74.92–130.50) | 99.60 (77.83–131.30) | 102.80 (73.89–144.50) | 0.80 |
| FRC (L) | 3.44 (3.10–3.79) | 3.86 (3.14–4.59) | 3.89 (3.46–4.31) | 0.27 |
| FRC (% pred) | 105.50 (96.54–114.50) | 122.50 (104.00–141.10) | 124.50 (111.50–137.5) | 0.06 |
| RV (L)+ | 2.55 (1.85–4.28) | 3.15 (1.93–5.58) | 3.26 (1.48–5.14) | 0.06 |
| RV (% pred) | 114.80 (103.1–126.5) | 132.60 (112.60–152.60) | 143.60 (127.60–159.60)* | 0.02 |
| RV:TLC | 0.44 (0.41–0.47) | 0.51 (0.46–0.55)§ | 0.52 (0.49–0.55)** | <0.01 |
| DLCO (mmol·min-1·kPa-1)+ | 4.15 (1.80–9.30) | 4.50 (2.70–11.50) | 4.20 (1.60–13.10) | 0.47 |
| DLCO (% pred) | 53.04 (44.21–61.87) | 58.74 (45.50–71.98) | 51.60 (45.15–58.04) | 0.56 |
| KCO (mmol·min-1·kPa-1·L-1)+ | 0.88 (0.33–1.76) | 1.12 (0.71–2.14) | 0.91 (0.45–4.26) | 0.11 |
| KCO (% pred)+ | 62.88 (26.00–124.50) | 73.00 (53.00–148.00) | 64.34 (33.11–115.00) | 0.33 |
| VA (L) | 4.91 (4.41–5.41) | 4.40 (3.92–4.88) | 4.26 (3.93–4.58) | 0.05 |
| VA (% pred) | 81.02 (76.57–85.48) | 75.65 (69.44–81.86) | 73.52 (69.03–78.00) | 0.06 |
Data are presented as mean (95% CI), unless otherwise stated. BMI: body mass index; FFMI: fat-free mass index; ICS: inhaled corticosteroid; mMRC: modified Medical Research Council questionnaire; CAT: COPD Assessment Test; SGRQ: St George's Respiratory Questionnaire; BD: bronchodilator; FEV1: forced expiratory volume in 1 s; % pred: % predicted; FVC: forced vital capacity; Ig: immunoglobulin; R5: resistance at 5 Hz; R20: resistance at 20 Hz; AX: reactance area; X5: reactance at 5 Hz; ΔX5: difference in total reactance between inspiration and expiration; TLC: total lung capacity; FRC: functional residual capacity; RV: residual volume; DLCO: diffusing capacity of the lung for carbon monoxide; KCO: carbon monoxide transfer coefficient; VA: alveolar volume. #: EFLHigh (ΔX5 ≥0.28 kPa·L−1·s−1), EFLIntermediate (ΔX5 0.10–0.27 kPa·L−1·s−1), EFLNone (ΔX5 <0.10 kPa·L−1·s−1); ¶: did not produce technically acceptable results for lung volumes (n=5), no data for FFMI (n=4), did not complete 6-min walk test (n=4); +: data are presented as median (range). p-value corresponds to one-way ANOVA, Kruskal–Wallis or Chi-squared test, as appropriate. *: p<0.05; **: p<0.01 (using Tukey's or Dunn's post hoc test) for EFLNone versus EFLHigh. §: p<0.05; §§: p<0.01 (using Tukey's or Dunn's post hoc test) for EFLNone versus EFLIntermediate. ƒ: p<0.05; ƒƒ: p<0.01 (using Tukey's or Dunn's post hoc test) for EFLIntermediate versus EFLHigh.