Table 2. Comparison between patients without preexisting respiratory disease presenting with a restrictive ventilatory defect at the follow-up visit and those not presenting with a restrictive ventilatory defect at the follow-up visit.a .
| Variable | RVD | No RVD | p |
|---|---|---|---|
| n = 42 | n = 53 | ||
| Age, years | 53.9 ± 11.3 | 58.4 ± 11.3 | 0.061 |
| Male sex, n (%) | 22 (52.4) | 27 (50.9) | 0.527 |
| Weight, kg | 93.6 ± 17.9 | 84.0 ± 15.7* | 0.007 |
| Height, m | 1.68 ± 0.1 | 1.64 ± 0.1 | 0.084 |
| BMI, kg/m2 | 33.0 ± 5.8 | 30.9 ± 5.0 | 0.067 |
| Current or former smoker, n (%) | 10 (24.4) | 24 (45.3)* | 0.037 |
| Comorbidities | |||
| Hypertension | 24 (57.1) | 24 (45.3) | 0.251 |
| Diabetes | 13 (31) | 12 (22.6) | 0.361 |
| Obesity | 24 (57.1) | 17 (32.1)* | 0.014 |
| Cardiovascular disease | 4 (9.5) | 3 (5.7) | 0.371 |
| Cerebrovascular disease | 3 (7.1) | 2 (3.8) | 0.390 |
| Chronic liver disease | 0 (0.0) | 1 (1.9) | 0.558 |
| Chronic kidney disease | 2 (4.8) | 1 (1.9) | 0.413 |
| Cancer | 3 (7.1) | 3 (5.7) | 0.545 |
| Charlson Comorbidity Index | 1 (0-3) | 2 (1-3) | 0.784 |
| mMRC dyspnea scale score before COVID-19 | 0 (0-1) | 0 (0-0) | 0.070 |
| Symptoms before admission, days | 6 (4-10) | 8 (6-10)* | 0.028 |
| Data during hospitalization | |||
| Length of stay, days | 24 (15-45) | 10 (9-15)* | < 0.001 |
| ICU admission, n (%) | 31 (73.8) | 17 (32.1)* | < 0.001 |
| NIV, n (%) | 11 (26.2) | 19 (35.8) | 0.315 |
| IMV, n (%) | 19 (45.2) | 4 (7.5)* | < 0.001 |
| Duration of IMV, days | 0 (0-20) | 0 (0-0)* | 0.002 |
| Chest CT score | 21 (16-24) | 13 (11-18)* | < 0.001 |
| Follow-up study visit | |||
| Number of weeks after COVID-19 diagnosis | 17.7 ± 5.9 | 16.8 ± 5.6 | 0.489 |
| mMRC dyspnea scale score | 2 (0-3) | 1 (0-2)* | 0.008 |
| mMRC dyspnea scale score ≥ 2, n (%) | 24 (57.1) | 13 (24.5)* | 0.001 |
| Spirometry | |||
| FVC, % predicted | 72.3 ± 15.9 | 100.9 ± 60.0* | 0.006 |
| FEV1, % predicted | 80.0 ± 17.7 | 103.4 (93.2-111.5)* | 0.007 |
| FEV1/FVC | 0.87 ± 0.00 | 0.85 ± 0.00 | 0.061 |
| FEV1/FVC, % predicted | 110.2 ± 7.2 | 107.5 (104-11.5) | 0.569 |
| FEV1/FVC < LLN, n (%) | 0 | 0 | |
| Plethysmography | |||
| TLC, % predicted | 72.7 (61.6-77.6) | 91.7 (87.8-96.1)* | < 0.001 |
| FRC, % predicted | 71.41 ± 13.10 | 88.7 (80.7-99.8) | 0.071 |
| RV, % predicted | 84.4 ± 18.9 | 101.6 (92.2-119.1)* | 0.009 |
| Diffusing capacity of the lung | n = 40 | n = 53 | |
| DLCO, % predicted | 70.73 ± 18.40 | 90.6 (79.2-98.4)* | 0.001 |
| DLCO < LLN, n (%) | 28 (66.7) | 9 (17.3)* | < 0.001 |
| Impulse oscillometry | n = 24 | n = 38 | |
| Resistance at 5 Hz, % predicted | 140.8 ± 41.7 | 134.9 ± 41.2 | 0.587 |
| Resistance at 20 Hz, % predicted | 110.5 (94.2-143.2) | 125 ± 35.6 | 0.601 |
| R5-R20, Kpa/L/s | 0.12 ± 0.00 | 0.07 (0.0-0.1)* | 0.027 |
| Reactance at 5 Hz, Kpa/L/s | −0.13 ± 0.00 | −0.10 (−0.10 to 0.00) | 0.116 |
| Resonance frequency, 1/s | 17.4 ± 4.4 | 15.6 ± 4.2 | 0.108 |
| Area of resonance, Kpa/L | 0.67 (0.4-1.6) | 0.48 (0.2-0.8) | 0.124 |
| 6MWT | n = 38 | n = 52 | |
| 6MWD, m | 385.7 ± 94.6 | 430.2 ± 109.1 | 0.051 |
| 6MWD, % predicted | 72.2 ± 15.7 | 77.9 ± 28.5 | 0.275 |
| 6MWD < LLN, n (%) | 20 (52.6) | 15 (28.8)* | 0.020 |
| Resting SpO2, % | 95 (2) | 96 (3)* | 0.030 |
| Final SpO2, % | 93 (6) | 95 (3)* | 0006 |
| Final Borg dyspnea scale score | 2 (0-5) | 0 (0-2)* | 0.014 |
| Final Borg leg fatigue scale score | 2 (0-4) | 0 (0-2) | 0.164 |
| Final Borg dyspnea score/6MWD, n/km | 6.06 (0-13) | 0 (0-5.3)* | 0.011 |
| Psychological symptoms | n = 29 | n = 40 | |
| Beck Anxiety Inventory | 22.0 ± 17.4 | 8 (3-21)* | 0.008 |
| Beck Depression Inventory | 11 (6-17) | 8 (3-16) | 0.128 |
| PCL-C | 29 (23-42) | 28 (22-39) | 0.952 |
RVD: restrictive ventilatory defect; mMRC: modified Medical Research Council; NIV: noninvasive ventilation; IMV: invasive mechanical ventilation; LLN: lower limit of normal (i.e., below the 5th percentile); FRC: functional residual capacity; R5-R20: resistance at 5 Hz-resistance at 20 Hz; 6MWT: six-minute walk test; 6MWD: six-minute walk distance; and PCL-C: Posttraumatic Stress Disorder Checklist, Civilian Version. aData presented as mean ± SD, median (IQR), or n (%). *p < 0.05.