TABLE 2.
Long COVID magnetic resonance imaging (MRI) cluster summary#
| Cluster 1 (n=24) | Cluster 2 (n=22) | Cluster 3 (n=19) | Cluster 4 (n=8) | p-value ¶ | |
| Age (years) | 43±13 | 55±10 | 49±11 | 52±13 | 0.004 |
| Female | 12 (50) | 15 (68) | 12 (63) | 5 (63) | 0.6 |
| Caucasian | 20 (83) | 19 (86) | 17 (89) | 6 (75) | 0.2 |
| BMI (kg·m−2) | 26±4 | 28±5 | 31±8 | 33±7 | 0.02 |
| Hospitalised for COVID-19 during acute infection | 3 (13) | 7 (32) | 3 (16) | 5 (63) | 0.03 |
| Time between COVID-19 diagnosis and MRI (days) | 429±222 | 446±246 | 381±191 | 358±276 | 0.7 |
| SGRQ Total + | 31±23 | 36±14 | 37±16 | 60±13 | 0.2 |
| SGRQ Symptom + | 42±24 | 39±17 | 39±26 | 59±14 | 0.6 |
| SGRQ Activity + | 37±29 | 57±16 | 57±17 | 84±4 | 0.02 |
| SGRQ Impact + | 24±24 | 22±17 | 23±16 | 46±21 | 0.4 |
| FEV1 (% pred) | 100±15 | 101±19 | 104±18 | 82±22 | 0.057 |
| FVC (% pred) | 107±15 | 103±20 | 105±18 | 79±23 | 0.005 |
| FEV1/FVC (%) | 76±6 | 79±6 | 81±6 | 85±4 | 0.005 |
| RV (% pred) | 118±24 | 104±34 | 103±24 | 71±29 | 0.006 |
| TLC (% pred) | 100±14 | 95±19 | 95±15 | 70±20 | 0.002 |
| RV/TLC (% pred) | 118±17 | 111±30 | 110±21 | 103±24 | 0.4 |
| DLCO (% pred) | 109±18 | 93±20 | 108±18 | 61±29 | <0.001 |
| VDP (%) | 0±0 | 2±3 | 1±1 | 1±1 | 0.004 |
| Mem/Gas (×10−2) | 0.62±0.09 | 0.64±0.14 | 0.92±0.14 | 1.23±0.19 | <0.001 |
| RBC/Mem | 0.51±0.07 | 0.33±0.07 | 0.42±0.08 | 0.22±0.06 | <0.001 |
| RBC/Gas (×10−2) | 0.33±0.06 | 0.22±0.05 | 0.40±0.07 | 0.29±0.09 | <0.001 |
| Comorbidities | |||||
| Hypertension | 2 (8) | 7 (32) | 6 (32) | 4 (50) | 0.052 |
| Diabetes | 0 (0) | 1 (5) | 4 (21) | 2 (25) | 0.06 |
| GORD | 3 (13) | 9 (41) | 4 (21) | 1 (13) | 0.1 |
| OSA | 4 (17) | 4 (18) | 6 (32) | 2 (25) | 0.7 |
| Asthma | 5 (21) | 8 (36) | 6 (32) | 1 (13) | 0.5 |
| COPD | 0 (0) | 1 (5) | 1 (5) | 0 (0) | 0.6 |
| Persistent symptoms | |||||
| Dyspnoea | 19 (79) | 21 (95) | 14 (74) | 8 (100) | 0.5 |
| Chest tightness | 6 (25) | 9 (41) | 3 (16) | 1 (13) | 0.2 |
| Cough | 6 (25) | 6 (27) | 5 (26) | 3 (38) | 0.6 |
| Fatigue | 15 (63) | 19 (86) | 17 (89) | 5 (63) | 0.2 |
| Nausea | 2 (8) | 3 (14) | 3 (16) | 0 (0) | 0.8 |
| Loss of taste/smell | 9 (38) | 5 (23) | 2 (11) | 2 (25) | 0.4 |
| CT patterns § | (n=19) | (n=14) | (n=15) | (n=8) | |
| GGOs | 0 (0) | 1 (7) | 1 (7) | 8 (100) | <0.001 |
| Reticulation | 0 (0) | 2 (14) | 2 (13) | 3 (38) | 0.046 |
| Honeycombing | 0 (0) | 0 (0) | 0 (0) | 1 (13) | 0.1 |
| Consolidation | 0 (0) | 0 (0) | 0 (0) | 2 (25) | 0.02 |
| Emphysema | 1 (5) | 1 (7) | 0 (0) | 0 (0) | 0.8 |
Data are presented as mean±sd or n (%), unless otherwise stated. BMI: body mass index; COVID-19: coronavirus disease 2019; SGRQ: St George's Respiratory Questionnaire; FEV1: forced expiratory volume in 1 s; FVC: forced vital capacity; RV: residual volume; TLC: total lung capacity; DLCO: diffusing capacity of the lung for carbon monoxide; VDP: ventilation defect percent; Mem/Gas: membrane-to-gas ratio (membrane uptake); RBC/Mem: red blood cell-to-membrane ratio; RBC/Gas: red blood cell-to-gas ratio (red blood cell transfer); GORD: gastro-oesophageal reflux disease; OSA: obstructive sleep apnoea; CT: computed tomography; GGO: ground-glass opacity. #: pulmonary function test measurements included where available (all long COVID: n=66 for FEV1 and FVC, n=57 for RV, n=61 for TLC, n=62 for DLCO; Cluster 1: n=23 for FEV1 and FVC, n=21 for RV, n=22 for TLC, n=22 for DLCO; Cluster 2: n=18 for FEV1 and FVC, n=15 for RV, n=17 for TLC, n=17 for DLCO; Cluster 3: n=18 for FEV1 and FVC, n=15 for RV, n=16 for TLC, n=16 for DLCO; Cluster 4: n=7 for FEV1 and FVC, n=6 for RV, TLC, n=7 for DLCO); ¶: p-values shown for long COVID cluster comparisons only: using one-way ANOVA for parametric variables, Kruskal–Wallis tests for non-parametric variables or Fisher's exact test for categorial variables (bold p-values indicate p<0.05); +: SGRQ administered at Site 1 only (n=15 Cluster 1, n=6 Cluster 2, n=8 Cluster 3, n=3 Cluster 4); §: CT patterns identified as present or absent by qualitative radiologist review (percentages shown as fraction of subset of patients with CT in each cluster).