| Characteristics | Number of studies (%) |
|---|---|
| Continent | |
| Europe | 41 (62.1) |
| Asia | 18 (27.3) |
| North America | 5 (7.6) |
| South America | 2 (3.0) |
| Study design | |
| Prospective cohort | 25 (37.9) |
| Retrospective cohort | 24 (36.4) |
| Retrospective case–control | 2 (3.0) |
| Cross-sectional | 2 (3.0) |
| Not specified | 13 (19.7) |
| Clinical setting where LUS was performed | |
| ED | 22 (33.3) |
| Hospital (wards and ICU) | 13 (19.7) |
| Wards | 12 (18.2) |
| ICU | 11 (16.7) |
| ED and ICU | 1 (1.5) |
| Pregnancy wards | 3 (4.5) |
| Home | 1 (1.5) |
| Nursing home | 2 (3.0) |
| Rehabilitation unit | 1 (1.5) |
| Number of COVID-19 patients included | |
| 10–29 | 23 (34.8) |
| 30–99 | 31 (47.0) |
| 100–500 | 12 (18.2) |
| Time of LUS acquisition | |
| Withing 24 h of admission | 40 (60.6) |
| Withing 5 days of admission | 6 (9.1) |
| After a median time of >5 days | 5 (7.6) |
| At discharge | 1 (1.5) |
| Following fetal assessment | 1 (1.5) |
| Not specified | 13 (19.7) |
| Blinded operators | |
| Yes | 34 (51.5) |
| No | 32 (48.5) |
| Type of blinding | |
| To clinical data | 16 (47.1) |
| To PCR status | 15 (44.1) |
| To CT scan or chest radiography | 12 (35.3) |
| Not specified | 4 (11.8) |
| Chest anatomical areas scanned | |
| <12 | 16 (24.2) |
| 12 | 35 (53.0) |
| >12 | 8 (12.1) |
| Not specified | 7 (10.6) |
| Main type of ultrasound probe used | |
| Convex | 41 (62.1) |
| Linear | 7 (10.6) |
| Phased array | 4 (6.1) |
| Not specified | 14 (21.2) |
*ED: Emergency Department, ICU: Intensive Care Unit specified