Study | Country | Sample size, N | Diabetes, N (%) | Hypertension, N (%) | CVD, N (%) | Pulmonary disease, N (%) | Active smokers, N (%) | Former smokers, N (%) | ICU admission, N (%) | Mortality, N (%) | Notes |
Original studies | |||||||||||
Huang et al
14
| China | 41 | 8 (19.5) | 6 (14.6) | 6 (14.6) | 1 (2.4) | 3 (7.3) | NR | 7 (17.1) | 6 (14.6) | – |
Guan et al
15
| China | 1085 | 81 (7.5) | 165 (15.2) | 27 (2.5) | 12 (1.1) | 137 (12.6) | 21 (1.9) | 55 (5.0) | 15 (1.4) | – |
Zhang et al
16
| China | 140 | 17 (12.1) | 42 (30.0) | 12 (8.6) | 2 (1.4) | 2 (1.4) | 7 (5.0) | – | – | – |
Yang et al 17 | China | 52 | 9 (17.3) | – | 5 (9.6) | 4 (7.7) | 2 (3.8) | NR | 52 (100.0) | 32 (61.5) | – |
Mo et al
18
| China | 155 | 15 (9.7) | 37 (21.9) | 15 (9.7) | 5 (3.2) | 6 (3.9) | NR | – | – | – |
Zhou et al
19
| China | 191 | 36 (18.9) | 58 (30.4) | 15 (7.9) | 6 (3.1) | 11 (5.8) | NR | 50 (26.2) | 54 (28.3) | – |
Guo et al
20
| China | 187 | 28 (14.9) | 61 (32.6) | 21 (11.2) | – | 18 (9.6) | NR | – | 43 (23.0) | – |
Richardson et al
28
| USA | 3567 | 1808 (50.7) | 3026 (84.8) | 966 (27.1) | 920 (25.8) | 558 (15.6) | NR | 1281 (22.5) | 553 (9.7) | – |
Goyal et al
26
| USA | 393 | 99 (25.2) | 197 (50.1) | 82 (20.9) | 69 (17.6) | 20 (5.1) | NR | – | 40 (10.2) | – |
Qin et al
21
| China | 452 | 75 (16.6) | 135 (29.9) | 27 (5.9) | 12 (2.7) | 7 (1.5) | NR | – | – | – |
Cummings et al
27
| USA | 257 | 92 (35.8) | 162 (63.0) | 49 (19.1) | 24 (9.3) | 33 (12.8)* | NR | 203 (79.0) | 101 (39.3) | – |
Meta-analyses | |||||||||||
Farsalinos et al
22
| China | 5960 | – | – | – | – | 450 (7.6) | 35 (0.6) | – | – | Pooled prevalence of smokers among hospitalised patients with COVID-19 in China was 6.5% (95% CI 4.9% to 8.2%) |
Lippi et al
40
| China | 1399 | – | – | – | – | – | – | – | – | No significant association between active smoking and COVID-19 severity (OR 1.69 (0.41 to 6.92); p=0.254) |
Preprints | |||||||||||
Miyara et al
24
| France | 482 | 102/473 | 158/473 | – | 29/473 | 34/473 | 285/473 | – | – | Daily smokers have lower probability of developing severe COVID-19 when compared with the general population |
OpenSAFELY Collaborators31
| UK | 17 425 455 | 489 297 (2.8) | 5 962 122 (34.2) | 1 173 433 (6.7) | 707 284 (4.1) | 2 962 373 (17.0) | 5 737 545 (32.9) | 5683 (0.03) | On adjustment for multiple covariates, smoking was associated with a reduced risk for COVID-19 mortality (OR 0.88 (0.79 to 0.99)) |
*Study reported ‘current or former smokers’.
CI, Confidence interval; CVD, cardiovascular disease; ICU, Intensive care unit; NR, not reported; OR, Odds ratio; UK, United Kingdom; USA, United States of America.