Clinical characteristics of the study population by healthcare worker status.
| Covid-19 | Covid-19 | |||
| All | Healthcare worker | Non-healthcare worker | P value* | |
| n=168 | n (%) = 36 (21) | n (%) = 132 (79) | HCW vs non-HCW | |
| Demographic | ||||
| Age±SD, years | 54.2±11.8 | 51.3 (8.7) | 55.0 (12.4) | 0.09 |
| Male sex, n (%) | 94 (56%) | 10 (28%) | 84 (64%) | <0.001 |
| Female sex, n (%) | 74 (44%) | 26 (72%) | 48 (36%) | 0.168 |
| Most deprived SIMD quintile (Q1), n (%) | 65 (41%) | 17 (52%) | 48 (38%) | 0.168 |
| Ethnicity, n (%) | ||||
| White | 147 (88%) | 28 (78%) | 119 (90%) | 0.051 |
| Asian | 15 (9%) | 7 (19%) | 8 (6%) | |
| Other | 6 (4%) | 1 (3%) | 5 (4%) | |
| Presenting characteristics, mean (SD) | ||||
| Body mass index, kg/m2 | 30.9 (7.2) | 28.8 (7.5) | 31.4 (7.1) | 0.053 |
| Heart rate, bpm | 95 (19) | 92 (20) | 96 (19) | 0.209 |
| Systolic blood pressure, mmHg | 130 (20) | 127 (18) | 130 (21) | 0.43 |
| Peripheral oxygen saturation, % | 93 (6) | 95 (5) | 93 (7) | 0.072 |
| WHO clinical severity score for COVID-19, n (%) | ||||
| Hospitalised, no oxygen therapy | 54 (32%) | 17 (47%) | 37 (28%) | 0.044 |
| Oxygen therapy by mask or nasal prongs | 77 (46%) | 12 (33%) | 65 (49%) | |
| Non-invasive ventilation | 22 (13%) | 2 (6%) | 20 (15%) | |
| Mechanical ventilation | 15 (9%) | 5 (14%) | 10 (8%) | |
| Radiology, chest radiograph or CT scan, n (%) | ||||
| Typical features of COVID-19 | 118 (76%) | 23 (70%) | 95 (77%) | 0.399 |
| Normal | 24 (15%) | 8 (24%) | 16 (13%) | |
| Acute COVID-19 therapy, n (%) | ||||
| Oxygen | 114 (68%) | 19 (53%) | 95 (72%) | 0.043 |
| Steroid | 91 (54%) | 16 (44%) | 75 (57%) | 0.194 |
| Antiviral | 43 (26%) | 6 (17%) | 37 (28%) | 0.2 |
| Non-invasive respiratory support | 33 (20%) | 5 (14%) | 28 (21%) | 0.478 |
| Intensive care | 24 (14%) | 6 (17%) | 18 (14%) | 0.601 |
| Invasive ventilation | 15 (9%) | 5 (14%) | 9 (7%) | 0.182 |
| Cardiovascular history, n (%) | ||||
| Smoking: never | 110 (65%) | 28 (78%) | 82 (62%) | 0.08 |
| Smoking: former | 47 (28%) | 5 (14%) | 42 (32%) | |
| Smoking: current | 11 (7%) | 3 (8%) | 8 (6%) | |
| Hypercholesterolemia | 80 (48%) | 12 (33%) | 68 (52%) | 0.061 |
| Hypertension | 56 (33%) | 8 (22%) | 48 (36%) | 0.162 |
| Diabetes mellitus | 37 (22%) | 6 (17%) | 31 (23%) | 0.498 |
| Chronic kidney disease | 7 (4%) | 1 (3%) | 6 (5%) | 1 |
| Cardiovascular disease and/or treatment | 77 (46%) | 14 (39%) | 63 (48%) | 0.451 |
| Risk scores, mean (SD) | ||||
| ISARIC-4C in-hospital mortality risk, % | 11.5 (10.1) | 7.3 (10.2) | 12.7 (9.8) | 0.004 |
| Q-Risk 3, 10 year cardiovascular risk, % | 13.7 (11.2) | 8.1 (7.9) | 15.0 (11.5) | 0.006 |
| Charlson Comorbidity Index | 1.8 (1.8) | 1.4 (1.6) | 1.9 (1.8) | 0.132 |
| Laboratory results, index admission | ||||
| Initial haemoglobin, mean (SD), g/L | 141 (16) | 138 (13) | 142 (16) | 0.276 |
| Initial platelet count, mean (SD), x109/L | 238 (92) | 234 (78) | 239 (95) | 0.778 |
| Initial white cell count, mean (SD), x109/L | 7.4 (5.4) | 5.9 (1.9) | 7.8 (6.0) | 0.073 |
| Peak D-Dimer, mean (SD), ng/mL | 1609 (5342) | 1409 (2239) | 1658 (5865) | 0.853 |
| Acute kidney injury, n (%) | 20 (15%) | 4 (13%) | 16 (15%) | 1 |
| Peak hs-troponin I, median (IQR), ng/L | 4.0 (3.0, 11.0) | 4.0 (2.0, 14.8) | 4.0 (3.0, 11.0) | 0.237 |
| Peak ferritin, mean (SD), mg/L | 356 (168, 906) | 243 (88, 610) | 368 (189, 947) | 0.142 |
| Peak C reactive protein, median (IQR), mg/L | 104 (37, 180) | 48 (14, 165) | 112 (52, 181) | 0.028 |
| HbA1c, mean mmol/mol Hb, % | 47.9 (18.1) | 45.6 (16.1) | 48.4 (18.5) | 0.472 |
| Timelines | ||||
| Duration of admission, median (IQR), days | 5 (2, 11) | 4 (2, 6) | 6 (3, 12) | 0.0496 |
| Symptom onset to enrolment, median (IQR), days | 26 (13, 38) | 29 (15, 38) | 24 (13, 38) | 0.38 |
| Hospital discharge to visit 2 (28–60 days post-discharge), median (IQR), days | 48 (37, 55) | 42 (35, 51) | 48 (38, 56) | 0.11 |
Missing data in healthcare worker post-COVID-19 patients: postcode for SIMD, n=3; typicality of radiology for COVID-19, n=3; standard care blood tests: D-Dimer, n=16; HbA1c, n=9; ferritin, n=6; troponin I, n=8. Missing data in non-healthcare worker post-COVID-19 patients: postcode for SIMD, n=5; typicality of radiology for COVID-19, n=9; standard care blood tests: D-Dimer, n=50; HbA1c, n=13; ferritin, n=11; troponin I, n=11.GFR—glomerular filtration rate was estimated using the Chronic Kidney Disease Epidemiology equation,33 In the control group, the Abbott Architect CMIA SARS-CoV-2 IgG assay was used to confirm the absence of prior infection with COVID-19. The primary outcome evaluation (visit 2) was scheduled for 28–60 days post-discharge.
*Categorical data are summarised as frequency and percentage and compared between groups using Fisher’s Exact tests. Continuous data are summarised as mean and SD, or median and interquartile range (IQR, defined as the upper and lower quartiles), and compared between groups using Kruskal-Wallis tests. A p value of less than 0.05 was considered significant.
HbA1c, haemoglobin A1c; HCW, Healthcare worker; ISARIC-4C, Coronavirus Clinical Characterisation Consortium; SIMD, Scottish Index of Multiple Deprivation.