Baseline characteristics
| Non-severe, n=101 | Severe, n=41 | Total, n=142 | P value* | |
| Demographics | ||||
| Age, mean (SD) | 58 (17.1) | 69 (14.9) | 61 (17.1) | <0.001 |
| Males, no (%) | 65 (64.4) | 28 (68.3) | 93 (65.5) | 0.65 |
| Nursing home resident, no (%) | 9 (8.9) | 2 (4.9) | 11 (7.7) | 0.51 |
| Comorbidities, no (%) | ||||
| Any type of comorbidity | 66 (65.3) | 26 (63.4) | 92 (64.8) | 0.83 |
| Diabetes mellitus | 22 (21.8) | 13 (31.7) | 35 (24.6) | 0.21 |
| Cardiovascular disease† | 23 (22.8) | 11 (26.8) | 34 (23.9) | 0.61 |
| Pulmonary disease‡ | 23 (22.8) | 6 (14.6) | 29 (20.4) | 0.28 |
| Malignancy | 11 (10.9) | 6 (14.6) | 17 (12) | 0.57 |
| Neurological disease§ | 10 (9.9) | 6 (14.6) | 16 (11.3) | 0.40 |
| Renal disease¶ | 8 (7.9) | 4 (9.8) | 12 (8.5) | 0.74 |
| Charlson Comorbidity Index, median (IQR) | 2 (0–3.5) | 3 (1.5–4.5) | 2 (0–4) | <0.01 |
| Symptoms and vital signs at presentation | ||||
| Time since onset of symptoms, days, median (IQR) | 9 (7–12) | 7 (4–11) | 8 (6–11) | 0.03 |
| Temperature, °C, mean (SD) | 38.6 (0.9) | 38.4 (1) | 38.5 (0.9) | 0.23 |
| Respiratory rate, breaths/min, mean (SD) | 24.9 (6.3) | 29.5 (7.6) | 26.2 (7) | <0.001 |
| Saturation, %, median (IQR) | 95 (93–96) | 91 (88–95) | 94 (91–96) | <0.001 |
| Heart rate, beats/min, mean (SD) | 98 (17) | 99 (20) | 98 (18) | 0.62 |
| Systolic blood pressure, mm Hg, mean (SD) | 129.9 (21.7) | 132.2 (31.9) | 130.6 (25) | 0.62 |
| Diastolic blood pressure, mm Hg, mean (SD) | 75.7 (12.7) | 75.2 (15.7) | 75.6 (13.6) | 0.88 |
| Glasgow Coma Score, median (IQR) | 15 (15–15) | 15 (15–15) | 15 (15–15) | 0.66 |
| q-SOFA score, mean (SD) | 0.7 (0.6) | 1 (0.5) | 0.8 (0.6) | <0.01 |
| PSI score, mean (SD)** | 74.2 (31.9) | 99.7 (37.5) | 82 (35) | <0.001 |
| PSI 1, no (%) | 22 (21.8) | 3 (7.3) | 25 (17.6) | |
| PSI 2, no (%) | 30 (29.7) | 4 (9.8) | 34 (23.9) | |
| PSI 3, no (%) | 20 (19.8) | 10 (24.4) | 30 (21.1) | |
| PSI 4, no (%) | 24 (23.8) | 18 (43.9) | 42 (29.6) | |
| PSI 5, no (%) | 5 (5) | 6 (14.6) | 11 (7.7) | |
| Use of antibiotics in last 7 days, no (%) | 30 (30) | 9 (22) | 39 (27.7) | 0.33 |
| Use of immunosuppressants, no (%) | 5 (5) | 3 (7.3) | 8 (5.6) | 0.69 |
| Laboratory findings at admission, median (IQR) | ||||
| Creatinine, µmol/L | 83 (66–101) | 101 (83–137) | 87 (69–108) | <0.001 |
| LDH, U/L | 284 (224–422) | 416 (264–517) | 317 (234–441) | <0.01 |
| Ferritin, µg/L | 534 (263–819) | 824 (369–1255) | 564 (273–987) | 0.03 |
| Thrombocytes, 109/L, mean (SD) | 202 (65) | 201 (78) | 202 (69) | 0.94 |
| White blood cell count, 109/L | 6.3 (5–8.1) | 6.8 (5–9.6) | 6.6 (5–8.3) | 0.22 |
| Lymphocyte count, 109/L | 1.02 (0.7–1.3) | 0.81 (0.6–1.2) | 0.96 (0.7–1.3) | 0.03 |
| CRP, mg/L | 74 (35–122) | 127 (82–203) | 86 (44–142) | <0.001 |
| PCT, ng/mL | 0.12 (0.08–0.23) | 0.3 (0.17–0.78) | 0.15 (0.09–0.3) | <0.001 |
| PCT >0.5, ng/mL, no (%) | 10 (9.9) | 14 (34.1) | 24 (16.9) | <0.001 |
| CT value of PCR, mean (SD) | 24.6 (4.9) | 23.2 (5.4) | 24.2 (5.1) | 0.17 |
| Outcomes, median (IQR) | ||||
| Admission, no (%) | 79 (78.2) | 41 (100) | 120 (84.5) | <0.01 |
| Number of days admitted | 3 (2–6) | 7 (4–24) | 4 (2–8) | <0.001 |
| Start of antibiotics, no (%) | 25 (24.8) | 21 (51.2) | 46 (32.4) | <0.01 |
No. of missing values per variable (n): days since onset of symptoms (16), respiratory rate (7), heart rate (3), systolic and diastolic blood pressure (2), use of antibiotics in last 7 days (1), creatinine (1), LDH (9), ferritin (18), lymphocyte count (6), CT value PCR (8).
Statistically significant data is highlighted in bold.
*No adjustment for multiple testing was made.
†Cardiovascular diseases includes i.a. a history of (un)stable angina pectoris, heart rhythm disorder, myocardial infarction, chronic heart failure, peripheral vascular disease.
‡Pulmonary disease includes chronic obstructive pulmonary disease, asthma, cystic fibrosis, obstructive sleep apnoea syndrome or pulmonary hypertension.
§Neurological disease includes cerebral vascular attack, transient ischaemic attack, multiple sclerosis, amyotrophic lateral sclerosis and Parkinson disease.
¶Renal disease includes an eGFR <50 mL/min, proven kidney disease or kidney transplant.
**PSI group 1: 0–50, group 2: 51–70, group 3: 71–90, group 4: 91–130, group 5: 131–395.
CRP, C reactive protein; CT, cycle threshold; eGFR, estimated glomerular filtration rate ; LDH, lactate dehydrogenase; PCT, procalcitonin; PSI, Pneumonia Severity Index; q-SOFA, quick sequential organ failure assessment.