Baseline characteristics of the unmatched and propensity score-matched groups of patients#
| Unmatched cohort | Matched cohort | |||||||
| Early oseltamivir | Later oseltamivir | SMD | p-value | Early oseltamivir | Later oseltamivir | SMD | p-value | |
| Demographic characteristics | ||||||||
| Age years | 57 (46–68) | 52 (42–63) | 0.2309 | <0.001 | 57 (46–68) | 56 (46–67) | 0.0159 | 0.49 |
| Male | 325 (61.4) | 974 (61.1) | 0.92 | 325 (61.4) | 657 (61.7) | 0.84 | ||
| Disease severity | ||||||||
| APACHE II score | 16 (12–23) | 15 (11–21) | 0.1941 | <0.001 | 16 (12–23) | 17 (12–22) | 0.0011 | 0.52 |
| SOFA score | 6 (4–9) | 6 (4–8) | 0.38 | 6 (4–9) | 6 (4–8) | 0.56 | ||
| Pulmonary infiltrates | −0.1931 | <0.001 | −0.0025 | 0.78 | ||||
| ≤2 | 328 (62.0) | 780 (48.9) | 328 (62.0) | 647 (61.1) | ||||
| >2 | 201 (38.0) | 815 (51.1) | 201 (38.0) | 411 (38.9) | ||||
| Disease timeframe | ||||||||
| Time from symptom onset to hospital admission days | 2 (1–2) | 5 (3–6) | <0.001 | 2 (1–2) | 4 (3–6) | <0.001 | ||
| Time from symptom onset to oseltamivir initiation days | 2 (1–2) | 5 (4–7) | <0.001 | 2 (1–2) | 5 (4–7) | <0.001 | ||
| Time from hospital admission to ICU admission days | 1 (1–2) | 1 (1–2) | 0.002 | 1 (1–2) | 1 (1–1) | 0.04 | ||
| Time from symptom onset to ICU admission days | 3 (2–4) | 6 (5–8) | <0.001 | 3 (2–4) | 6 (4–8) | <0.001 | ||
| Laboratory data | ||||||||
| White blood cell count ×109 L−1 | 9.1 (4.7–13.7) | 6.9 (3.9–11.2) | <0.001 | 9.1 (4.7–13.7) | 7.4 (4.0–12.3) | <0.001 | ||
| Creatinine mg·mL−1 | 1 (0.7–1.5) | 0.9 (0.7–1.4) | 0.05 | 1 (0.7–1.5) | 1 (0.7–1.6) | 0.36 | ||
| Urea mg·mL−1 | 45 (30–72) | 41 (28–67) | 0.33 | 45 (30–72) | 48 (31–77) | 0.13 | ||
| Underlying conditions | ||||||||
| Any comorbidity | 401 (75.8) | 1099 (68.9) | 0.003 | 401 (75.8) | 738 (69.7) | 0.01 | ||
| Asthma | 62 (11.7) | 103 (6.4) | 0.1634 | <0.001 | 62 (11.7) | 100 (9.4) | 0.0704 | 0.18 |
| COPD | 116 (21.9) | 277 (18.1) | 0.02 | 116 (21.9) | 204 (19.3) | 0.24 | ||
| Congestive heart failure | 81 (15.3) | 148 (17.4) | 0.1673 | <0.001 | 81 (15.3) | 138 (13.0) | 0.0629 | 0.24 |
| Chronic kidney disease | 44 (8.3) | 128 (8.0) | 0.90 | 44 (8.3) | 107 (10.1) | 0.28 | ||
| Haematological disease | 49 (9.3) | 112 (7.0) | 0.11 | 49 (9.3) | 101 (9.5) | 0.92 | ||
| Immunosuppression | 89 (16.8) | 174 (10.9) | 0.1579 | <0.001 | 89 (16.8) | 160 (15.1) | 0.0454 | 0.42 |
| Obesity | 132 (24.9) | 543 (34.0) | −0.2098 | <0.001 | 132 (24.9) | 261 (24.6) | 0.0065 | 0.95 |
| Pregnancy | 54 (10.2) | 182 (11.4) | 0.49 | 54 (10.2) | 131 (12.3) | 0.23 | ||
| HIV/AIDS | 10 (1.9) | 40 (2.5) | 0.52 | 10 (1.9) | 31 (2.9) | 0.28 | ||
| Neuromuscular disease | 15 (2.8) | 39 (2.5) | 0.73 | 15 (2.8) | 23 (2.1) | 0.52 | ||
| Autoimmune disease | 17 (3.2) | 65 (4.0) | 0.44 | 17 (3.2) | 51 (4.8) | 0.17 | ||
| Complications | ||||||||
| Acute renal failure | 154 (29.1) | 457 (28.6) | 0.88 | 154 (29.1) | 358 (33.8) | 0.06 | ||
| Mechanical ventilation¶ | 420 (79.4) | 1289 (80.2) | 0.51 | 420 (79.4) | 869 (82.1) | 0.21 | ||
| Septic shock | 294 (55.6) | 863 (54.1) | 0.59 | 294 (55.6) | 608 (57.4) | 0.50 | ||
| Bacterial co-infection | 144 (27.2) | 394 (24.7) | 0.27 | 144 (27.2) | 308 (29.1) | 0.46 | ||
| Treatment | ||||||||
| Oseltamivir treatment duration days | 7 (5–10) | 8 (6–10) | <0.001 | 7 (5–10) | 8 (5–10) | 0.02 | ||
| Adjuvant corticosteroids | 209 (39.5) | 598 (37.5) | 0.43 | 209 (39.5) | 407 (38.4) | 0.72 | ||
| Antibiotic combination | 439 (82.9) | 1398 (87.6) | 0.008 | 439 (82.9) | 919 (86.8) | 0.05 | ||
| Outcomes | ||||||||
| ICU length of stay days+ | 8 (4–16) | 10 (5–21) | <0.001 | 8 (4–16) | 10 (5–21) | <0.001 | ||
| Duration of mechanical ventilation days+ | 5.7 (2.7–12) | 7 (2.3–16) | <0.001 | 5.7 (2.7–12) | 8 (3–18) | <0.001 | ||
| ICU mortality | 101 (19.1) | 351 (22.0) | 0.17 | 101 (19.1) | 261 (24.6) | 0.01 | ||
Data are presented as median (interquartile range) or n (%), unless otherwise stated. SMD: standardised mean difference; APACHE: Acute Physiology and Chronic Health Evaluation; SOFA: Sequential Organ Failure Assessment; COPD: chronic obstructive pulmonary disease; ICU: intensive care unit. #: unmatched cohort n=2124 (early oseltamivir n=529; later oseltamivir n=1595) and matched cohort n=1587 (early oseltamivir n=529; later oseltamivir n=1058); ¶: noninvasive and invasive mechanical ventilation; +: only in survivors.