Table 1.
Baseline demographic and clinical characteristics of critically ill patients with H1N1 infectiona
| Characteristics | All patients (n = 25) | Patients with VAHS (n = 9) | Patients without VAHS (n = 16) | P value |
|---|---|---|---|---|
| Median age, yr (IQR) | 45 (35 to 56) | 53 (39 to 56) | 38 (32 to 52) | 0.32 |
| Sex, F/M | 9/16 | 2/7 | 7/9 | 0.52 |
| Any comorbidity, n (%)b | 18 (72%) | 5 (56%) | 13 (81%) | 0.36 |
| Obesity, n (%)c | 10 (40%) | 3 (33%) | 7 (44%) | 0.67 |
| Median APACHE II score at admission (IQR) | 21 (19 to 30) | 28 (23 to 32) | 21 (18 to 23) | 0.29 |
| Median SOFA score at admission (IQR) | 11 (10 to 13) | 13 (11 to 16) | 11 (9 to 12) | 0.22 |
| Median duration of mechanical ventilation, days (IQR) | 19 (13 to 26) | 25 (17 to 26) | 18 (11 to 25) | 0.69 |
| Patients on ECMO support, n (%) | 17 (68%) | 9 (100%) | 8 (50%) | 0.02e |
| Median duration of ECMO support, days (IQR) | 10 (6 to 19) | 10 (4 to 19) | 11 (8 to 20) | 0.90 |
| Median duration of viral shedding, days (IQR) | 19 (14 to 26) | 21 (14 to 26) | 15 (12 to 22) | 0.13 |
| Patients treated with oseltamivir, n (%)d | 24 (96%) | 9 (100%) | 15 (94%) | 0.44 |
| Median duration of oseltamivir treatment, days (IQR) | 7 (4 to 10) | 10 (5 to 12) | 7 (4 to 10) | 0.32 |
| Patients treated with intravenous zanamivir, n (%)d | 15 (60%) | 6 (67%) | 9 (56%) | 0.61 |
| Median duration of zanamivir treatment, days (IQR) | 7 (5 to 12) | 6 (5 to 7) | 10 (5 to 13) | 0.32 |
| Median peak CRP level, mg/l (IQR) | 313 (271 to 344) | 337 (324 to 345) | 302 (241 to 315) | 0.03f |
| Median peak LDH level, U/l (IQR) | 1,175 (703 to 3,744) | 3,819 (1,096 to 9,403) | 933 (674 to 1,729) | 0.03g |
| Median peak serum sIL-2R level, kU/l (IQR) | 2,289 (1,416 to 5,793) | 8,188 (5,120 to 10,650) | 1,433 (1,092 to 1,904) | 0.001f |
| Median peak serum ferritin level, μg/l (IQR) | 1,067 (835 to 5,986) | 7,576 (4,708 to 68,070) | 861 (487 to 1,060) | <0.001g |
| Patients requiring renal replacement therapy, n (%) | 14 (56%) | 8 (89%) | 6 (38%) | 0.03e |
| Mortality, n (%) | 12/25 (48%) | 8/9 (89%) | 4/16 (25%) | 0.004h |
aVAHS, virus-associated hemophagocytic syndrome; IQR, interquartile range; APACHE II, Acute Physiology and Chronic Health Evaluation II; SOFA, ; ECMO, extracorporeal membrane oxygenation; CRP, C-reactive protein; LDH, lactate dehydrogenase; sIL-2R, soluble interleukin-2 receptor; bcomorbidities were obesity, cardiovascular or chronic pulmonary disease, chronic renal insufficiency, immunosuppressive therapy after organ transplantation, diabetes mellitus, liver disease, malignant lymphoma and pregnancy (see Materials and methods for details); cobesity was defined as body mass index >30 kg/m2; dpatients received sequential therapy, that is, antiviral therapy was started with oseltamivir but was switched to intravenous zanamivir in patients with persistent viral shedding; one patient received intravenous zanamivir as initial therapy; edifference between VAHS and non-VAHS was significant based on Fisher's exact test for count data; fdifference between VAHS and non-VAHS was significant based on the Welch two-sample t-test; gdifference between VAHS and non-VAHS was significant based on the Wilcoxon rank-sum test; hdifference between VAHS and non-VAHS was significant based on log-rank analysis.