General characteristics
In total, 138 severe patients were enrolled in our study. 109 (79.0%) patients were in antiviral group, and 29 (21.0%) in control group. The mean age of the 138 patients was 65.4 years old (SD: ± 12.6), and 90 (65.2%) patients were men (Table 1). Only 8 (5.8%) cases were smokers. 86 (63.3%) cases had coexisting disorders, including hypertension, diabetes, coronary heart disease, and renal insufficiency, chronic lung disease, cerebrovascular diseases, and malignant tumor (Table 1). 40 (29.0%) with a single co-morbidity and 46 (33.3%) with two or more co-morbidities. The most common symptoms at illness onset were fever, cough or expectoration, chest distress or dyspnea, fatigue, and breathlessness or wheezing (Table 1). The general characteristics were similar between the patients in antiviral group and that in control group. The vital signs and laboratory findings were also compared between the antiviral group and control group (Additional file 1: Table S1). No statistical differences in vital signs and most of laboratory findings were identified both groups.
Treatments
Among the 109 patients receiving the antiviral treatment, five different antiviral drugs were used. Ribavirin (36.2%) and oseltamivir (32.6%) were the mostly used antiviral drugs, followed by abidor (16.7%), interferon (11.6%), and Kaletra (5.1%) (Table 2). The duration of the antiviral treatment varied with the specific antiviral drugs, ranging from 3 days for Kaletra to 9 days for interferon. Most of the patients (85, 78.0%) in antiviral group received a single antiviral drug, and 24 (22.0%) received a combined antiviral therapy.
For the 29 patients in control group, the application of antibiotics was the main drug treatment (93.1%), followed by glucocorticoids (62.1%) and vasoactive drugs (34.5%). However, the patients in antiviral group also received antibiotics (97.2%), glucocorticoids (73.4%) and vasoactive drugs (30.4%) (Table 3). In these drugs treatments, only duration of glucocorticoids therapy has a significant difference between antiviral group and control group (P<0.05). The median duration of glucocorticoids therapy in antiviral group was 4.0 days (IQR: 2.0-9.0), and 8.0 days (IQR: 3.8-15.3) in control group. Moreover, the frequency of use of high-flow oxygen in antiviral group was significantly lower than that in control group (28.4% vs 48.3%, P<0.05). The utilization rate of non-invasive ventilation in antiviral group was also significantly lower comparing with the control group (28.4% vs 51.7%, P<0.05). However, the utilization rates of invasive mechanical ventilation were similar both groups (51.4% vs 58.6%, P>0.05). Moreover, 12 of 138 patients (8.7%) received prone position ventilation, nine (9/109, 8.3%) in antiviral group and three (3/29, 10.3%) in control group. 7 of 138 (5.1%) patients received continuous renal replacement therapy (CRRT), four (4/109, 3.7%) in antiviral group and three (3/29, 10.3%) in control group.
Outcomes and complications
In total, 63 (45.7%) patients died during hospitalization and 75 (54.3%) were discharged. The case-fatality rates were similar between the antiviral group and control group (44.0% vs 51.7%, P>0.05, Table 4). Moreover, the length of hospitalization of severe patients in antiviral group (median: 11.0, IQR: 6.5-18.0) was similar compared with that in control group (median: 16, IQR: 8.5-26.0, P>0.05, Table 4 and Fig. 1A). For the deaths, the in-hospital survival time did not significantly differ between these two groups (Fig. 1B). For the survival patients, the length of hospitalization also had not statistical difference between these two groups (Fig. 1C). In addition, the survival analyses stratified by the combined treatments showed no significant difference on survival time or hospitalization length between the antiviral group and control group (Additional file 1: Fig. S1-S3).
In total, 131 patients (94.9%) were admitted to the ICU, 106 (97.2%) from antiviral group and 25 (86.2%) from control group (Table 4). 56 (51.4%) and 17 (58.6%) patients were received mechanical ventilation in antiviral and control groups, respectively. The rates of ICU admission, mechanical ventilation, and the length of mechanical ventilation did not differ between these two groups (P>0.05, respectively, Table 4 and Fig. 3). However, length of ICU stays of severe patients in antiviral group was significantly shorter than that in control group (median [IQR], 9 [3-14] vs 15 [7-23.5], P=0.01, Fig. 2A). The length of ICU stays of deaths was shorter in antiviral group (median: 7.0, IQR: 3.0-14.3) than that in control group (median: 15.5, IQR: 8.3-21.8, P<0.05, Fig. 2B). The length of ICU stays of survival patients were similar both groups (Fig. 2C).
In total, 120 (87.0%) cases developed the complication, 99 (90.8%) were in antiviral group and 21 (72.4%) in control group. Respiratory failure (76.1%) was the most common complication, followed by ARDS (50.7%), sepsis (34.8%), acute cardiac injury (27.5%), acute liver injury (26.1%), acute kidney injury (22.5%), septic shock (17.4%), DIC (8.0%), arrhythmia (7.2%), gastrointestinal bleeding (5.1%) and acute cerebrovascular disease (3.6%) (Table 4). Only the sepsis incidence was significantly higher in antiviral group compared with the control group (40.4% vs 13.8%, P<0.01). The incidence of the remaining complications was similar both groups (Table 4).