In our study, 498 patients with confirmed COVID-19 were admitted to designated hospitals, and all of them were discharged or died before 30th March. A total of 461 (92.6%) patients had symptoms and were included in the symptomatic group, while the other 37 (7.4%) patients were included in the asymptomatic group. Of the 461 symptomatic patients, 430 (93.3%) had abnormal laboratory and chest CT findings and were included in the symptomatic with pneumonia group, while the other 31 (6.2%) were included in the symptomatic without pneumonia group. Of the 37 asymptomatic COVID-19 patients, 23 (62.2%) had abnormal laboratory and chest CT findings and were classified in the asymptomatic with pneumonia group, while the other 14 (37.8%) were classified in the asymptomatic without pneumonia group (Fig. 1). The greater frequency of pneumonia in the symptomatic group than in the asymptomatic group (P < 0.001 by Chi-square test) supports the theory that symptomatic COVID-19 might be more likely to be associated with lower airway infection than with upper airway infection.
Demographic characteristics and reported symptoms
The median age of the 430 symptomatic COVID-19 with pneumonia patients was 45.0 years (IQR 34.0–57.0), and 171 (39.8%) of the 430 patients were male (Table 1). The median ages of the 31 symptomatic COVID-19 without pneumonia patients, 23 asymptomatic COVID-19 with pneumonia patients and 14 asymptomatic COVID-19 without pneumonia patients were 35.0 years (17.0–50.0), 48.0 years (38.0–59.0) and 25.0 years (11.0-51.5), respectively (Table 1). Statistical analysis showed that COVID-19 patients without pneumonia were younger than COVID-19 patients with pneumonia (P = 0.001, Table 1). Of the 23 asymptomatic pneumonia patients, only 6 (26.1%) were male, presenting a significantly lower proportion of males than females (Table 1). There were no differences in comorbidities, except for a higher frequency of hypertension (39.1%) in the asymptomatic with pneumonia group, among the groups (Table 1).
Table 1
Epidemiological and clinical characteristics in symptomatic and asymptomatic COVID-19 cases
|
Symptomatic COVID-19
|
Asymptomatic COVID-19
|
|
Items
|
with pneumonia (n = 430)
|
without pneumonia (n = 31)
|
with pneumonia (n = 23)
|
without pneumonia (n = 14)
|
p-value
|
Age, years
|
45.0 (34.0–57.0)*
|
35.0 (17.0–50.0)*
|
48.0 (38.0–59.0)
|
25.0 (11.0-51.5)*
|
0.001
|
Sex, male
|
206 (47.9)
|
17 (54.8)
|
6 (26.1)*
|
7 (50.0)
|
0.175
|
Exposure to Wuhan
|
171 (39.8)
|
12 (38.7)
|
6 (26.1)
|
1 (7.1) *
|
0.055
|
Family clusters#
|
92 (47.9)*
|
13 (72.2)
|
8 (88.9)
|
5 (55.6)
|
0.018
|
Comorbidity
|
86 (20.0)
|
4 (12.9)
|
7 (30.4)
|
2 (14.3)
|
0.424
|
Influenza A or B#
|
0 (0)
|
0 (0)
|
0 (0)
|
0 (0)
|
NA
|
Cardiovascular disease
|
17 (4.0)
|
2 (6.5)
|
1 (4.3)
|
0 (0)
|
0.790
|
Diabetes mellitus
|
37 (8.6)
|
0 (0)
|
4 (17.4)
|
0 (0)
|
0.020
|
Hypertension
|
63 (14.7)
|
4 (12.9)
|
9 (39.1)*
|
1 (7.1)
|
0.032
|
COPD
|
12 (2.8)
|
1 (3.2)
|
0 (0)
|
0 (0)
|
0.374
|
Chronic liver disease
|
14 (3.3)
|
0 (0)
|
0 (0)
|
0 (0)
|
0.173
|
Chronic kidney disease
|
2 (0.5)
|
0 (0)
|
0 (0)
|
0 (0)
|
0.611
|
Malignancy
|
4 (0.9)
|
0 (0)
|
1 (4.3)
|
1 (7.1)
|
0.028
|
Cerebrovascular disease
|
9 (2.1)
|
0 (0)
|
0 (0)
|
0 (0)
|
0.278
|
Rheumatic disease
|
3 (0.7)
|
0 (0)
|
0 (0)
|
0 (0)
|
0.533
|
Signs and symptoms at admission
|
Temperature at admission, ℃
|
36.8 (36.5–37.3)*
|
36.7 (36.3–37.0)
|
36.6 (36.5–37.0)
|
36.6 (36.4–36.9)
|
0.021
|
Respiratory rate
|
20.0 (20.0–20.0)*
|
20.0 (20.0–20.0)
|
20.0 (20.0–20.0)
|
20.0 (18.0–20.0)
|
0.042
|
Fever
|
312 (72.6)
|
18 (58.1)
|
0 (0)
|
0 (0)
|
< 0.001
|
Cough
|
297 (69.1)**
|
14 (45.2)
|
0 (0)
|
0 (0)
|
< 0.001
|
Expectoration
|
178 (41.4)**
|
7 (22.6)
|
0 (0)
|
0 (0)
|
< 0.001
|
Dyspnea
|
36 (8.4)
|
0 (0)
|
0 (0)
|
0 (0)
|
0.012
|
Fatigue
|
156 (36.3)
|
8 (25.8)
|
0 (0)
|
0 (0)
|
< 0.001
|
Muscle soreness
|
56 (13.0)
|
5 (16.1)
|
0 (0)
|
0 (0)
|
0.016
|
Headache
|
34 (7.9)
|
1 (3.2)
|
0 (0)
|
0 (0)
|
0.053
|
Notes: Values are presented as median (IQR) or number (percentage); * p < 0.05 compared with other groups combined, ** p < 0.05 compared with symptomatic COVID-19 with pneumonia cases; #data were only analyzed using cases form Changsha (n=228); p values were compared by Chi-square test, Fisher’s exact test or One-way ANOVA.
Legends: COPD-chronic obstructive pulmonary disease; NA- not available.
Moreover, we found that the proportion of patients reporting an exposure history to Wuhan was significantly lower in the asymptomatic without pneumonia (7.1%) than in the other groups (Table 1), implicating that asymptomatic patients without pneumonia were more likely to be secondary cases than index cases. We have only collected family cluster history in 228 COVID-19 patients from the Public Health Treatment Center of Changsha. The results showed that symptomatic COVID-19 patients with pneumonia were less likely to be family cluster cases (47.9%, Table 1) than their counterparts.
As expected, the symptomatic with pneumonia group had higher rate of symptoms, including a higher body temperature at admission (℃) (36.8 [IQR 36.5–37.3]) and respiratory rate at admission (rate per min) (20 [IQR 20–20]), cough (69.1%), and expectoration (41.4%) than the other groups (Table 1).
Laboratory findings
Routine blood tests showed a higher white blood cell count (× 109 per L) (6.5 [IQR 4.7–7.5]) and lymphocyte count (× 109 per L) (2.4 [IQR 1.7-3.0]) in the asymptomatic without pneumonia group than in the other groups (Table 2). In contrast, the symptomatic with pneumonia group had a higher frequency of lymphocytopenia (37.7%) and lower platelet count (× 109 per L) (187.5 IQR [147.0-246.0]) than the other groups (Table 2). However, there were no differences in hemoglobin levels among groups.
Table 2
Laboratory findings in symptomatic and asymptomatic COVID-19 cases
|
Symptomatic COVID-19
|
Asymptomatic COVID-19
|
|
Items
|
with pneumonia (n = 430)
|
without pneumonia (n = 31)
|
with pneumonia (n = 23)
|
without pneumonia (n = 14)
|
p-value
|
White blood cell count, *109/L
|
4.6 (3.6–5.8)*
|
5.7 (4.0-6.8)
|
5.7 (4.8–7.8)*
|
6.5 (4.7–7.5)*
|
0.001
|
< 4*109/L
|
148 (34.4)*
|
9 (29.0)
|
3 (13.0)*
|
3 (21.4)
|
0.095
|
> 10*109/L
|
10 (2.3)
|
1 (3.2)
|
1 (4.3)
|
2 (14.3)
|
0.021
|
Neutrophil count, *109/L
|
2.9 (2.2–3.8)
|
3.3 (2.2–3.8)
|
3.6 (3.0-4.5)*
|
3.4 (2.1–4.6)
|
0.167
|
Lymphocyte count, *109/L
|
1.2 (0.8–1.6)*
|
1.8 (1.3–2.7)*
|
1.5 (1.3-2.0)*
|
2.4 (1.7-3.0)*
|
< 0.001
|
Lymphocytopenia
|
162 (37.7)*
|
4 (12.9)*
|
3 (13.0)*
|
3 (21.4)
|
0.001
|
Hemoglobin, g/L #
|
130.0 (119.0-140.0)
|
129.0 (119.8-147.8)
|
133.0 (127.0-151.0)
|
125.0 (119.0-139.5)
|
0.431
|
Platelet, *109/L
|
187.5 (147.0-246.0)*
|
221.0 (163.5–246.0)
|
238.0 (217.0-305.0)*
|
232.5 (187.8–261.0)
|
0.002
|
Alanine aminotransferase, U/L
|
21.3 (15.0-30.4)*
|
17.7 (11.7–24.7)*
|
20.5 (16.3–23.4)
|
16.7 (15.1–45.1)
|
0.139
|
Aspartate aminotransferase, U/L
|
23.4 (18.8–31.0)
|
23.3 (18.7–28.0)
|
20.8 (17.8–24.9)*
|
24.1 (18.3–33.4)
|
0.249
|
Total bilirubin, mmol/L
|
11.0 (8.1–17.0)
|
9.6 (6.6–12.6)
|
10.7 (9.0-19.5)
|
11.2 (8.3–13.5)
|
0.296
|
Lactose dehydrogenase, U/L
|
177.1 (145.6–221.0)*
|
155.7 (138.5-173.5)*
|
146.2 (133.0-185.0)*
|
146.5 (128.0-198.3)
|
0.002
|
Creatinine, µmol/L
|
62.0 (49.0–76.0)
|
57.0 (38.8–75.6)
|
59.8 (49.9–73.0)
|
51.2 (29.1–66.1)
|
0.280
|
D-dimer, mg/L
|
0.31 (0.18–0.52)*
|
0.24 (0.12–0.37)
|
0.26 (0.17–0.37)
|
0.14 (0.09–0.24)*
|
0.009
|
Prothrombin time (PT), s
|
12.0 (11.1–12.7)8
|
11.8 (11.1–12.8)
|
11.1 (10.3–12.4)*
|
11.8 (10.8–12.2)
|
0.066
|
Activated partial thromboplastin time (APTT), s
|
32.4 (29.2–35.6)
|
31.3 (30.3–33.7)
|
31.8 (29.6–36.8)
|
34.1 (32.0-36.1)
|
0.622
|
Creatine kinase (CK), U/L
|
66.9 (43.0-104.9)
|
78.0 (58.6–94.7)
|
67.1 (57.0-109.0)
|
76.2 (50.3-104.9)
|
0.736
|
Erythrocyte sedimentation rate (ESR), mm/h #
|
44.0 (22.0-67.3) *
|
18.0 (11.0-28.5) *
|
33.0 (9.5–65.5)
|
19.0 (7.0-22.8) *
|
0.001
|
Notes: Values are presented as median (IQR) or number (percentage); * p < 0.05 compared with other groups combined; #data were only analyzed using cases form Changsha (n=228); p values were compared by Chi-square test, Fisher’s exact test or One-way ANOVA.
Elevated alanine aminotransferase levels (ALT, U per L) and lactose dehydrogenase (LDH, U per L) were observed in the symptomatic with pneumonia group compared with the symptomatic without pneumonia group (21.3 [IQR 15.0-30.4] vs. 17.7 [IQR 11.7–24.7] and 177.1 [IQR 145.6–221.0] vs. 155.7 [IQR 138.5-173.5], respectively) (Table 2). Compared with those in the other groups, the symptomatic with pneumonia group had a significant higher level of D-dimer (mg per L) (0.31 [IQR 0.18–0.52]) (Table 2). In contrast, a significantly lower level of D-dimer was observed in the asymptomatic without pneumonia group (mg per L) (0.14 [IQR 0.09–0.24]) than in the other groups (Table 2).
We also found a higher erythrocyte sedimentation rate (ESR) (mm per hour) (44.0 [IQR 22.0-67.3]) and C-reactive protein (CRP) (U per L) (8.6 [IQR 2.8–24.0]) in symptomatic with pneumonia group than in the other groups, whereas the asymptomatic without pneumonia group had a lower level of CRP (U per L) (1.7 [IQR 0.3-3.0]) than the other groups (Table 2). Accordingly, among the 228 COVID-19 patients from the Public Health Treatment Center of Changsha, symptomatic COVID-19 with pneumonia patients were more likely to have procalcitonin (PCT) levels > 0.05 ng per mL (54, 28.1%) than the others (Table 2).
Treatments and outcomes
Excluding 10 patients who were only treated with traditional Chinese medicine in the symptomatic with pneumonia group and 1 patient who was treated with traditional Chinese medicine in the asymptomatic without pneumonia group, 487 patients received antiviral treatment, including arbidol, lopinavir/ritonavir, interferon, ribavirin and chloroquine phosphate. In total, 254 patients (51.0%) received antibiotics, indicating the presence of secondary or concomitant bacterial infection. The symptomatic with pneumonia group had higher frequencies of antibiotic use (54.2%) and corticosteroid use (28.8) than the other groups (Table 3).
Table 3
Treatments and outcomes in symptomatic and asymptomatic COVID-19 cases
|
Symptomatic COVID-19
|
Asymptomatic COVID-19
|
|
Items
|
with pneumonia (n = 430)
|
without pneumonia (n = 31)
|
with pneumonia (n = 23)
|
without pneumonia (n = 14)
|
p-value
|
Treatments
|
|
|
|
|
|
Antiviral therapy
|
420 (97.7)
|
31 (100)
|
23 (100)
|
13 (92.9)
|
0.865
|
Abidol
|
200 (46.5)
|
16 (51.6)
|
14 (60.9)
|
6 (42.9)
|
0.543
|
Lopinavir/Ritonavir
|
310 (72.1)
|
24 (77.4)
|
10 (43.5) *
|
8 (57.1)
|
0.022
|
Interferon
|
259 (60.2)
|
24 (77.4)
|
14 (60.9)
|
8 (57.1)
|
0.295
|
Ribavirin
|
44 (10.2)
|
2 (6.5)
|
2 (8.7)
|
1 (7.1)
|
0.876
|
Chloroquine phosphate
|
53 (12.3)
|
2 (6.5)
|
4 (17.4)
|
2 (14.3)
|
0.635
|
Antibiotic therapy
|
233 (54.2)*
|
11 (35.5)
|
7 (30.4)*
|
3 (21.4)*
|
0.004
|
Administration of corticosteroids
|
124 (28.8)*
|
2 (6.5)*
|
0 (0)*
|
0 (0)*
|
< 0.001
|
Noninvasive mechanical ventilation
|
18 (4.2)
|
0 (0)
|
0 (0)
|
0 (0)
|
0.121
|
Invasive mechanical ventilation
|
11 (2.6)
|
0 (0)
|
0 (0)
|
0 (0)
|
0.229
|
ECMO
|
7 (1.6)
|
0 (0)
|
0 (0)
|
0 (0)
|
0.339
|
CRRT
|
9 (2.1)
|
0 (0)
|
0 (0)
|
0 (0)
|
0.278
|
Clinical outcomes
|
|
|
|
|
|
Severe cases
|
61 (14.2)*
|
3 (9.7)
|
0 (0)
|
0 (0)
|
0.011
|
Admission to ICU
|
46 (10.7)*
|
1 (3.2)
|
0 (0)
|
0 (0)
|
0.019
|
ARDS
|
18 (4.2)
|
0 (0)
|
0 (0)
|
0 (0)
|
0.121
|
Death
|
3 (0.7)
|
0
|
0
|
0
|
0.533
|
Duration of viral shedding, days
|
14.0 (9.0–21.0)
|
15.0 (8.8–23.8)
|
13.0 (7.0–19.0)
|
13.0 (8.3–17.8)
|
0.524
|
Duration of hospitalization, days
|
16.0 (11.5–24.0)
|
16.0 (10.0–23.0)
|
16.0 (11.0–22.0)
|
12.0 (8.8–17.0)*
|
0.234
|
Notes: Values are presented as median (IQR) or number (percentage); * p < 0.05 compared with other groups combined; p values were compared by Chi-square test, Fisher’s exact test or One-way ANOVA.
Legends: ECMO - Extracorporeal membrane oxygenation, CRRT - Continuous renal replacement therapy, ARDS - acute respiratory distress syndrome; ICU - intensive care unit.
Both noninvasive (18, 4.2%) and invasive mechanical ventilation (11, 2.6%) were used in only the symptomatic with pneumonia group (Table 3). Likewise, extracorporeal membrane oxygenation (ECMO) and continuous renal replacement therapy (CRRT) were employed in only the symptomatic with pneumonia group (Table 3). The above results indicated that patients in the symptomatic with pneumonia group suffered from more severe conditions and consumed more medical resources than those in the other groups.
All 64 severe cases occurred in symptomatic COVID-19 patients; 47 of them were admitted to the intensive care unit (ICU), of which 18 developed acute respiratory distress syndrome (ARDS) and 3 died. Of the 430 symptomatic with pneumonia patients, 61 (14.2%) were had severe COVID-19, and 46 (10.7%) were admitted to the ICU, implying that patients in the symptomatic with pneumonia group were more likely to develop severe COVID-19 and be admitted to the ICU than those in the other groups (Table 3). Interestingly, we did not find differences in the duration of viral shedding and hospitalization among the groups.