Herein, we report results of the first comparison of clinical characteristics and risk factors among hospitalized patients with SARS-CoV-2, MERS-CoV, or SARS-CoV infection. In our statistical analysis of the available published data, we determined that man sex and hypertension were the most common risk factors for COVID-19. Moreover, in comparison with patients with SARS or MERS, patients with COVID-19 showed lower prevalence of fever, diarrhea, vomiting, or nausea, but higher prevalence of cough symptoms thrombocytopenia, high LDH, and elevated CRP.
For all three CoVs investigated, men were found to be relatively more susceptible than women; we also identified a higher sex ratio in our study population than that in the general population of China, which may be a trait of CoV infection (Table 1). Surprisingly, in patients with COVID-19 who had high blood pressure, although the prevalence was higher than that among patients with SARS, it is still significantly lower the prevalence of hypertension in the national population of China. Among the CoV infection groups, the median age of patients with MERS is 57 years, and the prevalence of hypertension is significantly higher than the population average. However, the average age of patients with SARS or COVID-19 was younger (48 for COVID-19; 38 for SARS) (Tables 1 and 2), and these patients had a relatively low incidence of hypertension. Additionally, ACE2 has a strong affinity with the Ang II type 1 and type 2 receptors, regulating blood pressure, and the gene encodes a protein that is a functional receptor for the S glycoproteins of SARS-CoV-2 and SARS-CoV. Which may be another reason for the low incidence of hypertension in COVID-19.
Interestingly, we found that a smoking history was associated with lower risk of hospitalization among patients with COVID-19 than among the general Chinese population (p < 0.001). This finding may be owing to differences in the statistical methods used in the included studies, or owing to the small proportion of past smokers (only 3.1%) among women in our study 28. However, a similar phenomenon has been reported for other viral agents 29; this finding may be worth further investigation.
Among common symptoms of fever and cough, the proportion of patients with COVID-19 who had fever was significantly lower than that in patients with SARS or MERS (Table 3). The prevalence of coexisting chronic diseases among patients with COVID-19 was not only higher than that among patients with SARS and MERS but was also higher relative to the average in the Chinese population. It believed that the disease history, such as low immunity 30, will also influence the common symptoms, relative to SARS and MERS have more higher rate of disease history (Table 1). Symptoms of the digestive tract are also less frequent in COVID-19, and the effect of SARS-CoV-2 on the digestive tract may be more limited than that of other viruses 14. However, a recent study SARS-CoV-2 has been found in the feces of patients, indicating that fecal–oral transmission may be possible and replication in the digestive tract cannot be ruled out 31. The probability of cough symptoms was 68% overall, and among the subgroups, dry cough symptoms was the most frequent (Table 3). The cause of frequent dry cough is inflammation of the lungs, even with a small amount of phlegm. It is possible that patients with dry cough have very thick sputum that is difficult to discharge; therefore, patients in the hospital who have this symptom should be closely monitored.
In patients with COVID-19, prolific thrombocytopenia, hemoptysis, elevated LDH, and elevated CRP were common (Table 4). Decreased lymphocytes and elevated AST, ALT, and CK are common in patients with SARS and are associated with a more severe prognosis. In one study, elevated LDH was found to be a risk factor for acute respiratory distress syndrome (ARDS) in patients with SARS 32. In patients hospitalized for SARS, a lower absolute lymphocyte count was associated with poorer prognosis 33. Hematological and serum chemical abnormalities indicate that hospitalized patients with COVID-19 have serious systemic disease 34. It is yet to be determined whether this is the result of severe pneumonia and poor tissue oxygenation (such as in SARS) or an excessive inflammatory response 35. It is known that these indexes exist in patients with COVID-19; however, further research is needed to confirm the correlation with severity of disease and whether these affect the course of this disease.
Table 4
Laboratory results on admission
Characteristic | COVID-2019 | SARS | P Value | MERS | P Value |
White cell count | Mean = 4.7265 SD = 0.575 n = 1278 | Mean = 5.3444 SD = 1.8319 n = 641 | 1 | Mean = 6.8645 SD = 1.3215 n = 465 | 0.121 |
Lymphocyte count | Mean = 0.972 SD = 0.1973 n = 1278 | Mean = 3.4658 SD = 5.2006 n = 479 | 1 | 0/0 | N/A |
Neutrophil count | Mean = 4.0072 SD = 1.2314 n = 278 | Mean = 2.6316 SD = 2.1397 n = 563 | 0.439 | 0/0 | N/A |
Platelet count | Mean = 167.3318 SD = 12.3628 n = 1278 | Mean = 162.7621 SD = 48.867 n = 543 | 1 | Mean = 176.1774 SD = 28.3151 n = 465 | 1 |
AST | Mean = 33.9964 SD = 6.408 n = 278 | Mean = 36.7 SD = 10 n = 68 | 1 | Mean = 61.4839 SD = 13.9459 n = 465 | 0.121 |
ALT | Mean = 29.036 SD = 6.4906 n = 278 | Mean = 27.9671 SD = 36.4892 n = 243 | 1 | Mean = 39.2581 SD = 10.3953 n = 465 | 0.439 |
Serum creatinine | Mean = 72.5039 SD = 5.2549 n = 179 | Mean = 43.164 SD = 49.97 n = 371 | 1 | Mean = 111.8065 SD = 32.996 n = 465 | 0.121 |
CK | Mean = 95.4802 SD = 36.8267 n = 278 | Mean = 49.5151 SD = 131.0857 n = 292 | 1 | 0/0 | N/A |
LDH | Mean = 291.3957 SD = 49.3863 n = 278 | Mean = 308.1137 SD = 115.0849 n = 387 | 1 | 0/0 | N/A |
Leukopenia | 372/1146(32%) | 387/1267(31%) | 0.311 | 0/0 | N/A |
Lymphopenia | 81/169(48%) | 305/390(78%) | ༜0.001 | 0/0 | N/A |
Neutrophilia | 38/99(38%) | 0/0 | N/A | 0/0 | N/A |
Thrombocytopenia | 329/1008(33%) | 150/979(15%) | ༜0.001 | 0/0 | N/A |
Elevated AST | 203/885(23%) | 182/385(47%) | ༜0.001 | 203/245(83%) | ༜0.001 |
Elevated ALT | 213/910(23%) | 234/686(34%) | ༜0.001 | 107/275(39%) | ༜0.001 |
Elevated CK | 116/796(15%) | 311/1557(20%) | 0.001 | 0/0 | N/A |
Elevated CRP | 508/822(62%) | 97/190(51%) | 0.006 | 0/0 | N/A |
Elevated LDH | 401/843(48%) | 371/1499(25%) | ༜0.001 | 0/0 | N/A |
Abbreviations: COVID-19, coronavirus disease 2019; SARS, severe acute respiratory syndrome-associated coronavirus; MERS, Middle East respiratory syndrome-associated coronavirus. AST, aspartate transaminase; ALT, alanine transaminase; CK, creatinine kinase; CRP, C-reactive protein; LDH, lactate dehydrogenase. |
Certainly, there are some limitations in this study. First, this was a meta-analysis and there were some missing data. Second, COVID-19 is a newly identified infectious disease, the understanding of which is still evolving; some clinical data and outcomes may be updated in the future.