Demographics, General Conditions, and the COVID-19 Classification
A total of 1,183 cases were enrolled, including 538 cases (45.48%) in the CUD group and 645 cases in the non-CUD group. There were 378 cases of hypertension (prevalence rate 31.95%, 378/1183), 164 cases of diabetes (prevalence rate 13.86%, 164/1183), 117 cases of respiratory disease (prevalence rate 9.89%, 117/1183), 81 cases of heart disease (prevalence rate 6.85%, 81/1183), and 40 cases of cerebral infarction (prevalence rate 3.38%, 40/1183) in the CUD group. Some patients presented with multiple underlying diseases. Of the 1,183 cases, 486 were male and 697 were female, with a male-to-female ratio of 1:1.43. There were 243 males and 295 females in the CUD group, with a male-to-female ratio of 1:1.21, and 243 males and 402 females in the non-CUD group, with a male-to-female ratio of 1:1.65.
The average age of the 1,183 patients was 58.76 ± 15.32 years. There were statistically significant differences in gender, age, weight, systolic blood pressure, and SpO2 between the two groups upon admission to the hospital. There was no statistically significant difference in height, body temperature, pulse rate, respiratory rate, or diastolic pressure.
In the CUD group, there was one mild case, 418 moderate cases, 100 severe cases, and 19 critical cases. In the non-CUD group, there were two mild cases, 584 moderate cases, 46 severe cases, and 13 critical cases. There was a total of 178 severe and critical cases between the two groups, accounting for 15.05%. The total proportion of severe and critical cases in the CUD group was 21.12%, while the total proportion of severe and critical cases in the non-CUD group was 9.15%, and the difference between the two groups was statistically significant (χ2 = 38.61, p-value < 0.001). Comparisons of the general conditions between the two groups is shown in table 1.
The white blood cell count, neutrophil count, C-reactive protein, urea nitrogen, creatinine, and cardiac troponin were significantly higher in the CUD group compared with the non-CUD group, while the lymphocyte count and albumin were significantly lower in the CUD group than that in the non-CUD group. There was no significant difference in procalcitonin, monocyte count, alanine aminotransferase, aspartate aminotransferase, total bilirubin, direct bilirubin, coagulation function indexes, erythrocyte sedimentation rate, or other indicators between the two groups. Details of the results of the two groups are shown in table 2.
SARS-CoV-2 Nucleic Acid and Antibody Tests
The average total number of nucleic acid tests for the 1,183 patients during hospitalization was 2.64 ± 1.11, among which the number of positive results was 0.24 ± 0.58, and the number of negative results was 2.39 ± 0.79. There was no significant difference in the total number of nucleic acid tests, the number of positive results, or the number of negative results between the two groups. Of the 1,183 confirmed cases, 458 had negative nucleic acid test results from disease onset to discharge (accounting for 38.72%), including 215 patients in the CUD group (accounting for 39.96%) and 243 patients in the non-CUD group (accounting for 37.67%); the difference between the two groups was not significantly significant (χ2 = 0.65, p-value = 0.421). The conditions of nucleic acid tests in the two groups are shown in table 3.
Among the 1,183 patients, 983 patients received tests for both IgG and IgM antibodies against SARS-CoV-2, 108 patients received tests for only IgM antibody, and 92 patients not receive any test for IgG or IgM antibody. As is shown in table 4, 734 (74.67%, 734/983) showed positive results for both antibodies while 155 (15.77%, 155/983) patients showed negative results for both antibodies. The 155 cases with negative results for both IgG and IgM antibodies were confirmed for COVID-19 by nucleic acid tests. Among those 155 cases, 80 (14.87%, 80/538) cases had underlying diseases while 75 (11.63%, 75/645) cases had no underlying disease and the difference between the two groups was statistically significant (χ2 = 5.57, p-value = 0.018).
Treatment and Prognosis
In both groups, mild and moderate cases were given symptomatic support treatment, while severe and critical cases were given oxygen inhalation, nutritional support, antiviral treatment, and as necessary, assisted respiration treatment.
The length of hospital stay in the CUD group was 13.15 ± 5.21 days and 11.88 ± 4.84 days in the non-CUD group (t = -4.30, p-value < 0.001). A total of 31 patients dead during hospitalization with a mortality rate of 2.62% (31/1183). There were 18 deaths (a mortality rate of 3.35%, 18/538) in the CUD group and 13 deaths (a mortality rate of 2.02%, 13/645) in the non-CUD group, however, the difference was not statistically significant (χ2 = 2.03, p-value = 0.154). All surviving patients were cured and discharged.
Two-week home quarantine was still required for the discharged patients, and SARS-CoV-2 nucleic acid tests were carried out on the 7th day and 14th day after discharge. A total of 33 patients had positive nucleic acid test results in the re-test one week after discharge (an incidence rate of 2.79%), including 14 patients with underlying diseases (an incidence rate of 2.60%, 14/538) and 19 patients without underlying diseases (an incidence rate of 2.95%, 19/645), without a statistically significant difference between the two groups (χ2 = 0.13, p-value = 0.721). Those 33 patients continued to receive treatment.