Demographic and clinical characteristics
During the study period, PCR was performed in 265 consecutive patients with suspected SARS-CoV-2 infection; 191 patients (72.1%) were confirmed SARS-CoV-2 cases. Of them, 164 patients (85.8%) met all the study criteria. In this population, 52 patients recovered (31.7%) and 112 (68.3%) died during hospitalization. (Figure 1)
The demographic and clinical characteristics of the patients are shown in Table 1. All patients were residents of Mexico City. The median age was 52.5 years (IQR 44 to 64.5), 68% (n=112) were male, median schooling was 9 years (IQR: 6 to 9), 48.7% (n= 74) were obese, 29% (n =44) were overweight, median BMI was 29.3 kg/m2 (IQR 25.5 to 34.7) and 24.3% (n=40) had a history of smoking. A total of 59.7% (n= 98) had comorbidities; diabetes (37.8%) and hypertension (37%) were the most common.
Comparing surviving vs. deceased patients, age (median 47.5 years [IQR: 38-54] vs. 55 years [IQR: 46.5-65.7], p <0.001), diabetes prevalence (21% vs. 45.5%, p 0.003), and smoking index (median of 1 pack/year vs 6 packs/year, p 0.005 were higher in deceased patients. Schooling (median of 9 years [IQR 6 to 12] vs. 7 years [IQR 6 to 9], p 0.01) was lower in deceased patients.
Comparing intubated vs. non-intubated patients, male sex (p 0.036), older age (p 0.024), and a higher smoking index (p 0.002) were observed in patients who needed mechanical ventilation.
Signs and symptoms
Clinical evaluation is summarized in Table 2. The most common symptoms were dyspnea in 82.9% (n=136), cough in 75.6% (n=124), fever in 69% (n=131), myalgias in 44% (n=72) and headache in 40.2% (n=66). On admission, the most common findings at physical examination were pharyngeal hyperemia in 15.2% (n=25) and cyanosis in 8.5% (n=14).
When comparing surviving vs deceased groups, dyspnea (73% in the survivor group vs. 83% in deceased group, p 0.02) and cyanosis (1.9% vs. 11.6%, p 0.03) were more frequently observed in deceased patients. Comparing the intubated vs. non-intubated groups, cyanosis (p 0.03) was associated with the requirement of mechanical ventilation.
At admission, only 17.6% (n=29) of patients presented with fever. During hospitalization, 62.2% (n=109) of patients continued or developed fever. The onset of fever in initially afebrile patients was a median of 2 days after admission (IQR 1-3). Comparing groups, fever at hospitalization (32.7% in the survivor group vs. 76% in the deceased group, p <0.001) with a higher temperature during hospitalization (median 37°C [IQR: 36.8-38.5] vs. 39°C [IQR: 38.2-40], p <0.001) were frequently observed in deceased patients who needed mechanical ventilation.
Radiographic and laboratory findings
Radiographic and laboratory features are summarized in Table 3. The most common findings were ground-glass opacities, interstitial abnormalities, and bilateral infiltrates. No difference was found in the radiographic features between groups.
With respect to laboratory findings, low PaO2/FiO2 ratio (mean 213 +/- 107), high WBC count (median 11,050 per mm3, IQR: 7,900-15,100), high neutrophil count (median 9,250 per mm3, IQR:6,475-13,025), high neutrophil-lymphocyte ratio (median 11, IQR: 6.5-19), high lactate dehydrogenase (median 406 U/L, IQR: 322-570), high D-dimer (median 1740 ng/ml, IQR: 728-3380), increased glucose (median 123 mg/dl, IQR: 93-198) and high C-reactive protein (median 21.4 mg/dl, IQR: 12-32) were observed.
After comparing surviving and deceased patients, the deceased group had lower PaO2/FiO2 ratio (mean 274 vs 184, p<0.001), higher WBC count (median 8,700 per mm3 vs 12,000 per mm3, p <0.001), increased neutrophil count (median 6,900 per mm3 vs 10,700 per mm3, p <0.001), higher neutrophil-lymphocyte ratio (median 7.6 vs 13, p <0.001), increased lactate dehydrogenase (median 322 U/L vs 482 U/L, p <0.001), increased D-dimer (median 845 ng/ml vs 2235 ng/ml, p <0.001), elevated glucose (median 101 mg/dl vs 138 mg/dl, p <0.001), and higher C-reactive protein (median 12 mg/dl vs 26.2 mg/dl, p <0.001) levels. The same findings with statistical significance (p <0.05) were observed in patients who needed mechanical ventilation.
Treatments and complications
Treatments and complications are described in Table 4. Overall, patients had a median hospital stay of 7 days (IQR: 4-11). Regarding treatment, 98.7% (n=162) had oxygen therapy, 76.2% (n=125) received oral antibiotics, 70.7% (n=116) received intravenous antibiotics, 59.8% (n=98) received hydroxychloroquine, and 25% (n=41) received systemic steroids. The most common complications during hospitalization were acute kidney injury (36%, n=59) and acute respiratory distress syndrome (34.8%, n= 57). Sixty-seven percent (n=110) of the patients required invasive mechanical ventilation, and 32.3% (n=53) needed vasopressor support.
Regarding in-hospital mortality, fewer days of hospital stay (median 10 days, IQR: 7-16 vs 5 days, IQR: 3.2-9, p <0.001), higher use of intravenous antibiotics (52% vs 79.5%, p <0.001), higher use of systemic steroids (13.5% vs 30.4%, p 0.02), higher incidence of ARDS (5.8% vs 48.2%, p <0.001) and AKI prevalence (11.5% vs 47.3%, p <0.001), and higher use of vasopressor support (3.8% vs 45.5%, p <0.001) were observed in deceased patients.
Risk factors for death
We summarize the analysis of risk factors for in-hospital mortality in Table 5. Mortality was significantly higher in patients who were male (RR 2.1, 95% CI 1.02-4.51, p 0.04), aged >50 years (RR 2.3, 95% CI 1.49-3.83, p <0.001), diabetes (RR 3.07, 95% CI 1.28-7.37, p 0.012), severe pneumonia at admission (RR 14.1, 95% CI 1.66-120.22, p 0.015), PORT/PSI score >91 (RR 6.5, 95% CI 1.33-32.23, p 0.021), SMART-COP score > 5 (RR 6.79, 95% CI 1.65-27.86, p 0.008), SCAP score >10 (RR 4.86, 95% CI 1.18-19.92, p 0.028), dyspnea at admission (RR 3.55, 95% CI 1.16-10.85, p 0.026), fever during hospitalization (RR 6.83, 95% CI 2.43-19.13, p <0.001), and were administered intravenous antibiotics (RR 3.45, 95% CI 1.69-7.06, p <0.001).