A total of 63 patients admitted to our hospital between March 13th and April 08th, 2020, were included; 2 patients were excluded because of simultaneous bacterial pneumonia present on admission.
The demographic, clinical, radiological and biological characteristics of patients are summarized in Table 1. Median age was 65 years (interquartile range [IQR] 57–76 years), with 56% (34/61) of males. At least 1 comorbidity was present in 80% (49/61) of patients, with majority of hypertension (56%) and diabetes (43%). The median delay between symptom onset and admission to hospital was 8 days (IQR, 5–12 days).
The PSI score was 1 or 2 for 24 patients (39%), 3 for 10 patients (16%), and 4 or 5 for 27 patients (44%). Regarding the ISS, patients were mostly in the high severity group (28/61, 46%).
CT scans were realized in 51 patients: 19 (37%) patients with scores 0–2, 15 (29%) in score 3, 17 (33%) in scores 4 or 5.
Median CRP level on admission was 108 mg/L (IQR, 48–174 mg/L).
Oxygen therapy has been used for at least one day in 82% (50/61) of patients, with a median duration of 9 days. Moreover, 30 (49%) patients required ICU admission: 17 (28%) were directly admitted in ICU, whereas 13 (21%) were transferred secondarily from a medical ward with a majority (11/13) being transferred during the first week of their hospital stay.
Finally, 20 (33%) patients needed mechanical ventilation, and 10 (16%) died. Median length of hospital stay (LOS) was 10 days (IQR, 6–16 days).
Of the 51 survivors, 49 patients were discharged. One patient was still in ICU but without invasive ventilation, and one patient was still in a medical ward without oxygen requirement.
Correlation of CRP with clinical and radiological severity on admission
Using the PSI while grouping the 5 risk classes into 3 (classes 1–2, 3 and 4–5), there was no statistical difference for CRP levels between these 3 groups (p = 0.212 and p = 0.104, see Figure 1A). Using the ISS, median (IQR) CRP levels were significantly different with respectively 18 (5–54), 130 (50–147) and 169 (97–241) mg/L in the low, intermediate and high severity groups. (p = 0.004 and p = 0.017, see Figure 1A).
Similarly, radiological score, while grouping the 6 scores into 3 categories (£25%, 26–50% and > 50% lung involvement), was also related to the level of CRP (p = 0.032 and p = 0.049, see Figure 1A).
Correlation of CRP on admission with respiratory support and death
As illustrated in Figure 1B, CRP levels on admission were significantly higher in patients requiring oxygen therapy (p = 0.0001) and in patients requiring mechanical ventilation (p = 0,0004) at any moment during their hospital stay, compared to patients not needing these supports. CRP was also significantly higher (p = 0.0013) in non-survivors compared to survivors. Using a cut-off of 100 mg/L, obtaining 2 groups of 28 and 33 patients, all those having a CRP value on admission > 100 mg/L (33/33) will need oxygen therapy at some point. Furthermore, all the patients who died were in this group (10/33, 30%), while no deaths occurred in patients having a CRP level on admission < 100 mg/L.
Finally, as we can see on Figure 1B, the kinetics of CRP during the 7 first days of hospitalization were clearly different between ventilated patients showing increasing levels of CRP and non-ventilated patients showing decreasing levels, with a significant difference at each time-point.