EPIDEMIOLOGICAL CHARACTERISTICS AND SEVERITY OF OMICRON VARIANT CASES IN THE APHP CRITICAL CARE UNITS
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Abstract
Importance
Information about the severity of Omicron is scarce.
Objective
To report the respective risk of ICU admission in patients hospitalized with Delta and Omicron variants and to compare the characteristics and disease severity of critically ill patients infected with both variants according to vaccination status.
Design
Analysis from the APHP database, called Reality, prospectively recording the following information in consecutive patients admitted in the ICU for COVID-19: age, sex, immunosuppression, vaccination, pneumonia, need for invasive mechanical ventilation, time between symptom onset and ICU admission, and in-ICU mortality. Retrospective analysis on an administrative database, “Système d’Information pour le Suivi des Victimes” (SI-VIC), which lists hospitalized COVID-19 patients.
Setting
39 hospitals in the Paris area from APHP group.
Participants
Patients hospitalized from December 1, 2021 to January 18, 2022 for COVID-19.
Main outcomes and measures
Risk of ICU admission was evaluated in 3761 patients and Omicron cases were compared to Delta cases in the ICU in 888 consecutive patients.
Results
On January 18, 45% of patients in the ICU and 63.8% of patients in conventional hospital units were infected with the Omicron variant (p < 0.001). The risk of ICU admission with Omicron was reduced by 64% than with Delta (9.3% versus 25.8% of cases, respectively, p < 0.001). In critically ill patients, 400 had the Delta variant, 229 the Omicron variant, 98 had an uninformative variant screening test and 161 did not have information on variant screening test. 747 patients (84.1%) were admitted for pneumonia. Compared to patients infected with Delta, Omicron patients were more vaccinated (p<0.001), even with 3 doses, more immunocompromised (p<0.001), less admitted for pneumonia (p<0.001), especially when vaccinated (62.1% in vaccinated versus 80.7% in unvaccinated, p<0.001), and less invasively ventilated (p=0.02). Similar results were found in the subgroup of pneumonia but Omicron cases were older. Unadjusted in-ICU mortality did not differ between Omicron and Delta cases, neither in the overall population (20.0% versus 27.9%, p = 0.08), nor in patients with pneumonia (31.6% versus 29.7%, respectively) where adjusted in-ICU mortality did not differ according to the variant (HR 1.43 95%CI [0.89;2.29], p=0.14).
Conclusion and relevance
Compared to the Delta variant, the Omicron variant is less likely to result in ICU admission and less likely to be associated with pneumonia. However, when patients with the Omicron variant are admitted for pneumonia, the severity seems similar to that of patients with the Delta variant, with more immunocompromised and vaccinated patients and no difference in adjusted in-ICU mortality. Further studies are needed to confirm our results.
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SciScore for 10.1101/2022.01.25.22269839: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Ethics not detected. Sex as a biological variable not detected. Randomization not detected. Blinding not detected. Power Analysis not detected. Table 2: Resources
No key resources detected.
Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).
Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:Our study has some limitations. First, there was a discrepancy between the numbers of critically ill patients with the Delta or Omicron variant in the Reality registry (629 patients) and in the administrative databases (579 patients). As noted in the …
SciScore for 10.1101/2022.01.25.22269839: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Ethics not detected. Sex as a biological variable not detected. Randomization not detected. Blinding not detected. Power Analysis not detected. Table 2: Resources
No key resources detected.
Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).
Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:Our study has some limitations. First, there was a discrepancy between the numbers of critically ill patients with the Delta or Omicron variant in the Reality registry (629 patients) and in the administrative databases (579 patients). As noted in the methods section, the explanation is that all but one hospital of the APHP group collected patient information in the laboratory information system. In Reality, variant screening test information was missing in 18% of cases, which could be explained by the fact that numerous patients were transferred to the ICU from another non-APHP hospital where they had already tested positive. As the test was not performed again we were not able to characterize the variant. Second, we did not have the time between the last injection of vaccine and admission to the ICU, which could limit our evaluation of the impact of vaccination on the Omicron variant. Third, in the adjusted risk of in-ICU mortality evaluation, some confounding factors may not have been taken into account and we do not have information on “do-not-intubate” decision in some patients. Finally, while to our knowledge we report here the largest cohort of critically ill patients comparing Delta and Omicron variant, our results should be confirmed in a larger cohort. A significant number of patients are still in the ICU, especially with the Omicron variant, which precludes any definitive conclusion regarding their respective outcomes.17 In conclusion, our study reports contrasting ...
Results from TrialIdentifier: No clinical trial numbers were referenced.
Results from Barzooka: We did not find any issues relating to the usage of bar graphs.
Results from JetFighter: We did not find any issues relating to colormaps.
Results from rtransparent:- Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
- Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
- No protocol registration statement was detected.
Results from scite Reference Check: We found no unreliable references.
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