Comparison of outcomes from COVID infection in pediatric and adult patients before and after the emergence of Omicron

  1. Lindsey Wang
  2. Nathan A. Berger
  3. David C. Kaelber
  4. Pamela B. Davis
  5. Nora D. Volkow
  6. Rong Xu

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Abstract

Background

The Omicron SARS-CoV-2 variant is rapidly spreading in the US since December 2021 and is more contagious than earlier variants. Currently, data on the severity of the disease caused by the Omicron variant compared with the Delta variant is limited. Here we compared 3-day risks of emergency department (ED) visit, hospitalization, intensive care unit (ICU) admission, and mechanical ventilation in patients who were first infected during a time period when the Omicron variant was emerging to those in patients who were first infected when the Delta variant was predominant.

Method

This is a retrospective cohort study of electronic health record (EHR) data of 577,938 first-time SARS-CoV-2 infected patients from a multicenter, nationwide database in the US during 9/1/2021–12/24/2021, including 14,054 who had their first infection during the 12/15/2021–12/24/2021 period when the Omicron variant emerged (“Emergent Omicron cohort”) and 563,884 who had their first infection during the 9/1/2021–12/15/2021 period when the Delta variant was predominant (“Delta cohort”). After propensity-score matching the cohorts, the 3-day risks of four outcomes (ED visit, hospitalization, ICU admission, and mechanical ventilation) were compared. Risk ratios, and 95% confidence intervals (CI) were calculated.

Results

Of 14,054 patients in the Emergent Omicron cohort (average age, 36.4 ± 24.3 years), 27.7% were pediatric patients (<18 years old), 55.4% female, 1.8% Asian, 17.1% Black, 4.8% Hispanic, and 57.3% White. The Emergent Omicron cohort differed significantly from the Delta cohort in demographics, comorbidities, and socio-economic determinants of health. After propensity-score matching for demographics, socio-economic determinants of health, comorbidities, medications and vaccination status, the 3-day risks in the Emergent Omicron cohort outcomes were consistently less than half those in the Delta cohort: ED visit: 4.55% vs. 15.22% (risk ratio or RR: 0.30, 95% CI: 0.28-0.33); hospitalization: 1.75% vs. 3.95% (RR: 0.44, 95% CI: 0.38-0.52]); ICU admission: 0.26% vs. 0.78% (RR: 0.33, 95% CI:0.23-0.48); mechanical ventilation: 0.07% vs. 0.43% (RR: 0.16, 95% CI: 0.08-0.32). In children under 5 years old, the overall risks of ED visits and hospitalization in the Emergent Omicron cohort were 3.89% and 0.96% respectively, significantly lower than 21.01% and 2.65% in the matched Delta cohort (RR for ED visit: 0.19, 95% CI: 0.14-0.25; RR for hospitalization: 0.36, 95% CI: 0.19-0.68). Similar trends were observed for other pediatric age groups (5-11, 12-17 years), adults (18-64 years) and older adults (≥ 65 years).

Conclusions

First time SARS-CoV-2 infections occurring at a time when the Omicron variant was rapidly spreading were associated with significantly less severe outcomes than first-time infections when the Delta variant predominated.

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  1. ScreenIT

    SciScore for 10.1101/2021.12.30.21268495: (What is this?)

    Please note, not all rigor criteria are appropriate for all manuscripts.

    Table 1: Rigor

    EthicsIRB: Because this study only queried statistics of de-identified patient records through web-applications and did not involve retrieval, storage, collection, use, or transmittal of individually identifiable data, Institutional Review Board approval and informed consent was not needed or sought.
    Consent: Because this study only queried statistics of de-identified patient records through web-applications and did not involve retrieval, storage, collection, use, or transmittal of individually identifiable data, Institutional Review Board approval and informed consent was not needed or sought.
    Sex as a biological variablenot detected.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.

    Table 2: Resources

    Software and Algorithms
    SentencesResources
    diseases, chronic kidney diseases, liver diseases, HIV infection, dementia, substance use disorders, depression and anxiety (assessed by ICD-10 codes); behavioral factors (tobacco smoking, alcohol drinking) (assessed by one or more encounter based on ICD-10 codes); COVID-19-related medications10 including remdesivir, dexamethasone, hydrocortisone, tocilizumab, fluvoxamine, and fluoxetine (assessed by RxNorm codes); and vaccination status documented in patient EHRs (Pfizer, Moderna
    RxNorm
    suggested: (RxNorm, RRID:SCR_006645)

    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 several limitations: First, the observational, retrospective nature of this study of patient EHR data could introduce selection, information, testing, reporting and follow up issues. However, because we compared the different population all from the TriNetX dataset, these issues should not significantly affect the relative risk analyses. Second, patients in the TriNetX EHR database are those who had medical encounters with healthcare systems contributing to the TriNetX Platform and do not necessarily represent the entire US population. Therefore, results from the TriNetX platform need to be validated in other populations. Third, both the Emergent Omicron and Delta cohorts in our study were defined based on CDC’s national genomic sequence surveillance. The Emergent Omicron cohort likely contained some infections with the Delta variant, but this admixture would tend to reduce the observed differences. However, our findings of reduced hospitalization in the Emergent Omicron cohort compared to the Delta cohort is consistent with findings from Africa4, Scotland5, and England6 that were based on genomic sequences, and goes further to indicate that the severity in hospitalization is reduced. The fact that there were no marked differences between the two Delta cohorts yet significant differences between the Emergent Omicron and Delta cohorts further corroborates that the differences in outcomes for infections occurring between 12/15/2021–12/24/2021 were likely to be cau...

    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.

    About SciScore

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  2. Version published to 10.1101/2021.12.30.21268495v1 on medRxiv