Clinical spectrum of coronavirus disease 2019 in Iceland: population based cohort study

  1. Elias Eythorsson
  2. Dadi Helgason
  3. Ragnar Freyr Ingvarsson
  4. Helgi K Bjornsson
  5. Lovisa Bjork Olafsdottir
  6. Valgerdur Bjarnadottir
  7. Hrafnhildur Linnet Runolfsdottir
  8. Solveig Bjarnadottir
  9. Arnar Snaer Agustsson
  10. Kristin Oskarsdottir
  11. Hrafn Hliddal Thorvaldsson
  12. Gudrun Kristjansdottir
  13. Brynja Armannsdottir
  14. Agnar Bjarnason
  15. Birgir Johannsson
  16. Olafur Gudlaugsson
  17. Magnus Gottfredsson
  18. Martin I Sigurdsson
  19. Olafur S Indridason
  20. Runolfur Palsson

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Abstract

Objective

To characterise the symptoms of coronavirus disease 2019 (covid-19).

Design

Population based cohort study.

Setting

Iceland.

Participants

All individuals who tested positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by reverse transcription polymerase chain reaction (RT-PCR) between 17 March and 30 April 2020. Cases were identified by three testing strategies: targeted testing guided by clinical suspicion, open invitation population screening based on self referral, and random population screening. All identified cases were enrolled in a telehealth monitoring service, and symptoms were systematically monitored from diagnosis to recovery.

Main outcome measures

Occurrence of one or more of 19 predefined symptoms during follow-up.

Results

Among 1564 people positive for SARS-CoV-2, the most common presenting symptoms were myalgia (55%), headache (51%), and non-productive cough (49%). At the time of diagnosis, 83 (5.3%) individuals reported no symptoms, of whom 49 (59%) remained asymptomatic during follow-up. At diagnosis, 216 (14%) and 349 (22%) people did not meet the case definition of the Centers for Disease Control and Prevention and the World Health Organization, respectively. Most (67%) of the SARS-CoV-2-positive patients had mild symptoms throughout the course of their disease.

Conclusion

In the setting of broad access to RT-PCR testing, most SARS-CoV-2-positive people were found to have mild symptoms. Fever and dyspnoea were less common than previously reported. A substantial proportion of SARS-CoV-2-positive people did not meet recommended case definitions at the time of diagnosis.

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  1. Version published to 10.1136/bmj.m4529
  2. ScreenIT

    SciScore for 10.1101/2020.08.09.20171249: (What is this?)

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

    Table 1: Rigor

    Institutional Review Board StatementIRB: The study was approved by the National Bioethics Committee (VSN-20-078).
    RandomizationFinally, a randomly chosen sample of 6782 Icelanders was offered testing via telephone text message on March 31 and April 1, 2020, of whom 2283 were included.
    Blindingnot detected.
    Power Analysisnot detected.
    Sex as a biological variablenot 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:
    This study does have some limitations. In order to accurately describe symptom progression, cases diagnosed before the implementation of the standardized clinical data entry form were excluded from the analysis of symptom development, representing 11% of all SARS-CoV-2-positive cases in Iceland. The date of implementation of the standardized data entry form was not influenced by the clinical characteristics of the patients being diagnosed, and therefore should not introduce bias. Furthermore, the demographics and clinical characteristics of excluded cases were largely comparable to those that were included in the study. Another limitation is that daily standardized documentation of symptoms was not available during hospital admission. This could conceivably lead to an underestimation of severe symptoms such as dyspnea. However, only 3.5% of the included patients were hospitalized, and symptoms prior to hospitalization were included in the analysis. It is important to note that the data were based on self-reported symptoms via telephone calls. This shortcoming is mitigated by the fact that experienced nurses and physicians conducted the interviews. A principal strength of the study is its population-based approach, which included all confirmed cases in the country during the study period, regardless of their need for medical care. Conclusion: This study describes the symptomatology and clinical severity of the initial phase of COVID-19 in Iceland. The incidence of COVID-19 was...

    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.

    About SciScore

    SciScore is an automated tool that is designed to assist expert reviewers by finding and presenting formulaic information scattered throughout a paper in a standard, easy to digest format. SciScore checks for the presence and correctness of RRIDs (research resource identifiers), and for rigor criteria such as sex and investigator blinding. For details on the theoretical underpinning of rigor criteria and the tools shown here, including references cited, please follow this link.

  3. Version published to 10.1101/2020.08.09.20171249v1 on medRxiv