Lockdown and non-COVID-19 deaths: cause-specific mortality during the first wave of the 2020 pandemic in Norway: a population-based register study

  1. Guttorm Raknes
  2. Marianne Sørlie Strøm
  3. Gerhard Sulo
  4. Simon Øverland
  5. Mathieu Roelants
  6. Petur Benedikt Juliusson

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Abstract

To explore the potential impact of the first wave of COVID-19 pandemic on all cause and cause-specific mortality in Norway.

Design

Population-based register study.

Setting

The Norwegian cause of Death Registry and the National Population Register of Norway.

Participants

All recorded deaths in Norway from March to May from 2010 to 2020.

Main outcome measures

Rate (per 100 000) of all-cause mortality and causes of death in the European Shortlist for Causes of Death from March to May 2020. The rates were age standardised and adjusted to a 100% register coverage and compared with a 95% prediction interval (PI) from linear regression based on corresponding rates for 2010–2019.

Results

113 710 deaths were included, of which 10 226 were from 2020. We did not observe any deviation from predicted total mortality. There were fewer than predicted deaths from chronic lower respiratory diseases excluding asthma (11.4, 95% PI 11.8 to 15.2) and from other non-ischaemic, non-rheumatic heart diseases (13.9, 95% PI 14.5 to 20.2). The death rates were higher than predicted for Alzheimer’s disease (7.3, 95% PI 5.5 to 7.3) and diabetes mellitus (4.1, 95% PI 2.1 to 3.4).

Conclusions

There was no significant difference in the frequency of the major causes of death in the first wave of the 2020 COVID-19 pandemic in Norway compared with corresponding periods 2010–2019. There was an increase in diabetes mellitus and Alzheimer’s deaths. Reduced mortality due to some heart and lung conditions may be linked to infection control measures.

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  1. Version published to 10.1136/bmjopen-2021-050525
  2. ScreenIT

    SciScore for 10.1101/2021.02.09.21251326: (What is this?)

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

    Table 1: Rigor

    Institutional Review Board StatementConsent: [16] Prior consent to the storage of personal data in the register is not obtained, and it is not possible to opt out.
    IRB: Approval from the ethics committee or privacy ombudsman for research was neither required nor expedient.
    Randomizationnot detected.
    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:
    Another limitation is the large and diverse number of outcomes. We examined 83 EU shortlist causes of deaths without correcting for multiple testing. Even under normal circumstances it is therefore likely that some rates would fall outside the expected prediction interval. We could have used wider prediction intervals to adjust for multiple comparisons and avoid false positive findings, but this would at the same time increase the probability of a false negative finding. A comparison of the causes of death in Table 3 with a 99% prediction interval, shows that only diabetes mellitus remains significantly outside the predicted range. This means that great care should be taken when interpreting the results. Strengths & weaknesses in relation to other studies & key differences: We have been unable to identify other studies with similar focus. The SARS-COV-2 virus was only identified in December 2019, and access to high-quality data with sufficient detail in such a short time is limited. Some studies reported on all-cause mortality, [3,19] in relation to COVID-19 and infection control measures, but data on specific causes of death is usually lacking. Possible mechanisms & explanations for findings: Only 216 Norwegians died from COVID-19 in March to May 2020, and the infection rate was also very low. Reports from the Norwegian National Institute of Public Health even showed a lower-than-expected mortality in some of the weeks in the first wave of the pandemic, [20] indicating that ...

    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.
    • No funding statement was detected.
    • 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 10.1101/2021.02.09.21251326 on medRxiv