Potential Protective Effect from COVID-19 Conferred by Altitude: A Longitudinal Analysis in Peru During Full Lockdown

  1. Timothy M. Thomson
  2. Fresia Casas
  3. Harold Andre Guerrero
  4. Rómulo Figueroa-Mujíca
  5. Francisco C. Villafuerte
  6. Claudia Machicado

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Abstract

Thomson, Timothy M., Fresia Casas, Harold Andre Guerrero, Rómulo Figueroa-Mujíca, Francisco C. Villafuerte, and Claudia Machicado. Potential protective effect from COVID-19 conferred by altitude: A longitudinal analysis in Peru during full lockdown. High Alt Med Biol . 22: 209–224, 2021.

The COVID-19 pandemic had a delayed onset in America. Despite the time advantage for the implementation of preventative measures to contain its spread, the pandemic followed growth rates that paralleled those observed before in Europe.

Objectives:

To analyze the temporal and geographical distribution of the COVID-19 pandemic at district-level in Perú during the full lockdown period in 2020.

Methods:

Analysis of publicly available data sets, stratified by altitude and geographical localization. Correlation tests of COVID-19 case and death rates to population prevalence of comorbidities.

Results:

We observe a strong protective effect of altitude from COVID-19 mortality in populations located above 2,500 m. We provide evidence that internal migration through a specific land route is a significant factor progressively overriding the protection from COVID-19 afforded by high altitude. This protection is independent of poverty indexes and is inversely correlated with the prevalence of hypertension and hypercholesterolemia.

Discussion:

Long-term adaptation to residency at high altitude may be the third general protective factor from COVID-19 severity and death, after young age and female sex. Multisystemic adaptive traits or acclimatization processes in response to chronic hypobaric hypoxia may explain the apparent protective effect of high altitude from COVID-19 death.

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  1. Version published to 10.1089/ham.2020.0202
  2. ScreenIT

    SciScore for 10.1101/2020.08.03.20167262: (What is this?)

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

    Table 1: Rigor

    Institutional Review Board Statementnot detected.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.
    Sex as a biological variablenot detected.

    Table 2: Resources

    Software and Algorithms
    SentencesResources
    Values for all variables were row median-normalized and subjected to PCA and CT as implemented in XLSTAT.
    XLSTAT
    suggested: (XLSTAT, RRID:SCR_016299)
    Generation of heatmaps: For heatmap generation, variables were row-normalized and heatmaps generated with the aid of Morpheus (https://software.broadinstitute.org/morpheus/).
    https://software.broadinstitute.org/morpheus/
    suggested: (Morpheus by Broad Institute, RRID:SCR_017386)
    Other statistical analyses: For non-paired, non-parametric data comparisons, Mann-Whitney tests were performed on GraphPad.
    GraphPad
    suggested: (GraphPad Prism, RRID:SCR_002798)

    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:
    However, these tests are applied to the general public free of charge by the Peruvian national health system, and there is no evidence of shortage of serological tests, although they are unevenly distributed throughout the territory (see Study Limitations). Likewise, high poverty levels could limit the availability of health care and may be expected to be associated with elevated case and death rates as observed elsewhere (e.g., https://www1.nyc.gov/site/doh/covid/covid-19-data.page). Contrary to this expectation, in our multivariate analyses, high poverty indexes were associated with higher altitude and lower, not higher, death rates. In conclusion, altitude appears to confer protection from COVID-19 incidence and death independent of population density and not offset by high poverty levels. The latter observation is at odds with the findings of the OpenSAFELY study, which detected an increased risk of COVID-19 death with greater deprivation in the United Kingdom8, not fully explained by pre-existing conditions or other risk factors. This reinforces the notion that additional local conditions are significant modifiers of sensitivity to COVID-19. We have found that the apparent protective effect of altitude was very strong when comparing populations below and above the accepted high-altitude threshold (2,500 m), with relative risks for low-altitude populations, both in coastal and Amazonian regions, between 6.5 and over 11-fold for cases and over 6.5 and 21.6-fold for deaths,...

    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

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  3. Version published to 10.1101/2020.08.03.20167262 on medRxiv