• Selection bias may lead to underestimati

    From ScienceDaily@1:317/3 to All on Thu Apr 28 22:30:44 2022
    Selection bias may lead to underestimation of risk of CTE in former
    football players
    New statistical methods to prove that dose-response relationship cannot
    be due to sampling bias

    Date:
    April 28, 2022
    Source:
    Boston University School of Medicine
    Summary:
    Researchers have been studying chronic traumatic encephalopathy
    (CTE) and while much has been learned, diagnosing the disease still
    needs to be done post-mortem on autopsied brains donated to a brain
    bank. One criticism of the research is that brain bank study results
    have a selection bias because they are based on a subset of players
    most affected by CTE, and therefore not representative of the
    population of football players. Now a novel study by researchers
    from BUSM and Boston University School of Public Health (BUSPH)
    provides further evidence suggesting a dose-response relationship
    between football and CTE even after adjusting for selection bias.



    FULL STORY ========================================================================== Since 2008, Boston University School of Medicine (BUSM) researchers
    have been studying chronic traumatic encephalopathy (CTE) and while
    much has been learned, diagnosing the disease still needs to be done post-mortem on autopsied brains donated to a brain bank. One criticism
    of the research is that brain bank study results have a selection bias
    because they are based on a subset of players most affected by CTE,
    and therefore not representative of the population of football players.


    ==========================================================================
    Now a novel study by researchers from BUSM and Boston University
    School of Public Health (BUSPH) provides further evidence suggesting a dose-response relationship between football and CTE even after adjusting
    for selection bias.

    CTE is a progressive brain disease associated with repetitive head
    impacts. It has been diagnosed after death in American football players
    and other contact sport athletes as well as members of the armed services
    and victims of physical abuse.

    "The validity of research involving CTE has been questioned due to the
    inherent bias in the selection process of brain donation studies. A prior
    BUSM study that identified a strong dose-response relationship between
    years of football played and likelihood of developing CTE, which supports
    a cause-effect relationship between repeated head impacts and CTE, has
    been ignored by some sports organizations due to claims of selection
    bias. To respond to such criticism, there is a significant need to adjust
    for it in the analytical phases of these studies," explains corresponding author Yorghos Tripodis, PhD, professor of biostatistics at BUSPH.

    Utilizing data from Veterans Affairs-Boston University-Concussion Legacy Foundation (VA-BU-CLF) Brain Bank, the researchers undertook a new
    study to analyze 290 male former football players to further clarify
    the dose-response relationship. After developing multiple statistical
    models to adjust for selection bias, college and professional football
    players respectively were found to have a 2.38 and 2.47 times higher
    risk of being diagnosed with CTE relative to high school players.

    "Strikingly, these risk ratios were actually heightened after accounting
    for selection bias. This is in stark comparison to the previous critiques received as it suggests that prior data may actually underestimate risk
    of CTE in these populations," said Tripodis.

    The researchers also calculated the minimum cumulative incidence of CTE
    for different levels of play. They found the minimum possible cumulative incidence for professional players is one in 10, one in 250 for college football players, and 1 in 20,000 for high school players. However,
    they anticipate future studies will reveal the actual risk is many times
    higher for each level of play.

    The authors end by prompting the need for further investigation into
    the type of participants that are under-represented in the brain bank
    leading to this selection bias and the need for additional recruitment
    efforts targeted at these populations to allow for additional study.

    "Our new study provides further evidence to support a dose-response relationship between playing football and developing CTE. We hope the
    football community will accelerate reforms aimed at preventing CTE
    by limiting head impacts for players and that parents will use this
    information to make more informed choices about sports participation
    for their children," he adds.

    These findings appear online in the American Journal of Epidemiology.

    Funding for this research was provided by the: The National Institute
    of General Medical Sciences (NIGMS) Interdisciplinary Training Grant for Biostatisticians (T32 GM74905); NIH National Institute on Aging (AG057902, AG06234, RF1AG054156, P30AG13846; supplement 0572063345, R01AG057902, R01AG061028, K23AG046377, R01AG1649, R21HD089088, F32NS096803); NIH
    National Institute of Neurological Disorders and Stroke (U54NS115266, U01NS086659, U01NS093334, K23NS102399, R01NS078337, R56NS078337); National Institute of Aging Boston University AD Center (P30AG13846; supplement 0572063345-5); Department of Veterans Affairs (I01 CX001135, CSP 501,
    B6796?C); Department of Defense (W81XWH?13?2?0095, W81XWH?13?2?0064, W81XWH1810580, PRARP?13267017); the Nick and Lynn Buoniconti Foundation;
    and BU-CTSI Grant Number 1UL1TR001430.


    ========================================================================== Story Source: Materials provided by
    Boston_University_School_of_Medicine. Note: Content may be edited for
    style and length.


    ========================================================================== Journal Reference:
    1. Jessica LeClair, Jennifer Weuve, Matthew P Fox, Jesse Mez, Michael L
    Alosco, Chris Nowinski, Ann McKee, Yorghos Tripodis. Selection
    Bias Analysis Supports Dose-Response Relationship between Level
    of American Football Play and Chronic Traumatic Encephalopathy
    Diagnosis. American Journal of Epidemiology, 2022; DOI:
    10.1093/aje/kwac075 ==========================================================================

    Link to news story: https://www.sciencedaily.com/releases/2022/04/220428103958.htm

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