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Association between TV viewing and heart disease mortality: observational study using negative control outcome
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  • Published on:
    Are Associations Between Television Viewing and Mortality Due to Confounding?
    • Sarah K Keadle, Assistant Professor Department of Kinesiology and Public Health, California Polytechnic State University , San Luis Obispo
    • Other Contributors:
      • Charles E. Matthews, Senior Investigator
      • Pedro Saint-Maurice, Postdoctoral Fellow
      • Alpa V. Patel, Sr Scientific Director

    We read with great interest the report from Hamer and colleagues that examined the hypothesis that associations between television (TV) viewing and mortality from heart disease (HD) are due to confounding (1). They employed a negative control approach (2) and report evidence of associations between TV viewing and HD mortality (HR=1.09 [1.06, 1.12] per 1 hr/day increase in TV) and accidental deaths (the negative control outcome; HR=1.06 [0.98, 1.15]) after adjusting for age, sex, smoking, education, and prevalent HD (1)

    The positive association between TV and accidental deaths was interpreted as evidence that the TV-HD mortality association was due to confounding. Although key study limitations were noted including a small number of accidental deaths and limited adjustment for confounding, the authors concluded that “observed associations between TV and HD are likely to be driven by confounding”. Although we agree that confounding is a worrisome threat to the internal validity of epidemiologic studies, we believe that the conclusion in the Hamer report is overstated.

    A critical additional strategy to understand bias due to confounding, one that was not employed in the current study, is to examine relevant results from published studies conducted in different study populations using different methods. (2) We previously reported results in two studies that examined associations for accidental deaths and HD mortality with TV viewing (3) and leisure-time sitti...

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    Conflict of Interest:
    None declared.