Tag Archive for: hazard ratio

Nutritional Epidemiology: Specification Curve Analysis

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Did you look up quadrillion? It’s a 1 with a whole lot of 0s—15 to be exact.

When I finished Saturday’s Memo, the researchers had chosen an area of nutritional epidemiology to focus on: the analytics used to analyze the data. They began with the premise that there are many ways to analyze any data set. They then identified published research studies that examined the consumption of red meat and mortality. They identified 15 publications reporting on 24 studies that examined the effect of red meat on all-cause mortality.

They weren’t doing a meta-analysis to see all the results of all the studies combined; they used a newer technique called specification curve analysis. They identified the type of data used in the analysis, the number of variables, the number of covariates, as well as demographic data. From that information, they then calculated the total number of ways each data set could be analyzed—the specification curve analysis. Turns out that number is 10 quadrillion! That exceeds the capacity of the computing power of a small country, and I can’t even imagine how much electricity that would consume.

They decided to take a randomized sample of the possible ways to analyze the data with specific variables and covariates in each and came up with 1,440 different approaches to analyzing the data. They ran additional tests on the data and eliminated 232 approaches because the data exceeded norms.

Then they ran the remaining analytic approaches on data from several years of the NHANES study. What did they find?

  • The median hazard ratio (HR) was 0.94 for the effect of red meat on all-cause mortality. That means the mortality risk was decreased 6% if the subject ate red meat.
  • HRs ranged from 0.51 to 1.75; 435 approaches yielded HRs more than 1.0 (increased risk) and 773 less than 1.0 (decreased risk). Most analyses showed that eating red meat reduced the HR, and thus reduced the risk of dying.
  • Of all the results, 48 (almost 4%) were statistically significant; of those, 40 indicated that red meat reduced all-cause mortality and 8 that red meat increased all-cause mortality.

Does this mean that eating red meat decreases your risk of dying early? We’re not done yet. We’ll put it all in perspective on Saturday.

What are you prepared to do today?

        Dr. Chet

References:
1. https://www.sensible-med.com/p/the-definitive-analysis-of-observational
2. Journal of Clinical Epidemiology 168 (2024) 111278

Do Artificial Sweeteners Increase Cancer Risk?

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Last week, my health news feed filled up with headlines that almost all sounded like this: “Artificial Sweeteners Linked to Higher Cancer Risk!” This isn’t the first study to suggest that relationship and it won’t be the last. This French epidemiological study of over 100,000 subjects collected data for more than seven years. One of the things I almost always criticize is data collection using food frequency questionnaires. Not this time.

The subjects completed at least two food diaries per year. Portions were assessed by comparing with pictures of portions sizes. What they did particularly well is to list all the foods that contained artificial sweeteners, including all brand names; then they tested most of the foods in the lab to verify the presence of artificial sweeteners. Researchers collected as many confounding variables as they could to account for everything that contributes to cancer.

After the statistical analysis, the overall hazard ratio demonstrated a 13% increase in the risk of cancer. Aspartame and acesulfame potassium were the artificial sweeteners with the highest hazard ratio among all those tested. Based on this information, do we need to avoid artificial sweeteners or at least lower the amounts we consume? I’ll talk about that Saturday.

What are you prepared to do today?

        Dr. Chet

Reference: https://doi.org/10.1371/journal.pmed.1003950