Epidemiology is a unique science. Since the outbreak of the COVID pandemic, epidemiology has been all-encompassing in the news; assuming a huge role in public perception.
Scientists have been challenged in trying to clarify how the virus is transmitted, in addition to determining the short- and long-term health effects of disease.
Epidemiology is a unique science
Epidemiology Is a Unique Science
More than a century-and-a-half ago, disease afflictions were a part of everyday life. It was then that facilitated the rise of epidemiology.
The word epidemiology comes from the Greek words epi, meaning on or upon, demos, meaning people, and logos, meaning the study of. In other words, the word epidemiology has its roots in the study of what transpires in a population. Many definitions have been projected, but the following definition captures the underlying principles and public health spirit of epidemiology:
“Epidemiology is the study of the distribution and determinants of health-related states or events in specified populations, and the application of this study to the control of health problems.”
During the 1850s, epidemiology’s leader was John Snow. Snow was broadly considered the ‘father of epidemiology’ after he demonstrated the cause of cholera was contaminated water and not “miasma.”
Shortly thereafter, more realization followed: identifying cigarette smoking as the cause of lung cancer and many other diseases; the eradication of smallpox; pinpointing the handful of risk factors contributing to heart disease; and unraveling the role of human papillomavirus as the cause of cervical cancer. These groundbreaking insights were made possible by use of the epidemiologic method to address public health crises of global dimensions.
To Isolate a Specific Factor
In recent decades, epidemiology has become more specialized, with researchers focusing on the social determinants of health, “life-course epidemiology,” and the contribution of specific genetic variants to the risk of particular diseases, as well as the study of “gene-environment interactions.”
However, a component of epidemiology that gets the most attention nowadays is what has been referred to as “risk factor epidemiology.” On average, studies of this kind isolate a specific factor…that is, a part of diet or exposure to a chemical and examine its relationship with a specific disease.
Quite often, these findings are at trace levels. When the results of a study are reported in the media, we get the message that “factor X is associated with increased risk of disease Y.”
Unlike the breakthrough findings that established the critical importance of epidemiology decades ago, risk factor epidemiology communicates directly to the public through the media, giving the viewers and readers the impression that the results have direct significance to our health. Ultimately, the daily news subjects the public with this narrative — even though the entire story is missing.
For example, a recent study, by researchers at Harvard and Washington University, found that, compared to individuals who drank sugar-sweetened beverages less than once a week, those who consumed these beverages two or more times per day experienced a doubling of the risk of early-onset colorectal cancer.
This result has potential interest because colorectal cancer, which is mainly a disease of older age, has been occurring more frequently in younger people…individuals below age 40. But for a variety of reasons, the result of the study fails in telling us that scientists have uncovered a cause of this new occurrence.
More importantly, the results don’t tell us the important cause of the new occurrence.
For many who read or view such a news story, they immediately take the highlighted finding as if it were true and worry that something we had considered relatively harmless…like drinking sweetened beverages…could be adversely affecting our health or the health of people close to us.
People who have an interest in publicizing this type of result — like journalists, journal editors, and scientist authors — know that stories like this provoke a visceral reaction. The logic behind this kind of reporting is like saying to us, “Start to worry — anticipate pending details!”
Here’s what one of many news reports made of the story.
Based on the headline and the highlighted result this appears quite scary. But unbeknownst to most readers, epidemiologists are well-aware that the results are merely hints that need to be confirmed or rejected with larger and more in-depth studies.
Many factors about the causes of colorectal cancer…the third most common cause of cancer in men and women…need to be looked into. But the headlines and the paper fail to communicate that most important point.
Few people are in a position to fully realize how many complexities, qualifications, and questions are hidden behind the plain statement of results like this.
Nonetheless, below, is a study checklist created by Geoffrey C. Kabat, an epidemiologist, cancer researcher, and author. You’ll find some of the most important questions needed to be asked when coming across the results of a study that appears to be drawing our attention to a new issue that may be affecting our health.
- How strong is the result?
- How consistent is the result within the study?
- What is the finding/main result?
- How good are the data from the study?
- How well did the researchers measure the study factor?
- Could the result be due to confounding, i.e., could some other factor that is correlated with the study factor be the true cause?
- Do they put their results in perspective?
- How does the result accord with the results of other studies?
- Do the authors report the “absolute risk,” as well as the relative risk? (“Absolute risk” conveys the population impact of the factor, i.e., how many cases of the disease would be prevented if the risk factor were eliminated). Reporting only the relative risk often makes the factor look more important than if one reported the absolute risk.
- Is there evidence of a dose-response relationship?
- How many different factors did the researchers examine?
- Is the finding the result of “multiple comparisons”/“data dredging”?
- Does the result pertain to the whole study population, or is it only present in a subgroup?
- How does the result comport with what we know about other established risk factors?
- Do the authors acknowledge the limitations of the data?
The length of this checklist tells us how carefully the results of a single study need to be examined and analyzed. Moreover, it must be placed in the framework of what is known about a particular disease in question.
Evaluate and Realize
Keep in mind that just because something is associated, that doesn’t necessarily prove the cause. When evaluating uncertain and weak associations that might likely be relevant to the risk of a serious disease, epidemiologists realize the limits of their study. Nevertheless, they don’t hesitate in emphasizing the possible importance of their findings.
Certainly, the earlier achievements of public health and epidemiology speak for themselves. Their potential significance didn’t need to be overstated or exaggerated. In addition, appealing to public concerns about harmful components of our diet weren’t necessary, as well.
Yes, epidemiology is a unique science. Nevertheless, it’s not enough to provide environmental activists with vague, blurred, or hazy evidence that exposure to trace amounts of a particular chemical are having distinct health effects.
Once we realize how big the chasm is between the bottom line or keynote of an epidemiologic study and that there are many links in the connecting sequence needing to be apprized, we can start to be more skeptical toward results that are the core and highlight of our media networks, and how, for the most part, the media provides little information we can use to improve