Epidemiology Traps, Research Paper Example

A team of visiting polio eradication workers were informed during their orientation session that villages in their host country varied greatly in economic/human development circumstances, ranging from those whose residents lived in hand-constructed huts with no running water, no latrines or sewage disposal areas, and no electricity, to others whose residents lived in wooden or adobe homes which, though modest by Western standards, had all of the above services in place and whose streetside craft shops and food markets did a brisk business, catering both to locals and visitors.

Knowing from the experience of previous teams that polio cases were more likely to be found in the poorer villages, as they went from village to village the team attempted a rough “human development” rating for each family based on that family’s income situation, access to running water, access to elementary school for their children, and condition of the home, and found to their surprise that there was no difference in polio incidence in any of the villages by the family’s human development index.

The apparent show of no differences in polio incidences among families, which seemed at high risk as against those at less risk, is an example of ecologic fallacy. This is when inaccurate inferences are made regarding an individual’s characteristic based on the probability of the population characteristic from which the individual came

 An epidemiologic investigation team traveled to several food processing plants in an attempt to learn the source of an outbreak of dysentery due to a rare Salmonella They observed that in plant A, the food preparation workers were much more likely to carry the serotype than workers in plant B.  They also observed that in plant A, workers wore blue jeans and white t-shirts to work, while those in plant B wore company-supplied uniforms.   They hypothesized that uniforms were protective against Salmonella infection.

This assumption made by the epidemiological team is another example of ecologic fallacy related to confounding the truth. Blue jeans are not the only variable of difference that should be considered and has no relationship on the infection.

A researcher wanted to know how well the U.S. population was informed about the risks of radiation due to exposure to dental X-rays. Ads were placed in community newspapers, on line at information tech websites, and in a selection of dental offices nationwide for volunteers to log in and complete an awareness survey about the topic.  To her surprise, the researcher found no association in her data set between knowledge level about radiation exposure, and the subject’s own experience with having had dental X-rays.  She went to her research committee chairperson, who agreed with her that her results were likely to be inaccurate.

This is an example of another type of fallacy related to a selection bias. Knowledge of radiation and exposure to dental x-rays seem not to have any analytical relationship because a lay man may not know that dental x-ray is radiation related.

200 women who were survivors of breast cancer, and 200 women controls matched for age and parity, were surveyed about a variety of prior exposures that could have a relationship to the development of breast cancer. Several items, including family history in third degree relatives, and history of exposure to specific types of pain relievers during the teen years, came up with significant odds ratios by chi-square test.  In an attempt to control for possible confounders, the researchers excluded anyone with family histories of breast cancer in first or second degree relatives, and all the relationships remained significant.  Encouraged by this result, they submitted their manuscript to a peer-reviewed journal, which promptly rejected it.

This is a classic example of recall bias because the  expected findings were based on a previous experience.

A new, popular energy drink was tested in a population of college students in the northeast from November through April. The promoters were encouraged because, at least if consumption could be held to reasonable levels and students could be convinced to space out the consumption throughout the week and to stay on a reasonably balanced diet, there seemed to be no harmful side effects from the drink.

Eager to cash in on the benefits, a competing company tested its drink, made from almost exactly the same formula, in college students in the southwest for five months beginning in May.  To their chagrin, they found that a high percentage of the students, both young men and young women, developed a blotchy appearance to the skin of their faces and arms after drinking the drink, which persisted throughout the day of consumption and into the next.  If they stopped drinking the drink, the blotches quickly cleared up.  The blotches were worse in those that consumed the highest volumes of energy drink.

This is very likely an example of effect modification. The researchers did not make an analysis all the factors affecting consumption of the drink.