Introduction
This paper analyzes an article on the roles and limitations of epidemiology studies. The paper begins by identifying the research question, hypothesis and study design. The paper then evaluates the method used in the research, study results and conclusion that emanates from the article. Following evaluation, the paper explains that the method used involved case-control studies.
Also, the paper explains that results may have obtained distortion due to errors of misclassification, confounding, biases and measurement. Misclassification errors may have occurred due to imprecision in measuring exposures or condition of ailments while confounding errors could have occurred due to intrusion of effects related to exposure. Lastly, the paper highlights that provided evidence is not enough to confirm the findings of the study.
Research Question, Hypothesis and Study Design
This study hypothesizes that epidemiology studies can prove the causal association between causes of cancer and putative exposures in populations (Franco, Correa, Santella, Wu, Goodmane, & Petersen, 2004). The study seeks to answer the question, “what are the roles and limitations of epidemiology as a discipline concerned with the discovery of carcinogens in the physical, chemical, and biological environment?” (Franco et al., 2004, p. 413). The study design involves reviewing two cases that show causative factors of the stomach and cervical cancer to set up cause-effect relationships.
An Evaluation of Methodology
The study uses case-control studies in establishing relationships. A case-control study gets defined as an exposition study whereby a cluster of subjects with a certain ailment obtains comparison with a control group of subjects, who are free from the ailment, to bear out whether the group that suffers from the ailment could be exposed to some elements that are different from the control group.
Case-control studies become used in observational studies because they take less time and are less expensive than cohort studies. Nevertheless, case-control studies are prone to issues like recall bias and choice bias, which may produce results that are less reliable compared to results that become obtained from other study designs. Recall bias occurs due to the time interval between the day of sample collection and building some cases, which allow approximation of relative risks with accuracy.
An Evaluation of Study Results
Interpretation of this study may have obtained distortion due to several factors including misclassification, confounding, biases and measurement errors.
Biases might have occurred at any point in the process of study, causing the wrong interpretation of the relationship between putative exposures and the risk of ailment. For instance, selection bias might have occurred during the course of choosing participants. The existence of errors during the selection process may yield results that are not representative of the entire population. That is to say, selection bias may have led to the interpretation that there is a relationship between putative exposures and cancer, as drawn from respondents, which could not be true of the general population. Also, recall bias might have caused bias on data as subjects are more opt to remember earlier exposures than controls. In addition, non-respondent bias might have influenced the results of the study, since the views of those who refused to take part in the study might have been different from those who agreed to take part. Other possible errors that may have interfered with the results include misclassification and confounding errors.
Misclassification Errors
Misclassification errors may have occurred due to imprecision in measuring exposures or conditions of ailments. As a result, the set-up of the relationship between putative exposures and causes of cancer may have been stronger or weaker than the real situation.
Confounding Errors
Confounding errors could have occurred due to intrusion of effects of other variables that could be related to the effects of putative exposure. For instance, this study established that there was a relationship between exposures to the chemical environment and cancer. Let us assume that the chemical environment was a result of taking alcohol. We all know that most alcohol users resort to eating roasted meat and that roasted meat is the main risk factor for stomach cancer. Unless roasted meat becomes considered, when analyzing data, taking alcohol will appear as a strong risk factor when indeed, alcohol does not cause stomach cancer and the consequences will arise from taking roasted meat.
An Evaluation of Conclusion
Hitherto, information on the relationship between causes of cancer and putative exposures in populations became derived from observational studies, which cannot be relied upon. Although there was some evidence supporting the relationship between causes of cancer and putative exposures in populations, the evidence was not adequate to confirm the conclusion that putative exposures in populations caused stomach or cervical cancers. Observational studies offer significant inferences on the association between causes of cancer and putative exposures in populations in the shape of measures of relationship. Nevertheless, these are mere speculations because almost all studies contain errors.
An increase in the number of studies with diverse populations, designs and integration of biases may result in enhanced perception relationships between cancer and putative exposures in populations, if upcoming observational studies will surmount the errors mentioned.
Reference
Franco, E.L., Correa, P., Santella, R.M., Wu, X., Goodmane, S.N., & Petersen, G.M. (2004). Role and limitations of epidemiology in establishing a causal association. Seminars in Cancer Biology, 14, 413–426.