|Year : 2015 | Volume
| Issue : 6 | Page : 1006-1007
Limitations of cross-sectional studies
Department of Community Medicine, IG Medical College, Shimla, Himachal Pradesh, India
|Date of Web Publication||20-Nov-2015|
Department of Community Medicine, IG Medical College, Shimla, Himachal Pradesh
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Mahajan A. Limitations of cross-sectional studies. Neurol India 2015;63:1006-7
Apropos the article "A study on cognitive decline with respect to metabolic syndrome and inflammation in elderly Indians." published in your journal. The authors have come to the conclusion that cognitive decline in the elderly may be associated with the presence of inflammation and metabolic syndrome. I read this article with great interest. By conducting this study, the authors have done a commendable job. However, I have few concerns about the study design chosen by the authors for the study.
In the materials and methods section, the authors have mentioned that the study design chosen to conduct this study was an observational, prospective cross-sectional study. It is imperative to mention that the study design cannot be observational and prospective at the same time. The basic design strategies used in epidemiological research can be broadly classified into descriptive and analytical study designs. The cross sectional studies are types of descriptive studies in which the status of an individual with respect to the presence or absence of both exposure and disease is assessed at the same point in time. Analytical study designs, on the other hand, can be further classified into observational (case control, cohort studies-prosective, retrospective) and experimental (controlled trials).
Furthermore it was observed in the present study that the cognitive impairment in the elderly patients with metabolic syndrome and having high inflammation was significantly more than in elderly patients without metabolic syndrome (MetS). The authors have further stated that MetS was found to increase the risk of cognitive decline. However, it is not possible to determine from such a design if the observed high hs-CRP values found in the group with metabolic syndrome preceded the development of metabolic syndrome, which might suggest a possible association, or whether the high values of CRP levels were in fact a result of the metabolic syndrome itself. The cross sectional studies cannot always distinguish whether the exposure preceded the development of the disease or whether presence of the disease affected the individual's level of exposure. Such studies cannot provide evidence of a valid statistical association for the evaluation of those associations where temporal relationship between exposure and disease cannot be clearly determined.
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| » References|| |
Ghosh A, Biswas AK, Banerjee A. A study on cognitive decline with respect to metabolic syndrome and inflammation in elderly Indians. Neurol India 2015;63:537-41.