Limitations of epidemiologic exposure studies on the health effects of asbestos
Dorsett D. Smith in The Health Effects of Asbestos, 2015
Epidemiologic studies are usually divided into four types: Cohort studies, or a prospective observational study, of a group that is exposed to asbestos as compared with a group not exposed to asbestos, and then following their outcomes over a defined period. The results in cohort studies are commonly expressed as the (RR; risk ratio), meaning the incidence of disease in the exposed group divided by the corresponding incidence in the unexposed group.Case–control studies are retrospective studies evaluating groups, in which a certain outcome such as mesothelioma is compared to a control group without a mesothelioma and then determining risk factors for the disease. The data are commonly expressed as the odds ratio (OR) or the odds of exposure in the group with disease as compared to the control group.Cross-sectional studies are observational studies that evaluate the absence or presence of an exposure and disease at a specific time.Case reports, or case series, are descriptive reports on a single case or series of cases with a specific disease and a specific exposure reported to raise a hypothesis, but they cannot test a hypothesis because they do not include an appropriate comparison group.
Understanding Studies of Resistant Organisms: Focus on Epidemiologic Methods
Robert C. Owens, Lautenbach Ebbing in Antimicrobial Resistance, 2007
A cross-sectional study assesses the status of subjects with regard to the risk factor and disease at the same point in time. A cross-sectional study to investigate FQREC might assess all patients currently hospitalized with regard to whether they have a FQREC infection as well as whether they are receiving FQs. A cross-sectional study is relatively easy to carry out since all subjects are assessed at only one point in time. As such, this type of study may provide early evidence for or against a hypothesis. A major disadvantage of a cross-sectional study is that it does not capture the concept of elapsed time (i.e., it is not possible to determine whether the risk factor or the outcome came first). Furthermore, a cross-sectional study does not provide information about the transition between health states.
Cancer Epidemiology
Trevor F. Cox in Medical Statistics for Cancer Studies, 2022
Cross-sectional studies collect data at one time point. They are inexpensive to run compared to cohort studies, can collect data on multiple outcomes and exposures and can estimate prevalence. On the downside, incidence cannot be measured and causality cannot be established, only association. You cannot show whether a risk factor caused the cancer, or that having cancer caused individuals to become more exposed to the risk factor. The latter is unlikely in most cases – I am not going to take up smoking because I have been diagnosed with lung cancer! To carry out a cross-sectional study, a sample of individuals needs to be chosen from the population of interest. Data collected can come from questionnaires, interviews and medical examinations. Bias can be a problem because of non-responders, participant recall of past events and selection bias.
Musculoskeletal disorders and related factors in the Colombian orthodontists’ practice
Published in International Journal of Occupational Safety and Ergonomics, 2022
Karina Andrea Ramírez-Sepúlveda, Martha Yojana Gómez-Arias, Andrés A. Agudelo-Suárez, Diana Milena Ramírez-Ossa
This article was written following the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines for observational studies [17]. A cross-sectional study was conducted. A survey form was completed by orthodontists who graduated between 1993 and 2018 from the Faculty of Dentistry at the University of Antioquia (Medellín, Colombia). This institution has graduated an average of six orthodontists per year (the same number of general dentists who are admitted to the orthodontics program). This program serves people from different socioeconomic strata of the city and the orthodontics’ students carry out clinical activities according to the objectives of the curriculum, i.e., to set braces for patients to align their teeth. Clinics to offer care for patients have the necessary biosafety elements, but the presence of occupational risks related to the type of work they perform is not ruled out. The survey employed two strategies: answering in person, or using a form created in Google Forms. Data were provided by the Association of Orthodontists of the University of Antioquia (Asociación de Ortodoncistas de la Universidad de Antioquia: https://ortodoncistasudea.com/who.html).
Built environment, physical activity, and obesity of adults in Pingshan District, Shenzhen City in Southern China
Published in Annals of Human Biology, 2021
Qianqian Dun, Yiting Duan, Maozhen Fu, Hongdao Meng, Wanglin Xu, Ting Yu, Dobbs Debra, Naidan Tu, Xin Li, Lu Ma, Yating Du, Longwei Chen, Xin Liu, Xiaorui Zhou, Mengxue Qin, Lu Shen, Nengjian Wu, Yuliang Zou
The study has a number of strengths and weaknesses. Based on the built environment in the early stage of urban development, this study is conducive to the timely adjustment of urban planning by the government to create a good living environment. This study has provided new evidence that confirms the relationship between built environment, physical activity, and obesity, lays the foundation for future research, and proposes a hypothesis between the built environment, walking, and physical fitness, which could be studied further in the future. In terms of weaknesses, one of the limitations is that this study is a cross-sectional study, which rules out causality determination. Additionally, perceptions of environmental resources rather than actual features were assessed. It should also be noted that nutritional status is a key driver of obesity; however, the study does not include this information. During the investigation, self-reported availability of the environments may have been subject to inherent reporting bias, and this study only measured height and weight once, without calculating technical error of measurement (TEM).
Parents Talking to Middle School Children about Sex: A Protective Factor against Suicide in Sexually Active Teens
Published in American Journal of Sexuality Education, 2023
Monica St. George, Danielle R. M. Niemela, Robert J. Zeglin
The results of this study should only be considered in light of the study’s limitations. First, the sample was drawn from only one county in the urban coastal southeast United States. This may limit its generalizability to other, particularly more rural, populations. Also, the study instrument only offered “male” and “female” as gender identity options and did not ask about sexual orientation at all. This severely limits the study’s ability to assess whether the identified significant associations differ for sexual and gender minority adolescents, a growing cohort of young adults (Laughlin, 2016; White et al., 2018). A third limitation, one inherent in a non-experimental cross-sectional study, is the lack of causal inference that can be made based on the study’s results. Finally, the study instrument did not ask about the quality or reception of the parent’s conversation about sex. Young adults with varying levels of sexual knowledge, comfort, and values or those with stronger or weaker relationships with their parents may have experienced the conversation about sex markedly differently. Similarly, knowing whether the child or the parent initiated the conversation about sex could prove to be a significant moderator in the relationship between conversations about sex and suicidality. Other examples of possible mediating or moderating variables are perceived parental limit-setting and timing of conversation relative to sexual debut. The present study was not able to assess for such differences in these and similar variables. Despite these limitations, the present study was able to answer its guiding research question.
Related Knowledge Centers
- Observational Study
- Prevalence
- Time Series
- Medical Research
- Dependent & Independent Variables
- Aggregate Data
- Case–Control Study
- Odds Ratio
- Absolute Risk
- Relative Risk