Abstract
Across-sectional study is an observational study in which the exposure and the outcome are determined at the same time point for each study participant. Cross-sectional studies comprise the simplest individual-level observational study design and are usually relatively inexpensive and easy to conduct compared with case-control or cohort studies. Cross-sectional studies can be descriptive or analytical depending on whether the outcomes are assessed for potential associations with risk factors or exposures. Another type of cross-sectional study is the serial crosssectional study, in which more than 1 data collection is conducted in the same study population at different time points. In a hypothetical example of a cross-sectional study, we can record the prevalence of periodontal disease and investigate the association between periodontal disease and oral hygiene habits in adult patients. The outcome is the presence or absence of periodontal disease, and the exposure is current oral hygiene practices such as frequency of brushing and use of dental floss. This study can be carried out by interviewing participants about their oral hygiene habits and at the same time by assessing periodontal status clinically. Thus, outcomes and exposure data are assessed at the same time. Cross-sectional studies measure prevalence and therefore are suitable for examining the burden of the disease or condition and are useful for health care services planning, as I discussed previously. A crosssectional study recording the prevalence of caries in adolescents can provide useful information for determining caries prevention plans. Analytical cross-sectional studies provide only weak evidence between exposures and outcomes, since it is difficult to separate the cause and effect. For example, in the previous scenario, it is difficult to determine whether periodontal disease preceded or followed the exposure (oral hygiene practice). In fact, an important issue is what is called reverse causality, which in this
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have