Welcome to the sixth video in this series of critical appraisal modules cross sectional design in research, cross sectional research design
in this module we’ll be focusing on the critical appraisal of cross-sectional studies using the critical appraisal skills program or cusp approach for the learning outcomes.
We will introduce you to the main features of the design of a cross-sectional study and discuss their benefits and value in healthcare we also want to get you thinking about those critical appraisal concepts relating to validity trustworthiness of results and value and relevance in the context of cross-sectional studies and how they might be applied in practice using an open-access example of a recent study.
Finally there will be a link to a short quiz at the end of this video which will give you the opportunity to test your knowledge on concepts we will have discussed using multiple-choice questions and answers we’ve now considered cohort and case-control studies as two kinds of observational study cohort studies cross sectional design in research, cross sectional research design are generally the strongest design in terms of their robustness in quantifying the relationship between exposure and outcome and case control studies are a useful design if we are investigating the rare outcome and we need to find the first answer to a public health question and would be possible in conducting the cohort study cross-sectional studies are another kind of observational study which typically uses a survey our questionnaire design to survey people who are representative of a population at one point in time to assess the relationship between an exposure and outcome for example we might be interested in the relationship between exercise and depression so we can undertake cross-sectional study cross sectional design in research, cross sectional research design by identifying representative population sample asking them about their levels of exercise and simultaneously about depression symptoms to see if the two are associated cross-sectional studies are usually relatively simple to undertake and they are often conducted as a preliminary investigation into the causes of a disease or outcome there is no available checklist for appraising a cross-sectional study cross sectional design in research, cross sectional research design in the casper toolkit however the criteria for assessing their quality are similar to considerations used for cohort and case-control studies we’ll talk through a few key themes and as an example we’ll look at a cross sectional study by Bowdoin natal 2010 on cigarette smoking and depression tests of causal linkages using a longitudinal birth control cross sectional design in research, cross sectional research design which you can access by following the link below this video as with other observational studies.
We wanted to be sure there’s a cross sectional study has addressed a clearly focused questioned in this study the cross sectional design in research, cross sectional research designers were interested and whether or not there is an association are potentially a causal link between cigarette smoking and depression their cross sectional design in research, cross sectional research design question is contextualized against previous epidemiological findings and the subject in this study an experimental study would not be possible as it would not be practical or ethical to randomize people to smoke cigarettes when we know this is harmful to health a cohort study was also require a long latency period and years of follow-up a cross-sectional design therefore seems reasonable as a first step to answer in this question as in a case control study it.
Vital the participants I recruited into a cross-sectional study cross sectional design in research, cross sectional research design irrespective of their exposure status to allow for a true representation of the potential relationship between an exposure and an outcome in a cross-sectional study selection bias can usually arise from either and non-representative sample been chosen by the cross sectional design in research, cross sectional research designers are by people who are selected to be cross sectional design in research, cross sectional research design participants not responding to the study this can introduce bias because those who for example do not complete a survey may be different to those who do for example people who are motivated to complete surveys may be more health conscious than those who do not take part in this study the participants were assessed at multiple points in time as part of the longitudinal Christchurch health and development study in New Zealand.
The arthurs do acknowledge that there was a tendency for children from our disadvantaged segments of society to be underrepresented in the study like other observational studies cross-sectional studies cross sectional design in research, cross sectional research design can be afflicted by recall bias if self-report measurements are used to classify exposure and our outcome this study was a cross-sectional study at multiple points in time so the multiple time points element of the study means it is less likely to be susceptible to recall bias cross sectional design in research, cross sectional research design but it is still important to bear this point in mind when critically appraising cross-sectional studies confounding is an important phenomenon to consider in cross-sectional studies as with case control and cohort studies just to recap a confounder is a factor independently associated with both an exposure and an outcome and it can hide true associations between exposures and outcomes are it may suggest that there is an association when in fact on his present it is possible to statistically adjust for confounding in cross-sectional studies cross sectional design in research, cross sectional research design and in fact the authors factored important confounders such as employment status or cannabis use into their statistical modeling after accounting for confounders the authors found that the association between cigarette smoking and depression was statistically significant a hallmark of the cross-sectional design is this it measures exposure and outcome at a single point in time this specific feature leads to a potential drawback which is that it is problematic to access the time directionality of an effect how can we be sure that an exposure did precede an outcome if both have been measured at a single point in time also it may even be that the outcome is causing the exposure a problem in cross-sectional studies cross sectional design in research, cross sectional research design that we call reverse causality to take the exercise and depression example again a study may find an inverse relationship between depression and exercise with high levels of exercise being associated with low levels of depression we might then conclude that exercise could be protective against developing depression are beneficial for people with depression in alleviating their depression symptoms however if this issue is being measured at one point in time how do we know that it isn’t the case that it says our way around that is that people who are not depressed.
Amahl moated cross sectional design in research, cross sectional research design to exercise this study concluded that the association between cigarette smoking and depression was causal with the direction of causality being from cigarette smoking depression it is always possible however that the direction of causality may be the other way around in a cross-sectional study or in fact the manufacturer could have caused both the exposure and the outcome the believability of results can be assessed by considering the factors we have previously discussed such as confounding or bias it’s also important to consider whether the results may have been affected by chance assessing the believability results requires judgment and consideration of factors such as the biological plausibility of the relationship between exposure and outcome and the contextualization of the cross-sectional study in the wider body of cross sectional design in research, cross sectional research design in the field judgment is also required to consider the potential local applicability and the results the 7th module in this series we’ll look at diagnostic studies and we will be following a similar format that we used in this video to appraise an example of a recent study.
Thank you for listening these training videos have been developed by the Cochran common mental disorders group at the university of york with support from TSS can reevaluate Jai’s Foundation Trust Northumberland Tyne and Wear NHS Foundation Trust and the Economic and Social Cross sectional design in research, cross sectional research design Council.
If you’d like to test your knowledge on the topics introduced in this module please select the link below the video you.