Critical Appraisal of Multivitamin Use & the Risk of Orofacial Clefts in Infants Report Answer

Introduction

Evidence-based public health involves the application of evidence-based practice in the field of public health. The benefits of the use of an evidence-based approach are access to high-quality information on best practices, a high likelihood of implementing successful prevention programs and more efficient use of public resources. It involves looking at best practices through a review of the best available research evidence and the use of critical appraisal skills (Lhachimi, Bala & Vanagas, 2016). This report aims to conduct a critical appraisal of the study by Shaw et al. (1995) and critically evaluate the rationale for the use of the case-control method as a research design. In addition, a detailed assessment of the main features of the study design will be done and the assessment of study results.

Rationale For the Research Design

The aim of the study by Shaw et al. (1995) was to explore whether the use of periconceptional multivitamins containing folic acid (MFA) among women decreases the risk of orofacial clefts. The research was conducted using a case-control study design. The case-control study design is a type of observation study where participants with the target outcome status are selected. The two groups selected are those with outcome of interest known as cases and those without the disease known as control (Setia, 2016). Thus, in this study, the outcome should be present in any of the groups. In this study, the participants were California infants with or without orofacial clefts. These participant groups were selected from medical records at all hospitals. The diagnostic information of all fetuses and infants was reviewed from medical records and surgical reports. The case-control study design then focuses on developing a control group and looking at historical factors to identify the exposure. The cases were categorized into infants with cleft of the palate (CP) or lip or both (CL+P). All mothers of these infants were contacted via telephone and they were asked to report about the use of MFA. Thus, the review of the history of mothers helped to identify the exposure of interest. Hence, it reflects that aim was to evaluate the relation between exposure and outcome in the participants and it is linked to the case-control study design.

The author could have used this study design because it mainly aimed to look at the factors that are associated with the presence of orofacial cleft in infants. The outcome of interest is the problem but there is a gap in knowledge regarding the exposure which is the effect of folic acid supplementation on the outcome. Hence, the researcher used this study design to gain a insight into the factors linked to the disease. The use of a case-control study design is useful in the study or investigation of rare diseases. The second advantage of the use of a case-control study design is that it allows looking at multiple risk factors or exposures at the same time (Tenny, Kerndt & Hoffman, 2017). In this investigation, cases of children with orofacial clefts and controls were identified retrospectively from existing data sources, reducing the time required to recruit and follow up with participants. The researchers were able to identify cases and controls by utilising existing data sources, such as medical records and birth defect registries. This eliminated the need for extensive data collection, follow-up visits, and intervention administration, resulting in cost savings. The researcher might have chosen a case-control study design rather than a cohort study design because a cohort study design focus on studying a group of people over time to explore the frequency or prevalence of disease in exposed and non-exposed individuals (Song & Chung, 2010).

Evaluation of the Crude Association

The two groups of focus in the study were children with orofacial cleft versus control. The main exposure that was evaluated was the use of any vitamin supplement one month before to three months after conception. The main purpose behind collecting such detailed data was to evaluate the crude association between maternal vitamin use and the case of orofacial cleft versus the control group. The effect was evaluated using the odds ratio along with a 95% confidence interval. The advantage of using the odds ratio as an effect measure is that it can help determine the extent of risk of developing orofacial cleft compared to the duration and frequency of multivitamin use.

In the selected study, there were 763 case mothers and 734 eligible controls. The 731 cases consisted of 348 infants with isolated CL±P, 100 with multiple CL±P, 141 with isolated CP, 74 with multiple CP, and 68 clefts with unknown etiology. The comparison was done with women having multivitamins containing folic acids one month before to the first two months after conception compared to women who did not take any pills. The odds ratio was found to be 1.0 for each of the case groups. The odds ratio of less than one indicates that the case mothers were less likely to have taken multivitamins before conception. One of the important findings was that women using multivitamins with folic acid had a 25-50% reduction in risk for offspring with cleft compared to the control groups. However, this finding indicates that the above association may not be just because of the effect of multivitamin use with folic, but it could be due to the effect of other components in the multivitamins and the use of other folate-antagonist medications. Thus, the strength of the effect measure is that it helped in understanding the impact of exposure on the research outcome.

The strength of the summary analysis is that the study clearly defines the outcome for all sub-groups such as those with CP cleft, those with CP+L and isolated CP. In addition, the use of an odds ratio can ensure estimating the extent of association. The use of confidence intervals helped in estimating the statistical significance of the association. In addition, the analyses were controlled for factors such as maternal, race, ethnicity and education. The limitation includes the study's retrospective methodology that could have resulted in recollection bias or other drawbacks from relying on pre-existing data sources. Second limitation is potential confounding variables that can affect the association between maternal vitamin use and orofacial clefts are not taken into consideration in the summary analysis. Confounder adjustments would result in a more precise estimation of the connection. Since the study was observational, causality cannot be proved by the summary analysis. Although the study indicates a link between maternal vitamin use and orofacial clefts, more investigation is required to establish a cause-and-effect connection (Hazra, 2017).

Impact of the Main Features of the Research

One of the characteristics of the case-control study design is the selection of cases and control. According to Pearce (2016), the selection of cases is the starting point of all case-control studies. It involves developing a suitable case definition first. The case definition is based on different criteria. Children born with orofacial clefts were considered cases in this study, while children born without such clefts were considered controls. To make sure that the cases are representative of the target community, cases are chosen from already-existing data sources including medical records and birth defect registries (Setia, 2016). The key criteria given in the case definition were infants and foetuses with orofacial defects who were diagnosed within a year after birth. The restrictions in the case definition are that the study was restricted to the cleft of the palate (CP) or lip or both (CP+L). Infants with trisomy 21 or Turner Syndrome were excluded.

In case-control studies, the selection of control is more problematic. However, while selecting a control, it is important to fulfil two criteria. Firstly, they should not have the disease. Secondly, the exposure of controls should be measured with similar accuracy compared to those of the cases. Controls can be selected from the general population and they have the advantage of being representative of the population who has the risk of becoming cases (Ranganathan & Aggarwal, 2019). In the selected study, the control infants were born during the same period of 1987-1989. The mothers of the infants were from the same country compared to the cases. It reflects that the cases as well as controls were enrolled from the same pool of population.
Another important feature of a case-control study design is that the exposure should be measured similarly in both the controls and the case group. By using the same criteria for measuring the exposure, it may cause information bias (Gail et al., 2019). The exposure of interest in the study was the use of multivitamins with folic before conception. The data on the use of multivitamins was collected using the interview method. During the interview, women inquired about the type of vitamin supplements they used, the rate of use and the exact amount taken. The folic acid concentration in each supplement was calculated and fortified cereal consumption was estimated to be around 25% of the folic acid content. The risk was calculated using the odds ratio and confidence interval. The use of the odds ratio is an appropriate measure for evaluating risk as it can tell about the odds of exposure among case patients compared to controls (Labrecque et al., 2021).

To enhance the validity of the findings, it is important to identify and eliminate confounding factors in the research design. One of the approaches to do this is by matching. It ensures that the cases and the controls are similar in characteristics. This technique can enhance the efficiency of the study. In the selected article, individual matching was done by ensuring that the infants born in the same year were taken as the cases. In order to establish a more precise correlation between maternal vitamin use and orofacial clefts, possible confounders must be taken into account. Case-control studies frequently use matching, stratification, or multivariable regression analysis to adjust for confounding. It is difficult to assess the efficacy of confounding control in this study without precise information (Mansournia, Jewell & Greenland, 2018). To investigate potential heterogeneity in the association between maternal vitamin consumption and orofacial clefts, cases could be divided into sub-groups depending on features such cleft type or severity. This makes it possible to analyse data in a more detailed manner and pinpoint particular risk factors for certain orofacial cleft subtypes. The case-control study can only measure the association between exposure and that particular outcome (Setia, 2016).

Interpretation of the Results

The purpose of the study is to look into the chances of orofacial clefts in kids whose mothers took multivitamins containing folic acid around the time of conception. Strength of connection, consistency, timing, biological plausibility, dose-response relationship, and experimental evidence are a few of the elements that must be taken into account in order to prove causation. The results of this study show that use of MFA decreases the risk of having a child with an orofacial cleft. This was proved based on calculating the crude odds ratio for different sub-groups and controls. The greatest risk reduction was found for isolated CL+P compared to other sub-groups. The association was modified by alcohol use and a 0.61 odds ratio was found for women who did not take alcohol for the four months. The rigour in the analysis is seen as the effect of other confounding factors such as the family history of orofacial clefts and mothers with a history of diabetes or seizures were considered. Thus, the finding proves the effect of taking multivitamins with folic acid on decreased risk of orofacial cleft. However, the findings need to be interpreted with caution as it does not prove if the risk reduction is due to folic acid, multivitamin components or the use of cereals. The participants could not confirm the use of supplements containing only folic acid. Although the study had an adequate sample size and various confounding elements were reduced, one of the limitations of the study is the possibility of recall bias. Selection bias, recollection bias, and confounding are a few potential sources of bias in this study that are covered below. It is crucial to take the study design, data collection techniques, and other sources of error into account when assessing if bias is present. As the mothers were providing data based on interviews, there is a chance that they may be underreporting their vitamin intake. Similarly, control groups could be overestimating it. Hence, due to these limitations, the findings cannot be directly applied in practice.

Conclusion

From the critical appraisal of the study by Shaw et al. (1995), it can be concluded that the study was successful in proving the association between women taking multivitamins peri-conceptually and children with orofacial clefts. Based on the analysis of the purpose of the study, the use of a case-control study design was appropriate. The strength of the study is the use of rigorous criteria to select cases and control and measure the exposure of interest. The use of odds ratio and confidence interval helped in estimating the association for different sub-groups. There is also the possibility of recall bias as mothers may have under-reported their use of vitamins. Hence, future research is required to further prove the causality.

References

Gail, M. H., Altman, D. G., Cadarette, S. M., Collins, G., Evans, S. J., Sekula, P., ... & Woodward, M. (2019). Design choices for observational studies of the effect of exposure on disease incidence. BMJ open, 9(12), e031031. http://dx.doi.org/10.1136/bmjopen-2019-031031 Hazra, A. (2017). Using the confidence interval confidently. Journal of thoracic disease, 9(10), 4125. 10.21037/jtd.2017.09.14

Labrecque, J. A., Hunink, M. M., Ikram, M. A., & Ikram, M. K. (2021). Do case-control studies always estimate odds ratios?. American journal of epidemiology, 190(2), 318-321. https://doi.org/10.1093/aje/kwaa167

Lhachimi, S. K., Bala, M. M., & Vanagas, G. (2016). Evidence-based public health. BioMed research international, 2016. https://doi.org/10.1155/2016/5681409

Mansournia, M. A., Jewell, N. P., & Greenland, S. (2018). Case–control matching: effects, misconceptions, and recommendations. European journal of epidemiology, 33, 5-14. https://doi.org/10.1007/s10654-017-0325-0

Pearce, N. (2016). Analysis of matched case-control studies. bmj, 352. https://doi.org/10.1136/bmj.i969

Ranganathan, P., & Aggarwal, R. (2019). Study designs: Part 3-Analytical observational studies. Perspectives in clinical research, 10(2), 91. 10.4103/picr.PICR_35_19

Setia, M. S. (2016). Methodology series module 3: Cross-sectional studies. Indian journal of dermatology, 61(3), 261. 10.4103/0019-5154.182410

Song, J. W., & Chung, K. C. (2010). Observational studies: cohort and case-control studies. Plastic and reconstructive surgery, 126(6), 2234. 10.1097/PRS.0b013e3181f44abc

Tenny, S., Kerndt, C. C., & Hoffman, M. R. (2017). Case control studies. https://europepmc.org/article/nbk/nbk448143

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