The Steps of a Meta-Analysis 1. Define Research Question and Review Literature. Meta-analyses begin with defining the research question. A defined 2. Select Appropriate Studies. Selecting the appropriate studies is probably the most important step of a meta-analysis. 3. Extract Data. The next Meta-analysis is quite common nowadays. In the past, most reviews were based on what we call systematic reviews. In systematic reviews, researchers felt free to include some studies to make their · Systematic Reviews and Meta Analysis Databases and Sources Search this Guide Search. Systematic Reviews and Meta Analysis. A resource for finding data sources, filters, and standards to support systematic searches of the biomedical literature. Databases and Sources;
5 key things to know about meta-analysis - Scientific American Blog Network
The role of children in the spread of severe acute respiratory syndrome coronavirus 2 Meta analysis article remains highly controversial. Only 8 3. Asymptomatic index cases were associated with a lower secondary attack in contacts than symptomatic index cases estimate risk ratio [RR], 0. To determine the susceptibility of children to household infections the secondary attack rate in pediatric household contacts was assessed. The secondary attack rate in pediatric household contacts was lower than in adult household contacts RR, 0.
These data have important implications for the ongoing management of the COVID pandemic, including potential vaccine prioritization strategies. Large data analyses have shown that the elderly are particularly susceptible to severe forms of coronavirus disease COVID [ 2 ]. However, the role of children in the transmission of SARS-CoV-2 remains controversial [ 3—9 ]. Accordingly, children may play a major role in the spread of influenza virus and are a key target population for influenza vaccination to prevent infection and reduce transmission [ 10 ].
In the context of coronaviruses, pediatric infections with SARS-CoV-1, SARS-CoV-2, and Middle East respiratory syndrome are typically mild [ 910 ]. Nevertheless, meta analysis article lower incidence of clinical symptoms raises concerns that children could be an important, undetected source of SARS-CoV-2 in transmission in the community [ 811 ].
Answering this question is of key importance to public health because it will help identify priority groups for vaccination, meta analysis article. However, findings remain controversial, with some studies suggesting that children may play a key role in disease transmission and shed virus at equivalent titers to adults [ 12—17 ].
In contrast, others find little evidence of pediatric infections or spread [ 7818—21 ]. Moreover, it is unclear if SARS-CoV-2 transmission differs among children of differing age groups. Studying the source and route of viral transmission from children in the community is fraught with difficulties because of the multiple different potential sources of infection. Furthermore, it is thought that households are one of the most common settings in SARS-CoV-2 transmission [ 22 ].
Household transmission clusters therefore offer the unique opportunity to study viral transmission and susceptibility to infection in a more defined setting. To address the role of children in the transmission of SARS-CoV-2, we performed meta analysis article meta-analysis on household transmission clusters. We investigated prevalence of pediatric index cases in household transmission clusters of SARS-CoV-2 as well as the secondary attack rate of different age groups.
The index case was defined as the individual in the household cluster who first developed symptoms. Household contacts were defined as cohabiting individuals, typically family members, close relatives, housemates, or house helpers. An individual with laboratory confirmation of SARS-CoV-2 was considered to be infected.
Household secondary attack rates were defined as the proportion of confirmed infections among all household contacts. Following the Preferred Reporting Items for Systematic Reviews and Meta-analysis statement for the reporting of meta-analysis [ 23 ], we searched published, deidentified data made available between December meta analysis article,and August 24, Information was accessed from the World Health Organization news [ 11 ], Google Scholar, PubMed, the Lancet COVID resource center [ 12 ], Clinical Infectious Disease Journaland New England Journal of Medicine.
To identify missing studies, we checked the reference list for each selected paper. Preferred Reporting Items for Systematic Reviews and Meta-analysis PRISMA flow diagram. Depending on the level of information available, studies were included in the index case analysis or the secondary meta analysis article rate meta-analysis.
All studies included in the index case analysis were household SARS-CoV-2 transmission clusters that 1 identified the index case of the cluster, 2 defined the number of infected contacts in the household, meta analysis article, meta analysis article 3 recorded the initial disease onset date of all cases in the cluster. All studies included in the secondary attack rate meta-analysis were household SARS-CoV-2 transmission clusters that 1 defined the secondary attack rate within the cluster and 2 defined the age of contact cases in the cluster.
Studies that did not meet bare minimum data required for the index case analysis nor the secondary attack rate meta-analysis were excluded Figure 1. Where the same family cluster was included in more than published report, data were only extracted from 1 study. Collected data were verified by a second researcher. Susceptibility to infection was estimated by calculating the secondary attack rate for household close contacts associated with the index case in each transmission cluster.
We estimated the relative risk RRs for SARS CoV-2 infection stratified by the age of household contacts for each study. We then pooled these RRs using a random effects model with DerSimonian and Laird weights [ 24 ]. We used a random effects model, equalizing the weight of the studies to the pooled estimate. Where relevant, we stratified the analysis by prespecified characteristics.
Ninety-five percent confidence intervals CI were used to assess statistical significance in all models. The I 2 statistic was used to evaluate heterogeneity between studies. All summary analyses and meta-analysis were performed using R statistical software version 3.
We identified articles that described SARS-CoV-2 household transmission clusters, meta analysis article, rejected articles from a lack of sufficient and or appropriate data, and derived a total of 57 articles. Household transmission clusters were drawn from cases in 12 countries: China, Japan, meta analysis article, France, Germany, meta analysis article, Italy, United States, meta analysis article, Vietnam, Malaysia, Singapore, Morocco, Greece, and South Korea, meta analysis article.
Forty-three articles were included in the index case analysis [ 525—66 ], whereas 14 articles were used in the meta analysis article attack rate meta-analysis [ 66—79 ]. The full detail of all family clusters and characteristics of studies included in meta-analysis are shown in Supplementary Tables 1 and 2. In analysis of the cluster index cases, we included 43 articles, in which there were SARS-CoV-2 transmission clusters; only 3.
Meta analysis article individuals in the clusters, there were children, meta analysis article. These pediatric cases only caused 4. Household Transmission Clusters of SARS-CoV-2 Stratified by the Age of the Index Case. The limited number of defined SARS-CoV-2 household clusters with children as the index case could have been influenced by the fact that COVID in children is frequently asymptomatic [ 11 ]. Accordingly, it is possible that within a household cluster, children were not correctly identified as the index case of the infection ie, meta analysis article, the first to develop symptoms and were instead mistakenly identified as a contact case.
To exclude this possibility, we reanalyzed the data looking at household clusters where a pediatric contact case was SARS-CoV-2—positive but asymptomatic.
Even with this broader definition, only 39 Household Transmission Clusters of SARS-CoV-2 Where any Asymptomatic, SARS-CoV-2 Positive Children are Assumed to be the Index Case of the Cluster.
It is also possible that these data were influenced by the fact that early in the SARS-CoV-2 outbreak, infections were associated with travel to outbreak areas ie, initially to Wuhan itself and later to the entirety of Hubei. Travel is much more likely to be undertaken meta analysis article an adult in the family, meta analysis article, potentially cofounding the results. To control for this factor, we reanalyzed the data, only including household transmission clusters where the index case had no history of travel or the whole family was associated with an outbreak area.
Clusters where this information was not available were excluded from the analysis. This resulted in a total clusters, 32 of which Household Transmission Clusters of SARS-CoV-2 Accounting for the Travel of Adults to Outbreak Areas. A final factor that may have confounded this analysis is that, in some countries, a strict lockdown was imposed during the period of data collection.
This would have limited the activity of children outside of the house and may therefore have artificially reduced the number of children identified as an index case, meta analysis article. To control for this factor, a subanalysis was performed using only data collected when the regional area or country was not in a period of lockdown.
In this subanalysis, only meta analysis article. Household Transmission Clusters of SARS-CoV-2 in the Absence of Regional or National Lockdown. We then further examined the household clusters identified in Table 1 where a child was identified as the index case to define the secondary attack rate of cohabiting family members Supplementary Table 4. Clusters where the total number of infected and uninfected family members were not recorded were excluded from the analysis.
Therefore, meta analysis article, there were insufficient case numbers to determine whether children are more or less able to transmit SARS-CoV-2 in a household setting compared with adult index cases. It has previously been suggested that asymptomatic individuals may be less infectious than those who develop symptoms [ 78081 ].
To assess this possibility, we examined the secondary attack rate in household clusters where the index case was symptomatic versus the secondary attack rate in household clusters where the index case was asymptomatic but known to be SARS-CoV-2—positive Figure 2. The secondary attack rate of household transmission stratified by severe acute respiratory syndrome coronavirus 2—positive symptomatic and asymptomatic index cases. Abbreviation: CI, confidence interval.
Several studies have suggested that children are less likely than adults to be infected with SARS-CoV-2 [ 2082 ]. However, small-scale studies can be biased by the fact that community testing is often only performed on symptomatic individuals, few of whom may be children.
We therefore used the second data set collected in this study to examine the secondary attack rate of children versus adults in household clusters where an adult was identified as an index case. Relative risk RR for the secondary attack rate of children and adults in household severe acute respiratory syndrome coronavirus 2 SARS-CoV-2 transmission clusters.
Events describe the number of SARS-CoV-2 positive individuals identified in the study. Relative risk RR for the secondary attack rate of younger and older children in household severe acute respiratory syndrome coronavirus 2 SARS-CoV-2 transmission clusters.
The transmission of SARS-CoV-2 to and from children has remained controversial throughout the course of the COVID pandemic. In the present study, we recorded only a limited number of household transmission clusters 3. This observation is supported by previous study from China, where a study of 66 family transmission clusters showed that children were never the first in the family to be diagnosed with COVID [ 83 ].
Other reviews have also found limited evidence of children as the index cases in household transmission clusters [ 420 ]. A more recent study meta analysis article households in Tennessee and Wisconsin suggested that of family SARS-CoV-2 clusters, only 14 had pediatric index cases [ 85 ].
There are multiple possible reasons as to why children may be infrequently identified as the index cases in household transmission clusters, meta analysis article. This may reflect limited interaction of children outside the home during the period in question or the higher probably of an adult traveling to a COVID endemic area meta analysis article a child. An alternate hypothesis is that children are less susceptible to SARS-CoV-2 infection than adults. Indeed, this is consistent with our observation that in household transmission clusters, children were significantly less likely to acquire SARS-CoV-2 than their adult family members.
Interestingly, we found that older children were not significantly more likely than younger children to acquire the virus, in contrast to previous pre-print suggestions [ 4 ]. A reduced incidence of SARS-CoV-2 infection in children outside the home has previously been reported [ 2481886meta analysis article, 87 ]. Here, all age groups were homogenously sampled yet no children tested positive for SARS-CoV-2 infection.
This was despite the fact that at least 13 of these children lived together with infected family meta analysis article [ 88 ]. Once infected, it remains to be determined whether children are more or less likely to transmit the SARS-CoV-2 to a family member as an infected adult.
Although the mean number of infected household members was lower when a child was identified as the index case of the cluster, the low number of clusters eligible for inclusion in this analysis precluded any definitive conclusions. It has previously been suggested that children are less likely to transmit SARS-CoV-2 compared with adults [ 7meta analysis article18—20 ], meta analysis article. Such suggestions have remained controversial among other findings that children have equivalent nasopharyngeal viral loads to adults [ 141617 ].
Should children be less likely to transmit the virus, it is interesting to speculate the possible mechanism by which this occurs. There is an emerging body of evidence that mild or asymptomatic patients are less infectious than those with pronounced clinical symptoms [ 7meta analysis article, 13808189 ]. Indeed, our meta-analysis showed that an asymptomatic index case was associated with a significantly lower secondary attack rate compared with a symptomatic index case.
Systematic Reviews and Meta-Analyses - How to Interpret the Results
, time: 7:57Meta-Analysis: Definition, Methods & Examples - Biology Class [ Video] | blogger.com
· The Five-step process Step 1: the research question. A clinical research question is identified and a hypothesis proposed. The likely clinical Step 3: data extraction. Once studies are selected for inclusion in the meta-analysis, summary data or outcomes are Step 4: Cited by: 12 A meta-analysis is a statistical analysis that combines the results of multiple scientific studies. Meta-analysis can be performed when there are multiple scientific studies addressing the same question, with each individual study reporting measurements that are expected to have some degree of error · Systematic Reviews and Meta Analysis Databases and Sources Search this Guide Search. Systematic Reviews and Meta Analysis. A resource for finding data sources, filters, and standards to support systematic searches of the biomedical literature. Databases and Sources;
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