Why perform a meta-analysis?ĭecisions about the utility of an intervention or the validity of a hypothesis cannot be based on the results of a single study, because results typically vary from one study to the next. When the effect varies from one study to the next, meta-analysis may be used to identify the reason for the variation.
When the treatment effect (or effect size) is consistent from one study to the next, meta-analysis can be used to identify this common effect. Meta-analysis is the statistical procedure for combining data from multiple studies. The set of conditions that studies must meet to be included in the review (or for individual studies - the set of conditions that participants must meet to be included in the study often comprises age, gender, disease type and status, etc.).Why perform a meta-analysis? What is a meta-analysis? Since systematic reviews seek to include all relevant studies, exclusion criteria are not generally utilized in this situation. other health conditions, taking specific medications, etc.). The set of conditions that characterize some individuals which result in being excluded in the study (i.e. These findings may explain better health outcomes in vegetarians, but additional research is needed to remove any possible confounding variables.Ī highly-regarded database of systematic reviews prepared by The Cochrane Collaboration, an international group of individuals and institutions who review and analyze the published literature. In nine of the twelve studies, vegetarians had higher overall diet quality compared to non-vegetarians. Vegetarians more closely met recommendations for total fruit, whole grains, seafood and plant protein, and sodium intake. This systematic review was interested in comparing the diet quality of vegetarian and non-vegetarian diets. Diet quality of vegetarian diets compared with nonvegetarian diets: a systematic review. Additional research is needed to determine if there is an effect due to acupuncture that lasts at least seven days. Due to the low quality of evidence in these studies and lack of blinding, it is not possible to link any short-term decrease in blood pressure to the use of acupuncture. This systematic review analyzed twenty-two randomized controlled trials to determine whether acupuncture is a safe and effective way to lower blood pressure in adults with primary hypertension. The Cochrane Database of Systematic Reviews, 11(11), CD008821. Yang, J., Chen, J., Yang, M., Yu, S., Ying, L., Liu, G. The thirty studies were reviewed and showed a strong positive relationship between daily wearing of sunscreen and a reduced diagnosis of melanoma. Each study was then evaluated to determine whether the study focused specifically on ultraviolet-blocking sunscreen and melanoma prevention 30 of the 54 studies were retained.
Some reviews may group and analyze studies by variables such as age and gender factors that were not allocated to participants.ĭo the analyses in the systematic review fit the variables being studied in the original studies?ĭoes the regular wearing of ultraviolet-blocking sunscreen prevent melanoma? An exhaustive literature search was conducted, resulting in 54 studies on sunscreen and melanoma. Is each study included in the review studying the same variables? Studies included in systematic reviews may be of varying study designs, but should collectively be studying the same outcome.
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