Systematic Reviews
Meta Analysis
General Article Ques
Other Questions
Figure 2
100
What are the two requirements of a systematic review?
1. Must be appropriate for addressing a single focused question 2. There must be some level of disagreement in the literature
100
What is one assumption of a meta-analysis?
The studies included must be homogeneous.
100
What question was the systematic review addressing?
Does aquatic exercise relieve pain in adults with neurologic or musculoskeletal disease? 2 elements of the question: 1. Is aquatic exercise and effective treatment for pain? 2. How does pain relief in aquatic exercise compare with other interventions?
100
Why was a meta-analysis of aquatic therapy vs immersion therapy not performed?
Because only 2 of the studies in the systematic review compared aquatic exercise to immersion therapy and of these studies one of them was assed to be of low quality. Therefore, since there were not enough studies of a sufficient quality, a meta-analysis was not conducted.
100
What is the name of the type of graph show in figure 2?
Forrest Plot
200
Name the four components of PICO?
1. Patient Population 2. Intervention 3. Comparison 4. Outcomes
200
What is the benefit of conducting a meta-analysis?
1. You have a larger sample size because you are pulling several studies together. 2. You will get a more precise estimate for the topic you are analyzing
200
Describe the focused clinical question in regards to PICO. Discuss if you think the population used in the study was appropriate?
P = adults with neurologic and musculoskeletal disease I = aquatic therapy C = no therapy, land-based therapy, immersion therapy O = pain outcome
200
What were the reasons reported for not including articles in the meta-analysis that were used in the systematic review?
If you look at figure 1, you see that articles were excluded either for high risk of bias or inappropriate data.
200
What does SMD stand for and why was it used?
a. SMD = Standard Mean Difference b. Since each study used different outcome measures this lets you standardize across the studies so that you can compare them. c. If all the studies had used the same outcome measure, you could have simply used the effect size rather than the SMD.
300
What is a publication bias?
When only the studies that have a large effect are published and studies that find small effects are not published.
300
What is an example of a null hypothesis for a test of heterogeneity and do you want to accept or reject this null hypothesis when you are trying to conduct a meta-analysis?
1. The null hypothesis for heterogeneity would be “There is no difference between the effect size estimates for the studies that want to be used in the meta-analysis.” 2. You do not want to reject the null hypothesis because in order to conduct a meta-analysis you need the studies to be homogeneous. This means that the only variability in effect size between the studies is due to random sampling. If you were to reject the null hypothesis then you would be saying that were is heterogeneity.
300
Explain the process for collecting the studies for the systematic review and how many studies were included.
a. 19 included b. The inclusion process involved a 3 stage process. In stage 1 the titles of the articles were checked against predetermined criteria. In the next 2 stages the abstracts and articles were checked against a similar set of criteria. c. Specific inclusion criteria included: i.The titles, abstracts and articles had to suggest some aspect of aquatic exercise in adults with neurological and musculoskeletal pathology and use an outcome measure of pain ii. Also, the studies had to be RCT that compared aquatic therapy to not treatment or other interventions such as land based therapy or immersion therapy d. Figure 1 shows a breakdown of the excluded studies and why they were excluded for the systemic review and the meta-analysis.
300
What are the steps of a systematic review?
a. Develop a question b. Perform an exhaustive literature search c. Determine and apply inclusion and exclusion criteria to select articles for the systematic review d. Summarize the results found
300
What was the result from comparison A and how do you know from figure 2 that this was the result?
a. Comparison A found that there was a difference between aquatic exercise vs no treatment. Looking at the SMD for the studies combined, you can see that is falls on the side of aquatic exercise. Therefore, you now that aquatic exercise was better/favored over no treatment. b. You know this because the test for overall effect found that P =0.04 and assuming a p-value of 0.05 was used 0.04 < 0.05. and this means there is a significance.
400
How do you assess for a publication bias?
A funnel plot.
400
What is the name of a test statistic that tests for homogeneity?
Mantel Haenszel Q or Cochrane’s Q or I2
400
What interventions were compared to aquatic therapy in this systematic review?
Land based therapy, immersion therapy, and no therapy
400
What is the difference between a systematic review and a meta-analysis?
a. A systematic review is simply a collection of articles that are compared to one another. b. A meta-analysis actually conducts statistics to find a pooled estimate from all the articles.
400
What were the results in comparison A and B for the tests for heterogeneity and what do these mean?
a. In comparison A the test for heterogeneity had a p = 0.65 and I2 = 0% b. In comparison B, the test for heterogeneity had a p = 0.91 and I2 = 0% c. This means that for both comparisons the null hypothesis cannot be rejected. Therefore, there is homogeneity among the studies
500
Draw a picture of a funnel plot that depicts a publication bias.
See picture.
500
Explain why studies are weighted in a meta-analysis and give 2 examples of factors that are considered in the weighting.
1. Studies are weighted because they are of differing quality. Therefore, studies that are of better quality are weighted heavier than studies of a lesser quality. When calculating the pooled estimates, the weighting of each study is taken into account. 2. The weighting is based on the quality or methods used in the study. This could include the size of the sample, how the sample was collect, whether or not randomization was used, if there was blinding of participants or researchers, ect.
500
How many studies were included in the meta-analysis and what were there criteria for determining inclusion into the meta-analysis?
a. 5 studies included b. The studies had to be of high to moderate quality to be included and they had to have adequate raw data.
500
Looking at figure 2, what was the result of comparison B and how do you know from figure 2 that this was the result?
a. For comparison B, the test for overall effect was p = 0.58. Assuming a p = 0.05, 0.58 is much larger than 0.05 and therefore you can concluded that this was not a significant test. When no significance is found, you can conclude that there is no difference. b. Also, when you look at the forest plot, you can see that the overall point estimate falls on the line and therefore is most likely not significant.
500
Looking at the forest plots in figure 2, do you think it was necessary to conduct a meta-analysis of these 5 studies?
a. Since all of the SMDs and the overall point estimates are roughly in line with one another, it was most likely not necessary to conduct a meta-analysis. b. Despite this, conducting a meta-analysis of these studies does give the results greater power because a much larger sample size was used in the meta-analysis.
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