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meta analysis

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medoo saleh

on 10 October 2012

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Transcript of meta analysis

Meta-analysis Effects of
Percutaneous Coronary Intervention(PCI)
Versus Medical Therapy on Angina Relief CAD (Coronary artery disease) is a non-surgical procedure used to treat the stenotic  (narrowed) coronary arteries of the heart found in coronary heart disease PCI (percutaneous coronary intervention) 1-aspirin
2- beta blockers
3- statin
4-ace inhibitors
5-nitrats
6-ca chanel blockers Medical therapy What is the difference between a
"systematic review" and a "meta-analysis"?  is a narrowing or blockage of the arteries and vessels that provide oxygen and nutrients to the heart. A form of bypass surgery that can create new routes around narrowed and blocked coronary arteries
, permitting increased blood flow to deliver oxygen and nutrients to the heart muscle. CABG (coronary artery bypass graft) is a thorough, comprehensive, and explicit way of interrogating the medical literature.
It typically involves several steps, including :- systematic review asking an answerable question
(often the most difficult step) . 1 identifying one or more databases to search . 2 developing an explicit search strategy. 3 selecting titles, abstracts, and manuscripts based on explicit inclusion and exclusion criteria. 4 abstracting data in a standardized format.  5 Therefore, every meta-analysis should be based on an underlying systematic review, but not every "meta-analysis" is a statistical approach to combine the data derived from a systematic-review. systematic review leads to a meta-analysis Several meta-analyses have evaluated the efficacy of percutaneous coronary intervention (PCI)
compared with medical therapy, but none has focused on angina relief. Back Ground To summarize the evidence on the degree of angina relief from PCI compared with medical therapy in patients with stable coronary artery disease. purpose -The Cochrane Library (1993 to June 2009),

-EMBASE(1980 to June 2009),

-MEDLINE (1950 to June 2009),


with no language restrictions..
(included records published in all languages) Data Source We developed and adhered to a standard protocol for study identification,
inclusion, and data abstraction for all steps of our systematic review.

All subgroup and metaregression analyses were prespecified in this protocol. Methods We have gone through
Cochrane Library (1993 to June 2009),
EMBASE (1980 to June 2009) and MEDLINE (1950 to June 2009)
Using the terms transluminal percutaneous coronary angioplasty and angina pectoris with no language restriction.

They yield 320 studies Data Sources and Searches Two independent reviews, Have chosen 22 studies out of 320
They included fourteen out of them based on Randomized trail Stable CAD comparing PCI with medical therapy

Recent coronary syndrome that have been stabilized for 1 week ?
- patients with minimal or no angina with stable CAD.
 

They have excluded 8 studies out of the 22 due to :
  
- Studies did not report symptoms: 4
- Studies did not distinguish between PCI and CABG as methods of coronary revascularization: 4
 
  Study Selection Data Extraction Two independent reviewers abstracted study data on patient characteristics, study conduct, and outcomes.
The primary outcome was freedom from angina.
To ensure that each study will have the appropriate effect in the final result of the meta-analysis we used :
- number of patients for whom symptom assessments were available at follow-up as the denominator in our calculations when determining the proportion of patients who were angina-free. for
randomization a description of the method an account of patients who withdrew proper concealment of the allocation
sequence, We evaluated study quality on the basis of the 5-point scale outlined by Jadad and colleagues with criteria : blinding of the patient and investigator to treatment allocation. We did analysis for :


1- the studies combined .

2- sub groups based on :
A/ Used of evidence based med?
B/ Follow up periods
C/ Use of stent ?
D/ Having a previous M.I.

3-meta regression analysis to see affect of the evidence based medication on the final results Data Synthesis and Analysis We assessed publication bias qualitatively by using a funnel plot and Egger test of the intercept.
Both tests are against publication bias.
Statistical significance was set at a P value less than 0.05.
We did all statistical calculations with the use of Comprehensive Meta-Analysis Software, version 2 (Biostat, Englewood, New Jersey). Continue We used a random-effects model based on the Der- Simonian and Laird method for combining results from individual trials.
We calculated the summary odds ratio (OR) and 95% CI.
We evaluated heterogeneity by calculating
the Cochran Q statistic, and significant heterogeneity was present, and the I2 statistic, which describes the proportion of variability due to
heterogeneity between individual trials. Continue Articles selected for full review
by 2 reviewers (n = 22) Studies excluded after full review
(n = 8)
Studies did not report symptoms: 4
Studies did not distinguish between
PCI and CABG as methods of
coronary revascularization: 4 Spark Trials included in
analysis (n = 14) Potentially relevant citations reviewed
after electronic literature search
(n = 310) Study Flow Diagram 1-Dr. Wijeysundera.

2-Dr. Nallamothu.

3-Dr. Krumholz.

4-Drs. Tu and Ko. Authors This study was funded in part by operating grants from the Canadian Institutes of Health Research (MOP 82747) and a Canadian Institutes of Health Research Team Grant in Cardiovascular Outcomes Research. Role of the Funding Source Annals of Internal Medicine 2010. magzine Result We based our meta-analysis
on the remaining 14 randomized trials, enrolling a total of 7818 patients. Results analysis At the end of trial follow-up, 73.0% of PCI
patients were angina-free,
compared with 63.9% of patients
who received medical therapy alone ,
so PCI was associated with improvement in freedom from angina compared with medical therapy. Freedom From Angina Significant heterogeneity across studies was observed (P _ 0.001), with an I2 statistic of 72.7%, indicating marked variation
in the estimates of freedom from
angina for PCI versus
medical therapy across studies. we evaluated the effect of PCI on freedom from angina on the basis of the length of
follow-up in the studies. Sub group analysis based on
follow – up periods: - with less than 1-year follow-up
(71.4% of PCI patients vs 64.3% of patients who received medical treatment were angina-free)
- trials with 1- to 5-year follow-up (71.3% vs. 61.9%).
- Among the 5 trials with more than 5-year follow-up,
the incremental benefit of PCI versus medical therapy did not reach statistical significance Percutaneous coronary intervention was associated with significant angina relief among trials: Our results did not change substantially
with the exclusion of the 6 trials that
enrolled patients with myocardial
infarction that stabilized.
  Subgroup Analysis on Trials With or Without Patients With Recent Myocardial Infarction: OR (1.92 [CI, 1.11 to 3.33]) for these 6 trials, with 3010 Subgroup Analysis on Coronary Stent Use :

The effect of stent use does not
affect the results but surprisingly
the PCI with out stent is better than
PCI with stent

OR (1.13
[CI, 0.76 to 1.68] for stent.
2.15 [CI, 1.48 to 3.13]). Without stent. Meta-regression of Freedom From
Angina and Medical Therapy:

We observed a statistically significant
inverse relationship between freedom
From angina and number of
evidence-based medications
used in a trial Discussion -PCI (when added to medical therapy) is better than medical therapy alone in angina relief for patient with stable CAD.
-There is a large variation among old trials and contemporary trials regarding the incremental benefit of PCI on angina relief compared to medical therapy :
-the benefit in angina relief associated with PCI was predominantly restricted to
older trial
New trail didn’t show a significant deference.
-There are many hypotheses that explain the variation of result among different trials. over all Heterogeneity Subgroups … ?

Meta regression…? Current practice guidelines recommend doing PCI for angina relief in patients with stable angina without specifically alluding to the role of medical therapy
But in contemporary practice, many patients would respond to medical therapy and the incremental benefit of PCI on angina relief may be substantially smaller than previously believed. Implications >> so , optimize medical therapy before referring patients for PCI (the new appropriateness guidelines ) Limitations -No complete information on the use of medical therapy.
-The studies used freedom from angina rather than angina severity as main outcome measure
-Assessing a single covariate on the basis of study-level (freedom from angina only ) >> so, our analysis should be considered exploratory and hypothesis-generating, not conclusive -The freedom from angina associated with medical therapy in recent randomized trials and
-a relatively limited incremental benefit of PCI for angina relief, probably due to the greater use of evidence-based medications in contemporary studies. Conclusion Thank you for listening ,,
Good luck in your exam next week fahad al malki , mohammad al twergy Mohammad al mowallad
Haytham nasur al din
Mohammad melebary ,
Khalid al qurashi , Talal al ghamdi ,
Omar al ghamdi , Abdulwahid al ghamdi ,,
Faris kalantn -ceno- , Majed toonsi ,
-Ahmad a`bed , Hossam al suhaimi ,
Wleed al qurashi , Abdulrahman al ahmdi ,
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