Dear Heba, most of the systematic reviews, specially the ones that focus on intervention studies, are made with RCTs. However you can definitely perform a systematic review (and meta-analysis) with non-RCTs. First you have to understand which topic your systematic review will focus on (intervention, etiology, prognosis, diagnosis, economics) and then you have to look for proper tools to evaluate the studies. There are not many specific tools for non-RCT evaluation, but they exist. I know the dutch cochrane group website has some (for cohort studies, ...), but not in english. 

Hello Heba! Yes, systematic reviews/meta-analysis can be done for any type of research design, the only difference would be where the paper would fall on the hierarchical level of evidence. A systematic review of RCT's is considered the highest level of evidence (level 1), whereas a systematic review of expert opinion papers or case studies is considered low level evidence (level 5 or 4, respectively).

Dear Heba,

yes, it is possible to include nonrandomised trials in systematic reviews of effectiveness of interventions. The tool for evaluation of nonrandomised studies developed by two Cochrane groups is ROBINS-I (earlier was the ACROBAT-NRSI), you can download it and obtain more information about it here: https://sites.google.com/site/riskofbiastool/welcome/home

There is an entire issue of "Research synthesis methods" that is actually on inclusion of nonrandomised studies in systematic reviews. I attach some of the papers of the issue. 

Regards,

Nicola

Hi,

yes, this is possible

There are several reporting guidelines that can help you

you could use the PRISMA  (Preferred Reporting Items for Systematic Reviews and Meta-Analyses: The PRISMA Statement) or the The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) Statement: guidelines for reporting observational studies. There are many others, suggest you check out the EQUATOR network at the following link

http://www.equator-network.org/?post_type=eq_guidelines&eq_guidelines_study_design=observational-studies&eq_guidelines_clinical_specialty=0&eq_guidelines_report_section=0&s=

kind regards 

carolina

Yes, systematic reviews of non-randomized trials can indeed be done. However, they offer a lower level of scientific evidence, compared to randomized trials. Results of a meticulously done single RCT  can provide evidence that is superior to that of a systematic review of several non-randomized trials

Yes. You can make a systematic review of non-randomized studies.

yes this is possible. besides ROBINS-I tool the Newcastle-Ottawa Scale could be used to assess the risk of bias of non-randomized studies of interventions

Yes you can. Please read this article for details:

Article Meta-analyses including non-randomized studies of therapeuti...