I'm involved in writing a review of surgical approaches to a very rare type of tumour. So rare that, forget randomised control trials comparing treatment options, here there are only about 80 cases ever published. The information I'm finding so far (reviews on writing reviews!) suggests case studies and series can be included in systematic reviews, but I'm wondering whether it be done where ONLY these types of studies are available. I think we can tick most of the boxes on the attached (narrative vs. systematic review) but still would like some confirmation that it is valid before I resort to writing a narrative review. I would greatly appreciate some examples of similar reviews as a guide. I've also read that meta-analysis cannot be before on studies without control groups, but wonder if that means more complex analysis that what we had in mind. For instance, can I at least give the male:female breakdown of the combined cases? Median age etc? Surely yes. Many thanks in advance.
Hi Chanel,
Meta-analysis can definitely be performed without control groups - it all depends on the research question and the effect size metric of interest. If you have all the cases, you could think about treating each individual case as its own primary study and use regular regression-based analyses to aggregate the body of literature. I'm not sure how you can get study-level effect sizes/means with individual cases. There are also meta-analyses of single-subject research studies, but those data are collected very differently. Another option would be to consider a best-evidence synthesis instead of a meta-analysis (see Bob Slavin's work). Best of luck! Sounds like you've put a lot of thought into this.
yes you can,
see these sources
1-this paper with the title 9Methods for the Synthesis of Studies without Control Groups)
Methods for the Synthesis of Studies without Control Groups | Publication Detail | National Collaborating Centre for Methods and Tools
http://www.nccmt.ca/resources/publications/10
2- Chambers et al. Not only randomized controlled trials, but also case series should be considered in systematic reviews of rapidly developing technologies. J Clin Epidemiol. 2009 Dec;62(12):1253-1260.e4.
https://www.researchgate.net/deref/http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fpubmed%2F19349144
3-Using Multiple Types of Studies in Systematic Reviews of Health Care Interventions – A Systematic Review
PLOS ONE: Using Multiple Types of Studies in Systematic Reviews of Health Care Interventions – A Systematic Review
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0085035
example will help you alot ,
this is asytematic review based on case series , its title :
Adverse effects of homeopathy: a systematic review of published case reports and case series
Adverse effects of homeopathy: a systematic review of published case reports and case series - Posadzki - 2012 - International Journal of Clinical Practice - Wiley Online Library
http://onlinelibrary.wiley.com/doi/10.1111/ijcp.12026/full
hope that help you.
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