Background: Although there are many systematic reviews (SRs) that evaluate observational studies or clinical trials, those that evaluate only case reports or series tend to be scarce and without adequate criteria to assess their methodological features.
Objective: To describe and assess the methodological features of SRs of case series or case reports in humans.
Method: We searched on Scopus, Embase, Pubmed/Medline, Web of Science and Scielo from inception to June 2022. Methodological quality of included SRs was assessed using the AMSTAR-2 tool, without taking into account the 4 criteria considering meta-analysis (12/16 items). We presented the results in a descriptive manner.
Results: We included 220 SRs (5040 patients) that met the inclusion criteria. The most evaluated topic was the one describing adverse effects to a drug or clinical condition (125/220) and the majority of studies (180/220) did not refer to the elaboration of a protocol prior to the execution of the review. Also, while all studies reported a screening process, the majority (195/220) did not use a reporting guideline or evaluate the methodological quality of the cases. Two hundred SRs scored “Critically low” with a median 5 [IQR: 3 to 7] in the methodological quality assessment.
Conclusion: We found that the evidence on systematic reviews involving only case reports or case series is limited and of poor methodological quality. These findings outline the necessity of future SR of case or case series have adequate methodological and reporting quality.
Keywords: Systematic Review, Case report, Case Series, Methodological quality