Random effects meta-analysis
The statistical analysis includes both fixed and random effect models. In contrast to fixed effect models, which are used to estimate a common effect, random effect models estimate an average effect, and the variability of the effects represented by their average may have clinical implications. This can be discussed using a prediction interval, see Riley RD, Higgins JPT, Deeks JJ. Research Methods & Reporting: Interpretation of random effects meta-analyses. Br Med J 2011;342:d549.
The authors claim that their study was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) statement. PRISMA is, however, a reporting guideline (an evidence-based minimum set of items for reporting in systematic reviews and meta-analyses), not a guideline on how to conduct studies. I recommend rephrasing the sentence.