Should systematic reviews be submitted to journals as original or review articles?
I can see a good case to be made on either side:


A systematic review, unlike a more traditional narrative review, is often an explicit numerical meta-analysis of prior data.  Its systematicity allows it to be an actual experiment with objectively verifiable conclusions, and thus it may be reasonably considered original research on a new data set drawn from the literature. 
Systematic reviews still, however, are organization and analysis of other studies, and so could be grouped in with other reviews.


Since both of these are reasonable, I suspect that there is no way to tell which perspective a particular publication subscribes to without reading their guidance to authors or asking their editorial staff (who will no doubt be happy to answer the question).