In fairness it's not a trial, it's a meta-analysis. So people looking at papers and creating a spreadsheet or something. They can be pretty cheap, rather than the billion or two it takes to get a new drug to market.

I haven't read the paper but the absolute best outcome would be that they list all the studies they evaluate for inclusion (which is most of the work, finding and evaluating) so that others could perform similar analyses with a big head start.