Scientific hypotheses can be tested by comparing the effects of one treatment over many diseases in a systematic review
Journal of Clinical Epidemiology (2014) - Comments
pubmed: 25282131  doi: 10.1016/j.jclinepi.2014.08.007  issn: 1878-5921  issn: 0895-4356 

Yen-Fu Chen, Karla Hemming, Peter J. Chilton, Keshav K. Gupta, Douglas G. Altman, Richard J. Lilford