Problems with the zinc and common cold review by Caruso et al . ( 2007 )

In their systematic review, Caruso et al. identified 14 zinc trials (the above paper). They used the quality scoring approach so that for the identified trials they gave one point for each of 11 quality items if it was satisfied. In two tables and one figure, Caruso et al. described the distribution of quality scores and the individual quality features of the trials. They considered that only studies with full 11 points were valid: “Four studies met all 11 criteria. Three of these studies reported no therapeutic effect from zinc lozenge or nasal spray. One study reported positive results from zinc nasal spray.” On the basis of this 3 vs. 1 comparison (“vote counting”) Caruso et al. concluded that “the therapeutic effectiveness of zinc lozenges has yet to be established.” They proposed that the positive findings with zinc could be explained by methodological faults in the studies.