Table 6.
Quality of randomized controlled studies.
| Study (Reference) | Allocation Concealment | Masking of Participants | Masking of Researchers | Dropouts Clearly Reported | Industry Funding | Cocoa Products as Gift from Industry | Compliance Measured | Crossover Design | Carry-Over Effects Possible a | Dietary Intake Documented | Dietary Restrictions |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Bolus consumption | |||||||||||
| Schramm et al., 2001 [43] | Y | Y | Y | Y | N | Y | - | Y | N | - | Y |
| Heptinstall et al., 2006 [44] | ? | Y | Y | - | N | Y | - | Y | N | - | Y |
| Flammer et al., 2007 [45] | Y | Y | Y | - | N | Y | - | N | - | - | Y |
| Davison et al., 2012 [47] | Y | N | Y | - | Y | Y | - | Y | N | Y | Y |
| Flammer et al., 2012 [48] | Y | Y | Y | Y | Y | Y | - | N | - | - | Y |
| Mellor et al., 2013 [49] | Y | Y | Y | - | Y | Y | - | Y | N | - | Y |
| Vázquez-Agell et al., 2013 [46] | ? | N | N | Y | N | Y | - | Y | N | - | Y |
| Loffredo et al., 2014 | Y | N | Y | - | N | N | - | Y | N | - | N |
| Basu et al., 2015 [50] | ? | Y | Y | - | N | N | - | Y | N | - | Y |
| Regular consumption—healthy | |||||||||||
| Grassi et al., 2005 [51] | ? | N | N | Y | N | ? | N | Y | N | Y | Y |
| Kurlandsky and Stote, 2006 [ 52] | Y | N | N | Y | N | Y | N | N | - | Y | Y |
| Crews et al., 2008 [53] | Y | Y | Y | Y | Y | Y | Y | N | - | N | Y |
| Njike et al., 2011 [54] | Y | Y | Y | Y | Y | Y | N | Y | N | Y | Y |
| Tzounis et al., 2011 [55] | Y | Y | Y | Y | N | Y | Y | Y | N | Y | Y |
| Ibero-Baraibar et al., 2014 [56] | ? | Y | Y | N | N | N | Y | N | - | Y | Y |
| Sarriá et al., 2014 [57] | N | N | N | Y | Y | Y | Y | Y | Y | Y | Y |
| West et al., 2014 [58] | ? | Y | Y | Y | Y | Y | N | Y | N | N | Y |
| McFarlin et al., 2015 [59] | ? | Y | Y | N | Y | Y | N | Y | N | N | Y |
| Regular consumption—pre-/hypertension | |||||||||||
| Grassi et al., 2005 [51] | ? | N | N | Y | N | ? | N | Y | N | Y | Y |
| Wang-Polagruto et al., 2006 [60] | ? | Y | Y | Y | Y | Y | Y | N | - | Y | Y |
| Grassi et al., 2008 [61] | ? | N | Y | Y | N | Y | N | Y | N | Y | Y |
| Muniyappa et al., 2008 [62] | Y | Y | Y | Y | N | Y | Y | Y | N | N | Y |
| Regular consumption—diabetes, impaired glucose tolerance | |||||||||||
| Balzer et al., 2008 [63] | ? | Y | Y | Y | N | Y | Y | N | - | N | N |
| Grassi et al., 2008 [61] | ? | N | Y | Y | N | Y | N | Y | N | Y | Y |
| Monagas et al., 2009 [64] | ? | N | Y | Y | N | Y | Y | Y | Y | Y | Y |
| Mellor et al., 2010 [65] | Y | Y | Y | Y | N | Y | Y | Y | N | Y | N |
| Stote et al., 2012 [66] | ? | N | Y | Y | N | Y | N | Y | N | N | Y |
| Parsaeyan et al., 2014 [67] | N | N | N | - | N | N | N | N | - | Y | N |
| Rostami et al., 2015 [68] | Y | N | Y | Y | N | Y | Y | N | - | Y | N |
| Regular consumption—coronary heart disease | |||||||||||
| Farouque et al., 2006 [69] | Y | Y | Y | N | Y | Y | Y | Y | Y | N | N |
| Heiss et al., 2010 [70] | ? | Y | Y | N | Y | Y | N | Y | N | N | N |
| Flammer et al., 2012 [48] | Y | Y | Y | Y | Y | Y | Y | N | - | N | Y |
| Horn et al., 2014 [72] | Y | Y | Y | - | Y | Y | N | Y | N | N | N |
a concerns studies with crossover design: In case of washout periods were reported, carry-over effects could be excluded, but not if washout periods were missing or not reported. All criteria except for “dietary intake documented” and “dietary restrictions” are GRADE criteria. N: no, Y: yes; ?: unclear.