On 2016 Feb 03, Jos Verbeek commented:

It is interesting to see that the conclusions of this review are at odds with a Cochrane Review on the same topic that concluded that there was no evidence of an effect for safety engeneered devices. The reason is that the authors of this review included uncontrolled before-after studies. They took the reduction of sharps injuries at one point in time after the introduction as the control condition. Of course, this carries a very high risk of bias because many things change over time and it is difficult to ascribe the change to the intervention. Using the GRADE qualification moderate quality evidence for evidence based on uncontrolled before-after studies is therefore misleading. I rather believe the results of the Cochrane Review

On 2016 Feb 03, Jos Verbeek commented:

It is interesting to see that the conclusions of this review are at odds with a Cochrane Review on the same topic that concluded that there was no evidence of an effect for safety engeneered devices. The reason is that the authors of this review included uncontrolled before-after studies. They took the reduction of sharps injuries at one point in time after the introduction as the control condition. Of course, this carries a very high risk of bias because many things change over time and it is difficult to ascribe the change to the intervention. Using the GRADE qualification moderate quality evidence for evidence based on uncontrolled before-after studies is therefore misleading. I rather believe the results of the Cochrane Review