Abstract
I read with interest the article by Nagao and colleagues in your journal. 1 The authors evaluated the correlation between hemostatic difficulty after dental extraction and platelet aggregation test in patients receiving antiplatelet therapy.
A strength point of this study is having control group to resolve the biases made by some cofounders such as dentist’s expertise, patients’ age, weight, gender, blood pressure, and underlying diseases. I think the effects of some confounders on bleeding and hemostatic difficulty are missing. 2,3 They need to mention the details about the number of extracted teeth and roots and type of them in each patients as confounders for results of bleeding. These confounders should not be statistically different between the patients taking antiplatelet therapy and the control group.
The authors tried to control the type of antiplatelet therapy as the most important confounder for these results. The effects of antiplatelet therapy duration (new vs old consumption) and manufacturing company are missing in their study. It seems that the only group with an adequate number of patients for a good conclusion is the group of patients taking aspirin (46 patients). Other patients taking clopidogrel (17 patients) and other antiplatelet therapies (less than 10 patients in each group) are inadequate for a good conclusion. In addition, the reason for antiplatelet therapy mentioned as an important factor affecting bleeding results in previous studies. 2 To omit the effect of 2 above factors, some studies enrolled only the patients taking the unique type of antiplatelet therapy and because of only 1 reason, for example, extracting 1 tooth in patients taking both aspirin and clopidogrel for stenting after coronary intervention. 4
The results of this study about correlation between hemostatic difficulty and aggregometry seem to be more reliable only in patients taking aspirin (65 of 79). Furthermore, this correlation should be optimized for other confounders in the future studies.