Article / Study design
Random sequence generation
Allocation concealment
Blinding of participants and personnel
Blinding of outcome assessment
Incomplete outcome data
Selective reporting
Other bias
Directness
Precision
Edman Tynelius
et al
. [13] / RCT
+
+
-
-
+
+
+
?
+
Artun
et al
. [11] / RCT
?
?
-
-
+
+
+
-
?
Cerny
et al
. [12] / CT
Na
Na
-
-
+
+
?
-
-
Levin
et al
. [16] / CT
Na
Na
-
-
+
+
?
?
-
Rody
et al
. [15] /CT
Na
Na
-
-
+
+
?
-
-
Artun [14] / CT
Na
Na
-
-
+
+
?
-
-
+ = low risk/no problems; ? = unclear risk/some problems; -= high risk/major problems; CT = non-randomised controlled study; Na=Not applicable; RCT = Randomised controlled trial
Table 3:
Study limitations in controlled studies.
