“…31,[34][35][36][37][38][39]63,67,69,72,[78][79][80]84,[86][87][88][89] urinary or saliva cotinine (six trials), 65,68,70,71,75,81 or saliva thiocyanate (one trial) 40 and nine trials 41,64,66,73,74,76,77,82,85 presented self-reported abstinence only. All studies used a parallel group design except one which was cluster randomised; 41 however, any dependency in the data due to clustering was found to be negligible and, therefore, this study was analysed with the others.…”