We found no evidence of an increased risk of irritability (odds ratio 0.98, 05% confidence interval 0.81 to 1.17; P=0.79, I2=0.0%), aggression (0.91, 0.52 to 1.59; P=0.75, I2=20.8%), or somnolence (1.23, 0.94 to 1.62; P=0.13, I2=10.4%) as the confidence intervals included the null value of 1. Varenicline was associated with an increased risk of sleep disorders (1.63, 1.29 to 2.07; P<0.001, I2=0.0%), insomnia (1.56, 1.36 to 1.78; P<0.001, I2=0.0%), abnormal dreams (2.38, 2.05 to 2.77; P<0.001, I2=22.3%), and fatigue (1.28, 1.06 to 1.55; P=0.01, I2=6.3%), with some evidence of a reduced risk of anxiety (0.75, 0.61 to 0.93; P=0.008, I2=5.7%). Consistent findings were observed for the risk differences (table 4).
