Publication bias
There was no significant publication bias for any of the psychiatric co-morbidity: alcohol abuse (intercept = 2.86, 95% CI: -28.9-34.6, τ = 1.14, df = 1, P = 0.458), ADHD (intercept = 2.19, 95% CI: 4.63-9.10, τ2 = 1.38, df = 2, P = 0.3), depression (intercept = 0.29, 95% CI: -6.42-6.99, τ2 = 0.14 df = 3, P = 0.90) and anxiety (intercept = 3.24, 95% CI: -9.26-15.7, τ2 = 1.12; df =2, P = 0.38).