Covariation, co-occurrence and epiphenomenal correlation of empirically based syndromes in children and adolescents

BACKGROUND: This paper determines the co-occurrence and correlations of different problem behaviours in children and adolescents in German clinical and general population samples. SAMPLING AND METHODS: The 2 samples were matched by age and gender (each sample n = 1,760). Including both categorical and dimensional models, rates of co-occurrence, relative risks, odds ratios and Pearson correlations were calculated. Results: The bidirectional comorbidity rates ranged from 7.3 to 34.3% (epidemiological sample) and from 22.5 to 54.8% (clinical sample). Most correlations between syndrome scales show medium or large effects. Many can be identified as 'epiphenomenal'; partial correlations from each pair, excluding influences of other syndromes, are much lower. CONCLUSIONS: This study shows the cross-cultural generalizability of comorbidity rates. The epiphenomenal nature of some comorbidities warrants future attention.