Impulsivity or comorbidity in bulimia nervosa. A controlled study of deliberate self-harm and alcohol and drug misuse in a community sample

Authors:Welch, S. L. and Fairburn, C. G.
"Sampling bias is present in clinic-based studies of comorbidity in bulimia nervosa. Those with comorbid substance misuse and deliberate self-harm are probably heterogeneous in character, and their classification as a subgroup would therefore be premature."