This study aimed to analyse the course of eating disorders (ED) over thirty months emphasizing comorbidity and stability of the ED diagnoses. Particularly attention was given to the eating disorders not otherwise specified (EDNOS) subjects in comparison with anorexia nervosa (AN) and bulimia nervosa (BN) patients.

192 women with a DSM IV eating disorder diagnosis - 55 AN, 108 BN, 29 EDNOS - was assessed with the structured interview (SCID I) at the baseline, one year and thirty months after the first assessment.

83.3% of the total sample had in addition to the ED diagnosis one or more lifetime axis I diagnoses. We found no significant differences between the most common axis diagnoses - anxiety and affective disorders, or dependence disorders - in the three diagnostic groups, excepted for social phobia, in fact this disorder was significantly often present in AN. The distribution of the lifetime suicidal attempt was very similar in the three diagnostic groups.

The stability of the ED diagnoses was low, but EDNOS was the most instable ED diagnosis with a tendency to remission.

The axis I comorbidity of ED was very high, and the EDNOS subjects showed a very similar axis I comorbidity compared with subjects with AN and BN. The stability of the ED diagnoses was low and the EDNOS group showed the highest ED diagnosis instability and tendency to remission. The relationship between axis I comorbidity, and ED instability is unclear, further studies in these fields are needed.