In our clinical study on 169 female anorexia nervosa inpatients, we found 24.3% of the patients with a comorbid somatic disease. These diseases were partly related (7.7%) and more frequently unrelated (15.4%) to anorexia nervosa. For both subgroups, internal diseases were observed most frequently. Overall, diverse somatic comorbidities from different medical fields were reported. Somatically ill anorexia nervosa patients showed higher age at the time of treatment, a later onset of anorexia nervosa and had a longer duration of treatment. Mortality was observed in nine of one hundred patients and was significantly higher in somatically ill patients. The relationship between mortality and somatic comorbidity was also statistically shown in a survival analysis, revealing somatic comorbidity as a significant coefficient.
The small sample of deceased anorexia nervosa inpatients did not allow us to conduct more sophisticated statistical analyses, such as regression analyses or survival analyses. The interpretation and generalization of our results is limited. No information on the causes of death was available for us. Therefore, we cannot draw confident causal conclusions between the observed correlation of mortality and somatic comorbidity.
The relatively high rate of somatically ill anorexia nervosa inpatients can be explained with the specific referral procedure to our university medical centre. Moreover, the intensive cooperation between our psychosomatic department and other units, such as the gastroenterological, neurological, and endocrinological departments, probably led to frequent referrals of patients with somatic illnesses.
Long-term mortality in anorexia nervosa has been intensively studied, and mortality rates vary together with the follow-up interval . Data on the outcome of anorexia nervosa after more than 15 years is rare, and our follow-up interval of 21 years can be considered as relatively long. The observed mortality rate in our sample is in the rage of mortality rates to be expected with regard to the existing literature. However, we cannot confirm the reported correlations of laxative use/purging behaviour, BMI, duration of illness/onset, and psychiatric comorbidity. We only can confirm the relationship between substance abuse and mortality, which has also often been described in former studies . The reason for this discrepancy is probably our small and specific sample.
To our knowledge, the present study is the first empirical sample that describes anorexia nervosa inpatients with a somatic comorbidity. The correlation with mortality might at least indicate a poor outcome for inpatients in this subsample, which confirms the clinical impression of medical practitioners treating anorexia nervosa patients. The relatively high co-occurrence of anorexia nervosa and somatic diseases in all medical fields is probably an issue that medical professionals are not overly aware of in clinical practice. Especially, in cases of patients where the somatic disease is associated with alterations in food intake and weight, such as inflammatory bowel diseases, medical professionals may not consider the possible existence of a comorbid anorexia nervosa. Moreover, we observed a high age and a late onset of anorexia nervosa in this subgroup, features that may not "fit" into the clinical idea medical practitioners have of the "typical" anorexic individual. The high rate of mortality in this group could reflect the "result" of this supposed problematic constellation.
To assure a good therapeutic outcome for anorexia nervosa patients with a somatic comorbidity, a high level of interdisciplinary treatment including all medical fields and early interventions by professionals in the field of psychosomatic medicine is needed. This group of patients might be at a specific risk for particularly poor long-term outcome. Further studies are needed to confirm these findings.