Our study investigated the prevalence of suicidality in a group of adolescents with onset of AN. First, we evaluated the diagnostic conceptualization based on the present criteria distinguishing the R-AN forms from the A-AN. Furthermore, we investigated the prevalence of suicidality among different AN subtype. Additionally, we assessed the association between suicidality, severity of ED specific symptoms and psychiatric comorbidity in relation to the diagnosis (R-AN or A-AN).
Our data show that among children and adolescent inpatients, R-AN is the most frequent subtype of AN, regardless of the four diagnostic criteria used. It is interesting to note that despite the different presentation in terms of BMI, weight loss rate is not different in the two forms of the disease, as if to indicate that it is independent of the starting.
We focused on the diagnostic criterion because the DSM-5  changed the BMI cut-off for AN diagnosis, from 17.5 kg/m2 to 18.5 kg/m2 for adults, in accordance with the definition of underweight in adult age proposed by the World Health Organization (WHO) . Instead, in children and adolescents, age- and sex-adjusted BMI was considered more appropriate and underweight was defined as a BMI below the 5th percentile of age according to CDC growth charts . This value makes the weight limit for diagnosing AN in children and adolescents stricter than in adults. Literature studies [27, 28, 29, 30] have suggested the use of the 10th percentile BMI criterion. Furthermore, in the evaluation of weight and height by age, geographical and ethnic variability must also be considered, as suggested by various pediatricians . Patients who meet psychiatric criteria but who have a BMI > 18.5 or a pBMI > 5 should be diagnosed with A-AN . We therefore tried to evaluate how the diagnostic distribution changes based on the BMI criterion used, noting that for 31% of patients the diagnosis changes. In addition A-AN shows EDI-3 higher scores  in the ED specific psychopathology and in “Ineffectiveness", in "Interpersonal Problems", in "Affective Problems" and "Overcontrol". Our data confirm that symptoms in adolescents with AN are independent from weight severity , while the reduced ability to recognize the body and inner states may be the specific pathway that associates the identity problems and eating symptoms . BMI appear to be a prognostic parameter in relation to mortality [32, 33, 34] and it is not clear what implication it may have with respect to AN psychopathology and suicidality. Persistently uncontrolled eating behaviors  or persistent low BMI  or severe psychiatric comorbidities especially in depressive disorders [8, 9, 37], seem more frequently related to suicide, especially in patients with a long-standing psychiatric history. Thus, an assessment of the relationships between general psychopathology, ED symptoms and childhood suicidality could clarify the implications of psychopathological and specific ED symptoms with respect to suicidality in young people with a short illness duration. In our sample there were no significant differences in the frequency of psychiatric comorbidities and suicidality between patients with R-AN and A-AN, consistent with literature [14, 15, 16].
The suicidality among our patients is according with literature data . To our knowledge, no studies on adolescents have evaluated suicidality in A-AN. In our sample, suicidality is not influenced by BMI and therefore it is not differently distributed between R-AN and A-AN. In addition, regardless of the R-AN and A-AN diagnosis, patients with suicidality show higher scores on all EDI-3 scales (disorder specific scale diet, psychological trait, and composite scale), and the suicidality is more common in patients whit comorbidities particularly with depressive disorder. These results are also confirmed for subgroups with self-harm and suicide ideation / attempts.
We can provide a possible explanation for this starting from the Interpersonal Psychological Theory of Suicide (IPTS) , which partly explains the relationship between suicidality and AN. It is theorized that the ability to commit suicide builds up over time through repeated experiences with painful and / or frightening events; these repeated experiences lead to the habit of pain and fear . The frequent involvement of patients with AN in painful stimuli (intake food restriction) associated with a sense of ineffectiveness, interpersonal, emotional problems, general psychological maladjustment, can lead to a very high suicide capacity. In line with this theory , depressive symptoms such as social isolation, guilt, feeling a burden for others and the sense of lack of belonging, seem to be able to add to the greater insensitivity to pain felt by patients with AN, thus favoring a risk suicidal who is independent of body weight. Since interpersonal difficulties and comorbid psychiatric symptoms gradually worsen as the disease progresses, assessing the severity and implication of these factors in patients at symptom onset we think it could have significant clinical and treatment implications.
Strength and limits
A relevant aspect of our study is that the diagnosis of AN in developmental age can change depending on diagnostic criteria used. Moreover, it provides new information on the association between AN and suicidality among adolescents.
The limitations of the study are the small sample size and the cross-sectional nature of our investigation, with data collected retrospectively at the time of hospitalization, which may tend to elicit recall bias. A prospective study enrolling a larger and more heterogeneous population of ED adolescent patients and evaluating treatment outcomes by type of diagnosis and their predictors would be needed to confirm our findings.
What is already known on this subject?
To our knowledge, no adolescent studies have evaluated suicidality in the diagnosis of A-AN.
What this study adds?
Our work shows that the specific psychopathology of ED and suicidality are not influenced by BMI. In fact, we observed that patients with suicidality showed higher scores on all EDI-3  scales (disorder-specific diet, psychological trait, and composite scale), regardless of the type of diagnosis (R-AN and A-AN). These data suggest that in developmental age suicidality should always be evaluated in adolescents and should be related to the psychopathological core and associated comorbidities.