The present study identified two subtypes of restrictive food intake disorder in children using LCA based on clinical information, growth chart analyses and socio-demographic parameters available at hospital admission. The clusters found with LCA based on the parameters at admission were consistent with the diagnoses of EOAN and ARFID made at the end of hospitalisation. Clinical and socio-demographic characteristics other than the core symptoms of EOAN (i.e., fear of gaining weight and disturbed body image) available at admission to hospital can help obtain a highly accurate diagnosis of children with food intake disorder (only two ARFID patients were misclassified in EOAN group).
Cluster 1, representing 74% of the sample, was mostly associated with a diagnosis of EOAN at the end of hospitalisation. Patients in cluster 1 were more often girls, with a higher socio-economic level, intensive sports activity, more frequent familial eating disorders other psychiatric histories and more frequently had an identified trigger for the onset of their eating disorder. Although these features are consistent with the classic features of EOAN (Herpertz-Dahlmann & Dahmen, 2019), it should be noted that they are not always present in single patients. In our sample, none of the patients from cluster 1 had associated ADHD but all had a retarded growth curve. These features must be interpreted as a whole to determine the diagnosis. Cluster 2 represented 26% of the sample, had features suggesting a diagnosis of ARFID (Fisher et al., 2014) and was associated with a diagnosis of ARFID at the end of hospitalisation.
We found significant differences between ARFID and EOAN groups which are consistent with previous studies comparing these two disorders (Cañas et al., 2021; Fisher et al., 2014) and helped characterise patients with ARFID (see Supp Table S1). A comparison of ARFID EOAN, confirmed the presence of more males (37% vs 16%, p = 0.06), earlier onset of symptoms with frequent onset from Tanner stage 1 (63% vs 44%, p = 0.06), more comorbid psychiatric and neurodevelopmental disorders (70% vs 41%, p = 0.03) and a higher likelihood of a history of chronic disease (45% vs 20%, p = 0.04), respectively (Bourne et al., 2020; Cañas et al., 2021; Fisher et al., 2014; Norris et al., 2014; Pinhas et al., 2011). Unlike one previous observational study, we found that children with EOAN more frequently had first-degree psychiatric histories (including a history of ED ) than those with ARFID (Kurotori et al., 2019). This difference may be explained by different samples size in the two studies (13 ARFID patients in Kurotori study versus 27 in ours).
To our knowledge, this is the only study that has compared auxological parameters in children with ARFID and those with EOAN. Children with EOAN had more frequent early adiposity rebound (50% vs 33%, p = 0.02) than those with ARFID while the adiposity rebound did not occur in more children with ARFID (41% vs 17%, p = 0.07). We reported growth retardation in 33% of ARFID patients at hospitalisation. Although this was less frequent than in children with EOAN (95%, p = 3.02e-5), undernutrition can also lead to growth impairment in ARFID patients. In ARFID, the health consequences of reduced food intake may be to those in EOAN (hypothermia, anaemia, bradycardia, tooth decay) (Pinhas et al., 2011) thus, early and intensive treatment to restore weight is indicated (Bourne et al., 2020).
ARFID is a heterogeneous group that includes various subtypes: chronic low appetite, or limited interest in feeding, specific phobias (fear of choking or vomiting), severe selective eating and/or food neophobia. A single patient may belong to more than one subtype due to frequent overlap of eviction drivers (Bryant-Waugh, 2019). A larger sample of patients more representative of the entire ARFID population is needed to explore the heterogeneity of this population. Also, our results do not exclude diagnosis overlap in some children initially diagnosed with ARFID and who may secondarily develop EOAN. Some of these children continue to have EOAN while others will recover from anorexia but continue to meet the diagnostic criteria for ARFID. Restrictive eating disorder may be a spectrum of disorders sharing certain common risks factors.