EEN has been established as the gold standard in induction therapy for children and adolescents with CD, but large differences in the administration were observed among the pediatric gastroenterology centers of CEDATA-GPGE®. The variation was observed in the formula used, the application, the addition of flavorings to formula, and foods allowed during the period of EEN as well as the reintroduction of conventional foods after EEN was concluded.
While almost 90% of CD patients at the CEDATA-GPGE® clinics were recommended EEN to induce remission, the use of this dietary intervention varied between 12 and 89% at international studies [8, 9, 11, 14, 15]. 31% of North American medical professionals surveyed reported that they never used an EEN to induce remission, and only 4% prescribed it regularly [10, 14]. The main reason for this was that the medical professionals were concerned about the difficulty in administering EEN and the resulting lack of compliance by the patient and/or family. In addition, the experience of the pediatric gastroenterologists and the frequency in which they used EEN in the past was crucial for the use of this dietary intervention in induction therapy in pediatric CD patients [14, 15]. Our study shows that despite the wide variation in administration and support, EEN is feasible and should be widely used in luminal Crohn’s. The variation in structures and outcomes did not yield clear associations, but should still be used to clarify, compare, standardize, and optimize procedures around EEN.
The international consensus guidelines have recommended that EEN is administered over 6 to 8 weeks [6, 7]. The majority of the German and Austrian practitioners in the current survey utilized EEN over 6 to 8 weeks. In comparison to international practices, a wide difference is evident. Fifty-two percent of Swedish medical professionals recommended a duration of 6 weeks, while 30% of North American medical professionals recommended less than 6 weeks [14, 16]. The majority of Japanese gastroenterologists (76%) prescribed EEN until the person’s symptoms improved (15.9 days on average) .
Our study also showed that duration does not seem to influence dropout rate as badly as previously thought, but is more a question of intensive support and reassurance.
Various types of enteral formula can be used for EEN. English and Canadian doctors preferred administration via a nasogastric tube, while the German and Austrian pediatric gastroenterologists of CEDATA-GPGE® and Spanish doctors preferred an oral intake of the formula [14, 15, 17]. These differences may be due to the formula. While the CEDATA-GPGE® clinics and the hospitals in Spain mainly used polymeric formulas for EEN, the physicians from North America, Canada, and Japan mainly used elemental formulas [9, 14, 15]. Due to the poor taste and the associated lower acceptance by the patients, elementary diets usually require application via a gastric tube . According to the S3 and ECCO/ESPGHAN guidelines, low-molecular diets show no advantages in terms of effectiveness compared to high-molecular formula and should only be used in the presence of concomitant diseases, such as a cow’s milk protein allergy [6, 7, 19]. Polymer diets should be preferred to elementary diets .
A completion of EEN, which lasts several weeks, is a great challenge for pediatric CD patients and their families. This very monotonous and restrictive form of nutrition, the avoidance of conventional food and drinks, and the taste of the formula often lead to non-compliance and thus to premature termination of EEN [20,21,22]. In the S3 guideline and in a systematic review by Narula et al., a dropout rate of 20% was reported [21, 22]. The surveyed CEDATA-GPGE® physicians also stated that around a fifth of CD patients discontinued this dietary intervention prematurely. Therefore, the patient’s motivation, close care, and regular follow-ups during the period of EEN are crucial for the full implementation and thus successful treatment of EEN [12, 15].
Although there is no recommendation in the international guidelines regarding flavoring, four-fifths of the CEDATA-GPGE® clinics surveyed allowed the use of flavoring additives during EEN. In international studies, 50 to 81% of gastroenterologists allowed the addition of flavorings to the formula [8, 11, 15, 16]. The intention of medical professionals’ efforts is to avoid taste fatigue or refusal of taste and thus a premature termination of EEN .
For the same reasons, a third of the surveyed CEDATA-GPGE® clinics allowed certain conventional foods to be consumed during EEN. In the surveys by Navas-Lopez and Grafors, 9.3 to 81% of gastroenterologists, respectively, allowed the consumption of predefined normal foods and beverages [15, 16].
Although the total exclusion of conventional food and beverages during EEN appears to be crucial for the success of induction therapy for pediatric CD, new modalities of dietary treatment are increasingly being investigated for the nutritional management of CD . For example, the CDED, a food-based diet coupled with PEN, was associated with stable remission rates and a reduction in fecal inflammation levels in pediatric patients with CD [13, 24, 25]. Nevertheless, the CED Working Group of ESPGHAN and the GPGE opposed CDED in the induction therapy of pediatric MC, and thus, the consumption of conventional food and beverages during EEN due to the lack of randomized controlled trials [26, 27]. Further clinical studies are needed to investigate the more tolerable food-based diets—especially regarding the mucosa healing .
Regarding the dropout rate, there was no statistically significant correlation between the CEDATA-GPGE® clinics with a short (< 45 min) and long (≥ 45 min) patient education about EEN. However, a tendency was observed in which longer patient’s education about EEN was associated with a lower dropout rate. Comparing the three specialists, pediatric gastroenterologist, IBD nurse, and dietician, it was also observed that a dietician tended to spend more time on the patient education about EEN. This suggests that a dietician should take over the patient information about EEN for pediatric CD patients or that the practitioner should ensure extensive and repetitive advice and support during the process.
The fact that a longer explanation of EEN tended to be associated with a lower dropout rate could be explained by the fact that the professional was able to devote more time to the affected person in a longer consultation or to respond more to them and their needs and wishes. Worries that lead to premature termination of EEN can be reduced during the educational discussion.
There is also no significant correlation between the dropout rate of EEN and the average age of CD patients at diagnosis. Since a premature dropout of the patients is not recorded at the registry, the estimated values of the doctors were used here. To find significant associations, the dropout rates should be included within the documentation sheet of CEDATA-GPGE® in the future.
After EEN, a period of 2 to 3 weeks is recommended for reintroducing conventional foods, with a gradual reduction in formula every 2 to 3 days [7, 19]. There are also considerable differences internationally. While almost 90% of the CEDATA-GPGE® hospitals reduced the formula for 1 to 2 weeks, this period varied between 1 and 12 weeks in European, North American, and Asia-Pacific clinics [11, 15]. In the studies by Stewart and Ho et al., 57 to 76% of North American, Australian, and New Zealand medical professionals allowed one normal meal at a time [8, 14]. Others were guided by the fiber and/or allergen content of the food when reintroducing conventional diets [8, 11, 14].
After the period of EEN, no special diets were recommended to the patients of the clinics of CEDATA-GPGE® for the maintenance therapy. Almost four-fifths of the clinics surveyed recommended a balanced mixed diet, taking individual aversions and intolerances into account. In the studies by Whitten and Ho et al. 45 to 50% of the physicians recommended starting with a low-fiber diet and 17% with a low-allergen diet after the end of EEN [8, 11].
Currently, there is no special “Crohn’s diet” that equally relieves symptoms in all pediatric CD patients [3, 6, 28, 29]. Instead, as part of nutritional therapy with an experienced dietician, the individual diet suitable for the patient should be found on the basis of the severity of the illness, drug treatment, surgical measures, and its accompanying symptoms (e.g., stenosis, short bowel syndrome, stoma) .
One of the strengths of this study is the selected data collection technique. A written survey, compared to an interview, is characterized by a fast processing time for the participants. The high response rate of this study should also be emphasized. Postal surveys are usually associated with high non-response rates, which is why this survey clearly stands out with a response rate of 81.6%  compared to similar surveys with response rates between 42 and 54% [8, 11].
A major weakness of this study is the small sample size of centers questioned (N = 31). In order to identify significant correlations the study should be repeated on a larger scale for multifactorial models and association with outcome parameters.
Another weakness of the survey is the estimated values of the pediatric gastroenterologists for the number of patients who got recommended, started, and stopped EEN prematurely. Specific numbers of patients are missing and should be reevaluated. All data obtained is based on a subjective assessment by the physicians and are therefore inevitably subject to possible bias.
Also to be mentioned is the missing data regarding the PEN (recommended daily calories and how long patients continue to use PEN after EEN) and the formula used by the clinics (e.g., do all centers offer EEN orally first or if the patient struggles with oral formula, do centers switch to different formula type first, or do they immediately escalate to nasogastric tube).
In conclusion, the current study described the wide variation in the attitudes and practice of the German and Austrian pediatric gastroenterologists of the IBD register CEDATA-GPGE® toward the use of EEN in children and adolescents with CD. An active participation of patient registers and further studies is needed to compare existing strategies and to develop consistent approaches to this therapy. Furthermore, on the basis of clinical trials, nutritional interventions should be optimized for induction and maintenance therapy of pediatric CD—including acceptance by the patients and families.