Introduction/Purpose

Obesity is increasing worldwide, including in the pediatric and adolescent populations, and is now recognized as a chronic disease, with a chronic inflammatory state and immune dysfunction [1] [2]. These trends are particularly concerning since gaining weight in childhood and adolescence is likely to lead to lifelong overweight and obesity and the potential development of comorbidities including type 2 diabetes, gastrointestinal problems, sleep apnea, cardiac diseases, and psychosocial conditions [3,4,5,6,7]. Adolescents with severe obesity have a shorter life expectancy compared to peers of normal weight, making it important to establish a treatment plan to reverse the condition as early as possible [8, 9]. In response to the increasing weight crisis, the World Health Organization’s Global Strategy on Diet, Physical Activity and Health called for global efforts to improve the well-being of children as it pertains to weight loss, and endorsed a “no increase in childhood overweight by 2025” [10, 11].

Studies in childhood obesity have shown that early intervention and reduction of weight can positively alter behaviors that lead to continued or worsening obesity [6] Despite the importance of early treatment, comprehensive pediatric clinical guidelines are limited by ethical and practical challenges of conducting randomized controlled studies in the pediatric population [12]. Available guidelines are based on limited evidence and generally recommend low-calorie, low-sugar and high-protein diet first, and changes in behavior and daily lifestyle, or project evidence based on adult data [13,14,15,16,17,18,19]. Current adult guidelines recommend metabolic and bariatric surgery for individuals with a body mass index (BMI) > 35 kg/m2, regardless of presence, absence, or severity of co-morbidities, and consideration for individuals with metabolic disease and BMI of 30–34.9 kg/m2 [20].

Adolescent patients using behavioral and dietary interventions alone often do not respond to treatment, particularly in patients with metabolic issues or severe obesity. Data have shown that without engagement and motivation of the adolescent it can be difficult to shift current habits to restrict caloric intake and change food and lifestyle choices needed to produce lasting effects [21]. Lack of compliance results in ongoing problems with excess body weight [22,23,24]. While bariatric metabolic surgical procedures have become common treatment in adults with obesity, there is hesitancy on the part of families and providers to perform these invasive procedures in pediatric patients due to their potential risk and permanence [22, 23]. This leaves the adolescent population with an unmet medical need and the important evaluation of other options to support weight loss.

Intragastric balloons (IGBs) are recognized as effective treatments to support weight loss in adults [25]. Due to their temporary nature (4–6 months), IGBs can support adolescent’s efforts for weight loss without the permanence of surgical techniques. The International Pediatric Endosurgery Group (IPEG) published a series of guidelines proposing criteria for bariatric procedures, including placement of IGBs, for children with comorbidities and a body mass index (BMI) greater than 35 kg/m2, or those with a BMI greater than 40 kg/m2 without comorbidities. According to experts, the minimum age for balloon implant is 12 years, after established puberty, with multidisciplinary evaluation and parental consent [26]. However, there is a lack of evidence on which to make firm recommendations, and there is limited evidence regarding which patients are most likely to benefit from a given treatment [27]. In addition, most IGBs are placed endoscopically and require anesthesia for placement and extraction.

A novel swallowable gastric balloon (SGB), the Allurion Balloon (Allurion Technologies, Natick, MA, USA) can be placed in an outpatient setting without endoscopy or anesthesia. The encapsulated device is designed to be swallowed by the patient. After confirmation of placement in the stomach by fluoroscopy or abdominal X-ray, the balloon is filled with 550 mL of distilled water per the device instructions for use (Fig. 1). Patients are provided with the SGBP (Fig. 2), consisting of a digital scale and smartphone App which delivers nutritional and lifestyle changes program and allows patients to interact with their care team between follow-up visits. After approximately 4 months, the balloon empties itself of the distilled water and is expelled naturally via the gastrointestinal tract [28, 29].

Fig. 1
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The swallowable balloon (SGB) placement and passage

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Fig. 2
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Swallowable intragastric balloon program (SGBP): virtual follow-up system connected scale and app

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The purpose of this study was to evaluate the performance and safety of the Allurion SGBP in adolescent patients living with overweight or obesity.

Methods

Study Design and Patients

This was a single-arm, multi-center, retrospective data collection study conducted across eight obesity clinician-led centers in Italy, Spain, and Chile. The study adhered to the principles outlined in the 1964 Declaration of Helsinki and its subsequent amendments. Prior to enrollment, patients and their parents/guardians received comprehensive education about the SGBP, including thorough disclosure of potential risks and adverse events. Adolescent participants provided written assent, while parents/guardians furnished written informed consent before any data collection commenced, with all data anonymized for publication. Participants were apprised of the voluntary nature of their involvement, as well as the off-label status of the SGBP for the age group as per standard product labeling. Outcome measures assessed changes in weight parameters, BMI, and % total body weight loss (%TBWL), while safety endpoints encompassed the frequency and severity of procedure-related and device-related adverse events.

Inclusion Criteria

Inclusion criteria were age 15 to 17 years with previous non-responsive behavioral and dietary weight-loss attempts, BMI ≥ 27 kg/m2, and ability to provide assent and informed consent confirming understanding of the study, interest in participation and willingness to complete follow-up appointments in conjunction with the SGBP.

Exclusion Criteria

Exclusion criteria aligned with contraindications from the product labeling, including difficulty swallowing, conditions that predispose to bowel obstruction, gastric perforation, GI bleeding, and other conditions such as psychiatric illness, eating disorders, pancreatitis, and significant respiratory disease.

The SGB Placement and Passage

SGB placements were completed per the standard placement technique and consisted of a 10- to 15-min placement process in an outpatient setting, without the need for endoscopy or sedation. After swallowing, the indication that the capsule has reached the stomach is by noting the three black stripes on the catheter reach the lips of the patient, indicating the 50 cm marker. Stomach placement was then confirmed by taking an X-ray and visualizing the capsule and radiopaque marker in the stomach. Balloons were filled with 550 mL of distilled water per the device instructions for use and placement was re-confirmed using X-ray. The SGB is self-emptying via a release valve that opens at approximately 4 months, allowing the empty balloon to pass naturally through the digestive tract (Fig. 1).

Treatment Protocol

Prior to placement, the care team obtained a detailed medical history, nutritional behavior history, and anthropometric evaluation (height, weight, BMI) per clinic standard of care. Patients started oral omeprazole (40 mg per day) 14 days prior to placement which continued for the entire period of treatment with the SGB. Patients were asked to consume only clear liquids 8 h prior to placement and stop all liquids 2 h prior to placement to reduce the risk of vomiting. To ensure anti-emesis, oral ondansetron (8 mg, three times per day, started on the day of placement, and continued for 3 days after) and oral aprepitant (80 mg, the morning of placement and for 2 days after placement) were prescribed. No screening endoscopy was performed prior to placement.

Lifestyle and Nutritional Change Program (SGBP)

The SGBP for patients under the age of 18 is recommended to be family-centered and age-appropriate, aligning with local pediatric clinical guidelines for the treatment of overweight and obesity, and based on individualized dietary requirements. Patients received similar dietary, exercise, and behavioral advice based on their current and preferred eating and activity patterns. The program also supports any specific gastric balloon-related dietary or symptom management, as needed; for example, conservative prevention or management of early nausea after balloon placement, and adaptations to eating slowly and to separate eating and drinking.

Patients were provided a multicomponent lifestyle modification program delivered by a team including a trained nutrition professional with adolescent experience. This included a balanced low calorie diet, higher protein recommendations (dependent on activity levels), and increasing the intensity and frequency of physical activity to age-appropriate clinical recommendations (including resistance and moderate intensity aerobic activity and reducing screen time) [30]. Each program was individualized, with adjustments made as needed, including (but not limited to) discussing weight status, using anthropometric measurements such as BMI for sex and age (measuring height regularly due to growth), and adjusting nutritional guidance to match age requirements (such as maintaining adequate calcium and vitamin D levels to support achievement of maximum bone mass and suitable nutritional supplementation).

Follow-up consisted of in-person visits at 1, 2, 3, and 4 months, with the 4-month visit occurring after the balloon self-emptied and was excreted, and via virtual visits utilizing a dedicated smartphone app. This app utilizes a wireless body composition scale (Fig. 2) which allowed patients to share their weight and body composition between clinic visits. Patients received motivational messages through the app by their care team encouraging them to engage in physical activity and to adhere to the diet provided by the nutritionist. During in-person visits, patients underwent a clinical and nutritional evaluation and an anthropometric exam (weight and BMI) and were asked about adverse events. At the final, 4-month visit, the patients were provided with a balanced, normo-caloric diet, with the aim of avoiding weight regain during long-term maintenance.

Safety Evaluations

Safety was monitored throughout the SGBP by collection of adverse events as well as a physical exam including vital signs during in-person visits. During the in-person visit the patient was asked to provide information regarding any adverse events that occurred since the prior visit, however only events considered to be at least possibly related to the study device are reported here.

Statistics and Statistical Analysis

Summary statistics were generated for baseline parameters (age, height, weight, BMI) and gender. Additional summary statistics were generated for on-study weight and BMI at the month 1 to 4 visits. Endpoint assessments for this study were based on change from baseline, with each patient’s baseline assessments serving as their own control. The only formal hypothesis test was a 1-sided t-test to compare %TBWL to zero.

Incidence and percentage of patients with device-related adverse events were reported. Results were expressed by mean, standard deviation, median, minimum, and maximum. Data analyses were conducted using SAS® version 9.4.

Results

From April 2018 to September 2022, 91 patients qualified to be included in this study after undergoing SGB placement, and completing follow-up through spontaneous passage of the SGB after 4 months. Sixty-nine (69) of the patients (75.8%) were female and 22 (24.2%) were male. The mean ± SD of age, weight, and BMI at baseline were 16.4 ± 0.77 years, 99.70 ± 21.33 kg, and 35.60 ± 5.59 kg/m2, respectively (Table 1).

Table 1 Baseline characteristics
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All patients (100%) had the device placed successfully and filled to the indicated fill volume of 550 mL. At approximately 16 weeks all balloons self-emptied through the release valve and were excreted naturally via the gastrointestinal tract.

The device was well-tolerated. There were no serious adverse events or premature device removals. Most patients (80) reported no adverse events (87.9%); 11/91 (12.1%) of the patients experienced an adverse event. Of these 9/91 (9.9%) experienced nausea and/or vomiting; 1/91 (1.1%) reported abdominal pain only; 1/91 (1.1%) reported flatulence only.

Although not all patients came for all monthly visits, weight loss was achieved by the represented group at each monthly follow-up and all of the 91 patients have data from the final month 4 follow-up visit. Monthly changes in weight are detailed in Table 2. After balloon excretion at the month 4 follow-up visit, BMI had decreased by a mean of 4.74 kg/m2 (Fig. 3) and the mean ± SD %TBWL was 13.05 ± 7.64 (Table 2). This mean %TBWL was significantly different from zero (1-sided t-test, p < 0.0001). No deviations from normal distributions were noted.

Table 2 On-study summary statistics for weight and BMI
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Fig. 3
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BMI changes during SGB treatment (mean ± SD). BMI: body mass index; SGB: swallowable intragastric balloon; SD: standard deviation

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Discussion/Conclusion

Research has documented the barriers encountered in the pathway to bariatric and metabolic surgery in adolescents including: lack of awareness and support, stigma of weight and surgery for weight loss, cost and insurance concerns, and parental concerns with youth undergoing surgery [31]. In this population, our clinics’ anecdotal data support this and the authors have found the SGBP a helpful tool for adolescent weight loss, providing an option for patients who would like to avoid surgery but still require support to change diet and lifestyle.

As growth trajectories suggest that childhood obesity is likely to continue to adulthood, such early intervention may allow for opportunity to change unhealthy eating habits before adulthood avoiding the development of comorbidities [27, 32]. As previously published in adults with comorbid obesity and type 2 diabetes (T2DM), the SGBP may be helpful in reducing glycated hemoglobin (HbA1c) and putting T2DM into remission [33] [34].

Prior studies have shown that the adolescent population has less success with weight loss compared with younger children using dietary and lifestyle approaches [22, 24]. Compared with their younger peers, they have had more time to establish eating patterns, have more autonomy over their diet, and present at an age with multiple psychosocial challenges. We were therefore unsure at the outset whether use of the SGBP would be as effective in adolescents as we have seen previously in adults using the device and program [28, 35,36,37]. Patients in this study achieved a %TBWL of 13.05 after 4 months of treatment with the SGBP. While we had no pre-defined definition of success in this initial study of adolescents, there are several reasons we consider the TBWL in our sample to be clinically meaningful. Modest weight loss (5–10%) is understood to deliver clinically meaningful benefits in patients with overweight or obesity, with weight losses of 10% or greater delivering major beneficial impacts on complications [38]. Also, these results are similar to those seen in adults with obesity where IGBs in general achieved TBWL between 8 and 15% [39]. Our results also align with prior studies on pediatric and adolescent use of IGBs, although our study included those with lower BMI and prior studies were limited to those with BMI > 30 kg/m2 or BMI/age index of greater than 97% [27, 40,41,42,43]. Anecdotally, in the experience of the authors, patients were pleased with their outcomes at the time of the follow-up and were confident in their ability to continue to follow the program after SGB passage, which we considered another marker of success. Furthermore, the SGB was safe and well-tolerated with only transient adverse events noted, no serious adverse events, and no premature device removals.

Several recent publications have highlighted the role of medical devices including IGBs and surgery in the support of pediatric patients due to the severity of comorbidities in those who continue into adulthood with obesity [22, 44,45,46]. While bariatric metabolic surgery is a guideline-driven option in adults, the data in pediatric patients is less clear. In a 2022 Cochrane meta-analysis evaluating surgery for children and adolescents, only one study was found to meet the criteria for evaluation [12]. In this single-center study of 50 patients (25 surgery, 25 lifestyle changes), laparoscopic gastric banding surgery reduced BMI by a mean difference of − 11.40 kg/m2 (95% CI − 13.22 to − 9.58) and weight by − 31.60 kg (95% CI − 36.66 to − 26.54) compared to a lifestyle modification program. However, 28% of adolescents needed to undergo revisional surgery. More recent recommendations derived from observation studies recommend avoidance of the use of banding in youth due to long-term reoperation rates. There remains insufficient high-quality evidence to inform the development of clinical guidelines.

Our study has several limitations. As the data were collected retrospectively, visits were conducted per standard of care, and we do not have data on all patients at each monthly timepoint though all have baseline and month 4, at minimum. The number of patients included reflects those available to the authors at the time of data collection and was not prospectively defined since no formal hypothesis testing was planned for this initial investigation. Furthermore, we did not collect information regarding other factors impacting weight such as psychological parameters, exercise, and dietary compliance or dietary changes. The current study only presents outcomes at the time of SGB passage, and we cannot comment on the durability of weight loss from these data. The study is also limited by the lack of a control group. Ideally a control group with a “sham balloon” placement would be important to determine the impact of the SGB since patients had other interventions including the attention of the clinical staff and the wireless scale and dedicated smartphone app which provided information and attention to dietary and lifestyle choices.

Nevertheless, the data provide important information on the safety and feasibility of SGB placement without endoscopy and weight loss achieved during the SGBP. Given the heterogeneity of the sample and the standard of care treatment, we are encouraged by the significant p-value for %TBWL (p < 0.0001) and the overall weight loss which occurred in all but one of the 91 patients. The nature of the adolescent population, challenges of interventional studies in this group, and the lack of available data necessitate a pragmatic approach to data collection to fill the gaps in currently available literature [12, 47]. Future studies can evaluate the impact of the adolescent SGBP on related factors including glucose and insulin laboratory testing, cholesterol, and hunger levels during and following SGB placement.

These data suggest that in the context of prior non-responsive weight loss attempts consisting of nutritional and lifestyle modifications alone, the SGBP offers a valuable option for weight loss in adolescents. Future studies on long-term outcomes and multiple, sequential SGBs in the adolescent population are warranted to determine if the SGBP can maintain weight loss and avoid surgery. Also, data are needed on the avoidance or correction of comorbid conditions in this population following the SGBP.