We performed a retrospective cohort study to evaluate the outcome of pediatric patients with achalasia who underwent POEM in comparison to the outcome of all adult patients who underwent POEM within the same period. Written informed consent was obtained from each patient, and the study was approved by the Medical Ethics Committee of The First Medical Center of Chinese PLA General Hospital. Informed consent for patients aged less than 18 years was provided by their guardian.

The inclusion criteria in this study included: (1) Achalasia diagnosed by Eckardt score ≥ 4 and further confirmed by esophagogastroduodenoscopy (EGD), barium esophagram, and/or esophageal manometry; and excluding others secondary to tumor, autoimmune diseases, etc.; and (2) Patients with age ≤ 65 when performing POEM. Those patients with severe cardiopulmonary disease, blood coagulation disorders, or other underlying diseases were excluded from this study.

Patients aged less than 18 years who underwent POEM in The First Medical Center of Chinese PLA General Hospital, Beijing, China from January 2012 to March 2020 were included in the pediatric group, whereas patients between the ages of 18-65 who underwent POEM in the same period were assigned to the control group. Demographic data and the disease course of the achalasia, including the manifestations, diagnosis, and prior treatments, were recorded in detail upon admission to the hospital. In addition, the Urbach scale questionaries were completed to assess the quality of life (QoL) of achalasia patients[14].

To evaluate the long-term outcomes of POEM in pediatric patients, we matched the pediatric group with patients from the control group in a 1:1 ratio. The matching principles were based on identical gender, the same type of Chicago classification and Ling classification, a surgery date that did not differ by more than three months, and the involvement of the same operating physician.

Patients were scheduled for follow-up visits at 3 mo, 6 mo, and 1 year after POEM, then yearly. EGD was performed to assess wound healing and to determine whether or not post-POEM reflux esophagitis existed. Moreover, esophageal high-resolution manometry, an X-ray barium meal, and 24-h esophageal pH monitoring were performed if possible. Patients were also contacted via telephone and the post-POEM complications, Eckardt score and the Urbach questionaries were recorded.

POEM was performed after the patients fasted for 48 h and underwent EGD to ensure that no food residue remained in the esophageal lumen. The standard POEM procedure was performed as previously described and generally consisted of the following major steps: First, a submucosal injection of methylene blue saline solution (1:10000) was administered, then a mucosal incision was made approximately 6–10 cm above the gastroesophageal junction (GEJ); second, a submucosal tunnel was established, passing over the GEJ and 2–3 cm into the proximal stomach; third, a myotomy started 2 cm distal to the incision and extended 2–3 cm into the stomach; and finally, after assuring hemostasis and verifying that the endoscope could easily pass the cardia, the mucosal incision was closed with clips (Figure 1). Adequate extension of the submucosal tunnel across the GEJ was confirmed by visualizing blanched gastric mucosa and a vascular pattern. Carbon dioxide gas was used for insufflation with a CO₂ insufflator (UCR; Olympus) during procedures.

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Figure 1 The procedure of per-oral endoscopic myotomy. A: Submucosal injection of methylene blue saline solution; B: Mucosal incision. The black arrow points to the inversed T-shaped incision; C: The submucosal tunnel establishment; D and E: Myotomy in the submucosal tunnel; F: Mucosal incision was closed with clips.

All patients were kept fasting for 3 d after the procedure. A liquid diet was started for an additional day. Antibiotics and proton pump inhibitor (PPI) were administered intravenously during the fasting period. An oral PPI was required for at least 4 wk subsequently. X-ray or chest and abdominal computed tomography was performed to evaluate gas-related adverse events.

The Ling classification was based on the endoscopic morphology of the esophageal lumen[15]. According to multiring structures, crescent-like structures, and diverticula, the Ling classification was recorded as Ling I, Ling IIa, Ling Ib, Ling IIc, and Ling III.

Perioperative outcomes and clinical follow-up were evaluated. Perioperative outcomes included technical success, and perioperative adverse events. Technical success was defined as the successful completion of the entire POEM procedure; if the procedure was not completed, it was defined as technical failure. Perioperative adverse events include mucosa injury, gas-related adverse events (pneumothorax, pneumoperitoneum and subcutaneous emphysema), pleural effusion, and bleeding. Procedure time was defined as the time from submucosal injection to the end of incision closure with clips. Clinical success was defined as a post-POEM Eckardt score ≤ 3. QoL was accessed by Urbach questionaries.

Depending on the distributional properties, outcome measures were expressed as the mean ± SD or as median values with ranges. For normally distributed continuous data, statistical significance was assessed by the Student’s t-test; for categorical data, significance was assessed by the χ² test with Yates’ correction when appropriate or by the Fisher’s exact test; and for non-normally distributed continuous data, statistical significance was assessed by the Wilcoxon test. A P value of < 0.05 was established as the significance level.

The demographic and clinical characteristics of the patients in the two groups are shown in Table 1. There was no significant difference in gender distribution between the two groups. The median age of the pediatric patients who underwent POEM in our hospital was 16 years (range 7-18 years). Compared with control group, body weight index of pediatric group was significantly lower (17.7 vs 20.9, P < 0.001). Although the median disease course was significantly shorter in the pediatric group (median 17.5 mo vs 48 mo, P < 0.001), no significant differences were observed between the two groups regarding the type of Chicago classification, type of Ling classification and residual LES pressure. Twelve pediatric patients and 183 adult patients had undergone prior treatments, including botulinum toxin injection, pneumatic balloon dilation, endoscopic stent placement, POEM and LHM. In terms of prior treatment history, there were 4 (8.3%) patients received botulinum toxin injection, 5 (10.4%) patients received pneumatic balloon dilation, 1 (2.1%) patient had POEM and 2 (4.2%) patients had more than one treatment method in pediatric group. While 46 (4.5%) patients had botulinum toxin injection, 92 (9.0%) patients had pneumatic balloon dilation, 9 (0.9%) patients had POEM, 10 (1.0%) had LHM, 14 (1.4%) patients had endoscopic stent placement, and 12 (1.2%) had more than one treatment method in control group.

The procedure results in the two groups are shown in Table 2. All pediatric patients successfully underwent POEM. Of the 1025 patients in control group, 1016 (99.1%) had technique success; nine patients could not complete the POEM procedure because of serious submucosal adhesions. No significant differences were observed between the pediatric and control groups regarding the length of tunnel, length of esophageal myotomy, length of gastric myotomy, types of myotomy and procedure time. The mean lengths of the tunnel were 10.8 cm (range, 7–14 cm) and 11.2 cm (range, 5-20 cm), respectively, whereas the length of the esophageal and gastric tunnels were 5.3 cm (range, 1-9 cm) and 1.9 cm (range, 0-4 cm) in pediatric group and were 5.2 cm (range, 3-15 cm) and 1.9 cm (range, 0-4 cm) in control group. A progressive full-thickness myotomy was the most common type of myotomy in both group (87.5% in pediatric group and 78.0% in control group). The types of myotomy in the remaining pediatric patients involved full thickness muscle myotomy (6.3%), circular muscle myotomy (2.1%), and other types (4.2%). In the control group, full-thickness myotomy accounted for 9.6%, circular myotomy accounted for 5.5%, and other incision types accounted for 6.9%. The mean procedure time was 43.9 min (range, 24-116 min) and 47.1 min (14-160 min) respectively.

No significant differences were observed between the pediatric and control groups regarding the overall complications of POEM (14.6 % vs 14.6 %; P = 0.997). All of the mucosa injuries were closed with titanium clips and porcine fibrin glue. Patients with pneumoperitoneum treated by puncture with a 10-mL syringe intra-operatively and patients with subcutaneous emphysema gradually absorbed the gas without special intervention. In the pediatric group, three complications of POEM occurred in seven patients (7/48; 14.6%), with three of these patients presenting with mucosa injury, two presenting with pneumoperitoneum, and two presenting with subcutaneous emphysema. In control group, in addition to mucosa injury and gas-related complications, a 27-year-old male patient had delayed bleeding with hematemesis 11 d after the POEM and he underwent gastroscopic hemostasis. The patient with pleural effusion was treated with closed thoracic drainage. None of the patients with complications required surgical intervention or intensive care unit (ICU) transfer.

The median follow-up period was 5.7 years (range 2.6-10.6 years) for the pediatric group and 14 patients were lost for long-term follow-up. Significant differences were shown in the Eckardt score, QoL, height, weight, residual LES pressure and numbers of months absent from school of the pediatric patients before and after POEM (Table 3). The Eckardt score after median 5.7 years of follow-up was significantly declined compared with the score before POEM (8.0 vs 1.1, P < 0.001) and all symptom component of the Eckardt score decreased significantly. QoL was assessed by Urbach scale questionaries, which is a 10-item measure of disease-specific health-related QoL that sampled the concepts of food tolerance, dysphagiarelated behavior modifications, pain, heartburn, distress, lifestyle limitation, and satisfaction. Scores on the Urbach scale questionaries range from 10-33, and lower scores indicate better QoL. Urbach scores were significantly lower in pediatric patients at long-term follow-up after POEM treatment compared with pre-treatment scores (24.7 vs 12.8, P < 0.001). The height and weight of pediatric patients also improved significantly at follow-up (163.7 cm vs 170.5 cm and 49.9 kg vs 64.3 kg, P < 0.001). Moreover, the absences from school decreased significantly (median 3.3 mo vs 0.1 mo, P < 0.001).

To compare the long-term outcomes of POEM in pediatric patients and adult patients, we matched the pediatric group with patients from the control group in a 1:1 ratio. The matching principles were based on identical gender, the same type of Chicago classification and Ling classification, a surgery date that did not differ by more than three months, and the involvement of the same operating physician. The long-term outcomes of POEM in pediatric patients and matched adult patients were shown in Table 4. The median follow-up time in pediatric group and matched adult group was 5.7years (range 2.6-10.6 years) and 6.0 years (range 2.7-10.7 years) respectively. Patients in both groups had clinical symptoms relief and QoL improvement after POEM. No significant differences were observed between the two groups regarding the Eckardt scores, Urbach scores, clinical failure and clinical reflux evaluation. Before POEM treatment and at post-operative follow-up, the body mass index (BMI) of matched control group was significantly greater than that of pediatric group (17.7 vs 20.0; 20.8 vs 24.0). However, the difference in BMI before and after POEM was similar in both groups (3.7 vs 3.5, P = 0.502).

All adult patients in matched group received clinical success. One pediatric patient was considered clinical failure because his Eckardt score was 4. The patient mainly has substernal pain and need to drink water to when eating dry food without weight loss and chest pain.

Gastroesophageal reflux disease (GERD) is the most common adverse event after POEM treatment[16]. Reflux esophagitis identified by EGD and assessed by the Los Angeles classification. A GerdQ score of GERD with a score of > 7 was defined as symptomatic reflux[11,13]. At median 5.7 years follow-up, 6 patients (6/34, 17.6%) were suffered from symptomatic reflux, with 2 patients (5.9%) showed reflux esophagitis (1 Los Angeles type A, 1 Los Angeles type B) on endoscopy and 4 patients (11.8%) were suffered from clinical reflux. In matched control group, 2 patients (5.9%) showed reflux esophagitis (1 Los Angeles type A, 1 Los Angeles type C) on endoscopy, 10 patients (29.4%) were suffered from clinical reflux. All patients were well controlled with medical therapy.

Achalasia is a rare disorder of the esophageal smooth muscle which cause dysphagia, regurgitation, chest pain and weight loss. In recent years, per-oral endoscopic myotomy (POEM) is emerging as a prefer treatment option for patients achalasia.

Although POEM was proved to be safe and efficacy for adult patients with achalasia, data of POEM in pediatric patients are limited.

To evaluate the safety and long-term efficacy of POEM for pediatric patients with achalasia.

We performed a retrospective cohort study to evaluate the outcome of pediatric patients with achalasia who underwent POEM in comparison to the outcome of all adult patients who underwent POEM within the same period. To evaluate the safety of POEM, we compare the operation-related parameters and complications in the two groups. To evaluate the long-term efficacy of POEM, we compare the body mass index, clinical symptoms, quality of life in pediatric group before and after POEM; and we also compare those outcomes in pediatric group and matched adult group.

The risk of complications relating to POEM was not increased in pediatric patients, and the long-term efficacy of POEM in pediatric patients were similar to the results of adult group.

POEM is safe treatment method and could achieve satisfactory long-term outcomes in pediatric patients.

POEM can be an an effective treatment option for achalasia in pediatric patients.