Persistent body-weight change on achalasia and peroral endoscopic myotomy: a multicenter cohort study.

Background: The distribution of body weight in patients with achalasia and after peroral endoscopic myotomy (POEM) has not been investigated. The role of body weight assessment after treatment remains unclear.

Methods: Using the multicenter achalasia cohort, the frequency of underweight (body mass index [BMI] < 18.5 kg/m²) and overweight (BMI ≥ 25.0 kg/m²) and their associated clinical characteristics were analyzed. After POEM, risk factors for insufficient- (underweight persistently) and excessive- (responded to overweight) weight gainers were investigated. The correlation between BMI-increase rate and severity of esophageal symptoms post-POEM was evaluated.

Results: Among 3,410 patients, 23.0% and 15.7% were underweight and overweight, respectively. Factors associated with underweight were higher age, female sex, severe symptoms, high lower esophageal sphincter (LES) pressure, and non-dilated esophagus (all p < 0.01). Longitudinal analyses revealed that weight gain post-POEM was achieved after a long duration (≥ 12 months; p < 0.01). In 528 patients post-POEM, the frequency of underweight reduced to 8.3% (p < 0.01). Risk factors for insufficient-weight gain (36.1% of underweight patients) included low BMI (p < 0.01) and high LES pressure (p = 0.03) and conversely for excessive-weight gain. Machine learning models based on patient characteristics successfully predicted insufficient- and excessive-weight gainers with an area under the curve value of 0.74 and 0.75, respectively. Esophageal symptoms post-POEM did not correlate with BMI increase.

Conclusion: Underweight is not solely a condition of advanced achalasia. After POEM, insufficient- or excessive-weight gainers are not rare and can be predicted preoperatively. Body weight change is an independent nutrition parameter rather than a part of the assessment of residual esophageal symptoms.