BACKGROUND

Achalasia is a well-known esophageal motility disorder, but epidemiological studies in Japan are lacking. We investigated the incidence and period prevalence of achalasia in Japan, including the rate of coexistence of esophageal carcinoma, and evaluated treatment trends.

METHODS

To estimate the nationwide number of patients with achalasia, a large-scale insurance claims database from 2005 to 2017 were used for our analyses. Patients with achalasia and coexistence of esophageal carcinoma were identified based on the diagnosis code registered. Interventional treatment was also evaluated.

RESULTS

Of the total 5,493,650 populations, 385 were diagnosed with primary achalasia. The incidence was calculated as 0.81-1.37 per 100,000 person-years (male-to-female ratio was almost 1; mean age at diagnosis was 43.3 ± 14.4 years). The period prevalence was 7.0 per 100,000 persons. There were statistically significant trends of increase in the incidence and period prevalence over age groups (all p values < 0.0001). Four men with achalasia developed esophageal carcinoma, and the incidence of esophageal carcinoma with achalasia was estimated as 0.25 per 100 person-years. With regard to intervention, esophageal dilation was performed as a first treatment in 64.7% of patients, with repeat intervention required in 56.9% of these. The proportion of patients treated using peroral endoscopic myotomy (POEM) increased annually to 41.1% in 2017.

CONCLUSIONS

In Japan, the incidence and period prevalence of achalasia is comparable to that in other countries. The absolute risk of esophageal carcinoma is rather low. Esophageal dilation has been the mainstay of achalasia treatment, and the role of POEM has increased annually.