Sex Differences and Age Distributions in Invasive Treatments for Chalazion and Hordeolum in Japan: A 9-Year Nationwide Claims Study

Purpose: To analyze nationwide trends and demographic patterns of invasive treatments for chalazion (ITC) and for hordeolum (ITH) in Japan.Design: Retrospective population-based cohort study.Participants: Patients undergoing ITC or ITH procedures from 2014 to 2022.Methods: Using the National Database of Health Insurance Claims and Specific Health Checkups (NDB) Open Data Japan, we calculated annual numbers and rates of ITC and ITH per 100,000 person-years.Sex-and age-stratified demographic peak patterns were analyzed, and annual trends were evaluated using linear and Poisson regression models. Main Outcome Measures: Procedure rates, demographic distributions, and annual trends of ITC and ITH.Results: A total of 1,104,078 procedures (ITC: 465,379; ITH: 638,699) were recorded over the 9-year study period.The annual average rates were 40.9 for ITC and 56.2 for ITH per 100,000 person-years.Sex differences were prominent in younger groups: the overall female-to-male ratio was 1.1:1 for ITC and 1.0:1 for ITH, with a greater female predominance in youth (ITC: 2.0 at age 15-19 years; ITH: 1.7 at age 20-24 years).ITC showed bimodal peaks in males (age 15-19 years: 40.9 procedures per 100,000 personyears; age 35-39 years: 56.0) and females (age 15-19 years: 80.6; age 30-34 years: 68.0).ITH showed bimodal peaks in males (age 10-14 years: 82.9; age 35-39 years, 72.1) and females (age 10-14 years: 102.4; age 30-34 years: 78.3).Both age-adjusted rates declined annually across all age groups and both sexes (P