New Research Compares Local Cohort Incidence to Nationwide Incidence
Researchers in Japan, concerned with rising worldwide incidences of autism spectrum disorder (ASD), set out to calculate their nation’s cumulative incidence of the disorder. The team had collected recent local cohort studies that consistently reported an autism incidence of over 3%. However, the researchers were unsure if the local incidence rate reports would match a national rate, so they conducted a nationwide incidence study. In order to orchestrate this research, data was collected from the National Database (NDB) of Health Insurance Claims of Japan for children born from 2009 to 2016 and diagnosed with ASD between 2009 and 2019. The study’s data was analyzed between December 2020 and March 2021. In total, 313,353 children (75% boys, 25% girls) were diagnosed with autism. Therefore, Japan’s estimated nationwide cumulative incidence of ASD was 2.75%. However, the lifetime cumulative incidence for each birth year cohort demonstrated a steady increase in ASD from 2.23% for the 2009 cohort to 3.26% for the 2014 cohort. Diagnostic incidence per year increased significantly from two years after birth and decreased slightly after six years after birth. Ultimately, the researchers found that the nationwide cumulative incidence of autism was proportional to those of the local cohorts. They also demonstrated that autism rates increased between 2009 and 2019. Sadly, the study concluded that the incidence of ASD in Japan was higher than what has been reported worldwide.
