Record-Based ASD Annual Prevalence for Children Ages 0-8 in Taiwan, 2004-2013

Background:  In the past decade, global prevalence estimates of Autism Spectrum Disorder (ASD) are between 1-2% among children of all ages. Since higher recognition and changes in diagnostic practice and service availability, the number of people with ASD in Taiwan increased 10-20% as compared to a decade ago. However, the data were from the National Disability Registry system in Taiwan only includes children who are eligible for social assistance payments. Taiwan implements a National Health Insurance (NHI) program since 1995. NHI offers comprehensive and universal health insurance to all citizens.

Objectives:  The objective of the study was to calculate the annual prevalence of ASD among 0 to 8-year-old children based on the National Health Insurance data from 2004 to 2013.

Methods:  The study utilized the NHI database that includes 96% medical claims of all citizens. The diagnosis coding of the national data follows the International Classification of Diseases, Ninth Revision, Clinical Modification diagnostic criteria. Children who were 0 to 8 years old at each year and had an outpatient service claim with a diagnosis of ASD during 2004 to 2013 were defined as the case. The denominator of calculating the prevalence rate was the total number of 0 to 8 years-old children in the database each year. Annual percentage change of prevalence which is the change in rates yearly over 2004 to 2013 was calculated.

Results:  The prevalent cases under 8 years of age were increasing from 5,455 cases in 2004 to 7,884 cases in 2013, whereas the total population for the children under 8 years of age were decreasing from 2,437,948 in 2004 to 1,763,147 in 2013. The prevalent rate of ASD increased from 2.24 in 2004 to 4.47 per 1,000 in 2013 (Table 1). The annual percentage change in ASD prevalence was 8.3% per year on average from 2004-2013, with a 99.5% increase from 2004 to 2013.

Conclusions:  Using NHI claim data in Taiwan, the results showed that ASD prevalence increases over time from 2004–2013. The increasing trends we found is in line with reports from existing studies. The increase of prevalence over the years could be in part due to the increase of awareness of the public. More investigation on potential factors that contribute to the increase of ASD diagnosis in children is warranted.