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Saturday, May 9, 2009
Northwest Hall (Chicago Hilton)
10:00 AM
Background: The reported prevalence of autism spectrum disorders (ASD) has increased dramatically over recent decades. Although recent studies reflect a 10-fold increase compared to studies of a half-century ago that chiefly targeted autistic disorder, most of the newer studies also included individuals with Asperger’s and PDD-NOS. There is a scarcity of reports of trends in the prevalence of ASD in large health care populations in the U.S..
Objectives: To present trends in a large health care population from 2001 to 2008 in: (1) ASD prevalence in children aged 0-18; (2) ASD prevalence by age group and gender; and (3) prevalence of subcategories of ASD diagnoses.
Methods: We studied children 0-18 years of age who were enrolled in Kaiser Permanente (KP) in northern California during the period 2001 through 2008. KP is an integrated, group-model, nonprofit health plan serving over 3.2 million residents of northern California. KP members are demographically similar to the population residing in the 14-county area served by the health plan. All inpatient and outpatient diagnoses are recorded in the KP electronic medical record system. All children with at least one outpatient ASD diagnosis (Autism [ICD-9-CM) 299.0]; Asperger’s disorder or Pervasive Developmental Disorder-Not Otherwise Specified [ICD-9-CM 299.8]) recorded in electronic medical records were identified. Prevalence of ASD was calculated for current members in the target age range for each of the following years (July-June): 2001, 2004, 2005, 2006, 2007, and 2008.
Results: There were 700,561 members aged 0-18 years in 2001 and 804,181 in 2008. (1) From a base of 2,699 children aged 0-18 with any ASD diagnosis in 2001 (prevalence: 3.9/1,000), the prevalence grew by 15% per year through 2005, and by 23% from 2005-2006 and 20% from 2006-2007. From 2007-2008, the prevalence grew by only 5% to a total of 7,479 children with any ASD diagnosis (current prevalence: 9.3/1,000). (2) Since 2001, the prevalence has remained highest in the 5-9 (2008: 12.5/1,000) and 10-14 (2008: 10.7/1,000) age groups. Since the first KP ASD evaluation and diagnostic center opened in 2004, there has been a more rapid increase in the prevalence of ASD in the 0-4 age group (2005: 3.1/1,000; 2008: 5.2/1,000). The relative prevalence between boys and girls has remained constant since 2001,with girls constituting 19% of the total throughout the time period (2001: boys = 6.1/1,000, girls = 1.5/1,000; 2008: boys = 14.1/1,000, girls = 3.4/1,000). (3) The proportion of Autism vs. Asperger’s /PDD-NOS diagnoses changed only slightly over the period from 54% (2.1/1,000) vs. 46% (1.8/1,000) in 2001 to 60% (5.6/1,000) vs. 40% (3.7/1,000) in 2008.
Conclusions: In general, the trends in ASD prevalence in this large health care population are similar to those reported in previous epidemiologic studies. The most recent data suggest that there may be a plateau in the increase in ASD diagnoses. The increase over time in ASD prevalence in the 0-4 age group may indicate a change towards earlier detection.
Objectives: To present trends in a large health care population from 2001 to 2008 in: (1) ASD prevalence in children aged 0-18; (2) ASD prevalence by age group and gender; and (3) prevalence of subcategories of ASD diagnoses.
Methods: We studied children 0-18 years of age who were enrolled in Kaiser Permanente (KP) in northern California during the period 2001 through 2008. KP is an integrated, group-model, nonprofit health plan serving over 3.2 million residents of northern California. KP members are demographically similar to the population residing in the 14-county area served by the health plan. All inpatient and outpatient diagnoses are recorded in the KP electronic medical record system. All children with at least one outpatient ASD diagnosis (Autism [ICD-9-CM) 299.0]; Asperger’s disorder or Pervasive Developmental Disorder-Not Otherwise Specified [ICD-9-CM 299.8]) recorded in electronic medical records were identified. Prevalence of ASD was calculated for current members in the target age range for each of the following years (July-June): 2001, 2004, 2005, 2006, 2007, and 2008.
Results: There were 700,561 members aged 0-18 years in 2001 and 804,181 in 2008. (1) From a base of 2,699 children aged 0-18 with any ASD diagnosis in 2001 (prevalence: 3.9/1,000), the prevalence grew by 15% per year through 2005, and by 23% from 2005-2006 and 20% from 2006-2007. From 2007-2008, the prevalence grew by only 5% to a total of 7,479 children with any ASD diagnosis (current prevalence: 9.3/1,000). (2) Since 2001, the prevalence has remained highest in the 5-9 (2008: 12.5/1,000) and 10-14 (2008: 10.7/1,000) age groups. Since the first KP ASD evaluation and diagnostic center opened in 2004, there has been a more rapid increase in the prevalence of ASD in the 0-4 age group (2005: 3.1/1,000; 2008: 5.2/1,000). The relative prevalence between boys and girls has remained constant since 2001,with girls constituting 19% of the total throughout the time period (2001: boys = 6.1/1,000, girls = 1.5/1,000; 2008: boys = 14.1/1,000, girls = 3.4/1,000). (3) The proportion of Autism vs. Asperger’s /PDD-NOS diagnoses changed only slightly over the period from 54% (2.1/1,000) vs. 46% (1.8/1,000) in 2001 to 60% (5.6/1,000) vs. 40% (3.7/1,000) in 2008.
Conclusions: In general, the trends in ASD prevalence in this large health care population are similar to those reported in previous epidemiologic studies. The most recent data suggest that there may be a plateau in the increase in ASD diagnoses. The increase over time in ASD prevalence in the 0-4 age group may indicate a change towards earlier detection.