Changes in ASD Rates In Utah from 2002-2010: Explanations for increases?

Judith Pinborough Zimmerman, Ph.D.Assistant Research ProfessorUniversity of Utahjudith.zimmerman@hsc.utah.edu

Background•Autism spectrum disorders (ASDs) are a group

of developmental disabilities characterized by impairments in social interaction and communication, as well as restricted, repetitive, and stereotyped patterns of behavior

•Cause is unknown▫Genetics and environmental susceptibility

•Challenges in determining the prevalence of autism

•More affected versus more detected?

ASD Prevalence: Who, where, and how you count counts•Retrospective record reviews (Centers for

Disease Control and Prevention Autism and Developmental Disabilities Monitoring Network)▫1 in 47 in 2008 study year

•Administrative counts•Surveys•Direct Screening and Assessment

ADDM ASD Prevalence per 1000 Children

2002 2006 20080

2

4

6

8

10

12

6.6

9

11.3

Prevalence per 1000

Iden

tified

ASD

Pre

vale

nce

per 1

,000

Variation across Sites in Identified Prevalence of ASDsADDM Network, 14 Sites, 2008 (MMWR, 2012)

Alabama

Florid

a

Wisc

onsin

Pennsylvania

Missouri

Arkansas

S. Caro

lina

Colorado

Georgia

Maryland

N. Caro

lina

Arizona

New Jerse

yUtah

0

5

10

15

20

25

30

Prevalence for All Sites Combined

Health-Only Records AccessEducation & Health Records Access

Change in Identified Utah ASD Prevalence by Sex

2002 20080

5

10

15

20

25

30

35

Both SexesMaleFemale

Surveillance Year

Iden

tifie

d A

SD P

reva

lenc

e pe

r 1,

000

157%

103.3%

1168.5%

Change in Identified Utah ASD Prevalence by Intellectual Ability

2002 20080

2

4

6

8

10

12

14

IQ <70IQ=71-85IQ>85

Surveillance Year

Iden

tifie

d A

SD P

reva

lenc

e pe

r 1,

000

196.6%

NA

29%

Associated FeaturesEatingSleepingMoodDiscrepancy in cognitive

profileAggressionOppositionalMotor delaysHyperactivityLack or excessive fearOdd responses to sensory

stimuliSelf injurious behaviorSeizures/staring spellsTemper tantrums

9%

91%

Number of Asso-ciated Features

Per Child

<6>6

Earliest Known Utah ASD DiagnosisMedian Age and Proportion by Diagnostic Subtype

Subtype of Earliest Diagnosis:Autistic Disorder ASD/PDD Asperger

Disorder

Distribution of Subtypes: 42% 45% 13%

Median Age of Earliest Diagnosis: 52 Months 52 Months 68 Months

Limitations: 1) Diagnostic information obtained from evaluation records may not

capture the exact age of each child’s earliest diagnosis2) Instability of diagnostic subtypes over time

Utah ASD Administrative Prevalence

   2002*

 2006*

 2008*

 2010†

 Age

 8

 4

 6

 8

 4

 6

 8

 4

 6

 8

 Population Size

 26,213

 33,955

 32,801

 29,494

 35,803

 34,368

 33,210

 37,066

 37,134

 36,201

 Cases

 171

 256

 322

 301

 293

 418

 432

 342

 508

 573

 Prevalence (per 1,000)

 6.5

(1 in 153)

 7.5

(1 in 133)

 9.8

(1 in 102)

 10.2

(1 in 98)

 8.2

(1 in 122)

 12.2

(1 in 82)

 13.0

(1 in 77)

 9.2

(1 in 108)

 13.7

(1 in 73)

 15.8

(1 in 63)

* 2002-2008 includes Davis, Salt Lake, and Utah counties.† 2010 includes Davis, Salt Lake, Tooele, and Utah counties. Source: Pinborough-Zimmerman, J., Intveld, A., Kingsbury, C.M.B. Changes in the Administrative Prevalence of Autism Spectrum Disorders in Utah from 2002-2010, University of Utah, 2012.

Utah ASD Administrative by Gender

2002 2006 2008 20100

5

10

15

20

25

30

Boys Age 8 Age 6 Age 4Girls Age 8 Age 6 Age 4

Prev

alen

ce R

ate

per

1,00

0

ASD Prevalence: Use of surveys• Survey: caregiver report of ASD diagnosis.

▫2011 National Survey of Children’s Health telephone survey found 2% of 6 to 17 year olds had a diagnosis of ASD compared to the 2007 estimate of 1.16 %

▫Increase was greater for boys than girls, and among 14-17 years olds than younger children

▫Attribute change to doctors better identifying the disorder

ASD Prevalence: Direct Assessment• Direct Assessment: Screening &

comprehensive assessment of a population by clinicians. The “gold standard”.• Kim et al., (Am J Psychiatry, 2011) screened and

evaluated 7-12 year olds in a town in South Korea (n=55,000). Reported a prevalence of 1 in 38 or 2.64%

• Brugha et al., (Arch Gen Psychiatry, 2011 ) conducted diagnostic assessments in an adult population in England (n=7461) and found 1% prevalence without a significant reduction in the older part of the sample

Factors that may influence ASD prevalence trends•Intrinsic Identification: internal

methodology or measurement factors•Extrinsic Identification: external

classification and awareness factors involved in identifying people with ASD in a population

•Risk: Possible etiologic or true change in ASD symptoms among the population

Factors Explaining increase in ASD prevalence

44%

27%

16%

11%2%

UnexplainedDiagnostic Substi-tutionSocial InfluenceAdvance Parental AgeGeographic Cluster-ing

Chemical Pollutants and Autism• Traffic related air pollution

▫Volk et al (JAMA, 2013) Exposure to traffic related air pollution, nitrogen dioxide, PM2.5 and PM 10 during pregnancy was associated with autism (AOR, 1.98 during gestation and 3.10 during first year of life)

▫Becerra et al., (Environ Health Perspect, 2013) Association between autism and prenatal air pollution exposure related to traffic sources

▫Windham et al ((Environ Health Perspect, 2013) potential association between autism and estimated metal concentrations and possibly solvents in ambient air around birth residence

Maternal Residential Proximity to Toxic Release Inventory Sites•Identified by 2002 UT-ADDM (CDC, 2007;

Pinborough-Zimmerman, et al, 2009; Pinborough-Zimmerman, et al., 2007)

•Children living in Salt Lake, Davis, or Utah Counties in 2002 (born in 1994)

•Cases were matched to Utah birth records using a deterministic and probabilistic hybrid approach

•99% of maternal birth addresses geocoded for cases and controls

Toxic Release Inventory Sites• Sites listed in a publicly

available EPA database ▫ contains information on toxic

chemical releases and waste management activities reported annually

▫ TRI sites operational in 1993-1994 with annual reportable emissions of heavy metals (arsenic, cadmium, lead, nickel, and mercury) and halogenated chemicals (dioxins, PCB’s, trichloroethylene)

▫ Geocoded sites (n=54) (EPHT)

ChemicalsChemical Suspected

Neurological Toxicant

Recognized Developmental Toxicant

Suspected Endocrine Toxicant

Heavy Metals Arsenic Yes Yes Yes Cadmium Yes Yes Yes Lead Yes Yes Yes Nickel Yes ND ND Mercury Yes Yes YesHalogenated Chemicals Dioxin ND ND Yes PCBs ND ND Yes Trichloroethylene

Yes ND ND

Chemical Type and PoundageType of Exposure Contaminant

Level1 = Heavy Metals 1 = < 250 lbs2 = Halogenated Chemicals 2 = > 250 <

5,000 lbs3 = Both 3 = > 5,000 <

10,000 lbs4 = > 10,000 lbs

TRI sites by type of contaminant and poundage level

TRI site type TRI site (N) ASD (N) ID (N) CD (N) ADHD (N) Birth Cohort (N)

Heavy metal

< 250 lbs 7 yes yes yes yes 1843

> 250 lbs < 5,000 lbs 6 yes yes yes yes 571

> 5000 lbs < 10,000 lbs 0 0 0 0 0 0

> 10,000 lbs 0 0 0 0 0 0

Halogenated chemicals

< 250 lbs 2 yes yes yes yes 269

> 250 lbs < 5,000 lbs 1 0 0 0 0 0

> 5000 lbs < 10,000 lbs 5 yes yes yes yes 338

> 10,000 lbs 28 yes yes yes yes 3618

Halogenated chemicals and heavy metals

< 250 lbs 0 0 0 0 0 0

> 250 lbs < 5,000 lbs 0 0 0 0 0 0

> 5000 lbs < 10,000 lbs 0 0 0 0 0 0

> 10,000 lbs 5 yes yes yes 0 411

Total 54 yes yes yes yes 7050

Analysis•Primary Aim:

▫Created buffer zones (¼, ½ and 1 mile) around TRI facilities

▫Compared the proportion of cases vs. controls by buffer distance, case type, chemical group, and poundage level

▫Tested for significant difference

Annual Reportable Emissions

No. of TRI sites

(n=54)

No. of Controls living within 1 mile radius of

TRI site (n=7050) Speech-Language Impaired (838)

Heavy metals P-value Odds RatiosConfidence

Interval < 250 lbs 7 1843 0.17 0.8 0.58-1.10

> 250 lbs < 5000 lbs 6 571 0.35 0.78 0.47-1.31

> 5000 lbs < 10,000 lbs 0 0 * * * > 10,000 lbs 0 0 * * *

Halogenated chemicals < 250 lbs 2 269 0.23 0.58 0.24-1.42

> 250 lbs < 5000 lbs 1 0 * * *

> 5000 lbs < 10,000 lbs 5 338 0.53 1.21 0.67-2.16 > 10,000 lbs 28 3618 0.05 0.8 0.64-1

Halogenated chemicals and heavy metals < 250 lbs 0 0 * * *

> 250 lbs < 5000 lbs 0 0 * * *

> 5000 lbs < 10,000 lbs 0 0 * * * > 10,000 lbs 5 411 0.4 1.22 0.74-2.02

Annual Reportable Emissions

No. of TRI

sites (n=54)

No. of Controls

living within 1 mile

radius of TRI site (n=7050) Intellectual Disability (n=113)

Heavy metals P-value Odds RatiosConfidence

Interval < 250 lbs 7 1843 0.51 0.74 0.30-1.81 > 250 lbs < 5000 lbs 6 571 0.02 2.83 1.31-6.11 > 5000 lbs < 10,000 lbs 0 0 * * * > 10,000 lbs 0 0 * * *

Halogenated chemicals < 250 lbs 2 269 0.32 1.75 0.43-7.14 > 250 lbs < 5000 lbs 1 0 * * * > 5000 lbs < 10,000 lbs 5 338 0.05 3.05 1.12-8.32 > 10,000 lbs 28 3618 0.02 1.74 1.10-2.75

Halogenated chemicals and heavy metals < 250 lbs 0 0 * * * > 250 lbs < 5000 lbs 0 0 * * * > 5000 lbs < 10,000 lbs 0 0 * * * > 10,000 lbs 5 411 0.7 1.13 0.28-4.59

Annual Reportable Emissions

No. of TRI sites

(n=54)

No. of Controls living within 1 mile radius of TRI site (n=7050) Autism Spectrum Disorders (99)

Heavy metals P-value Odds RatiosConfidence

Interval < 250 lbs 7 1843 0.13 0.33 0.08-1.34

> 250 lbs < 5000 lbs 6 571 0.08 2.28 0.92-5.63

> 5000 lbs < 10,000 lbs 0 0 * * * > 10,000 lbs 0 0 * * *

Halogenated chemicals < 250 lbs 2 269 0.27 2 0.49-8.19

> 250 lbs < 5000 lbs 1 0 * * *

> 5000 lbs < 10,000 lbs 5 338 0.03 3.5 1.28-9.57 > 10,000 lbs 28 3618 0.0007 2.18 1.37-3.45

Halogenated chemicals and heavy metals < 250 lbs 0 0 * * *

> 250 lbs < 5000 lbs 0 0 * * *

> 5000 lbs < 10,000 lbs 0 0 * * * > 10,000 lbs 5 411 0.67 1.29 0.32-5.26

Annual Reportable Emissions

No. of TRI sites

(n=54)

No. of Controls living within 1 mile radius of TRI site (n=7050) All Groups Combined

Heavy metals P-value Odds RatiosConfidence

Interval

< 250 lbs 7 1843 0.07 0.76 0.57-1.02

> 250 lbs < 5000 lbs 6 571 0.24 1.25 0.86-1.8

> 5000 lbs < 10,000 lbs 0 0 * * *

> 10,000 lbs 0 0 * * *

Halogenated chemicals

< 250 lbs 2 269 0.8 1.08 0.6-1.93

> 250 lbs < 5000 lbs 1 0 * * *

> 5000 lbs < 10,000 lbs 5 338 0.03 1.62 1.04-2.5

> 10,000 lbs 28 3618 0.96 1 0.83-1.2

Halogenated chemicals and heavy metals

< 250 lbs 0 0 * * *

> 250 lbs < 5000 lbs 0 0 * * *

> 5000 lbs < 10,000 lbs 0 0 * * *

> 10,000 lbs 5 411 0.51 1.16 0.74-1.83

Strengths•Completeness of case ascertainment•Population-based sample•Geocoded maternal addresses for

cases and controls•Site specific addresses of TRI sites,

chemical and poundage type•Multiple measures of SES

Limitations

• Addresses for the first trimester of pregnancy are unknown

• Exposure estimates do not include other sources of chemical exposures

• Chemical concentrations represent annual measures by site

• No actual personal measurements in subjects• Unable to take into account mobility or specific

maternal activities• Findings are preliminary and further analysis

needed

Service and Research Implications• Better identification among certain subgroups

▫ Still concerned about disparities in identified prevalence Across sites (methodological: access to records / geographic: access to care) Among children of minority race/ethnicity, low socioeconomic status

• More children than ever are being recognized as having ASDs

• Still concerned that 20% are not classified with autism by community providers, others are not recognized as early as they can be

• Need to accelerate our research into risk factors and causes of ASD

▫ Highlights the need for further scientific investigation into the potential association of exposure to hazardous air pollutants and increased risk of ASD and other developmental disabilities