Table 2.
Characteristic | Earlier diagnosis | Later diagnosis | No relationship |
---|---|---|---|
Clinical characteristics | |||
Symptoms | More symptoms/greater level of impairment [15, 27, and 29] | Higher communication skills [36] | Repetitive and unacceptable social behavior [36] |
Developmental regression [28 and 39] and higher social function [36] | |||
Toe walking [13 and 42] | Oversensitivity to pain [13] | Not responding to name when called, self-injury, aggressive to others, insistence on sameness, echolalia, and spins self [13] | |
Language deficits, sustained odd play, and hand flapping [13] | Language regression [42] | ||
Cognition | IQ ≤ 70 versus >70 [28] | IQ ≥ 85 versus 50–84 [34] | Comorbid intellectual disability [36] |
Comorbid intellectual disability [39] | Intellectual disability [13, 15, and 37] | ||
Comorbid conditions | Major congenital anomaly [37] | Previous classification of ASD and co-occurring psychiatric or neurologic disorders or symptoms [32] | Epilepsy and cerebral palsy [37] |
Hearing impairment [13] | |||
Attention-deficit/hyperactivity disorder [37] | |||
Sociodemographic characteristics | |||
Sex | Female [15] | Female [8, 14, and 28] | 6, 9, 13, 19, 22, 26, 29, 33, 34, 36, 37, 39, and 41 |
Race/ethnicity | White versus all other racial groups [6] | Non-White or Hispanic versus White [36] | Race [14, 13, 15, 27, and 30] |
Visible minority [41] | White versus all other racial/ethnic groups [33] | Ethnicity [13, 30, and 39] | |
Other race and Hispanic ethnicity versus White [28] | |||
Black race [39] | |||
Hispanic and African-American versus White [42] | |||
Socioeconomic status | Higher parental [14 and 36] or maternal [39] education | Living close to versus above poverty level [13] | Maternal education [22, 27, and 42] |
Higher family income [14] | Maternal education less than college versus college graduate [28] | Parent education or employment [29] | |
Social status [34] | |||
Annual household income, parental education [30] | |||
Other factors | Firstborn [12] | Being adopted [13] | Maternal age [28, 36, and 42] |
Older maternal age [37] | Medicaid eligibility due to disability versus other categories [33] | Birth order [29 and 42] | |
Insurance type, parent age, and other children with ASD [29] | |||
Marital status, maternal mental illness, gestational age, and birth weight [37] | |||
Older siblings/family members with ASD [30, 41, and 42] | Born outside Canada [41] | Having health insurance [30] | |
Mother born outside the United States and children whose deliveries were paid for by Medicaid [36] | Being adopted [41] | ||
Firstborn [36, 37, and 39] | Medicaid participation, bilingual household, and mother US-born [42] | ||
Parental concern | Concern about social skills development and atypical behavior [29] | Attribution of symptoms to behavioral problems [27] | |
Worry about initial symptoms [27] | Recognizing medical problem as first concern versus other behaviors [9] | ||
First concern about nonautism specific behavioral problems [30] | |||
Systems interactions | |||
Health care | Physician referral to a specialist [13] | Visiting a greater number of clinicians/professionals prior to diagnosis [9, 13, and 14] | Physician-conducted developmental testing in response to concern [13] |
Screening in response to concern [30] | Switching pediatricians in the first 5 years of life [30] | ||
Using health versus health and education records to assign a diagnosis [28] | |||
Education | Diagnosis in a nonschool setting [15] | Placement in a nonautistic unit of school for learning difficulty versus mainstream school [10] | Use of standardized instrument to assign diagnosis [15] |
Referral from early intervention program versus physician office, school, or parent [29] | Using education records versus health and education records [28] | ||
Referral to early intervention [30] | |||
Geographic region and associated characteristicsb | |||
Region | Living outside northeastern United States [39] | ||
Living in the Midwest [30] | |||
Urban/rural | Urban vs. suburban and rural [20] | Larger urban or rural county [33] | City versus rural versus suburban [29] |
Living in nonmetropolitan area [39] | Urban versus rural [41] | ||
Rural [13] | |||
Community factors | Higher median property value [36] | Higher educated population [36] | Neighborhood median household income [41] |
Greater proportion of residents living in poverty [33 and 36] | Child psychiatrists nearby [36] | ||
Higher ASD prevalence [36] | Median income in second lowest versus lowest quartile, greater proportion of White residents second highest versus lowest quartile [39] | Per capita pediatricians or pediatric specialists, median income, percent residents on Medicaid, teacher student ratio, expenditures per student, percent non-English speaking students, and percent White residents [33] | |
Greater number of neurologists of psychiatrists nearby, close proximity to a medical school [38] | Close proximity to a Treatment and Education of Autistic and Communication–related handicapped children program [38] | Greater number of primary care physicians nearby, close proximity to early intervention services, and living in a Health Professional Shortage Area [38] | |
State factors | Low state Child Health Insurance eligibility [33] | Median income in second lowest versus lowest quartile, greater proportion of White residents second highest versus lowest quartile [39] | Proportion of children 0–5 years in early intervention [33] |
Cohort and period effects | |||
Birth cohort | Older versus more recent [1, 2, 10, 11, 13, 14, 21, 24, 25, 30, 36, and 39] | Older versus more recent [5] | |
Period | Prior to versus after 2000 [39] | Earlier versus later [7, 18, 26, 33, and 35] | Earlier versus later [34] |
2005–2006 versus 1997–1999 [41] |
ADDM: Automatic Database Diagnostic Monitor.
Numbers in parentheses reference included studies described in Table 1.
Not included here are specific differences across geographic region identified in the following studies: ADDM Network 2002 Principal Investigators, 2007; ADDM Network 2006 Principal Investigators, 2009; and ADDM Network 2008 Principal Investigators, 2012; Frenette et al. (2011); Howlin and Moore (1997); Ouellette-Kuntz et al. (2009); and Shattuck et al. (2009).