Introduction
Despite many advances in the knowledge of autism spectrum disorder (ASD), newer evidence is beyond the reach of the rural populations. The data of the mental health crisis reflects the significant disparity in quality, access, and costs. The increase in suicide rates among adolescents,Reference Fontanella, Hiance-Steelesmith and Phillips1 the opioid crisis in adults are a few recent trends that have bought widespread attention to the rural mental health crisis.2
ASD could be diagnosed at the age of 12 to 14 months,Reference Turner-Brown, Baranek, Reznick, Watson and Crais3 and it is a highly stable diagnosis maintained at age 3.Reference Pierce, Gazestani and Bacon4 It takes 36 months after parental concerns to have a formal diagnosis.Reference Oswald, Haworth, Mackenzie and Willis5-Reference Glascoe7 Parental concerns are known to detect 70% to 80% of children with disabilities.Reference Mitroulaki, Serdari and Tripsianis8 The Autism and Developmental Disabilities Monitoring (ADDM) Network surveillance is critical to accurately measure epidemiology and has highlighted the variability in the prevalence. The average age of diagnosis is between 4 and 7 years,Reference Baio, Wiggins and Christensen9, Reference van’t Hof, Tisseur and van Berckelear-Onnes10 and the global mean average age is around 60.8 months.Reference Maenner11
In 2021, the Centers for Disease Control and Prevention (CDC) has changed the prevalence of ASD from 1 in 54 (1.9%) to 1 in 44 (2.3%) 8-year-old children.Reference Aylward, Gal-Szabo and Racial12 There are many serious implications of this revised prevalence, first, the likelihood of underdiagnoses in children with specific ethnicity,Reference Constantino, Abbacchi and Saulnier13 race,Reference McNally Keehn, Ciccarelli, Szczepaniak, Tomlin, Lock and Swigonski14 and living in the underserved areas.Reference Antezana, Scarpa, Valdespino, Albright and Richey15 Second, if the prevalence was high then what happened to the undiagnosed, and finally, what is the extent of rural disparities.Reference Pierce, Courchesne and Bacon16
The 2016 U.S. Preventive Services Task Force recommendations against universal screenings were criticizedReference Hosozawa, Sacker and Cable17 but given the newer data, is it a serious public health concern, it should be reconsidered? We appraise some critical determinants and their impact on the clinical practices in rural areas.
Duration of untreated autism
Late diagnosis of ASD is associated with a higher incidence of depression and self-harm in adolescents.Reference Bargiela, Steward and Mandy18 The ADDM reports the median age of ASD diagnosis among children under age 8 was lowest in the urban population of California, Maryland, and New Jersey with California having the lowest median age of 36 months. And longest in rural states of Minnesota (63 months), Arizona (58 months), and Wisconsin (56 months).Reference Aylward, Gal-Szabo and Racial12 These data also suggest a significant disparity between states with the highest prevalence like California (1:26) with the lowest in Missouri (1:60).Reference Aylward, Gal-Szabo and Racial12 The ADDM Network surveillance found the prevalence is similar among Caucasians, African Americans, and Hispanic nationally.Reference Aylward, Gal-Szabo and Racial12 However, these data also vary between states with some states ASD is more prevalent among the Caucasian population while others like Maryland and Minnesota where ASD was more prevalent in an African American population.Reference Aylward, Gal-Szabo and Racial12
Females
The delay in females is more pervasive given only recently there is more recognition of a distinct phenotypeReference Leedham, Thompson, Smith and Freeth19 and also symptomatology is been different from males.Reference Kaat, Shui and Ghods20 There have been recent efforts in modifying the Autism Diagnostic Observation Scale Second edition (ADOS-2) text to identify femalesReference Kentrou, de Veld, Mataw and Begeer21 but they continue to be underrepresented in the overall prevalence of ASD with a sex ratio of 4.2 in favor of males.Reference Aylward, Gal-Szabo and Racial12
Comorbidity
It is also been reported that ASD has many overlapping symptoms with ADHD.Reference Casanova, Frye, Gillberg and Casanova22 It is widely accepted that the presence of comorbidity not only challenges treatment but also has diagnostic implications.Reference Leader, Hogan and Chen23, Reference Randall, Egberts and Samtani24 Another study suggests many with ASD were diagnosed with ADHD and as a result, there was a significant delay in the diagnosis.Reference Casanova, Frye, Gillberg and Casanova22 Table 1.
Abbreviations: ASD, autism spectrum disorder; CDC, Centers for Disease Control and Prevention.
The myths and utilities of testing
Diagnostic tools Autism Diagnostic Observation Scale Second edition, Autism Diagnostic Interview-Revised, Childhood Autism Rating Scale (ADOS-2, ADI, CARS) are recommended to be part of the multidisciplinary assessment in preschoolersReference Kamp-Becker, Albertowski and Becker25 and not as stand-alone measures. Despite improved accuracy of the gold standard tools like ADOS-2Reference Maddox, Brodkin and Calkins26, they may not identify all cases of ASD.Reference Miller, Adam and Aradhya27 There are concerns about the cost-effectiveness of ADOS-2 and the need for extensive training requirements.Reference Maddox, Brodkin and Calkins26 On comparative analysis of sensitivity, specificity, and the positive predictive value (PPV) of the diagnostic tools, ADOS was more sensitive but all three of them had the same specificity.Reference Kamp-Becker, Albertowski and Becker25
Genetic testing
Chromosomal microarray analysis (CMA) has been recommended as the standard of care for the initial evaluation of children with developmental disabilities and/or ASDs.Reference Kreiman and Boles28 The emergence of low-cost whole-exome sequence (WES) and whole-genome sequence (WGS), which are preferred over CMA.Reference Harris, Sideridis, Barbaresi and Harstad29 A study has found 12% with ASD have pathologic findings on the genetic testingReference Mehta30 and as per AACAP, it could be as high as one-third in suspected cases.Reference Guthrie, Wallis and Bennett31 Genetic testing is rarely done in rural areas although there is no data to support it.
Reasons for late diagnosis in the rural US
Two recent studies found the sensitivity and PPV of the most commonly used screening tool the Modified Checklist for Autism in Toddlers (MCHAT) was in the range of 33.1% to 38.8%, and 14.6% to 17.8%, respectively.Reference Carbone, Campbell and Wilkes32, Reference Wallis and Guthrie33 Both studies have called for a paradigm shift in screenings given current tools’ has poor sensitivity and false negatives.Reference Davidovitch, Levit-Binnun, Golan and Manning-Courtney34, Reference Hosozawa, Sacker, Mandy, Midouhas, Flouri and Cable35
A British population-based cohort found those living in poverty and with higher intelligence are likely to miss out on the initial screenings.Reference Zuckerman, Broder-Fingert and Sheldrick36 Therefore, testing preschoolers from low-income families and minorities may identify these children.Reference Kuhn, Levinson and Udhnani37 Multilingual staff may increase accuracy given MCHAT has a poor PPV in ethnic minority.Reference Ozonoff, Young and Brian38 There is presence of a distinct subtle phenotype that lacks symptoms at early stages and therefore detection before age 4 is difficult due to the heterogeneous nature of ASD.Reference Ozonoff, Young and Landa39 These studies emphasize the value of longitudinal follow-up beyond 36 months.Reference Rice, Rosanoff and Dawson40
There is a clear divide between the prevalence of ASD in states with urban populations (California and New Jersey) as compared to that with the rural population (Missouri and Wisconsin).Reference Aylward, Gal-Szabo and Racial12 These differences in the prevalence could be attributed to the changes in the diagnostic criteria and higher health care literacy in urban areas.Reference Palmer, Blanchard, Jean and Mandell41, Reference Mandell and Palmer42 The state public health awareness programs also contribute to improving awareness among parents.43
Evidence-based interventions which work is not available to many who needs the most
The higher prevalence could also be linked to the higher density of mental health workforceReference Chasson, Harris and Neely44 with Maryland being the only outlier.Reference Aylward, Gal-Szabo and Racial12 The services are clustered around urban pockets with higher per capita income. Also, the average cost for Applied Behavioral Analysis is $60,000 per year which totals to $240,000 for 4 years of treatment.Reference Siu and Bibbins-Domingo45
Discussion
Currently, MCHAT is recommended at 16 months of age in suspected cases and universal screening is not recommended.Reference Kim, Joseph and Frazier46 As the burden of missed or late diagnosis of ASD continues to mount, the scientific basis for controversial population-based universal screening growing. There is also a need for a screening tool that is highly specific, sensitive, and with a good PPV given MCHAT has both poor specificity and sensitivity.Reference Albores-Gallo, Roldán-Ceballos and Villarreal-Valdes47 Additionally, translated versions of MCHAT perform suboptimally.Reference Nukeshtayeva, Lubchenko, Omarkulov and DeLellis48, Reference Smith, Malcolm-Smith and de Vries49 Special attention is required for the underrepresented minority population. There is a need to modify questions in the ADOS-2 based upon the cultural context to reduce the diagnostics bias.Reference Magaña and Smith50 Even the Spanish-translated version is less accurate compared to English; despite Spanish being the second most spoken language in the US.Reference Horlin, Falkmer, Parsons, Albrecht and Falkmer51 Cost-effective, readily accessible tools assist in early diagnosis and the access to interventions may not only improve the long-term outcomes but also reduce the overall cost. The multidisciplinary approaches for diagnostics and treatments are expensive to set up and continue to remain a barrier in underserved areas.Reference Barrett, Mosweu and Jones52, Reference Abbas, Garberson, Liu-Mayo, Glover and Wall53
The emerging evidence of artificial intelligence-based platforms is encouraging since it has the potential to address diagnostics issues and are also cost-effective.Reference Kleberg, Högström, Nord, Bölte, Serlachius and Falck-Ytter54 Many diagnostic instruments that are underutilized, training staff to use ADI-R, ADOS-2, CARS-3, GADS may be highly prudent in rural areas with limited resources. The gold standard diagnostic tool ADOS is highly sensitive but lacks specificity.Reference Kamp-Becker, Albertowski and Becker25 This is observed in ones with fewer symptoms of ASD and when associated with comorbid ADHD or social anxiety disorder.Reference Kleberg, Högström, Nord, Bölte, Serlachius and Falck-Ytter55 Therefore, in many with fewer symptoms of ASD and associated comorbidities, diagnosis is more difficult.Reference Leader, Hogan and Chen23, Reference Randall, Egberts and Samtani24 The adults with high functioning ASD may compensate for their deficits, and never meet the criteria for autism even with ADOS-2.Reference Adamou, Jones and Wetherhill56
Finally, significant advocacy is needed for the rural low-income populations living in the underserved areas with a low incidence of ASD.
Author Contributions
Conceptualization: M.G., N.G., J.M.; Data curation: M.G., N.G.; Formal analysis: J.M.; Writing—original draft: M.G., N.G.; Writing—review and editing: N.G.
Disclosures
The authors declare none.