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. Author manuscript; available in PMC: 2026 Jan 8.
Published in final edited form as: Res Autism. 2025 Apr 2;124:202582. doi: 10.1016/j.reia.2025.202582

Mental health hospitalization and readmission in autistic adults in a national U.S. sample

Jessica E Rast 1,*, Joseph Wright 1, Samuelle Voltaire 1, Tamara Garfield 1, Anne M Roux 1
PMCID: PMC12777935  NIHMSID: NIHMS2126419  PMID: 41509504

Abstract

Objective:

The objectives of this study were to, 1) estimate U.S. national rates of mental health hospitalization (MHH) and all-cause readmission, and 2) explore characteristics associated with readmissions for autistic and non-autistic adults.

Methods:

This study used the National Readmission Database (NRD) 2019 to examine 30-day all-cause readmissions following MHH in adults with autism, intellectual disability, ADHD, and mental health conditions. Analysis estimated rates of MHH by group, rates and odds of readmission, and factors associated with readmission.

Results:

More than one-third (36 %) of all admissions for autistic adults in 2019 were MHH, with schizophrenia the most common reason. Of all MHH index events in autistic adults, 17 % had a 30-day all-cause readmission. Readmissions were more common in autistic adults with ID (25 %) than in autistic adults without ID (15 %). Readmission was also slightly more common in female autistic adults (20 %) than male autistic adults (16 %), and autistic females had greater odds of readmission (OR 1.30, 95 % CI 1.09, 1.55) than autistic males, which was not true in non-autistic adults. Initial admission for schizophrenia was associated with increased odds of readmission for all groups (OR 1.37, 95 % CI 1.32, 1.42).

Conclusions:

The complexity of mental health conditions and their care in autistic adults underscores the urgent need for accessible and tailored mental health care services. Addressing these challenges will require collaborative efforts across healthcare sectors to create comprehensive, inclusive, and person-centered approaches to mental health care delivery for autistic adults across often disjointed service sectors.

Keywords: Mental health hospitalization, Readmission, Autism, Adults

Introduction

Mental health conditions are common among autistic adults; half have a co-occurring condition, with anxiety, depression, and ADHD the most common (Lugo-Marin et al., 2019; Schott et al., 2021). Co-occurring mental health conditions are more common among autistic adults than their non-autistic peers, adversely impacting the quality of life, complexity, and cost of health care for autistic adults, creating a complex clinical picture (Croen et al., 2015; Lai et al., 2019; Rast et al., 2021; Zerbo et al., 2019). High rates of mental health conditions in autistic adults may be partially attributed to a service system that lacks an evidence base for effective care, stigma, trauma and financial hardship accumulating across the life course, and a desire for, but lack of, interpersonal social support (Dodds, 2021; Hedley et al., 2017; Hull et al., 2021; Maddox et al., 2020; Mitchell et al., 2021). Some studies also suggest there may be diagnostic overlap or shared etiology with autism and certain conditions, such as schizophrenia (King & Lord, 2011; Zheng et al., 2018). Mental health conditions, including mood disorders and schizophrenia, are the two most common reasons for inpatient hospitalization in autistic adults (Rast et al., 2021).

Mental health services play a key role in supporting people with mental health diagnoses by supporting symptom management for community participation (Maddox et al., 2020; Maddox & Gaus, 2019). Accessible services prevent an increase in the severity of mental health symptoms and decrease risk of crisis events (Maddox et al., 2020; Maddox & Gaus, 2019). However, the lack of an integrated mental health system across primary and specialty care results in gaps in care that lead to mental health crises and use of emergency and inpatient hospitalization as a recurrent care modality (Burns, 2017). These settings are not ideal treatment locations, as they often lack resources, training in autism competent care, and linkages to long term treatment options; care delivered in these settings is often more costly, intensive, and intrusive than community-based preventive care (Drake & Bond, 2021; Krupski et al., 2016; Navas et al., 2022). If hospitalization does occur, appropriate treatment and discharge instructions can connect a person to outpatient mental health care to reduce the risk of recurring crisis care.

Very little is known about readmission risk and associated factors in autistic adults. In non-autistic populations, previous studies have identified predictors of readmission after a mental health hospitalization (MHH) including diagnoses of substance use disorders, psychosis, and major depression; longer length of hospital stay; hospitalization and service use prior to MHH (Becker et al., 2017; Cheng et al., 2017; Kartha et al., 2007; Perlman et al., 2015); demographics and social determinants of health including race, sex, urbanicity, household income (Carroll et al., 2022); and social belonging (Zhao et al., 2020). People who do not receive appropriate follow-up care are more likely to experience hospital readmissions, service and medication non-compliance, and self-injurious and dangerous behaviors (Choi et al., 2020; Greenberg & Rosenheck, 2005; Puntis et al., 2015). People who are readmitted within 30 days experience an increased risk of two year all-cause mortality (Shaw et al., 2020). In a study of autistic youth, one of the few on readmission within autism, specific antipsychotic medication initiation following MHH was associated with reduced risk of psychiatric re-admission (Kompella et al., 2022). Readmission within 30 days is a common measure of health care quality; for example, it is the measure of readmissions used by the Hospital Readmissions Reduction Program by the Centers for Medicare and Medicaid Services (CMS).

Autistic adults have unique presentation and support needs that suggest their readmission risks may be different from non-autistic adults, requiring targeted inquiry. The accessibility of appropriate mental health care is limited in autistic adults by provider availability, impacting the ability to connect to outpatient care after discharge (Maddox et al., 2020). Even if there were providers to discharge to, hospital staff may not have resources or training in autism to deploy a thorough and accessible discharge plan. This planning is made more complex because many state policies and programs were designed with autistic children, not adults, in mind, and therefore autistic adults may not qualify for community services (Turcotte et al., 2016). The common co-occurrence of certain conditions in autistic adults, including intellectual disability (ID) and attention-deficit/hyperactivity disorder (ADHD), also complicates mental health care. These conditions commonly co-occur with autism and are themselves complicating conditions for mental health care. Patients without autism who have ID or ADHD may have similar mental health profiles and increased service needs as autistic adults, making them a useful comparison group for study.

The purpose of this study is to describe metal health hospitalizations (MHH) and all-cause readmission in autistic adults to begin to understand the specific needs of this population. Many studies of mental health readmission are international or are from a geographically limited area if conducted in the U.S., potentially due to the accessibility of data that allows the examination of readmission (Becker et al., 2017; Carroll et al., 2022; Cheng et al., 2017; Kartha et al., 2007; Perlman et al., 2015). To address this limitation, this study uses the National Readmission Database (NRD), which is a nationally representative sample of hospital discharges built to study readmissions. NRD allows for an all-payer, nationally representative examination of hospital admissions and readmissions within a calendar year. Using this data, we aim to 1) quantify national MHH characteristics and all-cause readmission and 2) examine characteristics associated with readmission for autistic and non-autistic adults.

Methods

Data source and population

This study used the National Readmission Database (NRD) 2019, a research database cataloging hospitalizations over a calendar year with the intent of performing readmission analysis. NRD is created from State Inpatient Databases by the Healthcare Cost and Utilization Project (HCUP) of Agency for Healthcare Research and Quality (AHRQ). Hospitalizations captured in NRD are all-payer admissions to community hospitals, excluding rehabilitation and long-term acute care hospitals. All admissions in a given year are linked via a personal identifier. Analysis of NRD is nationally representative; the 2019 data is comprised of about 18 million discharges (weighted to 35 million discharges) from 30 states with reliable patient linkage.

Index stay and all-cause readmission

Index stays were stays for a mental health hospitalization (MHH) captured as stays with any Clinical Classifications Software Refined (CCSR) code starting with mental behavioral disorder (“MBD”) in the primary position of the stay record, excluding autism, intellectual disability (ID), and attention deficit hyperactivity disorder (ADHD) based on the below-described ICD-10 codes. The primary position of the stay record, also called the principal diagnosis, is the first ICD code listed in the discharge record (of a possible 40 code positions). The principal diagnosis is generally considered to be the primary reason for a hospitalization, with some variability in coding based on insurance requirements and clinical judgement (McDermott KW (IBM Watson Health) & Roemer M (AHRQ), 2021). CCSR is a classification system that collapses international classification of diseases (ICD) codes into fewer, more clinically meaningful codes for research. Index events were limited to exclude hospitalizations beginning in January or December, to ensure that there were 30 days of observation before and after the index event to capture prior admissions or readmissions. An index event must have been the first mental health hospitalization within a 30-day period, to ensure they were not themselves a readmission.

This study used 30-day all-cause readmission as the outcome of interest. This was captured as any hospital admission within 30 days of discharge for the index event. All-cause readmission is a consistent care quality indicator and points to the accessibility of outpatient care after discharge.

Populations

This study compared four mutually exclusive groups of adults ages 18 and older experiencing mental health hospitalizations: autistic adults, adults with ID, adults with ADHD, and adults with any other mental health condition. Mental health hospitalization was identified by the diagnosis in the primary position of the stay record. Therefore, populations were categorized by conditions in any secondary position of the stay record (any of position 2 through 40, the maximum number). Autistic adults were those with any ICD-10 code F84. X in a secondary position, they may also have had any of the other conditions of ID, ADHD, or another mental health condition. Adults with ID were adults with any ICD-19 code F70. X-F79. X in a secondary position, with no autism code in a secondary position but could have had an ADHD or other mental health diagnosis. Adults with ADHD were adults with an ICD-10 code F90. X in a secondary position, with no autism nor ID code in a secondary position. Adults with other mental health conditions were those with any CCSR code beginning with “MBD” in a secondary position, but no autism, ID, or ADHD codes in a secondary position. These groups were chosen due to an assumed similar underlying risk for mental health hospitalization (MHH), which assisted in examination of differences in services related specifically to autism.

Patient and stay characteristics

Patient characteristics included age (grouped as 18–44, 45–64, and 65 years and older), sex, urbanicity, and the median household income of the patient’s zip code. Stay characteristics included length of stay, cost of stay, emergency department use before or during the admission, elective admission, primary expected payer, and presence of an injury code in the stay record. Specific mental health diagnoses that have been shown in prior research to be associated with greater risk of hospital readmission included substance use, depression, and schizophrenia in the principal position of the stay record (Becker et al., 2017; Kartha et al., 2007). Information on race and ethnicity was not available.

Statistical analysis

We first presented the proportion of all hospitalizations for each group that were for mental health conditions to examine the magnitude of the MHH frequency in hospitalizations for each population. We then presented the distribution of characteristics of the index MHHs for each group, including the reason (the principal diagnosis) for the admission. For each group, we examined the 30-day all-cause readmission rate. We also examined 30-day all-cause readmission among autistic adults by several key groups: ID status, sex, and age group. No statistical significance testing was performed between groups in this portion of the study. We generally deemed a finding clinically significant if the difference between groups was greater than 5 %.

Among those who had a readmission, we identified the most common reasons for readmission by group. We then built two multivariable logistic regression models to examine: 1) the association of covariables with readmission, with group status as covariables, and 2) the association of covariables with readmission within the autistic group only, including ID status as a covariable. All analysis accounted for the complex sampling design of NRD and was performed using SAS 9.4.

Results

Mental health hospitalization

More than one-third (36 %) of all admissions for autistic adults in 2019 were for mental health hospitalizations (MHH), compared to 23 % for adults with ID, 41 % for adults with ADHD, and 12 % for adults with other mental health conditions. There were 17,044 MHH in 2019 that counted as an index event for autistic adults in this study (Fig. 1).

Fig. 1.

Fig. 1.

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Prevalence of 1) mental health hospitalzation (weighted number of index events) and 2) 30-day readmission.

The patient and stay characteristics of the index MHH are seen in Table 1. Autistic adults were younger (average age 28.5), less often female (28.7 %), and more often lived in zip codes with higher median incomes than non-autistic adults. Stays were longer in autistic adults (8.5 days) and adults with ID (9.8 days) than in adults with ADHD (6.1 days) or another mental health condition (6.7 days). Cost per day was highest in adults with another mental health condition ($5390 compared to $4077 for autistic adults). Across all groups, most stays were based on emergent issues that were not elective or for scheduled procedures, and admission through the emergency department was seen in about two-thirds of adults in all four groups. Medicaid (40.6 %) and Medicare (24.7 %) were the primary expected payer for the majority of stays for autistic adults. The use of Medicaid as the primary payer was similar across groups. However, Medicare was more common in adults with ID (42.1 %) but less common in adults with ADHD (14.7 %) than autistic adults. About 1 in 12 (12.6 %) autistic adults had an injury code in their record upon admission, this was similar to adults in the other groups.

Table 1.

Demographic and stay characteristics of the index mental health hospitalization.

Autism
 Intellectual disability (ID)
 Attention deficit hyperactivity disorder (ADHD)
 Other mental health conditions
Demographic characteristics % SE % SE % SE % SE
Age at admission (mean) 28.5 0.2 38.6 0.3 33.4 0.1 43.2 0.2
Female 28.7 0.6 46.3 0.6 42.9 0.4 45.0 0.3
Median household income for patient’s ZIP Code
0 −25th percentile 29.1 1.3 46.5 1.4 27.7 1.0 36.5 0.9
26th to 50th percentile 28.4 0.9 28.0 0.9 27.5 0.8 26.5 0.6
51st to 75th percentile 24.6 0.9 17.4 0.8 25.3 0.7 21.9 0.5
76th to 100th percentile 18.0 1.0 8.1 0.6 19.5 1.0 15.1 0.7
Urbanicity
Urban 45.7 2.0 49.2 2.0 44.1 1.9 48.7 1.6
Suburban 40.3 1.9 31.7 1.7 41.9 1.8 36.3 1.5
Rural 13.9 1.0 19.1 1.2 14.0 0.9 15.0 0.7
Stay characteristics
Length of stay (mean) 8.5 0.3 9.8 0.3 6.1 0.1 6.7 0.1
Cost per day (mean) $4077 102 $3784 97 $4522 107 $5390 117
Emergency department use 63.4 1.8 65.3 1.8 65.2 1.6 67.2 1.3
Elective admission 7.8 0.7 9.5 0.9 9.3 0.8 9.3 0.6
Primary expected payer
Medicare 24.7 0.6 42.1 0.9 14.7 0.3 23.7 0.4
Medicaid 40.6 1.0 44.3 1.2 41.3 1.0 36.0 0.8
Private insurance 27.3 1.1 9.1 1.2 30.2 0.9 24.4 0.7
Other 7.3 0.5 4.5 0.4 13.8 0.7 16.0 0.7
Diagnoses recorded (mean) 9.7 0.1 10.9 0.2 11.2 0.1 10.4 0.1
Depression primary code 25.4 0.8 16.1 0.6 27.3 0.7 26.3 0.6
Substance use primary code 3.9 0.3 3.8 0.3 21.5 1.0 28.2 0.8
Schizophrenia primary code 30.4 0.9 51.0 1.0 14.2 0.4 19.6 0.5
Injury ICD10 code in record 12.6 0.5 9.1 0.3 15.8 0.4 14.2 0.2
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The most common reasons for mental MHH varied by group (Table 2). Schizophrenia was the most common reason for MHH in autistic adults and adults with ID: 30.4 % of all MHH in autistic adults and 51.0 % of all MHH in adults with IDD had schizophrenia as the principal diagnosis. In adults with ADHD and adults with other mental health conditions, depression was the most common reason for MHH (27.3 % for ADHD and 26.3 % for other conditions). Trauma- and stressor-related disorders and disruptive, impulse-control and conduct disorders were in the top five most common reasons for MHH in autistic adults and adults with ID. These conditions did not appear in the top five for adults with ADHD and adults with other mental health conditions. Alcohol-related disorders were the second most common reason for MHH in adults with other mental health conditions but did not make the top five in other adults.

Table 2.

Most common principal diagnoses for index admission and readmission by group.

Most common principal diagnoses for the index mental health hospitalization
Autism
 Intellectual disability (ID)
 Attention deficit hyperactivity disorder (ADHD)
 Other mental health conditions
Condition % Condition % Condition % Condition %
1st Schizophrenia 30.4 Schizophrenia 51.0 Depression 27.3 Depression 26.3
2nd Depression 25.4 Depression 16.1 Bipolar 22.3 Alcohol 19.7
3rd Bipolar 19.9 Bipolar 14.3 Schizophrenia 14.2 Schizophrenia 19.6
4th Trauma 5.0 Trauma 4.9 Alcohol 11.2 Bipolar 13.6
5th Disruptive 4.4 Disruptive 3.3 Suicide 4.5 Suicide 4.3
Most common principal diagnoses for the readmission
1st Schizophrenia 36.4 Schizophrenia 46.8 Bipolar 20.3 Schizophrenia 22.3
2nd Bipolar 17.0 Depression 12.1 Depression 17.3 Depression 15.1
3rd Depression 16.6 Bipolar 11.9 Schizophrenia 17.2 Alcohol 15.2
4th Neurodevelop 4.1 Trauma 3.1 Alcohol 12.6 Bipolar 11.7
5th Disruptive 3.5 Disruptive 1.9 Opioid 2.9 Septicemia 2.0
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Diagnoses based on Clinical Classifications Software Refined (CCSR) codes and are defined as follows: Schizophrenia spectrum and other psychotic disorders (MBD001); Depression and depressive disorders (MBD002); Bipolar and related disorders (MBD003); trauma- and stressor-related disorders (MBD007); Disruptive, impulse-control and conduct disorders (MBD008); Suicidal ideation/attempt/intentional self-harm (MBD012); Neurodevelopmental disorders (MBD014); Alcohol-related disorders (MBD017); Opioid-related disorders (MBD018); and septicemia (INF002).

30-day all-cause readmission

Of all the MHH index events in autistic adults, 17 % had a 30-day all-cause readmission, as did 25 % of adults with ID, 17 % of adults with ADHD, and 14 % of adults with other mental health diagnoses (Fig. 1). Further examination by characteristics in autistic adults (Fig. 2) revealed that readmissions were more common in autistic adults with ID (25 %) than in autistic adults without ID (15 %). This is commensurate with the finding that the readmission rate is 25 % in adults with ID without autism. Readmission was also slightly more common in female autistic adults (20 %) than male autistic adults (16 %). Readmission prevalence also varied by primary expected payer in autistic adults: readmission was more common among those with Medicare (20 %) or Medicaid (19 %) than those with private insurance (13 %) or another primary expected payer (14 %). Readmission prevalence also varied based on the reason for the index MHH, as 22 % those who had a primary mental health admission code of schizophrenia had a readmission, compared to 13 % with a primary code of depression.

Fig. 2.

Fig. 2.

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Readmission prevalence by key characteristics in autistic adults.

The most common reasons for hospital readmission varied somewhat by group (Table 2). Schizophrenia was the most common reason for readmission in autistic adults (36.4 %), adults with ID (46.8 %), and adults with other mental health conditions (22.3 %) (it was number three in adults with ADHD (17.2 %)). In autistic adults, neurodevelopmental disorders were among the top five reasons for readmission (4.1 %).

The odds of 30-day all cause readmission was higher for autistic adults (OR 1.49, 95 % CI 1.40, 1.60), adults with ID (OR 1.82, 95 % CI 1.73, 1.92), and adults with ADHD (OR 1.46, 95 % CI 1.41, 1.52) than adults with mental health conditions (Table 3). Admission for schizophrenia at the index event was associated with increased odds of readmission (OR 1.37, 95 % CI 1.32, 1.42), while admission for depression was associated with a decreased odds of readmission (OR 0.86, 95 % CI 0.84, 0.88). Having an injury present during the index stay was also associated with reduced odds of readmission (OR 0.73, 95 % CI 0.71, 0.76).

Table 3.

Multivariable logistic regression estimating odds of readmissions by index characteristics.

All-cause readmission within 30 days
 All-cause readmission within 30 days, autism only
OR 95 % CI OR 95 % CI
Condition
Autism 1.49 [1.40,1.60]
ID 1.82 [1.73,1.92]
ADHD 1.46 [1.41,1.52]
Other mental health reference
Autism with ID 1.96 [1.62, 2.37]
Autism without ID reference
Inpatient demographic characteristics
Age at admission 1.01 [1.01,1.01] 1.00 [0.99,1.01]
Female 0.83 [0.82,0.85] 1.27 [1.06,1.52]
Median household income for ZIP
0 —25th percentile 1.16 [1.10,1.21] 1.00 [0.78,1.27]
26th to 50th percentile 1.07 [1.03,1.11] 0.96 [0.76,1.22]
51st to 75th percentile 1.02 [1.00,1.06] 0.88 [0.69,1.13]
76th + percentile reference reference
Urbanicity
Urban reference reference
Suburban 0.99 [0.95,1.03] 1.00 [0.84,1.20]
Rural 0.80 [0.76,0.84] 0.64 [0.49,0.85]
Stay characteristics
Mean length of stay 1.00 [0.99,1.00] 1.00 [0.99,1.01]
Mean cost per day 1.00 [1.00,1.00] 1.00 [1.00,1.00]
Emergency department use 1.13 [1.08,1.18] 1.26 [1.05,1.50]
Elective admission 0.89 [0.84,0.94] 1.10 [0.73,1.64]
Primary expected payer
Medicare 1.56 [1.50,1.62] 1.35 [1.04,1.75]
Medicaid 1.56 [1.50,1.63] 1.22 [0.99,1.50]
Private insurance reference reference
Other 1.22 [1.16,1.29] 0.94 [0.66,1.34]
Number diagnoses recorded 1.03 [1.02,1.03] 1.03 [1.01,1.04]
Depression as primary code 0.86 [0.84,0.88] 0.93 [0.76,1.15]
Substance use as primary code 1.11 [1.07,1.16] 1.59 [1.09,2.32]
Schizophrenia as primary code 1.37 [1.32,1.42] 1.34 [1.10,1.64]
Injury ICD10 code in stay record 0.73 [0.71,0.76] 0.82 [0.64,1.05]
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We repeated this regression within autistic adults only, and there were not many differences in what was associated with readmission within the group. However, we did find that in autistic adults, females had greater odds of readmission (OR 1.30, 95 % CI 1.09, 1.55), but they had reduced odds of readmission in the model with all MHHs included (and autism as a covariate).

Discussion

Mental health hospitalization (MHH) is a common reason for hospitalization in autistic adults. In this study, 36 % of all admissions for autistic adults in 2019 were for MHH. This was similar to adults with ADHD (41 %), but higher than adults with ID (23 %) and adults with other mental health conditions (12 %), suggesting a heightened need for accessible mental health care in autistic adults and adults with ADHD. The presentation of crisis mental health concerns in autistic adults and in adults with ID may be more complex than peers, as autistic adults and adults with ID have the longest stays in this study. The reasons for readmission also suggest different origins or presentations of mental health concerns in autistic adults and adults with ID. Schizophrenia was a much more common reason for index MHH in autistic adult and adults with IDD than adults with ADHD and adults with other mental health conditions, where depression and alcohol-related disorders were more common. Schizophrenia is more commonly diagnosed in autistic adults than in adults without autism, which may explain some of the difference in rates seen in this study (Chien et al., 2021; Croen et al., 2015). However, it may also be related to the difficulty of differential diagnosis in settings without expertise in autism. For example, some autism behaviors or autism-associated neurodevelopmental conditions may be interpreted as symptoms of schizophrenia in non-autistic adults making differential diagnosis is difficult (Chien et al., 2021; Gadow & Drabick, 2012). Trauma- and stressor-related disorders were also common reasons for MHH in autistic adults and adults with ID, which supports a growing body of work stressing a need for trauma-informed care in autistic adults (Faccini & Allely, 2021; Houck & Dracobly, 2023).

Implications

The discontinuity of the mental health care system is a barrier to continuous quality care across the continuum of primary to crisis care. This likely contributes to the increased rate of both MHH and readmission seen in certain groups in this study. Another contributor to the increased rates of MHH seen in autistic adults and adults with ADHD is the increased rates of co-occurring mental health conditions in these groups (Kerns et al., 2020; Pehlivanidis et al., 2020). Increased MHH and subsequent readmission are compounded in adults with disabilities, particularly those with intellectual and neurodevelopmental disorders (like autism and ADHD), given additional barriers to appropriate care.

The highest rates of readmission were seen in adults with ID (including those with co-occurring autism). This suggests that barriers to quality outpatient care may be greatest in this group, including lack of services and practitioners to support this group, poor-quality or inappropriate services to meet needs, and deficits in practitioner and care navigator knowledge (Whittle et al., 2018). Healthcare practitioners, particularly adult health and mental health care providers, report feeling inadequately prepared to care for autistic patients and patients with ID, sometimes misattributing mental health symptoms to their intellectual disability (Ee et al., 2022; Zerbo et al., 2015), which is a barrier to appropriate care (Maddox et al., 2020). There are also few treatment modalities that are adapted for autistic adults (Kerns et al., 2016). Another possible explanation for the high rates of readmission in adults with ID lies in the disconnect between the state developmental disability (DD) and mental health service systems. Adults with ID are historically the group with the most direct access to the DD service system as many states use ID diagnosis and IQ as eligibility criteria for services (Barth et al., 2020; Hall-Lande et al., 2011). Adults with ID, whether or not they are also autistic, are likely to receive support through DD systems, where most providers do not have expertise in mental health care (Maddox et al., 2020; Maddox & Gaus, 2019). Even if adults with ID present with mental health systems, they are likely referred to the DD service system. Adults with ID may face unique systemic and interpersonal barriers to connecting to mental health care and mental health concerns may not be addressed as they emerge (Ee et al., 2022).

Several other characteristics were both elevated in certain groups in the index MHH and were important considerations for readmission. Medicaid was the primary expected payer for about 40 % of index MHH in autistic adults, adults with ID, and adults and ADHD, and Medicare was similarly common in adults with ID. Medicare was less common in autistic adults and adults with other mental health conditions, and even less common in adults with ADHD. In adjusted analyses, having Medicaid or Medicare as a primary expected payer were among the strongest associations with all-cause readmission. Prior studies have highlighted people with public health insurance have higher rates of readmission following a MHH (Rieke et al., 2016; Smith et al., 2015). This may be due to differing profiles of patients who are eligible for Medicaid (income or disability eligibility criteria) or Medicare (age and disability eligibility criteria), the care that is covered by these programs (Medicaid beneficiaries may be more likely to receive care in emergency settings than privately insured individuals), and differential enrollment in these programs (more women are enrolled in Medicaid than men) (Allen et al., 2021; Kaiser Family Foundation, 2025). Changes targeted at Medicaid and Medicare behavioral health coverage may then be especially impactful in reducing readmission. Median household income of the patient’s zip code also varied by group, with almost half of adults with ID living in neighborhoods with a median zip code below the 25th percentile, and in multivariable analysis, living in these zip codes was associated with an increase in the odds of readmission. Prior studies have also found an increased risk of readmission for people with lower incomes (Bui & Moriuchi, 2021), suggesting a need for outpatient care that is accessible and affordable. Finally, rurality was an important consideration for readmission, where rural patients had reduced odds of readmission. This has been seen in other studies of hospitalization and readmission (Wen et al., 2024) and may be due to recent findings of higher quality inpatient psychiatric care in rural versus urban locations (Hung et al., 2023).

Finally, within autistic adults, our findings highlighted two groups in need of additional attention, including females and people with schizophrenia. In autistic adults, females have greater rates and odds of readmission than autistic males. This is the opposite of what is seen in non-autistic populations, both in our study and in previous research (Zhou et al., 2023). This may be suggestive of inadequate inpatient and outpatient follow-up care for autistic women than men. Much research and clinical attention has focused on autism in males, with only recent attention paid to the differences in presentation and support needs for autistic women (Gould, 2017). Women may also face additional risk factors for poor mental health, including increased camouflaging and masking behaviors (Beck et al., 2020). This difference from population occurrence highlights the need for further attention on the population of autistic women generally, and their mental health needs in particular.

Schizophrenia was a risk factor for readmission in autistic adults, as it was in the other groups in this study and is in prior literature (Zhou et al., 2023). Co-occurring schizophrenia may result in greater barriers to services for autistic people because the siloing of service systems that support people with disabilities makes receipt of coordinated, continuous services difficult (Son et al., 2019). Adults with autism, especially those with ID, may receive services and support through state developmental disability (DD) services, while adults with schizophrenia may seek support through mental health systems and providers. A person with both conditions may have difficulty finding providers that feel confident managing both (Constantino et al., 2020; Son et al., 2019). Unaddressed schizophrenia may result in aggressive behavior that impacts social support, residential and day placements, care received, and social and professional relationships, resulting in long lasting negative impacts (Constantino et al., 2020). Adequate outpatient care for this group is imperative to reducing unwanted outcomes, such as readmission as examined in this study.

Limitations

There are several data and study limitations to highlight. The National Readmission Database (NRD) is a record of hospital stays experienced in 2019. The rate of admission for mental health conditions captures the percentage of all hospital stays that were for mental health conditions, and is not a prevalence of MHH in autistic adults. The classification of a hospitalization as a MHH relies on coding behavior of admitting physicians or staff and may not accurately capture clinical presentation. Further, there may be differences in coding behavior based on autism diagnosis. This difference is not known to be true, but studies do suggested that misdiagnosis and differentiation of autism and other clinical symptoms may be prevalent in autistic adults (Kentrou et al., 2024). However, presentation of symptoms that escalates to the need for hospital admissions is a notable event, whether or not the diagnosis is clinically correct. The NRD does not contain detailed information about patient characteristics or medication use, which could be pertinent information about care occurring during an MHH. Similarly, NRD does not contain information or care occurring after discharge or in outpatient settings, which would be illuminating in the examination of readmissions.

Conclusions

The complexity of mental health conditions and their care in autistic adults underscores the urgent need for accessible and tailored mental health care services. Our findings reveal higher readmission rates in autistic adults, particularly among those with intellectual disabilities (ID), emphasizing the importance of addressing the unique support needs of this population. The difference in readmission rates between autistic males and females may highlight the necessity for better identification and support of mental health in autistic females. Additionally, the intersectionality of autism and schizophrenia further complicates access to continuous care, emphasizing the imperative for integrated service systems to bridge existing gaps. Addressing these challenges will require collaborative efforts across healthcare sectors to create comprehensive, inclusive, and person-centered approaches to mental health care delivery for autistic adults. Next steps should focus on understanding the adequacy of discharge follow-up services to ameliorate disparities in readmission. Other system-level interventions to decrease rates of mental health crisis care and improve outpatient mental health care are needed.

Acknowledgements

This project was supported by NIH grant 1R03MH132034. This project was also supported by the Health Resources and Services Administration (HRSA) of the U.S. Department of Health and Human Services (HHS) under cooperative agreement UT6MC45902 Autism Transitions Research Project. The information, content, and/or conclusions are those of the author and should not be construed as the official position or policy of, nor should any endorsements be inferred by HRSA, HHS or the U.S. Government.

Footnotes

Declaration of Competing Interest

None.

Data availability

The authors do not have permission to share data.

References

  1. Allen H, Gordon SH, Lee D, Bhanja A, & Sommers BD (2021). Comparison of utilization, costs, and quality of Medicaid vs subsidized private health insurance for low-income adults. JAMA Network Open, 4(1), Article e2032669. -e2032669. [Google Scholar]
  2. Barth S, Lewis S, & Simmons T (2020). Medicaid Services for People with Intellectual or Developmental Disabilities - Evolution of Addressing Service Needs and Preferences. https://www.macpac.gov/wp-content/uploads/2021/01/Medicaid-Services-for-People-with-Intellectual-or-Developmental-Disabilities-–-Evolution-of-Addressing-Service-Needs-and-Preferences.pdf. [Google Scholar]
  3. Beck JS, Lundwall RA, Gabrielsen T, Cox JC, & South M (2020). Looking good but feeling bad:“Camouflaging” behaviors and mental health in women with autistic traits. Autism, 24(4), 809–821. [DOI] [PubMed] [Google Scholar]
  4. Becker MA, Boaz TL, Andel R, & Hafner S (2017). Risk of early rehospitalization for non-behavioral health conditions among adult Medicaid beneficiaries with severe mental illness or substance use disorders. The Journal of Behavioral Health Services & Research, 44(1), 113–121. [DOI] [PubMed] [Google Scholar]
  5. Bui QN, & Moriuchi E (2021). Economic and social factors that predict readmission for mental health and drug abuse patients. Sustainability, 13(2), 531. [Google Scholar]
  6. Burns TR (2017). Contributing factors of frequent use of the emergency department: A synthesis. International Emergency Nursing, 35, 51–55. [DOI] [PubMed] [Google Scholar]
  7. Carroll AR, Hall M, Brown CM, Johnson DP, Antoon JW, Kreth H, Ngo M-L, Browning W, Neeley M, & Herndon A (2022). Association of race/ethnicity and social determinants with rehospitalization for mental health conditions at acute care children’s hospitals. The Journal of Pediatrics, 240, 228–234. e221. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Cheng C, Chan CW, Gula CA, & Parker MD (2017). Effects of outpatient aftercare on psychiatric rehospitalization among children and emerging adults in Alberta, Canada. Psychiatric Services, 68(7), 696–703. [DOI] [PubMed] [Google Scholar]
  9. Chien YL, Wu CS, & Tsai HJ (2021). The comorbidity of schizophrenia spectrum and mood disorders in autism spectrum disorder. Autism Research, 14(3), 571–581. [DOI] [PubMed] [Google Scholar]
  10. Choi Y, Nam CM, Lee SG, Park S, Ryu H-G, & Park E-C (2020). Association of continuity of care with readmission, mortality and suicide after hospital discharge among psychiatric patients. International Journal for Quality in Health care, 32(9), 569–576. [DOI] [PubMed] [Google Scholar]
  11. Constantino JN, Strom S, Bunis M, Nadler C, Rodgers T, LePage J, Cahalan C, Stockreef A, Evans L, & Jones R (2020). Toward actionable practice parameters for “dual diagnosis”: Principles of assessment and management for co-occurring psychiatric and intellectual/developmental disability. Current Psychiatry Reports, 22, 1–13. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Croen LA, Zerbo O, Qian Y, Massolo ML, Rich S, Sidney S, & Kripke C (2015). The health status of adults on the autism spectrum. Autism, 19(7), 814–823. 10.1177/1362361315577517 [DOI] [PubMed] [Google Scholar]
  13. Dodds RL (2021). An exploratory review of the associations between adverse experiences and autism. Journal of Aggression, Maltreatment & Trauma, 30(8), 1093–1112. [Google Scholar]
  14. Drake RE, & Bond GR (2021). Psychiatric crisis care and the more is less paradox. Community Mental Health Journal, 57(7), 1230–1236. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Ee J, Stenfert Kroese B, & Rose J (2022). Experiences of mental health professionals providing services to adults with intellectual disabilities and mental health problems: A systematic review and meta-synthesis of qualitative research studies. Journal of Intellectual Disabilities, 26(3), 758–781. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Faccini L, & Allely CS (2021). Dealing with trauma in individuals with autism spectrum disorders: Trauma informed care, treatment, and forensic implications. Journal of Aggression, Maltreatment & Trauma, 30(8), 1082–1092. [Google Scholar]
  17. Gadow KD, & Drabick DA (2012). Symptoms of autism and schizophrenia spectrum disorders in clinically referred youth with oppositional defiant disorder. Research in Developmental Disabilities, 33(4), 1157–1168. [DOI] [PMC free article] [PubMed] [Google Scholar]
  18. Gould J (2017). Towards understanding the under-recognition of girls and women on the autism spectrum. Autism, 21(6), 703–705. [DOI] [PubMed] [Google Scholar]
  19. Greenberg GA, & Rosenheck RA (2005). Special section on the GAF: Continuity of care and clinical outcomes in a national health system. Psychiatric Services, 56 (4), 427–433. [DOI] [PubMed] [Google Scholar]
  20. Hall-Lande J, Hewitt A, & Moseley C (2011). A national review of home and community based services (HCBS) for individuals with autism spectrum disorders. Policy Research Briefing, 21(3), 1–11. [Google Scholar]
  21. Hedley D, Uljarević M, Wilmot M, Richdale A, & Dissanayake C (2017). Brief report: social support, depression and suicidal ideation in adults with autism spectrum disorder. Journal of Autism and Developmental Disorders, 47(11), 3669–3677. [DOI] [PubMed] [Google Scholar]
  22. Houck EJ, & Dracobly JD (2023). Trauma-informed care for individuals with intellectual and developmental disabilities: From disparity to policies for effective action. Perspectives on Behavior Science, 46(1), 67–87. [DOI] [PMC free article] [PubMed] [Google Scholar]
  23. Hull L, Levy L, Lai M-C, Petrides K, Baron-Cohen S, Allison C, Smith P, & Mandy W (2021). Is social camouflaging associated with anxiety and depression in autistic adults? Molecular Autism, 12(1), 1–13. [DOI] [PMC free article] [PubMed] [Google Scholar]
  24. Hung P, Probst JC, Shih Y, Ranganathan R, Brown MJ, Crouch E, & Eberth JM (2023). Rural-Urban disparities in quality of inpatient psychiatric care. Psychiatric Services, 74(5), 446–454. [DOI] [PubMed] [Google Scholar]
  25. Kaiser Family Foundation. (2025). Medicaid Enrolees by Sex. Retrieved 1/23/2025 from 〈https://www.kff.org/medicaid/state-indicator/medicaid-enrollees-by-sex 〉.
  26. Kartha A, Anthony D, Manasseh CS, Greenwald JL, Chetty VK, Burgess JF Jr, Culpepper L, & Jack BW (2007). Depression is a risk factor for rehospitalization in medical inpatients. Primary care Companion to the Journal of Clinical Psychiatry, 9(4), 256. [Google Scholar]
  27. Kentrou V, Livingston LA, Grove R, Hoekstra RA, & Begeer S (2024). Perceived misdiagnosis of psychiatric conditions in autistic adults. EClinicalMedicine, 71. [Google Scholar]
  28. Kerns CM, Rast JE, & Shattuck PT (2020). Prevalence and correlates of caregiver-reported mental health conditions in youth with autism spectrum disorder in the United States. J Clin Psychiatry, 82(1). 10.4088/JCP.20m13242 [DOI] [Google Scholar]
  29. Kerns CM, Roux AM, Connell JE, & Shattuck PT (2016). Adapting cognitive behavioral techniques to address anxiety and depression in cognitively able emerging adults on the autism spectrum. Cognitive and Behavioral Practice, 23(3), 329–340. 10.1016/j.cbpra.2016.06.002 [DOI] [Google Scholar]
  30. King BH, & Lord C (2011). Is schizophrenia on the autism spectrum? Brain Research, 1380, 34–41. [DOI] [PubMed] [Google Scholar]
  31. Kompella S, Vittori A, Kroin J, Kaushal S, Khan S, & Neuhut S (2022). Impact of antipsychotic use on readmission rates in children and adolescents with autism spectrum disorder and irritability. Cureus, 14(2). [Google Scholar]
  32. Krupski A, West II, Scharf DM, Hopfenbeck J, Andrus G, Joesch JM, & Snowden M (2016). Integrating primary care into community mental health centers: Impact on utilization and costs of health care. Psychiatric Services, 67(11), 1233–1239. [DOI] [PubMed] [Google Scholar]
  33. Lai M-C, Kassee C, Besney R, Bonato S, Hull L, Mandy W, Szatmari P, & Ameis SH (2019). Prevalence of co-occurring mental health diagnoses in the autism population: A systematic review and meta-analysis. The Lancet Psychiatry, 6(10), 819–829. [DOI] [PubMed] [Google Scholar]
  34. Lugo-Marin J, Magan-Maganto M, Rivero-Santana A, Cuellar-Pompa L, Alviani M, Jenaro-Rio C, Diez E, & Canal-Bedia R (2019). Prevalence of psychiatric disorders in adults with autism spectrum disorder: A systematic review and meta-analysis. Research in Autism Spectrum Disorders, 59, 22–33. [Google Scholar]
  35. Maddox BB, Crabbe S, Beidas RS, Brookman-Frazee L, Cannuscio CC, Miller JS, Nicolaidis C, & Mandell DS (2020). “I wouldn’t know where to start”: Perspectives from clinicians, agency leaders, and autistic adults on improving community mental health services for autistic adults. Autism, 24(4), 919–930. [DOI] [PMC free article] [PubMed] [Google Scholar]
  36. Maddox BB, & Gaus VL (2019). Community mental health services for autistic adults: Good news and bad news. Autism in Adulthood, 1(1), 15–19. [DOI] [PMC free article] [PubMed] [Google Scholar]
  37. McDermott KW, & Roemer M. (2021). Most Frequent Principal Diagnoses for Inpatient Stays in U.S. Hospitals, 2018. HCUP Statistical Brief #277. July 2021. Agency for Healthcare Research and Quality, Rockville, MD. 〈https://www.hcup-us.ahrq.gov/reports/statbriefs/sb277-TopReasons-Hospital-Stays-2018.pdf 〉. [Google Scholar]
  38. Mitchell P, Sheppard E, & Cassidy S (2021). Autism and the double empathy problem: Implications for development and mental health. British Journal of Developmental Psychology, 39(1), 1–18. [DOI] [PubMed] [Google Scholar]
  39. Navas C, Wells L, Bartels SA, & Walker M (2022). Patient and Provider Perspectives on Emergency Department Care Experiences among People with Mental Health Concerns. Healthcare, [Google Scholar]
  40. Pehlivanidis A, Papanikolaou K, Mantas V, Kalantzi E, Korobili K, Xenaki L-A, Vassiliou G, & Papageorgiou C (2020). Lifetime co-occurring psychiatric disorders in newly diagnosed adults with attention deficit hyperactivity disorder (ADHD) or/and autism spectrum disorder (ASD). BMC Psychiatry, 20, 1–12. [DOI] [PMC free article] [PubMed] [Google Scholar]
  41. Perlman CM, Hirdes JP, & Vigod S (2015). Psychiatric rehospitalization: development of a person-level indicator for care planning and quality assurance. The Primary care Companion for CNS Disorders, 17(4), 22833. [Google Scholar]
  42. Puntis S, Rugkåsa J, Forrest A, Mitchell A, & Burns T (2015). Associations between continuity of care and patient outcomes in mental health care: A systematic review. Psychiatric Services, 66(4), 354–363. [DOI] [PubMed] [Google Scholar]
  43. Rast J, Garfield T, Roux A, Anderson K, Miller KK, Hund L, Tao S, Kerns C, Rosenau K, Hotez E, Shattuck P, & Shea L (2021). National Autism Indicators Report: Mental Health. drexel.edu/autismoutcomes/mentalhealth. [Google Scholar]
  44. Rieke K, McGeary C, Schmid KK, & Watanabe-Galloway S (2016). Risk factors for inpatient psychiatric readmission: are there gender differences? Community Mental Health Journal, 52, 675–682. [DOI] [PubMed] [Google Scholar]
  45. Schott W, Tao S, & Shea L (2021). Co-occurring conditions and racial-ethnic disparities: Medicaid enrolled adults on the autism spectrum. Autism Research. [Google Scholar]
  46. Shaw JA, Stiliannoudakis S, Qaiser R, Layman E, Sima A, & Ali A (2020). Thirty-day hospital readmissions: A predictor of higher all-cause mortality for up to two years. Cureus, 12(7). [Google Scholar]
  47. Smith MW, Stocks C, & Santora PB (2015). Hospital readmission rates and emergency department visits for mental health and substance abuse conditions. Community Mental Health Journal, 51, 190–197. [DOI] [PubMed] [Google Scholar]
  48. Son J, Debono D, Leitner R, Lenroot R, & Johnson J (2019). Pass the parcel: Service provider views on bridging gaps for youth with dual diagnosis of intellectual disability and mental health disorders in regional areas. Journal of Paediatrics and Child Health, 55(6), 666–672. [DOI] [PubMed] [Google Scholar]
  49. Turcotte P, Mathew M, Shea LL, Brusilovskiy E, & Nonnemacher SL (2016). Service needs across the lifespan for individuals with autism. Journal of Autism and Developmental Disorders, 46(7), 2480–2489. [DOI] [PubMed] [Google Scholar]
  50. Wen H, Halbisen A, Johnston KJ, & Druss BG (2024). Rural and urban trends in mental health readmissions. JAMA Psychiatry, 81(8), 842–843. [DOI] [PMC free article] [PubMed] [Google Scholar]
  51. Whittle EL, Fisher KR, Reppermund S, Lenroot R, & Trollor J (2018). Barriers and enablers to accessing mental health services for people with intellectual disability: A scoping review. Journal of Mental Health Research in Intellectual Disabilities, 11(1), 69–102. [Google Scholar]
  52. Zerbo O, Massolo ML, Qian Y, & Croen LA (2015). A study of physician knowledge and experience with autism in adults in a large integrated healthcare system. Journal of Autism and developmental Disorders, 45(12), 4002–4014. [DOI] [PubMed] [Google Scholar]
  53. Zerbo O, Qian Y, Ray T, Sidney S, Rich S, Massolo M, & Croen LA (2019). Health care service utilization and cost among adults with autism spectrum disorders in a US integrated health care system. Autism in Adulthood, 1(1), 27–36. [DOI] [PMC free article] [PubMed] [Google Scholar]
  54. Zhao Y, Hoenig JM, Protacio A, Lim S, & Norman CC (2020). Identification of risk factors for early psychiatric rehospitalization. Psychiatry Research, 285, Article 112803. [Google Scholar]
  55. Zheng Z, Zheng P, & Zou X (2018). Association between schizophrenia and autism spectrum disorder: A systematic review and meta-analysis. Autism Research, 11 (8), 1110–1119. [DOI] [PubMed] [Google Scholar]
  56. Zhou H, Ngune I, Albrecht MA, & Della PR (2023). Risk factors associated with 30-day unplanned hospital readmission for patients with mental illness. International Journal of Mental Health Nursing, 32(1), 30–53. [DOI] [PubMed] [Google Scholar]

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