Table 1.

Summary Measures

Number	Title	Authors	Year	Country	Sample (Size)	Control Group (Size)	Independent Variables	Dependent Variables	Study Design	Results
1.	Predictors of Emergency Room and Hospital Utilization Among Adults with Intellectual and Developmental Disabilities23	Blaskowitz, M. G.; Hernandez, B.; Scott, P. W.	2019	USA	Adults with intellectual and developmental disability n: 597	None	Age, gender, level of intellectual disability, chronic health problems, mental health diagnoses, polypharmacy, supported living arrangement, region	ER use for a medical/physical reason, hospitalization for a medical/physical reason, ER use for a behavioral/psychiatric reason, hospitalization for a behavioral/psychiatric reason	Prevalence study, secondary data: survey of medical charts	Predictors (environmental and individual risk factors) for ED use: institutionalized people are less likely to be admitted; people from deprived neighborhoods with a lack of care are less likely to visit the ED
2.	Rate and characteristics of urgent hospitalization in persons with profound intellectual disabilities compared with general population24	Amor-Salamanca, A.; Menchon, J. M.	2018	Spain	Adults with severe/ profound intellectual disability n: 28	Other hospitalized ED patients n: 83	Gender, age, living arrangement	Emergency visits, admission to hospital after emergency visit	Retrospective cohort study, secondary data: discharge reports	No differences in the proportion of people with profound intellectual disability and controls admitted to hospital after their emergency visit; the median hospital stay was higher for people with profound intellectual disability s: 7.5 vs 4 days for controls
3.	Factors associated with ambulatory care sensitive emergency department visits for South Carolina Medicaid members with intellectual disability25	McDermott, S.; Royer, J. A.; Mann, J. R.; Armour, B. S.	2018	USA	Individuals with intellectual disability identified from ICD-9 CM codes n: 14.650	Subgrouping: moderate-to-profound intellectual disability (37. 8%), mild intellectual disability (33.8%), unspecified intellectual disability (16.4%), Down syndrome/other genetic causes (11.9%)	age, race, sex, rurality of county, residential service setting, years of enrollment, supplemental nutrition assistance	Primary care visits, ED visits, and subsequent inpatient hospital admission, timing of services	Retrospective cohort study, secondary data: discharge dataset	ED overuse of intellectual disability subgroups due to conditions that are manageable in primary care; living in the community, comorbidity, and previous primary care were associated with more frequent ED visits
4.	Postpartum Hospital Utilization among Massachusetts Women with Intellectual and Developmental Disabilities: A Retrospective Cohort Study26	Mitra, M.; Parish, S. L.; Akobirshoev, I.; Rosenthal, E.; Moore Simas, T. A.	2018	USA	Women with intellectual and developmental disability identified from ICD-9 CM codes n: 1104	Women without intellectual and developmental disability n: 778,409	Woman who gave birth, maternal age, race/ethnicity, education, marital status, type of health insurance, adequacy of prenatal care, diseases	Postpartum hospital admissions, ED visits during three critical postpartum periods (1–42, 43–90, and 1–365 days), nondelivered hospitalizations, observational stays	Retrospective cohort study, secondary data: Massachusetts Pregnancy to Early Life Longitudinal Data System (PELL)	Women with intellectual and developmental disability had markedly higher rates of postpartum hospital admissions and ED visits after a childbirth
5.	Antenatal Hospitalization Among US Women with Intellectual and Developmental Disabilities: A Retrospective Cohort Study27	Mitra, M.; Parish, S. L.; Clements, K. M.; Zhang, J.; Moore Simas, T. A.	2018	USA	Women with intellectual and developmental disability identified from ICD-9 CM n: 498	Women without intellectual and developmental disability n: 1,531	Women who gave birth, maternal age, education, race/ethnicity, marital status, health insurance; father named on the birth certificate; adequacy of prenatal care utilization, smoking during pregnancy, diseases	Hospital utilization during pregnancy: ED visit, observational stays, and non-delivery hospital stays	Retrospective cohort study, secondary data: Massachusetts Pregnancy to Early Life Longitudinal Data System (PELL)	Higher likelihood of women with intellectual and developmental disability to visit ED or get hospitalized during pregnancy
6.	Postpartum Acute Care Utilization Among Women with Intellectual and Developmental Disabilities28	Brown, H. K.; Cobigo, V.; Lunsky, Y.; Vigod, S.	2017	Canada	Women with intellectual and developmental disability n: 3803	Women without intellectual and developmental disability n: 378,313	Women who gave birth, maternal age, parity, neighborhood income quintile, region of residence, preexisting diseases, diseases during pregnancy	Postpartum hospital admissions, ED visits	Retrospective cohort study, secondary data: Ontario (Canada) health and social services administrative data	Women with intellectual and developmental disability, compared to those without, had an increased risk for postpartum hospital admissions overall, for psychiatric reasons but not for medical reasons
7.	Emergency department and inpatient hospitalizations for young people with fragile X syndrome29	McDermott, S.; Hardin, J. W.; Royer, J. A.; Mann, J. R.; Tong, X.; Ozturk, O. D.; Ouyang, L.	2015	USA	Adolescents and young adults with fragile x syndrome, identified from ICD-9 CM n: 125 (fragile x syndrome)	Adolescents and young adults with intellectual disability, people with autism spectrum disorder identified from ICD-9 CM. people without disability n: 2,592 (autism spectrum disorder) 10,685 (intellectual disability)	Gender, age, and insurance coverage	Hospital encounters	Prevalence study, secondary data: state’s health and human services data, hospital discharge dataset	People with fragile x syndrome, autism spectrum disorder, or intellectual disability are more likely to have had hospital encounters
8.	Predictors of emergency department visits by persons with intellectual disability experiencing a psychiatric crisis30	Lunsky, Y.; Balogh, R.; Cairney, J.	2012	Canada	Adults with intellectual disability who visited ED in response to a crisis n: 96	Adults with intellectual disability who did not visit ED in response to a crisis n:480	Persons who visited the ED in response to the first crisis, people who did not visit the ED in response to the first crises	Predictors of ED use: level of disability, type of residence, crisis plan, family physician, history of involvement with the criminal justice system, and history of ED visits	Cohort study, primary data: staff assessment	Significant predictors of ED visits: level of disability, type of residence, crisis plan, family physician, history of involvement with the criminal justice system, and history of ED visits
9.	Quantifying emergency department admission rates for people with a learning disability31	Williamson, T.; Flowers, J.; Cooke, M.	2012	UK	Persons with learning disability identified from the ICD-10 n: 246	None	Age, sex	Hospital admission via ED	Prevalence study, secondary data: Admission data from Birmingham Heartlands Hospital	Admission rates of patients with learning disability
10.	Life events and emergency department visits in response to crisis in individuals with intellectual disabilities32	Lunsky, Y.; Elserafi, J.	2011	Canada	Adults with intellectual disability who visited ED in response to a crisis n: 96	Adults with intellectual disability who did not visit ED in response to a crisis n:480	Stressful life events	Hospital use	Cohort study, primary data: Informants provided data (Psychiatric Assessment for Adults with Developmental Disabilities Checklist)	Individuals experiencing life events in the past year were more likely to visit the ED in response to crisis than those who did not experience any life events
11.	The Impact of Medicaid Managed Care on Health Service Utilization Among Adults with Intellectual and Developmental Disabilities33	Yamaki, K.; Wing, C.; Mitchell, D.; Owen, R.; Heller, T.	2019	USA	People with intellectual and developmental disability from a region that reformed Medicaid n: 1,121	People with intellectual and developmental disability from a different region n:1,102	Transition from fee-for-service to Medicaid managed care	Utilization of ED and/or primary care physicians, inpatient hospitalization	Quasi-experiment, secondary data: state Medicaid agency, integrated care program	Medicaid managed care reduced avoidable ED visits (manageable conditions, mental conditions)
12.	Emergency Department Use: Common Presenting Issues and Continuity of Care for Individuals with and without Intellectual and Developmental Disabilities34	Durbin, A.; Balogh, R.; Lin, E.; Wilton, A. S.; Lunsky, Y.24	2018	Canada	Adults with intellectual and developmental disability n: 66,484	Adults without intellectual and developmental disability n: 2,760,670	Level of continuity of primary care	ED visits	Retrospective cohort study, secondary data: administrative health and social services data	Individuals with intellectual and developmental disability were more likely than individuals with no intellectual and developmental disability to visit the ED; for both groups, greater primary care continuity was associated with less ED use, but this relationship was more marked for adults with intellectual and developmental disability
13.	Use of health services in the last year of life and cause of death in people with intellectual disability: a retrospective matched cohort study35	Brameld, K.; Spilsbury, K.; Rosenwax, L.; Leonard, H.; Semmens, J.25	2018	Australia	Decedents with intellectual disability identified from ICD n: 591	Decedents without intellectual disability n: 29,713	Cause of death	ED visit, hospital admissions	Retrospective cohort study, secondary data: Data Linkage Branch, Western Australian Department of Health, Intellectual Disability Exploring Answers (IDEA) Database	People with intellectual disability had increased odds of presentation, admission, or death from conditions that have been defined as ambulatory care sensitive and are potentially preventable
14.	Pain underreporting associated with profound intellectual disability in emergency departments36	Amor-Salamanca, A.; Menchon, J. M.	2017	Spain	Persons with profound intellectual disability n: 100	Patients without profound intellectual disability n: 300	Age, gender	Reasons and diagnoses in ED, patients behaviour while travelling to the hospital, time spent waiting and being examined in the ED	Retrospective cohort study, secondary data: clinical report from the ED, primary data: interview conducted by the person who had accompanied the patient to the hospital	Somatic complaints were the main reason for ED attendance among persons with profound intellectual disability; a diagnosis implying physical pain was given less often to people with profound intellectual disability than to controls

Abbreviations: ED-Emergency Department, ER-Emergency Room, CD-International Classification of Disease.