摘要：Objectives. We examined factors associated with frequent hospitalizations and emergency department (ED) visits among Medicaid members who were homeless. Methods. We included 6494 Massachusetts Medicaid members who received services from a health care for the homeless program in 2010. We used negative binomial regression to examine variables associated with frequent utilization. Results. Approximately one third of the study population had at least 1 hospitalization and two thirds had 1 or more ED visits. More than 70% of hospitalizations and ED visits were incurred by only 12% and 21% of these members, respectively. Homeless individuals with co-occurring mental illness and substance use disorders were at greatest risk for frequent hospitalizations and ED visits (e.g., incidence rate ratios [IRRs] = 2.9–13.8 for hospitalizations). Individuals living on the streets also had significantly higher utilization (IRR = 1.5). Conclusions. Despite having insurance coverage, homeless Medicaid members experienced frequent hospitalizations and ED visits. States could consider provisions under the Patient Protection and Affordable Care Act (e.g., Medicaid expansion and Health Homes) jointly with housing programs to meet the needs of homeless individuals, which may improve the quality and cost effectiveness of care. Homeless individuals experience very high rates of behavioral health disorders, chronic and acute physical conditions, and injuries related to assaults and accidents. 1–4 However, they face multiple competing demands in their daily life, such as food and shelter, and therefore sometimes cannot prioritize medical care. 5 In addition, many of them are uninsured or do not have a usual source of care, which often leads them to rely on emergency departments (EDs) as a source of routine medical care. Furthermore, when unmanaged symptoms trigger urgent events or injuries occur, homeless individuals may seek care in EDs, and they may be hospitalized. Consequently, homeless individuals experience frequent hospitalizations and ED visits. 3,4,6–9 Studies have reported that a quarter to one third of homeless people are hospitalized during a year, which is 4 times higher than the US average. 3,4 Also, one third to two thirds of homeless people have at least 1 ED visit, which is much higher than the national average of one fifth of the general population. 3,4,6,10 Furthermore, hospitalizations and ED visits account for approximately half of medical expenditures for insured homeless individuals. 4 Having a clear understanding of risk factors for frequent hospitalizations and ED visits among homeless individuals is crucial as many states expand Medicaid coverage under the Patient Protection and Affordable Care Act. 11 Individuals struggling with homelessness are more likely to be eligible to enroll because of their low income and lack of insurance. Medicaid programs could face significant challenges in managing homeless individuals’ complex needs and high health care utilization. Insurance coverage enables homeless people to access primary care, which might be expected to lower nonurgent visits to EDs or hospitalizations for preventable conditions. However, recent studies based on claims data have shown that insured homeless people in the United States and Canada still experience very high rates of hospitalization and ED visits. 4,7–9 In addition, survey-based studies have indicated that homeless people with insurance are more likely to be hospitalized than those without insurance, although the evidence regarding ED visits is mixed. 3,6,12 Studies of health care utilization among homeless people in the United States have not provided comprehensive information about what happens when they are insured, in particular, what factors are associated with frequent hospitalizations and ED visits. 3,6,12,13 Also, studies that rely on self-reported data or survey data are subject to recall bias, and those using records from a single clinic have less complete data than insurance claims. Although a Canadian study of insured homeless people has shown that several enabling and need factors (e.g., perceived unmet mental health needs, individual’s health being controlled by powerful others, and health status) are associated with hospitalizations and ED visits, these data are neither routinely collected nor readily available in existing databases. 8,9 Also, these results might not be fully applicable to homeless people in the United States because of differences in health care delivery and financing between the 2 countries. We analyzed Massachusetts Medicaid claims data for a large sample of homeless individuals with Medicaid coverage to enhance our understanding of factors associated with frequent hospitalizations and ED visits in the United States. Early Medicaid expansion in Massachusetts, beginning in the 1990s, provided health insurance coverage for a large number of individuals experiencing homelessness. A health insurance mandate implemented in 2006 further reduced the number of uninsured homeless people. Therefore, Massachusetts serves as a unique environment to better understand reasons for hospitalizations and ED visits and factors associated with frequent utilization for insured homeless people. These findings can be useful to states in developing care management strategies or other specialized interventions for this vulnerable population.
