Health Care Utilization Due to Substance Abuse Among Homeless and Nonhomeless Children and Young Adults in New York

We identified a total of 68,867 cases in which individuals visited the ED or were hospitalized for substance abuse in New York between 2013 and 2014. Among those, 749 cases involved individuals who were homeless, and 68,118 involved individuals who were nonhomeless. Nearly 25% of these cases were opioid related, and more than 50% were alcohol related.

Compared with nonhomeless patients, homeless patients were less likely to be discharged from the ED (p<0.01) (Table 1). Health care utilization by homeless patients was more likely to be opioid related and less likely to be alcohol related, compared with health care utilization by nonhomeless patients (p<0.01). Compared with nonhomeless patients, homeless patients were significantly older; less likely to be White; more likely to be male; more likely to list public insurance; and less likely to list self-pay (all p<0.01).

Homeless patients had substantially higher rates of ED visits and hospitalizations related to substance abuse (11.48/1,000), compared with nonhomeless youths (5.43/1,000). (Table 2). This difference was primarily driven by greater hospitalization rates among homeless youths ages 18 to 24 (64.48/1,000) versus nonhomeless youths (3.04/1,000). Stratified analyses for opioid-related health care utilization indicated that non–opioid-related hospitalization among patients ages 18 to 24 was more prominent with homeless youths (31.32/1,000) than nonhomeless youths (1.07/1,000).

Of all health care utilization related to substance abuse, opioid- and alcohol-related health care utilization were the most common (Table 3). Among patients ages 10 to 14 in both populations, alcohol was the primary substance involved in health care utilization. Opioid use increased with age among all youths, although alcohol remained the most common substance driving health care utilization among nonhomeless youths in the oldest age group. Stratified analyses by hospital setting showed that opioid use among homeless youths and alcohol use among nonhomeless youths were the most common substance-related drivers to ED visits, whereas opioid use drove the most substance-related hospitalizations for both homeless and nonhomeless youths.

Adjusting for age, race-ethnicity, insurance type, and discharge against medical advice with year fixed effect and a hospital or ED random effect, regression results showed that, compared with nonhomeless youths, homeless youths had significantly higher costs for ED visits or hospitalizations (cost estimate=3.47) and longer LOS (incidence rate ratio=4.02) (Table 4). Homeless patients were significantly more likely than nonhomeless patients to be admitted to the ICU during hospitalization (odds ratio [OR]=4.75) and more likely to be readmitted to the hospital or to revisit the ED (OR=1.41).

Because the sample size was reduced in the stratified sensitivity analyses, one model that included only patients with opioid-related health care utilization did not detect significant differences in ICU utilization between homeless and nonhomeless patients. However, the direction of the point estimate did not change. This indicated a higher likelihood of ICU utilization among homeless patients compared with nonhomeless patients, regardless of opioid use (see table in online supplement). Results of analyses including only patients ages <18 mirrored the original analyses (see table in online supplement).

Using the SID and SEDD from New York, this study demonstrated different characteristics of health care utilization, represented by hospitalizations and ED visits related to substance abuse among homeless and nonhomeless youths. We found that the rate of ED visits related to substance abuse was almost two times higher among homeless youths, compared with nonhomeless youths, and the hospitalization rate related to substance abuse was more than 10 times higher. This difference was mainly driven by a greater rate of non–opioid-related hospitalizations among homeless youths, especially among those ages 18 to 24.

Health care utilization could be used as a proxy for population well-being. For example, it could represent heavy substance abuse, because heavy use is more likely than casual use to result in health care utilization. However, differences in heavy use between homeless and nonhomeless youths could be greater in magnitude than the differences observed in this study because of disparities in access to care. Homeless youths face obstacles to receiving medical care, including a shortage of medical services in poor communities (29), lack of transportation, and social isolation. Our study showed that only 8.3% of homeless patients were directly discharged from the ED, whereas 81.4% of nonhomeless patients were directly discharged from the ED. Additionally, compared with nonhomeless youths, homeless youths had significantly higher ICU utilization, indicating that they did not utilize health care until their condition became severe.

Our models detected higher health care utilization cost and longer LOS among homeless youths, compared with nonhomeless youths. Health care cost and LOS are typically used as a proxy for severity. Specifically, if the condition is severe, the patient will require additional treatment, which will result in high costs and a long LOS. However, studies of patients experiencing homelessness have reported a pattern of a longer average LOS possibly not related to the severity of their condition, compared with their housed counterparts (30, 31). Some doctors may refrain from discharging a patient until a shelter or other more stable form of housing is arranged (30, 31). Therefore, our finding that homelessness was associated with higher costs and longer LOS does not necessarily mean that homeless youths experienced more severe medical conditions than nonhomeless patients, but their greater utilization of the ICU suggests that homeless patients did not utilize health care until their condition became severe (32). Detailed observations are needed to clarify whether homeless youths receive medical care for substance abuse when needed.

We demonstrated that, compared with nonhomeless patients, homeless patients were more likely to revisit the ED or be readmitted to the hospital. Several studies have cited high readmission rates and longer LOS among homeless individuals, compared with nonhomeless individuals (30, 33). Both factors are largely affected by care transitions. If the individual does not have a suitable place to recover after discharge, the physician may be incentivized to keep the individual in the hospital until coordination with a shelter or other care has been established (30). If the recovering patient is released to the streets or unstable housing, the patient’s condition will likely worsen, and he or she will likely return to the ED or hospital within 30 days of discharge (30, 33). Previous studies have reported high substance abuse rates among homeless youths, compared with nonhomeless youths (7–10), and developing programs to reduce substance abuse among homeless youths is particularly important. ED visits and admissions could be a good opportunity to provide prevention and education programs to these young homeless patients who would otherwise be difficult to identify and contact. Ensuring that these programs are available during their first visit to the hospital for substance abuse may help reduce the revisit and readmission rate as well as the mortality rate.

The opioid-related health care utilization rate among homeless patients ages 18 to 24 was much higher than the rate among their nonhomeless counterparts. Specifically, the opioid-related hospitalization rate among homeless patients was almost 17 times higher than the rate among nonhomeless patients in this age group. This result is consistent with previous studies for adults ages 18 and older (34–36). The magnitude of difference in the hospitalization rate was even greater for non–opioid-related hospitalizations. Alcohol accounted for the largest percentage of non–opioid-related ED visits and hospitalizations related to substance abuse, necessitating immediate prevention measures and education related to alcohol abuse among homeless youths.

Several limitations should be acknowledged. First, although 20% of homeless youths in the United States reside in New York, the results may not be generalizable to other parts of the country. New York provides various means of support to its homeless citizens, with 96.8% of those in our study utilizing public or private insurance—a likely result of the transition, beginning in 2012, into Medicaid managed care (37) by the state’s Office of Insurance Programs. Because New York law requires shelter for all who request it, 99% of youths ages 0–24 in New York were sheltered in 2013, contrasted with only 79% nationally (17, 38). Although we included only a single state in our analyses, our findings are novel because health care utilization due to substance abuse among homeless youths has not previously been reliably assessed.

Second, this study is a serial cross-sectional analysis of an administrative database, and causality between health care utilization related to substance abuse and housing instability is difficult to establish. Additionally, the database lacks clinical detail beyond ICD-9-CM codes, and only patients who visited the ED or were hospitalized were included in the study. The 2013 National Survey on Drug Use and Health reported that only 10.9% of individuals ages 12 and older, including adults, who needed treatment for illicit drug or alcohol abuse received treatment (39). As a result, rates of ED visits and hospitalizations from this study could, therefore, be underestimated when used as a proxy for needed substance abuse care. Rates of ED visits and hospitalizations related to substance abuse from this study may also be biased because of the quality of coding. However, a previous study found that ICD-9-CM coding accuracy for opioid overdose was high (40). We used the primary diagnosis code to identify the primary reason for health service utilization, as previously practiced. Song (41) argued that the primary diagnosis code reflects the physician’s professional opinion as to the primary cause of admission. We believe our method identified health service utilization related to substance abuse as the primary condition; however, it is still possible that substance abuse was secondary to another condition.

Third, the quality of coding for homelessness is unknown. For example, some patients or medical staff may report a shelter zip code as the zip code of residence, some patients may choose not to disclose their living status for fear of being stigmatized, and some health care facilities do not code homeless status (42). Health care staff familiar with patients who frequently utilize services, especially those with behavioral conditions such as substance abuse, may be more likely to accurately list housing insecurity as a result of recurrent interactions with such patients. Therefore, our results indicating that those experiencing homelessness were more likely to revisit health care facilities could be a result of reverse causation (i.e., individuals who were more likely to revisit health care facilities were more likely to be coded as homeless).

Fourth, estimates of the homeless population based on point-in-time counts of sheltered and unsheltered persons are likely to be conservative because of the transient nature of homelessness. Nonsheltered youths may be a particularly undercounted population, because they may be out of sight during the counts (43). In 2014, children and youths represented less than 1% of New York’s total counted unsheltered homeless population (15). Given that most homeless children and youths in New York are sheltered, they are less likely than other homeless groups to be undercounted. Despite the biases discussed, these counts are the best estimates available. Each city’s homeless coalition provides HUD with local counts to ensure properly allocated federal funding for programs and services aimed at assisting those experiencing homelessness (44).

Fifth, all primary analyses were conducted at the level of the ED visit or the hospital admission, with each visit or admission included as a unique observation. The personal identifiers provided in the HCUP databases allow only for tracking of patient revisits and readmissions within a given data year. Because of this limitation, we were unable to conduct analyses at the patient level, and patients who were discharged and subsequently revisited or were readmitted may have been double-counted.

Sixth, ED and hospitalization rates for those ages 0–9 most likely are not representative of substance abuse by infants or children. It is more likely that substances were passed through breast milk or accidentally ingested (45, 46).

Last, number of deaths due to opioid overdose increased steadily in 2013 (47). Our study period reflected only 2 years after the onset of this particular wave of the opioid epidemic. Further evaluation with additional years of data is needed.

This study demonstrated that, compared with nonhomeless youths, homeless youths experienced much higher rates of health care utilization related to substance abuse. Higher ICU utilization among homeless youths versus nonhomeless youths indicated that homeless youths did not utilize services until their condition had become severe. Detailed observation is needed to clarify whether homeless youths receive high-quality care for substance abuse when necessary.