Drug overdose was the leading cause of death in this cohort of currently and formerly homeless adults, occurring at substantially higher rates than in the Massachusetts general population. Despite comprising only 0.3% of the state's adult population, the study cohort accounted for 5% of all drug overdose deaths among Massachusetts adults in 2003–08. Opioids contributed to over 80% of these deaths. Cancer and heart disease were the leading causes of death among adults 45 years and older. In comparison to the general population, the greatest disparities in all-cause mortality occurred in the younger age groups.
There was no significant difference between the all-cause mortality rate in 2003–08 as compared to 1988–93. A 15% reduction in deaths due to natural causes was offset by an 83% increase in deaths due to external causes. Although HIV-related deaths decreased considerably, we found a 3-fold increase in drug overdose deaths and 2-fold increases in deaths due to suicide and psychoactive substance use disorders.
Similar to prior studies,6, 12, 18
we found significantly higher mortality rates among white homeless adults in comparison to other racial groups, which differs from the pattern in the general population. This may reflect underlying racial differences in the pathways to homelessness. Evidence suggests that African-Americans are more likely to be homeless because of structural factors such as discrimination and poverty, while homelessness among whites is more heavily linked to personal factors such as mental illness, trauma, family dysfunction, and substance abuse,34–36
placing these individuals at higher risk of death. This is supported by the finding that whites accounted for a particularly disproportionate percentage of deaths due to drug overdose (68%), substance use disorders (68%), and suicide (89%).
Our findings have implications for policymakers, public health professionals, and clinicians serving this population. The overall mortality pattern of homeless adults in this study demonstrates the substantial impact of substance abuse and mental illness, highlighting the need for integrated systems of care to address these complex issues. Interval increases in deaths due to drug overdose, psychoactive substance use disorders, and suicide suggest that chemical dependency counselors, psychiatrists, and other behavioral health specialists should be collocated with primary care practitioners serving this population. The dramatic rise in drug overdose deaths reflects a broader nationwide trend in drug poisoning mortality fueled largely by rising opioid-related deaths.37–39
Such deaths are fundamentally preventable. The bulk of opioid overdoses were due to non-heroin substances, including opioid analgesics and other narcotics. Given the high prevalence of both chronic pain and addiction in homeless persons,40
health care organizations serving this population may wish to develop standardized pain management protocols to help ensure safe, effective, and appropriate opioid prescribing. Efforts to curb prescription drug diversion should remain a national policy priority. Public health initiatives aiming to prevent and reverse opioid overdoses through education and the distribution of intranasal naloxone may also help reduce these deaths.41, 42
In addition to methadone maintenance programs, office-based buprenorphine treatment appears to be feasible in the setting of homelessness43
and may be an effective option for addressing opioid dependence in this population.
The impact of alcohol and tobacco use is also apparent. Alcohol was the principal substance implicated in 72% of deaths due to psychoactive substance use disorders and was a co-occurring substance in one-third of drug overdose deaths. The preponderance of deaths due to heart disease and cancer, particularly neoplasms of the trachea, bronchus, and lung, suggests a pressing need to address the 73% prevalence of cigarette smoking among homeless adults.44
The heavy burden of such deaths among the growing subset of individuals 45 years and older reinforces the need for primary care and preventive services that target the health issues of an aging homeless population.45
Between 1988 and 2008, BHCHP substantially expanded the scope of its clinical services in greater Boston.20
While causality cannot be determined, this expansion may partially explain the interim reduction in natural causes of death that may be more amenable to medical interventions than external causes. However, the lack of change in all-cause mortality is consistent with the fact that multiple factors other than health care influence population health.46
Addressing the substantial mortality disparities in homeless populations will require not only clinical innovation and tailored health care services, but also creative public health programming combined with policy initiatives to address homelessness and other social determinants of health.
We studied adults who used Health Care for the Homeless clinical services in Boston. Our findings may not be generalizable to homeless individuals who avoid such services or to homeless adults in other cities. Our study included both currently and formerly homeless adults, which likely exerts a conservative bias on our findings since individuals who have exited homelessness may have lower mortality rates.18
Finally, the accuracy of death certificates in identifying cause of death has been debated.47
Death certificates have poor sensitivity but high specificity for identifying drug poisoning deaths,48
implying a low likelihood for “false positive” drug overdose deaths in our study. Death certificates also appear relatively accurate in identifying cancer deaths,49, 50
the second most common cause of death in this study. Furthermore, decedents in this study underwent autopsy at a 6-fold higher rate than decedents in the Massachusetts general population, providing some reassurance that the cause of death information is not less accurate, and may be more accurate, than for non-homeless individuals.
Drug overdose has replaced HIV as the emerging epidemic among homeless adults. While mortality rates due to certain causes have decreased in comparison to 15 years prior, we found substantial increases in addiction-related and mental health-related mortality rates among homeless adults, resulting in no overall change in mortality despite a major expansion in clinical services for this population. Findings suggest the need to integrate psychiatric and substance abuse services into primary medical care and to expand public health efforts to curb the growing problem of opioid-related deaths. The mortality disparity between homeless individuals and the general population, particularly among those who are youngest, underscores the need to address the social determinants of health through policy initiatives to eradicate homelessness.