Deaths of profound despair: A retrospective cohort study of mortality among people experiencing homelessness.

INTRODUCTION: The number of people dying while unhoused is increasing nationally. In Santa Clara County (SCC), deaths of unhoused people have almost tripled in 9 years. This is a retrospective cohort study examining mortality trends among unhoused people in SCC. The objective of the study is to characterize mortality outcomes in the unhoused population, and compare these to the SCC general population. MATERIALS AND METHODS: We obtained data from the SCC Medical Examiner-Coroner's Office on unhoused people's deaths that occurred between 2011-2019. We analyzed demographic trends and cause of death, compared to mortality data on the SCC general population obtained from CDC databases. We also compared rates of deaths of despair. RESULTS: There were a total of 974 unhoused deaths in the SCC cohort. The unadjusted mortality rate among unhoused people is higher than the general population, and unhoused mortality has increased over time. The standardized mortality ratio for unhoused people is 3.8, compared to the general population in SCC. The most frequent age of death among unhoused people was between 55-64 years old (31.3%), followed by 45-54 (27.5%), compared to 85+ in the general population (38.3%). Over ninety percent of deaths in the general population were due to illness. In contrast, 38.2% of unhoused deaths were due to substance use, 32.0% illness, 19.0% injury, 4.2% homicide, and 4.1% suicide. The proportion of deaths of despair was 9-fold higher in the unhoused cohort compared to the housed cohort. DISCUSSION: Homelessness has profound impacts on health, as people who are unhoused are dying 20 years younger, with higher rates of injurious, treatable, and preventable causes, than people in the general population. System-level, inter-agency interventions are needed. Local governments need to systematically collect housing status at death to monitor mortality patterns among unhoused people, and adapt public health systems to prevent rising unhoused deaths.

Identity of Low-Molecular-Weight Species Formed in End-To-End Cyclization Reactions Performed in THF.

Cyclic polymers were produced by end-to-end coupling of telechelic linear polymers under dilute conditions in THF, using intramolecular atom transfer radical coupling or click chemistry. In addition to the expected shift to longer elution times on gel permeation chromatography (GPC) indicative of the formation of cyclic product, lower molecular weight species were consistently observed upon analysis of the unpurified cyclization reaction mixture. By systematically removing or altering single reaction components in the highly dilute cyclization reaction, it was found that THF itself was responsible for the low-molecular-weight material, forming oligomeric chains of poly(THF) regardless of the other reaction components. When the reactions were performed at higher concentrations and for shorter time intervals, conducive to intermolecular chain-end-joining reactions, the low-molecular-weight peaks were absent. Isolation of the material and analysis by ¹H NMR confirmed that poly(THF) was being formed in the highly dilute conditions required for cyclization by end-to-end coupling. When a series of mock cyclization reactions were performed with molar ratios of the reactants held constant, but concentrations changed, it was found that lower concentrations of reactants led to higher amounts of poly(THF) side product.