| Summary: | Opioid morbidity and mortality and suicide are two current and central public health problems in the U.S. Both have continuously increased in the last two decades, and disproportionately affected some groups more than others, leading to the suggestion that these epidemics are connected. However, there is little evidence on the potential role that the opioid epidemic had on the rise of suicides. The overarching goal of this dissertation was to advance our understanding of the effects of the opioid epidemic on the rise in suicide rates in the U.S. First, a systematic review of the literature was conducted to critically evaluate the evidence on the effects of different opioid exposures on suicidal outcomes (e.g., suicidal ideation, attempts and suicides). There was ample evidence of individual-level associations between opioid use and related abuse/ dependence on suicidal outcomes. In contrast, the gap in the literature on group-level effects was clear, with only two studies examining these effects and showing that opioid availability was associated with suicide behavior in different populations. Several limitations were also identified in the reviewed studies that could partially explain the observed associations, indicating the need for further research. Second, the individual-level effects of prescription opioids nonmedical use and related abuse/ dependence on persistence and onset of suicidal ideation and attempts were examined. Longitudinal data from a national representative sample of the adult U.S. population was used to examine these associations. Results showed that heavy/ frequent use of prescription opioids and related abuse/ dependence had an effect on persistence and onset of suicidal ideation and persistence of attempts. However, none of these exposures were associated with onset of suicide attempt. Overall, these findings suggest that by increasing the number of those using prescription opioids and with opioid abuse/ dependence, and in turn the number of those with suicidal ideation/ behavior, the prescription opioid epidemic could have led to increases in suicide rates in the population. Finally, the group-level (i.e., state level) effects of three state level exposures, i.e., increasing trends in the per capita volume of prescription opioids, in the nonmedical use of these drugs, and in unintentional fatal opioid overdoses, on the increase in suicide rates were examined. For this, pooled cross sectional time series data from the 50 states (1999-2016) were used in linear regression models with state and year fixed effects. Although the volume of prescription opioids and the rate of fatal opioid overdoses increased over the study period, the prevalence of nonmedical use of prescription opioids decreased in most states. Results showed that the rate of unintentional fatal prescription opioid overdoses was associated with an increase in the rate of suicides. The range of effects sizes compatible with the data also suggested that the increase in the per capita volume of prescription opioids was linked to increases in suicide rates. Overall, this dissertation increased our understanding of the possible role that the opioid epidemic played on the increase in suicide rates in the U.S. As public efforts continue to fight the opioid epidemic, these findings can help inform future research that will guide the development of suicide prevention strategies and approaches to reduce the burden that the opioid epidemic poses on communities.
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