Estimates indicate that up to 29% of persons misuse prescription pain relievers for chronic pain,[1] and between 8 to 12% develop a use disorder.[2, 3] The United States (US) Department of Health and Human Services declared the opioid crisis a public health emergency in 2017, although the first wave of the epidemic can be traced to the 1990s.[3] In 2016 alone, the record numbers of opioid misuse and overdose death provided a stark realization of how the epidemic has become a public health crisis.[2] For instance, opioid related deaths increased 345% between 2001 to 2016.[4] Subsequently, between July 2016 and September 2017 deaths due to illicit opioids overdose deaths increased by 30% leading to emergency declaration in 45 states.[4]
Projections revealed that if current prevention and intervention strategies do not change by 2025, the rate of misuse and overdose death will rise by 61%.[5] In response to the epidemic, multiple federal, state, and local agencies have implemented various strategies to address the opioid crisis. Current interventions such as increasing availability of naloxone are projected to result in approximately a 4% reduction in opioid-related deaths.[6] Similar interventions like reduced prescribing for pain patients and excess opioid management can increase life years and quality-adjusted life years, but overdose deaths would increase among those with opioid dependence due to a move from prescription opioids to heroin.[6] Overall, these strategies are found to have minimal impact preventing only 3.0% to 5.3% of overdose deaths.[5]
Studies by Chen and colleagues[5] and Pitt and colleagues[6] have further revealed that current universal interventions are not enough to address the multidimensional and dynamic aspects of the opioid epidemic. Improving universal opioid prevention strategies to more tailored approaches has been suggested.[7] Non-Hispanic whites, for instance, have become the primary focus for multiple prevention programs and strategies as they have been found to misuse opioid at greater rates.[8-10] However, multiple racial/ethnic groups have been found to be affected by opioid misuse and are at differential risk.[8-10] Other racial/ethnic groups found to experience high disparities in misuse and related outcomes include American Indian/Alaska Natives[8], Asians[11], and Hispanics.[12] As such, these epidemiological studies have revealed a possible racial/ethnic disparity.
Opioid misuse and/or use disorder are also linked to multiple risk factors not limited to race and ethnicity. Scholl et al.[9] revealed a complex relationship between sociodemographic factors and opioid misuse where age was a significant indicator, particularly among younger age groups. The current opioid misuse and/or use disorder literature has also found that the relationships of race/ethnicity and age are not strong predictors for misuse when considered in the context of other biopsychosocial factors. Other sociodemographic factors like sex/gender must be considered. For instance, Nicholson and Vincent [13] observed that the prevalence of prescription opioid misuse varied among Black women and men. Specifically, Black women with lower socioeconomic status had an increased the probability of misuse, while older age, higher educational attainment, and rural residence were associated with a lower probability.[13] Although men have been found to be more likely to misuse opioids at the population level, women in certain cases have been found to be at higher odds of misuse.[14-16] For example, Serdarevic, Striley, and Cottler [15] found women to have higher rates of lifetime prescription opioid use when compared to men.
Other biopsychosocial factors like criminality and sexual identity, although understudied, have been associated with misuse and/or use disorder. Individuals with criminality or involvement with the legal system had a prevalence of 22.4% for prescription opioid use, 33.2% for prescription opioid misuse, 51.7% for prescription opioid use disorder, and 76.8% for heroin use.[17] Similarly, Pierce et al. [18] found that, when adjusting for cocaine use, sex/gender, age, and birth cohort, individuals testing positive for opioid use had higher rates of criminality. Sexual minorities, such as those identifying as gay/lesbian or bisexual, have also been situationally reported to be at risk of opioid misuse. [19-21]. For instance, Duncan et al. [19] found that those identifying as bisexual or gay/lesbian were at 78% or 115% increased odds for opioid misuse than heterosexuals, respectively.
When considering opioid misuse and/or use disorder general health and health access have been found to have a role, although it is not clearly understood outside the context of physical pain or noninstitutionalized populations. Nicholson et al. [13] found that those who identified as being in poor health were more likely to misuse opioids. The relationship between opioid misuse and use disorder in the context of mental health is unclear. Epidemiological studies have not focused solely on the role of mental health indicators such as depression, anxiety, or suicidality. Opioid misuse and/or use disorder have been found to be associated with severe mental illness [22, 23] and suicidality [23-25]. Health insurance has also been identified as a having a role in opioid misuse, but the relationship is not well defined. Schatman [26] argues that health insurance companies may perpetuate suboptimal pain management that facilitates opioid misuse whereby health insurance may in turn facilitate opioid misuse. On the other hand, Wettstein [27] observed a dose-response relationship with access to insurance on opioid overdose deaths in which an increase of health insurance coverage among young adults reduced opioid related deaths.
The role of other substance dependence, abuse, and/or misuse, whether legal, illicit, or prescribed, has also been linked to opioid misuse and/or use disorder. Concurrent substance use such as nicotine and tobacco dependence [28, 29], alcohol [30], sedatives [31], methamphetamines [32], tranquilizers [33-35], other analgesics [36], and marijuana [37] have been positively associated with opioid misuse and use disorder [37, 38]. Marijuana may be context dependent as it has a mixed relationship with opioid use, misuse, and use disorder.[39] Medical cannabis use, specifically, has been suggested to reduce opioid use in general, and may also reduce opioid overdose deaths in states with medical cannabis laws.[39]
While epidemiologic studies have examined the relationship of various risk factors on opioid misuse and use disorder among non-institutionalized populations, comprehensive models are relatively absent. To ameliorate the effect of the opioid epidemic, we must identify the risk factors associated with the etiology of misuse to intervene and prevent the distal events of use disorder like overdose. Secondly, it is crucial to understand biopsychosocial characteristics in the presence of multiple sociodemographic factors and other substance dependence or abuse that underpin the risk profiles of misuse and use disorder at the population-level in order to stem overdose deaths. Biopsychosocial characteristics for our research purposes include socioecological (e.g., criminality) and health factors (e.g., self-reported general health; mental health, suicidality; access to health services). Therefore, to understand what factors are contributing to the increasing opioid epidemic, we comprehensively examined the relationship of opioid misuse and/or use disorder and biopsychosocial characteristics using four domains: (1) sociodemographic factors; (2) socioecological factors; (3) health factors; and (4) other substance dependence or abuse. We took this approach to determine the most salient risk factors for opioid misuse and/or use disorder in a representative, noninstitutionalized US adult sample.
We hypothesized that sociodemographic factors, while crucial to the comprehensive risk model, would not be critical predictors when included with socioecological and health factors, or other substance dependence or abuse. The purpose of this study was to add to a critical gap in the literature to improve population-level prevention strategies by identifying the most salient predictors of opioid misuse and/or use disorder.