The treatment of chronic pain has consistently posed a significant challenge for medical providers for a variety of reasons, such as the subjective nature of the condition, the complexity of pain, the presence of undetermined or multifactorial etiologies, the frequent presence of comorbidities, and the limited treatment options available. In 2019, the National Health Interview Survey reported 20.5 % of adults in the US suffer from chronic pain (Zelaya et al., 2020), defined in some studies as pain that persists or recurs for more than three months (Treede et al., 2019). Although recent trends emphasize behavioral treatments as a first-line approach for managing chronic pain (Skelly et al., 2020), for a large portion of the past three decades, the primary treatment for chronic pain was long-term opioid therapy (LTOT) (defined as opioid analgesic treatment for ≥ 90 days; Von Korff et al., 2008). LTOT is associated with a significantly high risk of developing opioid misuse behaviors and may be, paradoxically, associated with increased sensitivity to pain stimuli (Compton et al., 2020). An estimated 21 % to 29 % of chronic pain patients on LTOT misuse their opioid medication (Vowles et al., 2015). The challenges of addressing chronic pain, combined with rising rates of opioid use disorder (OUD) and overdoses, create a substantial public health concern. Notably, drug overdose deaths in the US surged by 31 % from 2019 to 2020. Chronic pain can amplify susceptibility to additional substance misuse, heightening concerns about the interplay between opioid and alcohol consumption. Concomitant use of alcohol and opioid analgesics can further escalate the risks of opioid misuse, OUD, and overdose (Witkiewitz & Vowles, 2018).

The relationship between pain and alcohol use is complex. The acute analgesic effects of alcohol are notable, and due to negative reinforcement patterns, pain flares may drive alcohol consumption, insofar as some individuals resort to drinking to cope with pain. On the other hand, excessive drinking and alcohol use disorders can lead to deleterious pain-related outcomes, like intensified pain severity (Zale et al., 2019). Moreover, forms of psychological distress common to chronic pain, such as depression, anxiety, negative affect, and pain catastrophizing, exacerbate pain and promote alcohol and opioid use (Zale et al., 2019).

Recent studies have found that nearly 30 % of individuals experiencing chronic pain turn to alcohol to alleviate symptoms of pain which may further reinforce alcohol use and co-use with opioid pain medications (Brennan et al., 2005). From 2019 to 2020, the US experienced a 41 % increase in the number of opioid overdoses that involved alcohol as a contributing factor (White et al., 2022). Although research regarding OUD is abundant, little attention has been paid to alcohol co-use with opioids among chronic pain patients. Many studies of OUD exclude patients who report severe alcohol use disorder (AUD); the same is true for studies of AUD excluding patients with OUD. This trend of exclusion has been comprehensively discussed in a review by Witkiewitz & Vowles (2018). According to the SAMHSA Treatment Episode Dataset (SAMHSA, 2014), 65 % of patients admitted for primary opiate abuse excluding heroin from 2002 to 2012 reported simultaneous abuse of other substances. Of these, alcohol was the secondary substance of abuse for 20 % of these patients. Further, the prevalence of DSM-IV alcohol dependence or abuse is nearly-three times higher for individuals meeting DSM-IV opioid dependence or abuse criteria than for individuals who use opioids as directed by providers (Winkelman et al., 2018). Similarly, individuals with chronic pain who misuse their opioid medication are at an increased risk of developing AUD (Vowles et al., 2018). However, existing literature fails to elaborate on how alcohol use might exacerbate opioid misuse and OUD among people with chronic pain.

One particular variable that might explain the link between alcohol use and opioid misuse is craving, a risk factor thought to contribute to the development and maintenance of addiction (Schneekloth et al., 2012). Craving has been theorized to be a central component of the downward spiral leading from chronic pain to opioid misuse and addiction (Garland et al., 2013). Craving can be defined as the strong urge or desire to consume a psychoactive substance. Pain severity has been assumed to be predictive of a chronic pain patient's craving for their medication; however, previous research has revealed weak correlations between the two factors (MacLean et al., 2020, Martel et al., 2016). Alternatively, opioid craving among chronic pain patients might be driven by a tendency toward addictive use of opioids. In that regard, Wasan and colleagues (2009) found that approximately 45 % of chronic pain patients on LTOT reported experiencing some degree of craving for their opioid medication, which predicted higher propensities for opioid misuse behaviors at a 6-month follow-up, suggesting that craving could serve as an early indicator for potential opioid medication misuse. This notion has been supported by other studies (Garland & Howard, 2014). Further elucidating such findings, Frimerman et al. (2021) found that the hedonic and calming effects of opioids were associated with higher levels of opioid craving among chronic pain patients on LTOT.

Although the literature on craving among chronic pain patients on LTOT is growing, surprisingly little is known about the relationship between alcohol use and prescription opioid craving. Prior studies demonstrate that alcohol use can increase craving for other substances, such as cocaine and marijuana (Weiss, 2005, Yurasek et al., 2017). Yet, the extent to which alcohol consumption influences opioid craving among chronic pain patients remains unclear. A better understanding of this relationship may offer valuable insights to clinicians and patients alike, who must navigate the complexities of pain management and opioid use. In one of the few studies to examine this phenomenon, patients with severe chronic pain attending outpatient programs for alcohol use disorder and opioid misuse reported significantly higher levels of craving than their counterparts who did not report having severe chronic pain (Sheu et al., 2008). Alcohol use may increase opioid craving due to the neuropsychopharmacologic impact of alcohol on brain reward pathways driving addictive behavior (Koob & Volkow, 2010). In that regard, alcohol use has been found to prime dopaminergic and opioidergic brain circuitry in rats (Gonzales et al., 2004), which may enhance the rewarding effects of opioids and contribute to increased cravings. Evidence also suggests that alcohol use may sensitize the brain to the effects of opioids, making them more rewarding and increasing the risk of misuse (Koob, 1992). However, data to support the relationship between alcohol use and opioid craving in humans is limited. Here we conducted an observational study to test the hypothesis that chronic pain patients on LTOT who consume alcohol will have more intense cravings for their opioid pain medications than chronic pain patients who do not regularly consume alcohol.