In this national study of heart failure hospitalizations in the United States from 2008–2018, we found that both OUD and CUD more than tripled in prevalence. Significantly, the racial distributions of HF with and without CUD and OUD co-diagnoses differed, with a relative over-representation of Black race in the OUD and CUD populations compared to the HF population without co-diagnosis of OUD and CUD. Hospitalizations with OUD and CUD co-diagnoses also were more likely to be from the lowest income quartile and had higher rates of obesity, OSA, and depression. In HF hospitalizations, both CUD and OUD were associated with increased costs of hospitalization, and OUD admissions were nearly 20% more expensive.

We found that among HF hospitalizations, OUD prevalence has increased by a 5-fold while CUD has more than doubled. The current literature on HF patients with OUD is mixed. Some studies have found higher readmissions and hospitalization rates with OUD, while others have found no effects [4, 10]. Meanwhile, studies have described CUD as an independent predictor for the development of HF [11]. Additionally, it has also been theorized that due to marijuana’s effect of increasing plasma volume, it could increase the likelihood of HF exacerbation and a result hospitalization [12]. Given the increasing prevalence of substance abuse and an increase in cannabis legalization, it is important for future projects to investigate these outcomes on a national scale.

In addition to the possibility of more frequent admissions for these patients over time, we found that HF with co-diagnosis of CUD or OUD was associated with higher costs as compared to admissions without them. Over the last decades, the financial burden of HF on the healthcare system has increased dramatically [13]. To our knowledge there is no national study of the costs implications for co-diagnosis of OUD or CUD and HF. OUD HF admissions in particular incurred hospital costs of more than 19% greater than those without OUD.

We found that historically disenfranchised populations, particularly Black and lowest income quartile patients are over-represented in HF hospitalizations with OUD/CUD co-diagnosis relative to the hospitalizations without these co-diagnoses. A previous retrospective study at a single west coast hospital, found that patients with heart failure and substance abuse co-diagnosis were younger, more likely to be male, to be black, and to lack medical insurance [4]. They also found that these patient’s had higher proportions of ischemic heart disease, cerebrovascular accidents, and endocarditis than patients without substance abuse. These differences were largely attributed to socioeconomic barriers to care.

However, there may also be toxicologic mechanisms relevant to heart failure and the readmission in these patients. Cannabis use is an independent risk predictor of heart failure [11]. Mechanistically, this could be in part due to cannabinoid agonisms of the CB-1 receptor which has been shown to have several affects in humans including decreased myocardial contractility, endothelial dysfunction, tissue injury fibrosis and cell death [14, 15].

While methadone has a well characterized side effect of prolonged QT interval, the other opioids may not have as direct cardiotoxicity [16]. However the combination of CHF and opioid use is associated with increased likelihood of cardiovascular events [17]. CHF is highly associated with central and obstructive sleep apnea and CHF patients have weakened respiratory mechanics [18, 19]. The central respiratory depressing effect of opioids may explain increased morbidity with co-diagnosis of CHF and OUD [20].

Prior studies found that lower socioeconomic status populations were more likely to suffer from opioid overdose events [21] and that recent increases in cannabis use have been especially pronounced in Black and lower income communities [22]. CUD and OUD HF admissions also have significantly higher proportions of Medicaid payments and patients from the lowest income quartile. We recommend future studies with more granular, longitudinal follow up data to investigate HF outcomes in these populations. These investigations may be able to better elucidate compounding deleterious affects of HF with CUD and OUD.