Variation in emergency department visit rates for opioid use disorder: Implications for quality improvement initiatives

Characteristics and co-morbidities associated with hospital discharges for opioid and methamphetamine co-use, United States 2016-2019

Introduction

The US overdose crisis is increasingly characterized by opioid and methamphetamine co-use. Hospitalization is an important opportunity to engage patients in substance use treatment. Understanding characteristics of co-use-related hospital stays can inform the development of services to better support this growing patient population.

Methods

We used 2016-2019 National Inpatient Sample data to conduct a cross sectional analysis of hospitalizations involving use of opioids, methamphetamine, or both. We used bivariate analysis to compare patient demographics. We then used multinomial logistic regressions to compare the proportion of hospital stays which indicated co-morbid diagnosis. To account for correlated data, we used generalized linear models to compare outcomes in hospital mortality, patient-directed discharge, and length of stay.

Results

Co-use-related stays had a higher proportion of co-morbid mental health (60.7%; 95% CI: 59.9-61.4%) and infectious diseases (41.5%; 95% CI: 40.8-42.2%), than opioid- or methamphetamine-related stays. Co-use-related stays increased between 2016 and 2019 and were associated with a higher proportion of patient directed discharge (10.7%; 95% CI: 10.4-11.0%) and longer length of stay (6.3 days; 95% CI: 6.2-6.4 days) compared to opioid (8.1%; 95% CI: 7.9-8.3% and 5.8 days; 95% CI: 5.8-5.9 days) and methamphetamine-related stays (6.5%; 95% CI: 6.3-6.6% and 5.5 days; 95% CI: 5.4-5.5 days).

Conclusion

Patients discharged with co-use differ from patients with opioid or methamphetamine use alone, representing a range of challenges and opportunities. In addition to offering treatment for both substance use disorders, hospital-based services that address co-occurring conditions may better support patients with co-use through targeted and tailored approaches.

Genetic Variants Associated with Opioid Use Disorder

Genetics are presumed to contribute 30-40% to opioid use disorder (OUD), allowing for the possibility that genetic markers could be used to identify personal risk for developing OUD. We aimed to test the potential association among 180 candidate single nucleotide polymorphisms (SNPs), 120 of which were related to the dopamine reward pathway and 60 related to pharmacokinetics. Participants were randomly recruited in 2020-2021 in a cross-sectional genetic association study. Self-reported health history including Diagnostic and Statistical Manual of Mental Disorders (DSM-5) OUD criteria and buccal swabs were collected. A total of 1,301 participants were included in the analyses for this study. Of included participants, 250 met the DSM-5 criteria for ever having OUD. Logistic regression, adjusting for age and biologic sex, was used to characterize the association between each SNP and DSM-5 criteria consistent with OUD. Six SNPs found in 4 genes were associated with OUD: increased odds with CYP3A5 (rs15524 and rs776746) and DRD3 (rs324029 and rs2654754), and decreased odds with CYP3A4 (rs2740574) and CYP1A2 (rs2069514). Homozygotic CYP3A5 (rs15524 and rs776746) had the highest adjusted odds ratio of 2.812 (95% confidence interval (CI) 1.737, 4.798) and 2.495 (95% CI 1.670, 3.835), respectively. Variants within the dopamine reward and opioid metabolism pathways have significant positive (DRD3 and CYP3A5) and negative (CYP3A4 and CYP1A2) associations with OUD. Identification of these variants provides promising possibilities for genetic prognostic and therapeutic targets for future investigation.