Healthcare utilization among adults with co-occurring substance use and mental health disorders (2018-2023): A study based on All of Us program

Co-occurring substance use and mental health disorders (COD) represent a growing public health concern, yet healthcare utilization studies with a large sample size remain limited. This study examined healthcare utilization patterns and sociodemographic correlates among COD adults using data from the All of Us Research Program (2018-2023).

Electronic health record data were analyzed for adults aged ≥18 years with confirmed diagnoses of substance use and mental health disorders recorded on at least two occasions. Healthcare services were identified using the standardized Current Procedural Terminology and Healthcare Common Procedure Coding System codes and categorized into counseling and therapy, medication/somatic services, online or telehealth care, and other supportive modalities. Multivariable logistic regression was employed to assess sociodemographic and structural correlates of healthcare utilization.

Among 19,423 adults with COD, 57.1% received healthcare. Counseling and therapy accounted for the largest share of encounters, while online services surged in 2020 during the COVID-19 pandemic. Healthcare utilization was higher among older adults (≥65 years: aOR=1.52, 95%CI:1.29-1.78), males (aOR=1.19, 95%CI:1.12-1.26), individuals with disabilities (aOR=1.46, 95%CI:1.36-1.56), and those with employer-sponsored (aOR=1.22, 95%CI:1.10-1.36) or other private insurance (aOR=2.15, 95%CI:1.97-2.34). The level of healthcare utilization was lower among participants with lower income (≤$25,000: aOR=0.75, 95%CI:0.69-0.81) or Medicaid coverage (aOR=0.83, 95%CI:0.77-0.89).

Despite high clinical need, healthcare utilization among adults with COD remains suboptimal and is shaped by structural inequities across income and insurance lines. Findings highlight the need to expand integrated healthcare services, strengthen Medicaid coverage, and sustain telehealth infrastructure to promote equitable, long-term engagement in care.