POUD was defined by NSDUH using Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) criteria for prescription opioid abuse or dependence. Of the 5,393 persons with POUD, 494 persons (9.30%, 95% CI 8.03–10.57) also met criteria for HUD. Because comorbid HUD can be viewed as a marker of disease severity in POUD (30–32), these persons were included in the main analyses, although heroin use was adjusted for in supplementary analyses.
