4122 — Variation in Clinical Characteristics and Longitudinal Outcomes in Individuals with Opioid Use Disorder Diagnosis Codes

Lead/Presenter: Victoria Powell,  COIN - Ann Arbor
All Authors: Powell VD (Geriatrics Research, Education, and Clinical Center, Ann Arbor VA; Division of Geriatric and Palliative Medicine, University of Michigan), Macleod C (Division of General Medicine, University of Michigan, Ann Arbor, MI); Sussman J (VA Center for Clinical Management Research (CCMR), VA Ann Arbor Healthcare System, Ann Arbor MI, Division of General Medicine, University of Michigan, Ann Arbor, MI); Lin LA (VA Center for Clinical Management Research (CCMR), VA Ann Arbor Healthcare System, Ann Arbor MI; Addiction Center, Department of Psychiatry, University of Michigan, Ann Arbor, MI); Bohnert ASB (VA Center for Clinical Management Research (CCMR), VA Ann Arbor Healthcare System, Ann Arbor MI; Department of Anesthesiology, University of Michigan, Ann Arbor, MI); Lagisetty P ((VA Center for Clinical Management Research (CCMR), VA Ann Arbor Healthcare System, Ann Arbor MI, Division of General Medicine, University of Michigan, Ann Arbor, MI)

Objectives:
Patterns of opioid use vary, including prescribed use without aberrancy, limited aberrant use, and potential opioid use disorder (OUD). In clinical practice, similar opioid-related International Classification of Disease (ICD) codes are applied across this spectrum, limiting understanding of how groups vary by sociodemographic factors, comorbidities, and long-term risks. This study aimed to 1) Examine how Veterans assigned opioid abuse/dependence ICD codes vary at diagnosis and with respect to long-term risks. 2) Determine whether those with limited aberrant use share more similarities to likely OUD vs those using opioids as prescribed.

Methods:
This was a longitudinal observational cohort study of a national sample of Veterans categorized as having: (1) likely OUD (2) limited aberrant opioid use or (3) prescribed, non-aberrant use based upon enhanced medical chart review. We compared sociodemographic and clinical factors at diagnosis and rates of age-adjusted mortality, non-fatal opioid overdose, and hospitalization after diagnosis. An exploratory machine learning analysis investigated how closely those with limited aberrant use resembled those with likely OUD.

Results:
Veterans (n = 483) were categorized as likely OUD (62.1%), limited aberrant use (17.8%), and prescribed, non-aberrant use (20.1%). Age, proportion experiencing homelessness, chronic pain, anxiety disorders, and non-opioid substance use disorders differed by group. All-cause mortality was high (44.2 per 1,000 person-years (95% CI 33.9, 56.7)). Hospitalization rates per 1,000 person-years were highest in the likely OUD group (831.5 (95% CI 771.0, 895.5)), compared to limited aberrant use (739.8 (95% CI 637.1, 854.4)), and prescribed, non-aberrant use (411.9 (95% CI 342.6, 490.4). The exploratory analysis reclassified 29.1% of those with limited aberrant use as having likely OUD with high confidence.

Implications:
Veterans assigned opioid abuse/dependence ICD codes are heterogeneous and face variable long-term risks. Limited aberrant use confers increased risk compared to no aberrant use, and some may already have OUD. Findings warrant future investigation of this understudied population.

Impacts:
Veterans assigned an OUD diagnosis code in medical records are highly heterogeneous. Overall, they face higher risks of all-cause mortality and hospitalization than general population samples of similar age. To our knowledge, this study provides the first estimate of how these outcomes differ when individuals with OUD-related ICD codes are grouped according to OUD likelihood. Those categorized as likely OUD were at the highest risk, followed by those with limited aberrant use; those with prescribed, non-aberrant use had the lowest risk. Preliminary analyses focusing on individuals with limited aberrant opioid use suggested approximately one-third share many features of OUD. These findings suggest that a simple binary classification of patients prescribed opioids for chronic pain and those with OUD is an over-simplification of the opioid use spectrum. While some with limited aberrant behaviors may have emerging or mild OUD, others may be experiencing a complex, dynamic relationship between chronic pain and opioid dependence, warranting further investigation into different treatment approaches.