1. 2021;24;327-334Characteristics of Hospitalized Adults with Opioid Use Disorder in the United States: Nationwide Inpatient Sample
   Retrospective Study
   Brook T. Alemu, PhD, Olaniyi Olayinka, MD, and Brian C. Martin, PhD.

BACKGROUND: Although the clinical significance and treatment management of opioid use disorder (OUD) is sufficiently discussed, utilization of healthcare services associated with OUD has not been adequately studied in the United States.

OBJECTIVE: To provide a descriptive assessment of the utilization of health care services for adults with OUD in the United States.

STUDY DESIGN: A retrospective cross-sectional study design based on the National Inpatient Sample (NIS) developed by the Healthcare Cost and Utilization Project.

SETTING: All OUD cases included in the 2016 NIS database. Adults aged 18 years or older were included in the study.

METHODS: We analyzed a stratified probability sampling of 7.1 million hospital discharges weighted to 35.7 million national discharges. We used ICD-10-CM codes to identify OUD cases. Groups were compared using the Student’s t-test for continuous variables and the chi-square test for categorical variables. Total cost per hospital discharge was determined by converting the total per case hospital charge to a hospital cost estimate (estimate = total charges X hospital cost-to-charge ratio).

RESULTS: In 2016, an estimated 741,275 Americans were associated with OUD. Among patients with OUD, 73% were White, 12% were African-American, 8% were Hispanic, 0.6% Asian-American/Pacific Islander, 0.9% were Native Americans, and 2% were other race; 49% of patients with OUD were women. A large proportion (43%) of the OUD hospitalizations were billed to Medicaid. The average hospital length of stay for all OUD patients was 5.6 days, and the average cost per discharge was $11,233. A higher average LOS was observed for patients who died during hospitalization (8.4 days), Asian-American/Pacific Islander patients (6.8 days), patients covered by self-pay (6.8 days), patients with median household income of 71,000 or more (5.8 days), patients discharged from hospitals in the Northeast ($10,540) and patients discharged from hospitals in large hospitals ($12,570). The most frequently observed diagnosis associated with patients with OUD were alcohol/drug abuse or dependence, psychosis, and septicemia.

LIMITATIONS: These data sources are comprised of hospital discharge records, originally collected for billing purposes, and may be subject to provider biases and variations in coding practices.

CONCLUSIONS: In the United States, very few health issues have garnered the attention of such diverse sectors as the opioid crisis. Our analysis of 2016 NIS data found that patients with OUD accounted for approximately 740,000 discharges that year. This represents about a 55% increase over 2015. We also demonstrate that inpatient settings provide a unique opportunity for targeting evidence-based, comprehensive interventions at patients with OUD.

Key words: Opioid use disorder, discharge diagnosis, hospital resource utilization, cost-to-charge ratio, HCUP, NIS, AHRQ