Multimorbidity and Inpatient Utilization Among Older Adults with Opioid Use Disorder in New York City.

Nationally, there is a sharp increase in older adults with opioid use disorder (OUD). However, we know little of the acute healthcare utilization patterns and medical comorbidities among this population. This study describes the prevalence of chronic conditions, patterns of inpatient utilization, and correlates of high inpatient utilization among older adults with OUD in New York City (NYC). Retrospective longitudinal cohort study. Patients aged ≥55 with OUD hospitalized in NYC in 2012 identified using data from New York State’s Statewide Planning and Research Cooperative System (SPARCS). The prevalence of comorbid substance use diagnoses, chronic medical disease, and mental illness was measured using admission diagnoses from the index hospitalization. We calculated the ICD-Coded Multimorbidity-Weighted Index (MWI-ICD) for each patient to measure multimorbidity. We followed the cohort through September 30, 2015 and the outcome was the number of rehospitalizations for inpatient services in NYC. We compared patient-level factors between patients with the highest use of inpatient services (≥7 rehospitalizations) during the study period to low utilizers. We used multiple logistic regression to examine possible correlates of high inpatient utilization. Of 3669 adults aged ≥55 with OUD with a hospitalization in 2012, 76.4% (n=2803) had a subsequent hospitalization and accounted for a total of 22,801 rehospitalizations during the study period. A total of 24.7% of the cohort (n=906) were considered high utilizers and had a higher prevalence of alcohol and cocaine-related diagnoses, congestive heart failure, diabetes, schizophrenia, and chronic obstructive pulmonary disease. Multivariable predictors of high utilization included being a Medicaid beneficiary (adjusted odds ratio [aOR]=1.70, 95% confidence interval [CI]=1.37–2.11), alcohol-related diagnoses (aOR=1.43, 95% CI: 1.21–1.69), and increasing comorbidity measured by MWI-ICD (highest MWI-ICD quartile: aOR=1.98, 95% CI=1.59–2.48). Among older adults with OUD admitted to the hospital, multimorbidity is strongly associated with high inpatient utilization.