Substance use disorders increase risk of unplanned hospital readmissions

People with any type of substance use disorder (SUD) stand a 24% higher risk of having an unplanned hospital readmission within 30 days of a previous discharge compared with those without the disorder, new UCLA-led research finds.

People with opioid use disorder had the highest 30-day readmission rates, at nearly 40%, the researchers found. Overall, people with SUDs comprise a disproportionate share of patients with multiple unplanned readmissions.

The higher risk was true only for people with substance use disorders who were discharged to homes without having been provided with post-acute care, said study co-author Steven Shoptaw, director of the Center for Behavioral and Addiction Medicine at UCLA. The findings identify a heretofore overlooked group with unique needs both during and after discharge, he said.

Identifying a substance use disorder in the medical record likely identifies patients who face problems with taking good care of themselves post discharge if there are few or no supports at home. Barriers to taking good care could include unmet social needs such as safe and affordable housing, healthy food, and employment. This can complicate tasks associated with post-discharge rehabilitation, including attending follow-up appointments, filling prescriptions at the pharmacy, and adhering to medications."

Steven Shoptaw, Director, Center for Behavioral and Addiction Medicine, UCLA

The findings will be published July 23 in the peer-reviewed journal Addiction.

Unplanned hospital readmissions are known to be expensive and have a negative impact on patients, such as increasing financial burdens, heightening the risk for hospital-acquired infections, and raising the likelihood of falls.

The researchers examined data from about 22,100 patients first admitted to two urban academic medical centers in 2022. They defined SUDs as diagnoses with one or more of the following: alcohol related disorders (AUD); opioid related disorders (OUD); sedative, hypnotic or anxiolytic related disorders; cocaine related disorders; other stimulant related disorders, and other psychoactive substance related disorders. They also used some other potential markers of SUDs such as alcoholic polyneuropathy, cardiomyopathy and fatty liver.

They found that 7.4% of the patients had at least one substance use disorder at first admission, including 4% with AUD and 2.4% had OUD, with the remainder spread over the other disorders. About 9.7% of patients with any of the diagnosed SUDs, 9.3% with AUD and 11% with OUD were re-admitted within the 30-day window.

While previous studies have specifically linked AUD to 30-day unplanned readmission, the researchers did not find an association in this study. They suspect this null finding could be explained by a combination of diagnostic procedures in inpatient settings as well as AUD severity, housing status, income and employment-covariates that they did not examine. They were surprised by the particularly high risk of 30-day unplanned readmission for patients with OUD, who were likely being treated for co-morbidities related to opioid use such as non-fatal overdoses and diseases such as endocarditis, cellulitis and osteomyelitis, as these hospitals did not have formal inpatient treatment units for primary OUD.

SUDs are not always detected in hospitalized patients, particularly when they are not the primary reason for the patient's hospitalization, which may have led to misclassification of SUDs, the researchers write. Other factors that may limit the findings include the possibility that not all readmissions were captured because some patients may have sought care at other hospitals not included in the study. The researchers also did not capture post-discharge mortality or unmeasured factors such as housing status or length of stay, and the findings may not be generalizable to other hospitals.

But the findings can point the way to improving care for patients with substance use disorders, said Allison Rosen, research epidemiologist at UCLA and the study's lead author.

"Implementing evidence-based practices for treating substance use disorders, such as starting patients on medication and/or behavioral therapy during their hospitalization and linking them to outpatient treatment at discharge, could have the potential to improve quality of care for patients with substance use disorders, as well as reducing costs related to 30-day unplanned readmissions," Rosen said.

Dr. Sae Takada, Dr. Catherine Juillard, Dr. Yulsi Fernandez Montero, Dr. Amy Richards, and Steven Shoptaw of UCLA; Dr. Michelle Bholat of UC Riverside, and Serge Ngekeng of the University of Buea in Cameroon were co-authors on the study.

The UCLA Department of Family Medicine funded the study.