# 448. Highs and Lows: Changes in National and Regional Patterns of Injection Drug Use Associated Endocarditis from 2016-2022

## TL;DR

Hospitalizations for infective endocarditis linked to injection drug use peaked in 2019 but declined through 2022, with stimulant use becoming more common than opioid use in some U.S. regions.

## Contribution

This study provides the first national and regional analysis of how drug use patterns have shifted the causes of injection drug use-associated infective endocarditis from 2016 to 2022.

## Key findings

- IDU-IE hospitalizations peaked in 2019 and declined through 2022, with a 13.1% drop between 2021 and 2022.
- Stimulant-related IDU-IE increased, surpassing opioid-related cases in the Pacific, Mountain, and West Central U.S. regions.
- Mixed use of opioids and stimulants rose from 22.9% to 28.6% of IDU-IE cases during the study period.

## Abstract

Infective endocarditis (IE) is among the most dangerous complications of injection drug use. IE related to injection drug use (IDU-IE) in the United States increased dramatically alongside the opioid overdose crisis. Drug use patterns have since evolved, with widespread fentanyl, rising methamphetamine and other stimulant use, falling overdose rates, and shifts towards more smoking or sniffing of drugs. The effect of these changes on IDU-IE hospitalizations is currently not known.Hospitalizations for IDU-IE by Drug TypeEstimated annual hospitalizations for injection drug use associated infective endocarditis (IDU-IE) in the United States, stratified by type of drug use coded in admission – opioids only, stimulants only, both opioids and stimulants (mixed use), or drug-related codes that do not specify substance (unspecified)Proportion of IDU-IE by Drug TypeProportion of estimated annual hospitalizations for injection drug use associated infective endocarditis (IDU-IE) in the United States, stratified by type of drug use coded in admission – opioids only, stimulants only, both opioids and stimulants (mixed use), or drug-related codes that do not specify substance (unspecified)

Hospitalizations for IDU-IE by Drug Type

Estimated annual hospitalizations for injection drug use associated infective endocarditis (IDU-IE) in the United States, stratified by type of drug use coded in admission – opioids only, stimulants only, both opioids and stimulants (mixed use), or drug-related codes that do not specify substance (unspecified)

Proportion of IDU-IE by Drug Type

Proportion of estimated annual hospitalizations for injection drug use associated infective endocarditis (IDU-IE) in the United States, stratified by type of drug use coded in admission – opioids only, stimulants only, both opioids and stimulants (mixed use), or drug-related codes that do not specify substance (unspecified)

We examined IDU-IE trends from 2016 through 2022 using the National Inpatient Sample, a representative sample of United States hospitalizations. We identified hospitalizations of individuals aged 18 and above with ICD-10 codes for IE, and used a previously published list of ICD-10 codes related to drug use to identify patients whose IDU-IE was likely caused by injection drug use. We examined number of IDU-IE hospitalizations and proportion of IE attributable to specific types of drug use, taking into account complex survey design, to generate national and regional weighted estimates for each year.Proportion of IDU-IE by Drug Type across US RegionsProportion of estimated annual hospitalizations for injection drug use associated infective endocarditis (IDU-IE) in the 9 major geographic areas of the United States, stratified by type of drug use coded in admission – opioids only, stimulants only, both opioids and stimulants (mixed use), or drug-related codes that do not specify substance (unspecified)

Proportion of IDU-IE by Drug Type across US Regions

Proportion of estimated annual hospitalizations for injection drug use associated infective endocarditis (IDU-IE) in the 9 major geographic areas of the United States, stratified by type of drug use coded in admission – opioids only, stimulants only, both opioids and stimulants (mixed use), or drug-related codes that do not specify substance (unspecified)

There were estimated 144,090 IDU-IE hospitalizations between 2016 and 2022. They peaked in 2019 with 22,695 hospitalizations, with an increasing rate of decline each year after (down 13.1% between 2021 and 2022). IDU-IE associated with types of drug use codes has changed over this period: opioid alone decreased from 48.5% to 39.2% of all IDU-IE, stimulant alone increased from 15.1% to 19.2%, and mixed use of stimulants and opioids increased from 22.9% to 28.6%; substance-nonspecific drug use codes remained stable at 13.2±0.6%. Regionally, IDU-IE hospitalizations involving stimulants overtook opioids as the leading involved substance in Pacific, Mountain, and West Central regions.

IDU-IE peaked in 2019 and declined through 2022, with greater reduction in hospitalizations involving opioid use compared to stimulant use. Consequently, the proportion of IDU-IE related to stimulant use has been rising, most sharply in people who use stimulants alone. This trend was most pronounced in the West, where IDU-IE involving stimulants surpassed those involving opioids. Understanding these shifts and their causes can help allocate prevention and treatment efforts.

All Authors: No reported disclosures