Studies analyze rise in infective endocarditis hospitalizations related to drug use

One recent study found an increase since 2008 in the hospitalization rate for stroke associated with infective endocarditis and opioid use, while another compared outcomes of infective endocarditis among patients who inject drugs versus those who do not.

Hospitalizations for strokes related to opioid use and infective endocarditis increased significantly between 2008 and 2015, a study found.

Researchers identified hospitalizations from 1993 through 2015 for opioid use, infective endocarditis, and stroke (defined as ischemic stroke, intracerebral hemorrhage, or subarachnoid hemorrhage) and calculated their frequency among the U.S. population using data from the National Inpatient Sample, ICD-9-CM codes, and the U.S. Census. Results were published online on Jan. 30 by Stroke.

From 1993 through 2015, there were 5,283 hospitalizations for stroke associated with infective endocarditis and opioid use (mean patient age, 41.2 years; 34.2% women; 57.6% non-Hispanic white). The rate of such hospitalizations increased from 2.4 per 10 million U.S. residents in 1993 (95% CI, 0.5 to 4.3) to 18.8 per 10 million in 2015 (95% CI, 14.4 to 23.3). The rate did not significantly change between 1993 and 2008 (annual percentage change, 1.9%; 95% CI, −2.2% to 6.1%), but from 2008 to 2015, it significantly increased (annual percentage change, 20.3%; 95% CI, 10.5% to 30.9%). Non-Hispanic white patients in the Northeastern and Southern U.S. had the greatest increases in the rate of hospitalization for stroke associated with infective endocarditis and opioid use.

The authors noted limitations of the study, such as potential misclassification of diagnoses in administrative claims data and a lack of access to granular clinical information (e.g., cause, severity, and location of stroke). “These novel findings indicate that increasing opioid abuse in the United States is not only causing more social/occupational dysfunction, cardiac complications, and premature mortality but may also be increasing the population burden of permanent functional disability as a result of stroke,” they wrote.

In another study, researchers analyzed recent trends in hospitalizations for infective endocarditis and injection drug use and characterized patients' clinical outcomes and 30-day readmissions using the National Readmissions Database from January 2010 to September 2015. They stratified patients by injection drug use status and surgical versus medical management. Results were published Feb. 5 by the Journal of the American College of Cardiology.

The survey-weighted sample contained 96,344 (77.8%) cases of infective endocarditis not related to injection drug use and 27,432 (22.2%) cases related to injection drug use. From 2010 through 2015, the proportion of infective endocarditis cases related to injection drug use increased from 15.3% to 29.1% (P<0.001). Compared to nonrelated cases, cases related to injection drug use at index hospitalization were associated with less mortality (6.8% vs. 9.6%; P<0.001) due to younger age, but similar risk of 30-day readmission (23.8% vs. 22.9%; P=0.077).

Compared with medically managed cases of infective endocarditis unrelated to injection drug use, medically managed patients with injection drug use had longer length of stay (β=1.36 d; 95% CI, 0.71 to 2.01 d), lower costs (β=−$4,427; 95% CI, −$7,093 to −$1,761), and more readmissions for endocarditis (18.1% vs. 5.6%; P<0.001), septicemia (14.0% vs. 7.3%; P<0.001), and drug abuse (4.3% vs. 0.7%; P<0.001). Compared to surgically managed patients with unrelated infective endocarditis, those with surgically managed infective endocarditis related to drug use had longer lengths of stay (β=4.26 d; 95% CI, 2.73 to 5.80 d) and more readmissions for septicemia (15.6% vs. 5.2%; P<0.001) and drug abuse (7.3% vs. 0.9%; P<0.001).

Limitations of the study include its retrospective nature, potential coding errors within the National Readmissions Database, and a lack of detailed data, the study authors said. Although patients with infective endocarditis related to injection drug use seem to have lower mortality, their long-term mortality remains unknown, an accompanying editorial noted. Future studies should assess the benefit of surgery in this population, particularly in the subgroup of those with persistent drug use, the editorialists said.

“[I]ncreased focus on addiction treatment and social support following hospital discharge is mandatory to reduce the risk of recurrent endocarditis,” they wrote.