Drug use impacts the care required by patients with infective endocarditis

Nov. 26, 2020

Results of a study of nearly 35,000 heart valve surgeries for infective endocarditis indicate that drug use-associated infective endocarditis (DU-IE) is changing the profile and altering the care needs of patients with the disease.

Hospitalizations for infective endocarditis have increased substantially since 2011. Heart valve surgeries for the treatment of patients who develop DU-IE also have risen. "To date, large-scale data about the clinical profiles and outcomes of patients who receive surgery for DU-IE has been limited. Existing studies have drawn from administrative data sets that lack reliable data on clinical comorbidities and relevant surgical characteristics, and from single-center studies or small cohorts that may impact generalizability," says Juan A. Crestanello, M.D., chair of Cardiovascular Surgery at Mayo Clinic in Rochester, Minnesota.

In 2020, Dr. Crestanello and fellow researchers analyzed The Society of Thoracic Surgeons (STS) Adult Cardiac Surgery Database to quantify valve surgeries for DU-IE, describe patient characteristics and evaluate early clinical outcomes. "The rise in the number of valve operations performed for DU-IE is an important manifestation of the opioid epidemic. We sought to definitively characterize the changing epidemiology and outcomes of patients receiving valve surgery for DU-IE in the U.S.," says Dr. Crestanello.

Study outcomes were presented at the annual meeting of The Society of Thoracic Surgeons and published in The Annals of Thoracic Surgery in 2020.

34,905 surgeries from 1,000 centers

Researchers assessed data for all patients older than 18 years of age who received valve surgery for active infective endocarditis between July 2011 and June 2018. They stratified the patients into DU-IE and non-drug use-associated infective endocarditis (NDU-IE) cohorts; DU-IE was defined as documented history of the illicit use of drugs such as heroin, cocaine or methamphetamine, or misuse of a controlled substance. The assessment resulted in 34,905 surgeries from 1,000 centers.

Primary clinical endpoints were operative mortality, defined as all deaths within 30 days of surgery, both in and outside of the hospital, and in-hospital mortality; and in-hospital mortality, defined as death occurring during index hospitalization. Major postoperative complications were defined by STS major morbidity categories. Composite STS major morbidity was defined as occurrence of any of these postoperative complications: deep sternal wound infection, renal failure, prolonged mechanical ventilation, reoperation and stroke.

Researchers summarized baseline patient characteristics and outcomes by the percentage distribution for categorical variables and by medians and 25th and 75th percentiles for continuous variables. The prevalence and incidence of valve surgery for DU-IE was stratified by U.S. census regions. Frequency of valve surgery and trend over time for illicit drug use and endocarditis culture were analyzed with a multinomial baseline-category logit model treating year as a linear variable.

The researchers performed risk adjustment when comparing outcomes between DU-IE and NDU-IE surgeries using logistic regression modeling for each endpoint with adjustment using variables from the 2018 STS valve risk model. When comparing primary and redo valve operations in the DU-IE cohort, the same risk model was used except that redo was defined as previous valve operation.

Regional variations

Of the 34,905 surgeries, 11,756 (33.7%) were for DU-IE and 23,149 (66.3%) were for NDU-IE. Overall, infective endocarditis surgeries increased 1.7-fold during the period studied. The increase was driven most strongly by an increase in DU-IE surgeries, which increased 2.7-fold. DU-IE accounted for 24% of infective endocarditis surgeries in 2011 and 38% in 2018.

The proportion of DU-IE among all infective endocarditis operations increased in all regions of the U.S. from 2011 to 2018. As of 2018, the regions with the greatest proportion of DU-IE were East South Central (58%), South Atlantic (45%) and New England (39%). DU-IE were least common in West North Central and West South Central regions (28%).

Cohorts reflect notable differences

Patients in the DU-IE cohort were younger (median age 36 years) and less frequently male (62.2%) compared with patients in the NDU-IE cohort (median age 60 years; 68.9% male). Patients in the DU-IE cohort more commonly smoked cigarettes (74.4% vs. 20.3%), reported more than seven drinks a week (12% vs. 7.6%) and more frequently had liver disease (46.3% vs. 9.4%).

Microbiology differed among the cohorts: Although Staphylococcus aureus and streptococcus spp were the most common bacteria in both cohorts, S. aureus constituted 42.1% of patients with DU-IE, compared with 24.3% of patients with NDU-IE.

In the adjusted analysis, compared with patients with DU-IE who received their first valve operations, patients with DU-IE receiving redo valve surgery had higher odds of major morbidity, operative mortality and in-hospital mortality.

"Our study supports that patients with infective endocarditis related to drug use are typically younger, with higher rates of smoking, drinking and liver disease. They are more likely to need emergency surgery, and be on Medicaid or uninsured," says Dr. Crestanello. "Patients with DU-IE are at higher odds of major morbidity and in-hospital mortality, and they experience poorer long-term outcomes. Recurrent drug use complicates postoperative care. We observed significantly longer hospital stays in patients with DU-IE."

Best practices, preventive strategies needed

"Our results robustly demonstrate that substance use is reshaping the landscape of infective endocarditis valve surgery in the U.S. In certain regions, DU-IE now constitutes a majority of infective endocarditis valve surgeries," says Joseph A. Dearani, M.D., with Cardiovascular Surgery at Mayo Clinic in Rochester, Minnesota, and current STS president. "The regional differences in disease burden indicate that both interventions and funding must be tailored to local needs. Best practices in the multidisciplinary management of DU-IE and the development of regional and national preventive strategies are urgently needed."

For more information

Geirsson A, et al. The evolving burden of drug use: Associated infective endocarditis in the United States. The Annals of Thoracic Surgery. 2020;110:1185.