Validation of an Algorithm to Identify Infective Endocarditis in People Who Inject Drugs

Perspectives on benefits and risks of creation of an "injection drug use" billing code

People with substance use disorder (SUD) face barriers to prevention and treatment services, increasing risk for hospitalization and death. Injection drug use (IDU) can lead to an increased risk of overdose and infections. However, identifying people who inject drugs (PWID) within healthcare systems is challenging. International Classification of Disease (ICD-10) codes are used for billing and tracking healthcare utilization. In this commentary, experts in the field weigh the benefits and risks of creating an IDU-specific ICD-10 code. Potential benefits include earlier identification, better access to health services, and improved systems of resource allocation. Potential risks include further stigmatization of PWID and, if not tied to financial reimbursement, low rates of code utilization. As the current systems of identifying PWID are lacking, we feel that a guided operationalization of an ICD code to identify PWID could improve quantitative and epidemiological research accuracy and, therefore, support the health and well-being of PWID.

Long-term Risk of Serious Infections and Mortality Among Patients Surviving Drug Use-Associated Infective Endocarditis

Among a statewide cohort of 1874 patients surviving hospitalization for drug use-associated endocarditis during 2017-2020, the 3-year risk of death or future hospitalization was 38% (16% for death before later infection, 14% for recurrent endocarditis, 14% for soft tissue, 9% for bacteremia, 5% for bone/joint, and 4% for spinal infections).

Validation of case-ascertainment algorithms using health administrative data to identify people who inject drugs in Ontario, Canada

OBJECTIVES

Health administrative data can be used to improve the health of people who inject drugs by informing public health surveillance and program planning, monitoring, and evaluation. However, methodological gaps in the use of these data persist due to challenges in accurately identifying injection drug use (IDU) at the population level. In this study, we validated case-ascertainment algorithms for identifying people who inject drugs using health administrative data in Ontario, Canada.

STUDY DESIGN AND SETTING

Data from cohorts of people with recent (past 12 months) IDU, including those participating in community-based research studies or seeking drug treatment, were linked to health administrative data in Ontario from 1992 to 2020. We assessed the validity of algorithms to identify IDU over varying look-back periods (ie, all years of data [1992 onwards] or within the past 1-5 years), including inpatient and outpatient physician billing claims for drug use, emergency department (ED) visits or hospitalizations for drug use or injection-related infections, and opioid agonist treatment (OAT).

RESULTS

Algorithms were validated using data from 15,241 people with recent IDU (918 in community cohorts and 14,323 seeking drug treatment). An algorithm consisting of ≥1 physician visit, ED visit, or hospitalization for drug use, or OAT record could effectively identify IDU history (91.6% sensitivity and 94.2% specificity) and recent IDU (using 3-year look back: 80.4% sensitivity, 99% specificity) among community cohorts. Algorithms were generally more sensitive among people who inject drugs seeking drug treatment.

CONCLUSION

Validated algorithms using health administrative data performed well in identifying people who inject drugs. Despite their high sensitivity and specificity, the positive predictive value of these algorithms will vary depending on the underlying prevalence of IDU in the population in which they are applied.

Everything but the Kitchen Sink: An Analysis of Bacterial and Chemical Contaminants Found in Syringe Residue From People Who Inject Drugs

Background

People who inject drugs (PWID) are at high risk of severe wounds, invasive infections, and overdoses. To date, there are few data on the bacterial and chemical contaminants PWID are exposed to when using illicitly manufactured fentanyls and stimulants.

Methods

Previously used injection drug use equipment was recovered in St Louis, Missouri, by harm reduction organizations over a 12-month period. Syringe residue was analyzed for bacterial contaminants by routine culturing followed by whole genome sequencing of single bacterial isolates. Chemical adulterants in syringe residue were identified by liquid chromatography-mass spectrometry.

Results

Bacteria were cultured from 58.75% of 160 syringes analyzed. Polymicrobial growth was common and was observed in 23.75% of samples. Bacillus cereus was the most common pathogen present and was observed in 20.6% of syringe residues, followed closely by Staphylococcus aureus at 18.8%. One hundred syringes underwent mass spectrometry, which demonstrated that chemical adulterants were common and included caffeine, diphenhydramine, lidocaine, quinine, and xylazine.

Conclusions

Analysis of syringe residue from discarded drug use equipment demonstrates both chemical and biological contaminants, including medically important pathogens and adulterants.

HIV and HCV testing at clinical encounters among people who inject drugs, 2013-2018-Opportunities for increased testing and prevention

People who inject drugs (PWID) with unsafe injection practices have substantial risk for HIV and hepatitis C virus (HCV) infections. We describe frequency of, and factors associated with, HIV and HCV testing during clinical encounters with PWID. Inpatient and Emergency Department clinical encounters at an Atlanta hospital were abstracted from medical records spanning January 2013-December 2018. We estimated frequency of HIV and HCV testing during injection drug use (IDU)-related encounters among PWID without previous diagnoses. We assessed associations between patient factors and testing using generalized estimating equations models. HIV testing occurred in 39.3% and HCV testing occurred in 17.1% of eligible IDU-related encounters. Testing was more likely in IDU-related encounters during 2017-2018 than in encounters during 2013-2014; (HIV, AOR = 2.14, 95% CI, 1.32-3.49, p < .01). Testing was less likely among Black/African American patients compared to White patients (adjusted odds ratio [AOR]: HIV, AOR = 0.48, 95% confidence interval [CI], 0.33-0.72, p < .01); HCV, AOR = 0.41, 95% CI, 0.24-0.70, p < .01). This difference may be attributable to recent testing among Black patients in non-IDU related encounters. HIV and HCV testing improved over time; however, missed opportunities for testing still existed. Strategies should aim to improve equitable HIV and HCV testing among PWID.

Missed opportunities for prevention: prevalence and incidence of human immunodeficiency virus and hepatitis C virus diagnoses among a cohort of individuals discharged from an urban hospital with injection drug-related diagnoses, 2012-2019

PURPOSE

Risk for human immunodeficiency virus (HIV) and hepatitis C virus (HCV) infections has increased due to the ongoing opioid epidemic and unsafe injection practices. We estimated the prevalence and incidence of HIV and HCV diagnoses among people who inject drugs from hospital-based clinical encounters.

METHODS

We linked clinical encounters at an Atlanta hospital during 2012-2018 with state HIV and HCV surveillance records to examine the prevalence of infections at discharge and incidence of infections post clinical encounter.

RESULTS

At discharge, 32.9% and 28.6% of patients with injection drug use-related clinical encounters had an HIV or HCV diagnosis, respectively. HIV and HCV diagnoses at the time of discharge were mostly among 40-64 years old patients, males, and Black/African Americans. Post clinical encounter, 3.8% of patients were later diagnosed with HIV, and 16.5% were later diagnosed with HCV, translating to incidence rates of 9.3 per 1000 person-years and 41.5 per 1000 person-years, respectively. The majority of HIV and HCV diagnoses post clinical encounter occurred among Black/African Americans and males. Of patients with HIV and HCV diagnoses post clinical encounter, 27.3% and 11.9% had been tested during their clinical encounter, respectively.

CONCLUSIONS

Targeted interventions for HIV/HCV prevention, screening, diagnosis, and linkage to treatment are needed to reduce the incidence of new infections among people who inject drugs.

Association of Intravenous Drug Use and Length of Stay Following Infective Endocarditis

INTRODUCTION

Intravenous drug use (IVDU) and associated infective endocarditis (IE) has been on the rise in the US since the beginning of the opioid epidemic. IVDU-IE has high morbidity and mortality, and treatment can be lengthy. We aim to quantify the association between IVDU and length of stay (LOS) in IE patients.

METHODS

The National Inpatient Sample database was used to identify IE patients, which was then stratified into IVDU-IE and non-IVDU-IE groups. Weighted values of hospitalizations were used to generate national estimates. Multivariable linear and logistic regression analyses were applied to estimate the effects of IVDU on LOS.

RESULTS

We identified 1,114,257 adult IE patients, among which 123,409 (11.1%) were IVDU-IE. Compared to non-IVDU-IE patients, IVDU-IE patients were younger, had fewer comorbidities, and had an overall longer LOS (median [interquartile range]: 10 [5-20] versus 7 [4-13] d, P < 0.001), with a greater percentage of patients with a LOS longer than 30 d (13.7% versus 5.7%, P < 0.001). After adjusting for multiple demographic and clinical factors, IVDU was independently associated with a 1.25-d increase in LOS (beta-coefficient = 1.25, 95% confidence interval [CI]: 0.95-1.54, P < 0.001) and 35% higher odds of being hospitalized for more than 30 d (odds ratio = 1.35, 95% CI: 1.27-1.44, P < 0.001).

CONCLUSIONS

Among IE patients, being IVDU has associated with a longer LOS and a higher risk of prolonged hospital stay. Steps toward the prevention of IE in the IVDU population should be taken to avoid an undue burden on the healthcare system.

Sensitivity, specificity and predictive values of ICD-10 substance use codes in a cohort of substance use-related endocarditis patients

Background: Healthcare databases have the potential to become efficient tools for epidemiological research in People Who Inject Drugs (PWID). The validity of ICD-10 codes for specific substances in this population has not been assessed.Objectives: Validate ICD-10 diagnosis codes relating to the use of specific substance classes in a cohort of endocarditis patients.Methods: Our study sample consisted of 379 first-episode infective endocarditis patients (Male: 208, Female: 171), aged 18-55, admitted to any of three hospitals in London, Ontario from 2007 to 2018. Of these, 287 used drugs. We validated ICD-10 substance use codes for opioids (F11), stimulants (F15), cocaine (F14) and multiple substances (F19). Sensitivity, specificity, Positive Predictive Value (PPV) and Negative Predictive Value (NPV) were calculated for each code, using self-reported substance use documented on medical record review as a gold standard. We conducted a comparative analysis between code-negative users and code-positive users for each substance.Results: All substance use codes shared the same pattern: high specificity, high PPV and low sensitivity, with code F11 yielding the highest PPV (96.3%; 95% C.I.: 90.8-98.6) and sensitivity (42.6%; 95% C.I. 36.3-49.1). The code-positives and code-negatives for each substance did not differ significantly in any characteristics compared.Conclusion: Our results suggest that the individual ICD-10 codes analyzed should not be used for research without adjustment for low sensitivity. However, due to high PPV and specificity, these codes may still have potential for research use. Because code-negative patients did not differ from code-positive patients, their data may be extrapolated to the overall group of substance users.

Natural Language Processing and Machine Learning to Identify People Who Inject Drugs in Electronic Health Records

Background

Improving the identification of people who inject drugs (PWID) in electronic medical records can improve clinical decision making, risk assessment and mitigation, and health service research. Identification of PWID currently consists of heterogeneous, nonspecific International Classification of Diseases (ICD) codes as proxies. Natural language processing (NLP) and machine learning (ML) methods may have better diagnostic metrics than nonspecific ICD codes for identifying PWID.

Methods

We manually reviewed 1000 records of patients diagnosed with Staphylococcus aureus bacteremia admitted to Veterans Health Administration hospitals from 2003 through 2014. The manual review was the reference standard. We developed and trained NLP/ML algorithms with and without regular expression filters for negation (NegEx) and compared these with 11 proxy combinations of ICD codes to identify PWID. Data were split 70% for training and 30% for testing. We calculated diagnostic metrics and estimated 95% confidence intervals (CIs) by bootstrapping the hold-out test set. Best models were determined by best F-score, a summary of sensitivity and positive predictive value.

Results

Random forest with and without NegEx were the best-performing NLP/ML algorithms in the training set. Random forest with NegEx outperformed all ICD-based algorithms. F-score for the best NLP/ML algorithm was 0.905 (95% CI, .786-.967) and 0.592 (95% CI, .550-.632) for the best ICD-based algorithm. The NLP/ML algorithm had a sensitivity of 92.6% and specificity of 95.4%.

Conclusions

NLP/ML outperformed ICD-based coding algorithms at identifying PWID in electronic health records. NLP/ML models should be considered in identifying cohorts of PWID to improve clinical decision making, health services research, and administrative surveillance.

Effect of leaving against medical advice on 30-day infective endocarditis readmissions

BACKGROUND

: The burden of against medical advice (AMA) discharges on the readmission rate of infective endocarditis (IE) patients has been largely ignored.

METHODS

We used the National Readmissions Database, years 2016 to 2019, to identify IE patients and categorized them into those who left AMA (IE AMA) and those who were discharged to home or skilled nursing facility (SNF)/other facility (IE non-AMA). The primary outcome was 30-day all-cause readmissions difference per AMA status.

RESULTS

Of 26,481 patients with IE who met the inclusion criteria, 4,310 (16.3%) left the hospital AMA. IE AMA patients were younger (mean years; 43.7 vs 34.2; p < 0.01) and had a higher prevalence of injection drug use (IDU) (89.4% vs 45.2%; p < 0.01) but fewer comorbidities compared to IE non-AMA. In adjusted analyses, IE AMA had higher hazards for 30-day readmissions compared to IE non-AMA [hazards ratio (HR): 3.1 (2.9 - 3.5); p < 0.01].

CONCLUSION

IE AMA are at increased risk of 30-day readmissions and higher resource utilization at the time of readmission compared to IE non-AMA. Considering the high prevalence of IDU in IE AMA, the role of mental health to curb the burden of IE readmissions is an area of further research.

Surgical outcomes of pulmonary valve infective endocarditis: A US population-based analysis

BACKGROUND

Pulmonary valve infective endocarditis (PVIE) represents a rare subset of right-sided IE. This study aimed to evaluate the population-level surgical outcomes of PVIE in the United States.

METHODS

We performed a retrospective observational study using the 2002-2017 National Inpatient Sample database. We included hospitalizations with both IE and PV interventions. We excluded Tetralogy of Fallot, congenital PV malformation, and those who underwent the Ross procedure. The primary outcome was in-hospital mortality. The secondary outcomes included major complications and length of hospital stay.

RESULTS

We identified 677 PVIE hospitalizations that underwent surgical treatment, accounting for 0.06% of all IE hospitalizations. The mean age was 35.2 ± 1.7 years; 60.0% were White, 30.3% were women, and 11.4% were intravenous drug users. Most were treated in large-sized (70.1%) urban teaching (88.8%) hospitals. Close to 30% of patients received at least one concomitant valve procedure. The in-hospital mortality was 5.5% for the entire cohort, and the median length of stay was 16 days. Major complications included complete heart block (8.7%), acute kidney injury (8.1%), and stroke (1.3%). The differences in mortality and complications rate comparing PV repair and replacement were not statistically significant. PV repair was associated with a longer length of hospital stay compared to PV replacement (median: 25 vs. 16 days, p = 0.03).

CONCLUSIONS

This study defines the population-level in-hospital outcomes after surgical intervention of PVIE. Surgically treated PVIE patients are associated with relatively low mortality and morbidities. The outcomes between PV replacement and repair are similar.

Hospitalisation with injection-related infections: Validation of diagnostic codes to monitor admission trends at a tertiary care hospital in Melbourne, Australia

INTRODUCTION

Injection-related infections (IRI) cause morbidity and mortality in people who inject drugs. Hospital administrative datasets can be used to describe hospitalisation trends, but there are no validated algorithms to identify injecting drug use and IRIs. We aimed to validate International Classification of Diseases (ICD) codes to identify admissions with IRIs and use these codes to describe IRIs within our hospital.

METHODS

We developed a candidate set of ICD codes to identify current injecting drug use and IRI and extracted admissions satisfying both criteria. We then used manual chart review data from 1 January 2017 to 30 April 2019 to evaluate the performance of these codes and refine our algorithm by selecting codes with a high-positive predictive value (PPV). We used the refined algorithm to describe trends and outcomes of people who inject drugs with an IRI at Alfred Hospital, Melbourne from 2008 to 2020.

RESULTS

Current injecting drug use was best predicted by opioid-related disorders (F11), 80% (95% confidence interval [CI] 74-85%), and other stimulant-related disorders (F15), 82% (95% CI 70-90%). All PPVs were ≥67% to identify specific IRIs, and ≥84% for identifying any IRI. Using these codes over 12 years, IRIs increased from 138 to 249 per 100 000 admissions, and skin and soft tissues infections (SSTI) were the most common (797/1751, 46%).

DISCUSSION AND CONCLUSION

Validated ICD-based algorithms can inform passive surveillance systems. Strategies to reduce hospitalisation with IRIs should be supported by early intervention and prevention, particularly for SSTIs which may represent delayed access to care.

International Classification of Diseases (ICD) Codes Fail to Accurately Identify Injection Drug Use Associated Endocarditis Cases

OBJECTIVES

Infective endocarditis (IE) secondary to injection drug use (IDU-IE) is a disease with high morbidity, cost, and rapid demographic evolution. Studies frequently utilize combinations of International Statistical Classification of Diseases (ICD) codes to identify IDU-IE cases in electronic medical records. This is a validation of this identification strategy in a US cohort.

METHODS

Records from January 1, 2004 to September 31, 2015 for those aged ≥18yo with any ICD-coded IE encounter (inpatient or outpatient) were retrieved from the electronic medical record and then manually reviewed and classified as IDU-IE by strict and inclusive criteria. This registry was then used to assess the diagnostic accuracy of 10 identification algorithms that combined substance use, hepatitis C, and IE ICD codes.

RESULTS

IE was present in 629 of the 2055 manually reviewed records; 109 reported IDU within 3 months of IE diagnosis and an additional 32 during their lifetime (141 cases). In contrast, no algorithm identified more than 46 (33%) of these cases. Algorithms assessing encounters with both an IE and substance use code had specificities >99% but sensitivities ≤11% with negative predictive values of 83% to 84% and positive predictive values ranging from 75% to 91%. Use of a hepatitis C OR substance use code with an IE-coded encounter resulted in higher sensitivities of 22% to 32% but more false positives and overall positive predictive value of <70%. This algorithm limited to age ≤45yo had the best, but still low, discrimination ability with an area under the receiver operating characteristic curve of 0.62.

CONCLUSION

Substance use and hepatitis C codes have poor ability to accurately classify an IE-coded encounter as IDU-IE or routine IE.

Diagnostic accuracy of ICD code versus discharge summary-based query for endocarditis cohort identification

Studies of infective endocarditis (IE) have relied on International Classification of Disease (ICD) codes to identify cases, a method vulnerable to misclassification. Clinical narrative data could offer greater accuracy and richness to cohort identification. We evaluated two algorithms: 1. a standard query of ICD-9/10 billing codes, with or without procedure codes for echocardiogram and 2. a text query of discharge summaries (DS) that selected on the term “endocarditis” in fields headed by “Discharge Diagnosis” or “Admission Diagnosis” or similar. Further coding extracted valve involved and organism responsible if present. All cases were chart reviewed using pre-specified criteria. Positive predictive value (PPV), sensitivity and specificity were calculated. The ICD-based query identified 612 individuals from July 2015 to July 2019 who had a hospital billing code for infective endocarditis; of these, 534 had an echocardiogram. The DS query identified 387 cases. PPV for the DS query was 84.5% (95% CI 80.6%, 87.8%) compared with 72.4% (95% CI 68.7%, 75.8%) for ICD only (P < .001) and 75.8% (95% CI 72.0%, 79.3%) for ICD + echo queries (P = .002). Sensitivity was 75.9% for DS query and 86.8% to 93.4% for ICD queries (P < .02 for these comparisons). Specificity was high for all queries >94%. The DS query also yielded valve data (prosthetic, tricuspid, aortic, etc) in 60% and microbiologic agent in 73% of identified cases with an accuracy of 94% and 90%, respectively when assessed by chart review. Compared with ICD-based queries, text-based queries of discharge summaries have the potential to improve precision of IE case ascertainment and extract key clinical variables.

Against Medical Advice Discharges in Injection and Non-injection Drug Use-associated Infective Endocarditis: A Nationwide Cohort Study

BACKGROUND

Among those with injection drug use-associated infective endocarditis (IDU-IE), against medical advice (AMA) discharge is common and linked to adverse outcomes. Understanding trends, risk factors, and timing is needed to reduce IDU-IE AMA discharges.

METHODS

We identified individuals ages 18-64 with International Classification of Diseases, 9thRevision, diagnosis codes for infective endocarditis (IE) in the National Inpatient Sample, a representative sample of United States hospitalizations from January 2010 to September 2015. We plotted unadjusted quarter-year trends for AMA discharges and used multivariable logistic regression to identify factors associated with AMA discharge among IE hospitalizations, comparing IDU-IE with non-IDU-IE.

RESULTS

We identified 7259 IDU-IE and 23 633 non-IDU-IE hospitalizations. Of these hospitalizations, 14.2% of IDU-IE and 1.9% of non-IDU-IE resulted in AMA discharges. More than 30% of AMA discharges for both groups occurred before hospital day 3. In adjusted models, IDU status (adjusted odds ratio [AOR], 3.92; 95% confidence interval [CI], 3.43-4.48)] was associated with increased odds of AMA discharge. Among IDU-IE, women (AOR, 1.21; 95% CI, 1.04-1.41) and Hispanics (AOR, 1.32; 95% CI, 1.03-1.69) had increased odds of AMA discharge, which differed from non-IDU-IE. Over nearly 6 years, odds of AMA discharge increased 12% per year for IDU-IE (AOR, 1.12; 95% CI, 1.07-1.18) and 6% per year for non-IDU-IE (AOR, 1.06; 95% CI. 1.00-1.13).

CONCLUSIONS

AMA discharges have risen among individuals with IDU-IE and non-IDE-IE. Among those who inject drugs, AMA discharges were more common and increases sharper. Efforts that address the rising fraction, disparities, and timing of IDU-IE AMA discharges are needed.

Trends in Hospitalizations for Serious Infections Among People With Opioid Use Disorder in Ontario, Canada

Opioid use among people who inject drugs can lead to serious complications, including infections. We sought to study trends in rates of these complications among people with an opioid use disorder (OUD) and the sequelae of those hospitalizations.

Effect of Publicly Reported Aortic Valve Surgery Outcomes on Valve Surgery in Injection Drug- and Non-Injection Drug-Associated Endocarditis

BACKGROUND

Injection drug use-associated infective endocarditis (IDU-IE) is rising and valve surgery is frequently indicated. The effect of initiating public outcomes reporting for aortic valve surgery on rates of valve surgery and in-hospital mortality for endocarditis is not known.

METHODS

For an interrupted time series analysis, we used data from the National Inpatient Sample, a representative sample of United States inpatient hospitalizations, from January 2010 to September 2015. We included individuals aged 18-65 with an International Classification of Diseases, Ninth Revision (ICD-9) diagnosis of endocarditis. We defined IDU-IE using a validated combination of ICD-9 codes. We used segmented logistic regression to assess for changes in valve replacement and in-hospital mortality rates after the public reporting initiation in January 2013.

RESULTS

We identified 7322 hospitalizations for IDU-IE and 23 997 for non-IDU-IE in the sample, representing 36 452 national IDU-IE admissions and 119 316 non-IDU admissions, respectively. Following the implementation of public reporting in 2013, relative to baseline trends, the odds of valve replacement decreased by 4.0% per quarter (odds ratio [OR] 0.96, 95% confidence interval [CI] 0.93-0.99), with no difference by IDU status. The odds of an in-patient death decreased by 2.0% per quarter for both IDU-IE and non-IDU-IE cases following reporting (OR 0.98, 95% CI 0.97-0.99).

CONCLUSIONS

Initiating public reporting was associated with a significant decrease in valve surgery for all IE cases, regardless of IDU status, and a reduction in-hospital mortality for patients with IE. Patients with IE may have less access to surgery as a consequence of public reporting. To understand how reduced valve surgery impacts overall mortality, future studies should examine the postdischarge mortality rate.

Misclassification Error-Adjusted Prevalence of Injection Drug Use Among Infective Endocarditis Hospitalizations in the United States: A Serial Cross-Sectional Analysis of the 2007-2016 National Inpatient Sample

Administrative health databases have been used to monitor trends in infective endocarditis hospitalization related to nonprescription injection drug use (IDU) using International Classification of Diseases (ICD) code algorithms. Because no ICD code for IDU exists, drug dependence and hepatitis C virus (HCV) have been used as surrogate measures for IDU, making misclassification error (ME) a threat to the accuracy of existing estimates. In a serial cross-sectional analysis, we compared the unadjusted and ME-adjusted prevalences of IDU among 70,899 unweighted endocarditis hospitalizations in the 2007-2016 National Inpatient Sample. The unadjusted prevalence of IDU was estimated with a drug algorithm, an HCV algorithm, and a combination algorithm (drug and HCV). Bayesian latent class models were used to estimate the median IDU prevalence and 95% Bayesian credible intervals and ICD algorithm sensitivity and specificity. Sex- and age group-stratified IDU prevalences were also estimated. Compared with the misclassification-adjusted prevalence, unadjusted estimates were lower using the drug algorithm and higher using the combination algorithm. The median ME-adjusted IDU prevalence increased from 9.7% (95% Bayesian credible interval (BCI): 6.3, 14.8) in 2008 to 32.5% (95% BCI: 26.5, 38.2) in 2016. Among persons aged 18-34 years, IDU prevalence was higher in females than in males. ME adjustment in ICD-based studies of injection-related endocarditis is recommended.

Not Just Endocarditis: Hospitalizations for Selected Invasive Infections Among Persons With Opioid and Stimulant Use Diagnoses-North Carolina, 2010-2018

BACKGROUND

While increases in overdoses, viral hepatitis, and endocarditis associated with drug use have been well-documented in North Carolina, the full scope of invasive drug-related infections (IDRIs) has not. We characterized trends in IDRIs among hospitalized patients in North Carolina.

METHODS

We compared invasive infections that were related or not related to drug use among hospitalized patients aged 18-55 years based on retrospective review of administrative records from 2010-2018. Hospitalizations for endocarditis, central nervous system/spine infections, osteomyelitis, and septic arthritis were labeled as IDRIs if discharge codes included opioid and/or amphetamine misuse. Trends, rates, and distributions were calculated.

RESULTS

Among 44 851 hospitalizations for the specified infections, 2830 (6.3%) were IDRIs. The proportion of infections attributable to drug use increased from 1.5% (2010) to 13.1% (2018), and the rate grew from 1.2 to 15.1 per 100 000. Compared with those who had non-drug-related infections, patients with IDRIs were younger (median age, 35 vs 46 years), more likely to be non-Hispanic white (81% vs 56%), and had longer hospitalizations (median, 8 vs 6 days). 43% of hospitalizations for IDRIs involved infective endocarditis.

CONCLUSIONS

The rate of IDRIs in North Carolina increased substantially during 2010-2018, indicating an urgent need for enhanced infection prevention, harm reduction, and addiction services aimed at community and inpatient settings.

Low Use of Outpatient Parenteral Antimicrobial Therapy for Drug Use-Associated Infective Endocarditis in an Urban Hospital System

Background

The opioid crisis in the United States has led to increasing hospitalizations for drug use-associated infective endocarditis (DUA-IE). Outpatient parenteral antimicrobial therapy (OPAT), the preferred modality for intravenous antibiotics for infective endocarditis, has demonstrated similar outcomes among patients with DUA-IE versus non-DUA-IE, but current studies suffer selection bias. The utilization of OPAT for DUA-IE more generally is not well studied.

Methods

This retrospective cohort study compared OPAT use for DUA-IE versus non-DUA-IE in adults hospitalized between January 1, 2015 and September 1, 2019 at 3 urban hospitals. We used multivariable regression analysis to assess the association between DUA-IE and discharge with OPAT, adjusting for clinically significant covariables.

Results

The cohort included 518 patients (126 DUA-IE, 392 non-DUA-IE). Compared to those with non-DUA-IE, DUA-IE patients were younger (53.0 vs 68.2 years, P < .001) and more commonly undomiciled (9.5% vs 0.3%, P < .01). Patients with DUA-IE had a significantly lower odds of discharge with OPAT than non-DUA-IE patients (adjusted odds ratio [aOR] = 0.20; 95% confidence interval [CI], 0.10–0.39). Odds of discharge with OPAT remained lower for patients with DUA-IE after excluding undomiciled patients (aOR = 0.22; 95% CI, 0.11–0.43) and those with patient-directed discharges (aOR = 0.27; 95% CI, 0.14–0.52).

Conclusions

Significantly fewer patients with DUA-IE were discharged with OPAT compared to those with non-DUA-IE, and undomiciled patients or patient-directed discharges did not fully account for this difference. Efforts to increase OPAT utilization among patients with DUA-IE could have important benefits for patients and the healthcare system.

Changes in Infective Endocarditis Admissions in Pennsylvania During the Opioid Epidemic

BACKGROUND

With the current opioid crisis in the United States, infectious complications related to injection drug use are increasingly reported. Pennsylvania is at the epicenter of the opioid crisis, with the third highest rate of drug overdose deaths in the United States.

METHODS

A retrospective cohort study was performed using the Pennsylvania Health Care Cost Containment Council database of all residents hospitalized for infective endocarditis (IE) in an acute care hospital from 1 January 2013 through 31 March 2017. Patients were separated into those with and those without substance use via diagnosis codes. The primary outcome was length of stay. Secondarily, we evaluated demographics, infection history, hospital charges, and insurance status.

RESULTS

Of the 17 224 hospitalizations, 1921 (11.1%) were in patients with drug use-associated IE (DU-IE). Total quarterly IE admissions increased 20%, with a 6.5% increase in non-drug use-associated IE (non-DU-IE) admissions and a 238% increase in DU-IE admissions. In adjusted models, DU-IE was not associated with significant changes in length of stay (incidence rate ratio, 1.02; 95% confidence interval, .975-1.072; P = .36). Patients with DU-IE were predominantly insured by Medicaid (68.3% vs 13.4% for non-DU-IE), they had higher hospital charges ($86 622 vs $66 802), and they were more likely to leave against medical advice (15.7% vs 1.1%) (all P < .001).

CONCLUSIONS

Our study demonstrates an increase in IE admissions, driven by an increase in admissions for DU-IE. The higher charges, proportion of patients on Medicaid, and rates of leaving against medical advice among the DU-IE group shows the downstream effects of the opioid crisis.

Association of Treatment With Medications for Opioid Use Disorder With Mortality After Hospitalization for Injection Drug Use-Associated Infective Endocarditis

IMPORTANCE

Although hospitalizations for injection drug use-associated infective endocarditis (IDU-IE) have increased during the opioid crisis, utilization of and mortality associated with receipt of medication for opioid use disorder (MOUD) after discharge from the hospital among patients with IDU-IE are unknown.

OBJECTIVE

To assess the proportion of patients receiving MOUD after hospitalization for IDU-IE and the association of MOUD receipt with mortality.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective cohort study used a population registry with person-level medical claims, prescription monitoring program, mortality, and substance use treatment data from Massachusetts between January 1, 2011, and December 31, 2015; IDU-IE-related discharges between July 1, 2011, and June, 30, 2015, were analyzed. All Massachusetts residents aged 18 to 64 years with a first hospitalization for IDU-IE were included; IDU-IE was defined as any hospitalization with a diagnosis of endocarditis and at least 1 claim in the prior 6 months for OUD, drug use, or hepatitis C and with 2-month survival after hospital discharge. Data were analyzed from November 11, 2018, to June 23, 2020.

EXPOSURE

Receipt of MOUD, defined as any treatment with methadone, buprenorphine, or naltrexone, within 3 months after hospital discharge excluding discharge month for IDU-IE.

MAIN OUTCOMES AND MEASURES

The main outcome was all-cause mortality. The proportion of patients who received MOUD in the 3 months after hospital discharge was calculated. Multivariable Cox proportional hazard regression models were used to examine the association of MOUD receipt with mortality, adjusting for sex, age, medical and psychiatric comorbidities, and homelessness. In the secondary analysis, receipt of MOUD was considered as a monthly time-varying exposure.

RESULTS

Of 679 individuals with IDU-IE, 413 (60.8%) were male, the mean (SD) age was 39.2 (12.1) years, 298 (43.9%) were aged 18 to 34 years, 419 (72.3) had mental illness, and 209 (30.8) experienced homelessness. A total of 134 individuals (19.7%) received MOUD in the 3 months before hospitalization and 165 (24.3%) in the 3 months after hospital discharge. Of those who received MOUD after discharge, 112 (67.9%) received buprenorphine. The crude mortality rate was 9.2 deaths per 100 person-years. MOUD receipt within 3 months after discharge was not associated with reduced mortality (adjusted hazard ratio, 1.29; 95% CI, 0.61-2.72); however, MOUD receipt was associated with reduced mortality in the month that MOUD was received (adjusted hazard ratio, 0.30; 95% CI, 0.10-0.89).

CONCLUSIONS AND RELEVANCE

In this cohort study, receipt of MOUD was associated with reduced mortality after hospitalization for injection drug use-associated endocarditis only in the month it was received. Efforts to improve MOUD initiation and retention after IDU-IE hospitalization may be beneficial.

Use of ICD-10 Codes for Identification of Injection Drug Use-Associated Infective Endocarditis Is Nonspecific and Obscures Critical Findings on Impact of Medications for Opioid Use Disorder

Background

No International Classification of Diseases, 10th revision (ICD-10), diagnosis code exists for injection drug use–associated infective endocarditis (IDU-IE). Instead, public health researchers regularly use combinations of nonspecific ICD-10 codes to identify IDU-IE; however, the accuracy of these codes has not been evaluated.

Methods

We compared commonly used ICD-10 diagnosis codes for IDU-IE with a prospectively collected patient cohort diagnosed with IDU-IE at Barnes-Jewish Hospital to determine the accuracy of ICD-10 diagnosis codes used in IDU-IE research.

Results

ICD-10 diagnosis codes historically used to identify IDU-IE were inaccurate, missing 36.0% and misclassifying 56.4% of patients prospectively identified in this cohort. Use of these nonspecific ICD-10 diagnosis codes resulted in substantial biases against the benefit of medications for opioid use disorder (MOUD) with relation to both AMA discharge and all-cause mortality. Specifically, when data from all patients with ICD-10 code combinations suggestive of IDU-IE were used, MOUD was associated with an increased risk of AMA discharge (relative risk [RR], 1.12; 95% CI, 0.48–2.64). In contrast, when only patients confirmed by chart review as having IDU-IE were analyzed, MOUD was protective (RR, 0.49; 95% CI, 0.19–1.22). Use of MOUD was associated with a protective effect in time to all-cause mortality in Kaplan-Meier analysis only when confirmed IDU-IE cases were analyzed (P = .007).

Conclusions

Studies using nonspecific ICD-10 diagnosis codes for IDU-IE should be interpreted with caution. In the setting of an ongoing overdose crisis and a syndemic of infectious complications, a specific ICD-10 diagnosis code for IDU-IE is urgently needed.

National Public Health Burden Estimates of Endocarditis and Skin and Soft-Tissue Infections Related to Injection Drug Use: A Review

BACKGROUND

Despite concerns about the burden of the bacterial and fungal infection syndromes related to injection drug use (IDU), robust estimates of the public health burden of these conditions are lacking. The current article reviews and compares data sources and national burden estimates for infective endocarditis (IE) and skin and soft-tissue infections related to IDU in the United States.

METHODS

A literature review was conducted for estimates of skin and soft-tissue infection and endocarditis disease burden with related IDU or substance use disorder terms since 2011. A range of the burden is presented, based on different methods of obtaining national projections from available data sources or published data.

RESULTS

Estimates using available data suggest the number of hospital admissions for IE related to IDU ranged from 2900 admissions in 2013 to more than 20 000 in 2017. The only source of data available to estimate the annual number of hospitalizations and emergency department visits for skin and soft-tissue infections related to IDU yielded a crude estimate of 98 000 such visits. Including people who are not hospitalized, a crude calculation suggests that 155 000-540 000 skin infections related to IDU occur annually.

DISCUSSION

These estimates carry significant limitations. However, regardless of the source or method, the burden of disease appears substantial, with estimates of thousands of episodes of IE among persons with IDU and at least 100 000 persons who inject drugs (PWID) with skin and soft-tissue infections annually in the United States. Given the importance of these types of infections, more robust and reliable estimates are needed to better quantitate the occurrence and understand the impact of interventions.

Tracking Substance Use Complications: A Collaborative Analysis of Public Health and Academic Medical Center Records on Drug Use-Associated Infective Endocarditis

BACKGROUND

Healthcare systems and public health agencies use different methods to measure the impact of substance use (SU) on population health. We studied the ability of systems to accurately capture data on drug use-associated infective endocarditis (DUA-IE).

METHODS

We conducted a retrospective analysis of patients with IE discharge diagnosis from an academic medical center, 2011-2017, comparing data from hospital Electronic Health Record (EHR) to State Uniform Hospital Discharge Data Set (UHDDS). To identify SU we developed a composite measure.

RESULTS

EHR identified 472 IE discharges (430 of these were captured in UHDDS); 406 (86.0%) were correctly coded based on chart review. IE discharges increased from 57 to 92 (62%) from 2012 to 2017. Hospitalizations for the subset of DUA-IE identified by any measure of SU increased from 10 to 54 (440%). Discharge diagnosis coding identified 128 (60.7%) of total DUA-IE hospitalizations. The composite measure identified an additional 65 (30.8%) DUA-IE hospitalizations and chart review an additional 18 (8.5%).

CONCLUSIONS

The failure of discharge diagnosis coding to identify DUA-IE in 40% of hospitalizations demonstrates the need for better systems to capture the impact of SU. Collaborative data sharing could help improve surveillance responsiveness to address an emerging public health crises.

Positive Predictive Values of 2 Algorithms for Identifying Patients with Intravenous Drug Use-Associated Endocarditis Using Administrative Data

Background

Prior studies have used International Classification of Disease (ICD) diagnosis codes in administrative data to identify patients with infective endocarditis (IE) associated with intravenous drug use (IVDU). Little is known about the accuracy of ICD codes for IVDU-IE.

Methods

We used 2 previously described algorithms to identify patients with potential IVDU-IE admitted to 125 Veterans Administration hospitals from January 2010 through December 2018. Algorithm A identified patients with concurrent ICD-9/10 codes for IE and drug use during the same admission. Algorithm B identified patients with drug use coded either during the IE admission or during outpatient or other visits within 6 months of admission. We reviewed 400 randomly selected patient charts to determine the positive predictive value (PPV) of each algorithm for clinical documentation of IE, any drug use, IVDU, and IVDU-IE, respectively.

Results

Algorithm A identified 788 patients, and B identified 1314 patients, a 68% increase. PPVs were high for clinical documentation of diagnoses of IE (86.5% for A and 82.6% for B) and any drug use (99.0% and 96.3%). PPVs were lower for documented IVDU (74.5% and 64.1%) and combined diagnoses of IVDU-IE (65.0% and 55.2%), partly because of a lack of ICD codes specific to IVDU. Among patients identified by algorithm B but not A, 72% had clinical documentation of drug use during the IE admission, indicating a failure of algorithm A to capture cases due to incomplete recording of inpatient ICD codes for drug use.

Conclusions

There is need for improved algorithms for IVDU-IE surveillance during the ongoing opioid epidemic.

Validity of ICD-based algorithms to estimate the prevalence of injection drug use among infective endocarditis hospitalizations in the absence of a reference standard

BACKGROUND

International Classification of Diseases (ICD) code algorithms are routinely used to estimate the frequency of illicit injection drug use (IDU)-associated hospitalizations in administrative health datasets despite a lack of evidence regarding their validity. We aimed to measure the sensitivity and specificity of ICD code algorithms used to estimate the prevalence of current/recent IDU among infective endocarditis (IE) hospitalizations without a reference standard.

METHODS

We reviewed medical records of 321 patients aged 18-64 years old from an urban academic hospital with an IE diagnosis between 2007 and 2017. Diagnostic tests for IDU included self-reported IDU in medical records; a drug use, abuse and dependence (UAD) ICD algorithm; a Hepatitis C Virus (HCV) ICD algorithm; and a combination drug UAD/HCV ICD algorithm. Sensitivity, specificity and the misclassification error (ME)-adjusted IDU prevalence were estimated using Bayesian latent class models.

RESULTS

The combination algorithm had the highest sensitivity and lowest specificity. Sensitivity increased for the drug UAD algorithm in the ICD-10 period compared to the ICD-9 period. The ME-adjusted current/recent IDU prevalence estimated using the drug UAD and HCV algorithms was 23 % (95 % Bayesian credible interval: 16 %, 31 %). The unadjusted prevalence estimate from the drug UAD algorithm underestimated the ME-adjusted prevalence, while the combination algorithm overestimated it.

CONCLUSION

The validity of ICD code algorithms for IDU among IE hospitalizations is imperfect and differs between ICD-9 and ICD-10. Commonly used ICD-based algorithms could lead to substantially biased prevalence estimates in IDU-associated hospitalizations when using administrative health data.

Hydromorphone and the risk of infective endocarditis among people who inject drugs: a population-based, retrospective cohort study

BACKGROUND

The incidence of infective endocarditis related to injection drug use is increasing. On the basis of clinical practice and epidemiological and in-vitro data, we postulated that exposure to controlled-release hydromorphone is associated with an increased risk of infective endocarditis among people who inject drugs.

METHODS

We used linked health administrative databases in Ontario, Canada, to assemble a retrospective cohort of adults (aged 18-55 years) who inject drugs for the period of April 1, 2006, to Sept 30, 2015. Cases of infective endocarditis among this cohort were identified using International Classification of Diseases 10 codes. We estimated exposure to hydromorphone and risk of infective endocarditis among this cohort in two ways. First, in a population-level analysis, we identified patients living in regions with high (≥25%) and low (≤15%) hydromorphone prescription rates and, after matching 1:1 on various baseline characteristics, compared their frequency of infective endocarditis. Second, in a patient-level analysis including only those with prescription drug data, we identified those who had filled prescriptions (ie, received the drug from the pharmacy) for controlled-release or immediate-release hydromorphone and, after matching 1:1 on various baseline characteristics, compared their frequency of infective endocarditis with that of patients who had filled prescriptions for other opioids.

RESULTS

Between April 1, 2006, and Sept 30, 2015, 60 529 patients had evidence of injection drug use, 733 (1·2%, 95% CI 1·1-1·3) of whom had infective endocarditis. In the population-level analysis of 32 576 matched patients, we identified 254 (1·6%) admissions with infective endocarditis in regions with high hydromorphone use and 113 (0·7%) admissions in regions with low use (adjusted odds ratio [OR] 2·2, 95% CI 1·8-2·8, p<0·0001). In the patient-level analysis of 3884 matched patients, the frequency of infective endocarditis was higher among patients who filled prescriptions for hydromorphone than among those who filled prescriptions for non-hydromorphone opioids (2·8% [109 patients] vs 1·1% [41 patients]; adjusted OR 2·5, 95% CI 1·8-3·7, p<0·0001). This significant association was seen for controlled-release hydromorphone (3·9% [73 of 1895 patients] vs 1·1% [20 of 1895]; adjusted OR 3·3, 95% CI 2·1-5·6, p<0·0001), but not for immediate-release hydromorphone (1·8% [36 of 1989] vs 1·1% [21 of 1989]; 1·7, 0·9-3·6, p=0·072.

INTERPRETATION

Among people who inject drugs, the risk of infective endocarditis is significantly higher for those exposed to controlled-release hydromorphone than to other opioids. This association might be mediated by the controlled-release mechanism and should be the subject of further investigation.

FUNDING

Ontario Ministry of Health and Long-Term Care, Academic Medical Organization of Southwestern Ontario, Schulich School of Medicine and Dentistry (Western University), and Lawson Health Research Institute.

The risk of infective endocarditis among people who inject drugs: a retrospective, population-based time series analysis

BACKGROUND

Infective endocarditis is an increasingly common complication among people who inject drugs. We conducted this study to determine whether the removal of traditional controlled-release oxycodone from the Canadian market would be associated with an increase in the use of hydromorphone and an increased risk of infective endocarditis.

METHODS

We conducted a retrospective, population-based time series analysis using the linked health administrative databases of Ontario, Canada. We measured the quarterly risk of admissions for infective endocarditis related to injection drug use and changes in opioid prescription rates from 2006 to 2015. We set the intervention point at the fourth quarter of 2011, when traditional controlled-release oxycodone was removed from the Canadian market.

RESULTS

We observed an increase in the risk of admissions for infective endocarditis related to injection drug use during the study period. Before the intervention point, we observed a mean of 13.4 admissions per quarter, and after the intervention, we observed a mean of 35.1 admissions per quarter. However, no significant change in this risk occurred at the intervention point. Rather, the risk of infectious endocarditis appeared to have increased earlier and in parallel with the rise in hydromorphone prescriptions. Hydromorphone represented 16% of all opioid prescriptions at the start of the observation period and 53% by the end.

INTERPRETATION

The risk of infective endocarditis related to injection drug use is increasing and is temporally associated with increasing prescriptions for hydromorphone. This relation warrants further exploration.

Touchpoints - Opportunities to predict and prevent opioid overdose: A cohort study

BACKGROUND

Medical care, public health, and criminal justice systems encounters could serve as touchpoints to identify and intervene with individuals at high-risk of opioid overdose death. The relative risk of opioid overdose death and proportion of deaths that could be averted at such touchpoints are unknown.

METHODS

We used 8 individually linked data sets from Massachusetts government agencies to perform a retrospective cohort study of Massachusetts residents ages 11 and older. For each month in 2014, we identified past 12-month exposure to 4 opioid prescription touchpoints (high dosage, benzodiazepine co-prescribing, multiple prescribers, or multiple pharmacies) and 4 critical encounter touchpoints (opioid detoxification, nonfatal opioid overdose, injection-related infection, and release from incarceration). The outcome was opioid overdose death. We calculated Standardized Mortality Ratios (SMRs) and Population Attributable Fractions (PAFs) associated with touchpoint exposure.

RESULTS

The cohort consisted of 6,717,390 person-years of follow-up with 1315 opioid overdose deaths. We identified past 12-month exposure to any touchpoint in 2.7% of person-months and for 51.8% of opioid overdose deaths. Opioid overdose SMRs were 12.6 (95% CI: 11.1, 14.1) for opioid prescription and 68.4 (95% CI: 62.4, 74.5) for critical encounter touchpoints. Fatal opioid overdose PAFs were 0.19 (95% CI: 0.17, 0.21) for opioid prescription and 0.37 (95% CI: 0.34, 0.39) for critical encounter touchpoints.

CONCLUSIONS

Using public health data, we found eight candidate touchpoints were associated with increased risk of fatal opioid overdose, and collectively identified more than half of opioid overdose decedents. These touchpoints are potential targets for development of overdose prevention interventions.

Trends in Drug Use-Associated Infective Endocarditis and Heart Valve Surgery, 2007 to 2017: A Study of Statewide Discharge Data

Background

Drug use-associated infective endocarditis (DUA-IE) is increasing as a result of the opioid epidemic. Infective endocarditis may require valve surgery, but surgical treatment of DUA-IE has invoked controversy, and the extent of its use is unknown.

Objective

To examine hospitalization trends for DUA-IE, the proportion of hospitalizations with surgery, patient characteristics, length of stay, and charges.

Design

10-year analysis of a statewide hospital discharge database.

Setting

North Carolina hospitals, 2007 to 2017.

Patients

All patients aged 18 years or older hospitalized for IE.

Measurements

Annual trends in all IE admissions and in IE hospitalizations with valve surgery, stratified by patients' drug use status. Characteristics of DUA-IE surgical hospitalizations, including patient demographic characteristics, length of stay, disposition, and charges.

Results

Of 22 825 IE hospitalizations, 2602 (11%) were for DUA-IE. Valve surgery was performed in 1655 IE hospitalizations (7%), including 285 (17%) for DUA-IE. Annual DUA-IE hospitalizations increased from 0.92 to 10.95 and DUA-IE hospitalizations with surgery from 0.10 to 1.38 per 100 000 persons. In the final year, 42% of IE valve surgeries were performed in patients with DUA-IE. Compared with other surgical patients with IE, those with DUA-IE were younger (median age, 33 vs. 56 years), were more commonly female (47% vs. 33%) and white (89% vs. 63%), and were primarily insured by Medicaid (38%) or uninsured (35%). Hospital stays for DUA-IE were longer (median, 27 vs. 17 days), with higher median charges ($250 994 vs. $198 764). Charges for 282 DUA-IE hospitalizations exceeded $78 million.

Limitation

Reliance on administrative data and billing codes.

Conclusion

DUA-IE hospitalizations and valve surgeries increased more than 12-fold, and nearly half of all IE valve surgeries were performed in patients with DUA-IE. The swell of patients with DUA-IE is reshaping the scope, type, and financing of health care resources needed to effectively treat IE.

Primary Funding Source

National Institutes of Health.