Author + information
- Anusha G. Bhat, MD∗ (, )
- Sudeep K. Siddappa Malleshappa, MD and
- Deepak K. Pasupula, MD
- ↵∗Department of Internal Medicine, Baystate Medical Center, 759 Chestnut Street, Springfield, Massachusetts 01199
We read the work of Rudasill et al. (1) with great interest. The authors did an admirable job in studying the outcomes of infective endocarditis (IE) among injection drug users (IDU). Epidemiological studies indeed are valuable in representing the disease burden in society, and therefore, identifying the appropriate cohort is quintessential. While reviewing the study, we developed curiosity and uncertainty about the methodology. First, the authors did not provide the specifics of the International Classification of Diseases-9th Revision-Clinical Modulation (ICD-9) used to recognize the diagnosis and procedures linked to “injected illicit drugs which included cocaine, heroin, or methamphetamine.” Additionally, they mentioned having adopted an algorithm developed by Cooper et al. (2) in 2007, which was created to identify IDU and strengthened by the use of hepatitis C infection ICD code to increase the sensitivity and specificity of identifying IDU, which was not considered in the current study. Although patients abusing the aforementioned drugs are at higher risk for IDU, it does not exclude other modalities (inhalation, ingestion, and smoking). Moreover, the ICD codes for substance abuse have never been validated to accurately identify the proportion of substance abusers (includes all the drugs with different modes of abuse) using these drugs intravenously. Therefore, generalizing the aforementioned drugs to have been used intravenously will falsely skew results, which can be especially concerning in national databases.
Second, the ICD-9 codes used to define IE would probably fail to capture all the IE patient population, because the validated IE ICD codes include 036.42, 098.84, 112.81, 115.04, 115.14, or 115.94, in addition to those used in this study (3). One of these codes identifies “candidial IE” and is a strong indication for surgical intervention by itself (3). These defects in methodology would concern for underestimation of the at-risk population.
Addressing these points will undoubtedly improve the reliability of the data presented and increase the creditability of the study.
Please note: The authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- 2019 American College of Cardiology Foundation
- Rudasill S.E.,
- Sanaiha Y.,
- Mardock A.L.,
- et al.
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