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Journal of Vascular and Interventional Radiology

Adverse events (AEs) in medicine are a well-known potential cause of injury to patients (1Brennan T.A. Leape L.L. Laird N.M. et al.Incidence of adverse events and negligence in hospitalized patients. Results of the Harvard Medical Practice Study I.N Engl J Med. 1991; 324: 370-376Crossref PubMed Google Scholar). It is certainly not a new phenomenon; however, interest increased considerably after the Institute of Medicine (IOM) published their report in 2000, “To Err Is Human: Building a Health System” (2Institute of MedicineTo err is human: building a health system. National Academies Press, Washington, DC2000Google Scholar), which exposed the magnitude of the consequences and recommended systematic reporting, analysis, and prevention. The IOM report drew upon a large study where 30,121 randomly selected patient charts were reviewed; AEs occurred in 3.7% of all patients. Of these AEs, 2.6% resulted in permanent disability and 13.6% resulted in death (1Brennan T.A. Leape L.L. Laird N.M. et al.Incidence of adverse events and negligence in hospitalized patients. Results of the Harvard Medical Practice Study I.N Engl J Med. 1991; 324: 370-376Crossref PubMed Google Scholar). A follow-up study showed that the most common subtypes of AEs were related to drug administration (19%), wound infections (14%), and technical factors (13%), and nearly half (48%) were associated with a surgical operation (3Leape L.L. Brennan T.A. Laird N. et al.The nature of adverse events in hospitalized patients - results of the Harvard Medical Practice Study II.N Engl J Med. 1991; 324: 377-384Crossref PubMed Google Scholar). Documenting and grading AEs in a structured, systematic, and reproducible method is a crucial component of measuring quality in patient care and the first step in its improvement. Between 1997 and 2003, the Society of Interventional Radiology (SIR) developed its own classification system for AEs in interventional radiology (IR) (4Sacks D. McClenny T.E. Cardella J.F. Lewis C.A. Society of Interventional Radiology clinical practice guidelines.J Vasc Interv Radiol. 2003; 14: S199-S202Abstract Full Text Full Text PDF PubMed Scopus (1231) Google Scholar). Although its simplicity made it user-friendly, simplicity also contributed to its flaws. Specifically, it was incomplete in evaluating certain AEs, did not facilitate instructive postevent analysis or evaluation of preventability, and lacked comparability with AE classification systems of collaborating specialties. For example, Degirmenci et al (5Degirmenci T. Gunlusoy B. Kozacioglu Z. et al.Utilization of a modified Clavien classification system in reporting complications after ultrasound-guided percutaneous nephrostomy tube placement: comparison to standard Society of Interventional Radiology practice guidelines.Urology. 2013; 81: 1161-1167Abstract Full Text Full Text PDF PubMed Google Scholar) demonstrated that the SIR classification fell short in the assessment of AEs from ultrasound-guided, percutaneous nephrostomies compared with the modified Clavien-Dindo classification system used in surgery, and a survey study by Leoni et al (6Leoni C.J. Potter J.E. Rosen M.P. Brophy D.P. Lang E.V. Classifying complications of interventional procedures: a survey of practicing radiologists.J Vasc Interv Radiol. 2001; 12: 55-59Abstract Full Text Full Text PDF PubMed Google Scholar) found moderate rates of disagreements among interventional radiologists in their interpretation. These studies and others demonstrated that the old AE classification system by SIR allowed too much opportunity for subjectivity and lacked the capacity to include adequate detail (7Khalilzadeh O. Baerlocher M.O. Shyn P.B. et al.Proposal of a new adverse event classification by the Society of Interventional Radiology Standards of Practice Committee.J Vasc Interv Radiol. 2017; 28: 1432-1437.e3Abstract Full Text Full Text PDF PubMed Scopus (331) Google Scholar). In response to critical evaluation of the original classification system, SIR published a proposal for a new, modified AE classification system in 2017 (7Khalilzadeh O. Baerlocher M.O. Shyn P.B. et al.Proposal of a new adverse event classification by the Society of Interventional Radiology Standards of Practice Committee.J Vasc Interv Radiol. 2017; 28: 1432-1437.e3Abstract Full Text Full Text PDF PubMed Scopus (331) Google Scholar). An international group of 18 members of the SIR Standards of Practice Committee developed the proposal after reviewing the most widely adopted AE classification systems in use and the US Office for Human Research Protections (8Office for Human Research Protections; Department of Health and Human ServicesReviewing and Reporting Unanticipated Problems Involving Risks to Subjects or Others and Adverse Events: OHRP Guidance.https://www.hhs.gov/ohrp/regulations-and-policy/guidance/reviewing-unanticipated-problems/index.htmlDate: 2007Date accessed: August 21, 2022Google Scholar) and Food and Drug Administration (FDA) (9US Department of Health and Human Services; Food and Drug AdministrationGuidance for Clinical Investigators, Sponsors, and IRBs. Adverse Event Reporting to IRBs—Improving Human Subject Protection.https://www.fda.gov/media/72267/downloadDate accessed: August 21, 2022Google Scholar) reporting guidelines. Twelve hypothetical AE scenarios were used to test the new classification via a survey study of practicing interventional radiologists. Survey questions tested various aspects of the new classification, including the unambiguity, consistency, and educational value, among other factors. The survey successfully validated the new classification system. The published proposal was confusing, listing the old system in Table 1 and the new system in the Appendix (7Khalilzadeh O. Baerlocher M.O. Shyn P.B. et al.Proposal of a new adverse event classification by the Society of Interventional Radiology Standards of Practice Committee.J Vasc Interv Radiol. 2017; 28: 1432-1437.e3Abstract Full Text Full Text PDF PubMed Scopus (331) Google Scholar), misleading many investigators to continue using the old system. The newer system has been in use for 5 years and has been accepted widely enough that it should no longer be considered a proposal. The current modified SIR AE classification system has 2 parts: A (description) and B (analysis). Part A (Table 1) entails description of the AE and grading of the severity, reflecting the required actions to address the AE and the subsequent outcomes. Part A is particularly relevant for the dissemination of scientific information, such as in publications and presentations. Part B (Table 2) provides a systematic structure for analysis of the AE, designed to be used for internal and confidential quality improvement programs.Table 1The Society of Interventional Radiology AE Classification System, 2017 Modification, Part APart A: AE descriptionA. Description narrative of AE (including sedation and anesthesia)B. AE severity assessment∗: escalation of level of care1.Mild AE: No therapy or nominal (nonsubstantial) therapy (postprocedural imaging performed and fails to show manifestation of AE); near miss (eg, wrong site of patient prepared, recognized and corrected before procedure, wrong patient information entered for procedure)2.Moderate AE: moderate escalation of care, requiring substantial treatment, eg, intervention (description of intervention and result of intervention) under moderate sedation, blood product administration, extremely prolonged outpatient observation, or overnight admission after outpatient procedure not typical for the procedure (excludes admission or hospital days unrelated to AE)3.Severe AE: marked escalation of care, ie, hospital admission or prolongation of existing hospital admission for >24 hours, hospital admission that is atypical for the procedure, inpatient transfer from regular floor/telemetry to intensive care unit, or complex intervention performed requiring general anesthesia in previously nonintubated patient (generally excludes pediatrics or in circumstances in which general anesthesia would primarily be used in lieu of moderate sedation, eg, in mentally challenged or severely uncooperative patients)4.Life-threatening or disabling event: eg, cardiopulmonary arrest, shock, organ failure, unanticipated dialysis, paralysis, or loss of limb or organ5.Patient death or unexpected pregnancy abortionAll AEs occurring within 30 days of a procedure should be included in the AE description and analysis, regardless of causality, in the interest of objectivity. The AE scale itself does not assess operator performanceNote–A marker of “M” is used to indicate multiple AEs, each of which is counted and evaluated separately if possible.Source–Khalilzadeh O, Baerlocher MO, Shyn PB, et al. Proposal of a new adverse event classification by the Society of Interventional Radiology Standards of Practice Committee. J Vasc Interv Radiol 2017; 28:1432–1437.e3.AE = adverse event. Open table in a new tab Table 2The Society of Interventional Radiology AE Classification System, 2017 Modification, Part BPart B: AE analysisA. Causality Category 1: AE not caused by the procedure Category 2: Unknown whether AE was caused by the procedure Category 3: AE caused by the procedureB. Patient and procedural risk modifier Category 1: High-risk patient and technically challenging procedure Category 2: High-risk patient (eg, American Society of Anesthesiologists status 4, uncorrectable coagulopathy, poor functional status [Eastern Cooperative Oncology Group performance status of 3/4], polypharmacy/polyintravenous therapy and transfusion, septicemia, hemodynamic instability, recent catastrophic event/intensive care unit admission/ major surgery or interventions) or low-risk patient and technically challenging procedure (eg, transjugular intrahepatic portosystemic shunt with occluded portal vein, percutaneous biliary drain placement in nondilated biliary system) Category 3: No modifierC. AE preventability Category 1: Rarely preventable, ie, well-described and “typical” for the procedure and occurring despite adequate precautionary and preventive measures Category 2: Potentially preventable Category 3: Consistently preventable, eg, inappropriateness of procedural indication (may use checklist; see further)D. AE management Category 1: Most operators would have handled the AE similarly Category 2: Some operators would have handled the AE differently Category 3: Most operators would have handled the AE differentlySource–Khalilzadeh O, Baerlocher MO, Shyn PB, et al. Proposal of a new adverse event classification by the Society of Interventional Radiology Standards of Practice Committee. J Vasc Interv Radiol 2017; 28:1432–1437.e3.AE = adverse event. Open table in a new tab Note–A marker of “M” is used to indicate multiple AEs, each of which is counted and evaluated separately if possible. Source–Khalilzadeh O, Baerlocher MO, Shyn PB, et al. Proposal of a new adverse event classification by the Society of Interventional Radiology Standards of Practice Committee. J Vasc Interv Radiol 2017; 28:1432–1437.e3. AE = adverse event. Source–Khalilzadeh O, Baerlocher MO, Shyn PB, et al. Proposal of a new adverse event classification by the Society of Interventional Radiology Standards of Practice Committee. J Vasc Interv Radiol 2017; 28:1432–1437.e3. AE = adverse event. The current modified classification system is similar to the Clavien-Dindo surgical complication classification system and comparable with the National Cancer Institute Common Terminology Criteria of Adverse Events scale (version 4.03 at the time of the proposal for modification of the SIR AE classification system) (10US Department of Health and Human Services, National Institutes of Health, National Cancer Institute Common Terminology Criteria for Adverse Events (CTCAE) v4.03.Google Scholar), but it is customized to be specific to IR. There are no longer classifications for major or minor AEs, but mild, moderate, severe, life-threatening/disabling, and fatal instead. Besides allowing for greater granularity and more interobserver consistency, an additional objective of the current modification was to improve harmonization with the Clavien-Dindo classification system. This is particularly relevant when an IR procedure is being studied as a potential replacement or alternative to a surgical procedure. The current modified SIR AE classification has facilitated these IR to surgery comparisons. The Cardiovascular and Interventional Radiology Society of Europe (CIRSE) classification system is similarly structured with minor differences from the SIR system, including being graded 1 through 6 with further nuance regarding permanent disability (11Filippiadis D.K. Binkert C. Pellerin O. et al.Cirse quality assurance document and standsrds for classification of complications: the cirse classification system.Cardiovasc Intervent Radiol. 2017; 40: 1141-1146Crossref PubMed Scopus (332) Google Scholar). Ideally, a comprehensive AE system should be developed that could be applied to all specialties. Because disease states are subject to an increasingly wide variety of competing potential treatment approaches, a universal AE classification system applicable to all areas of medicine would proffer a powerful research tool to facilitate more objective and useful comparisons between treatments. There is ongoing debate and inconsistency in the use of the terms “adverse event,” “complication,” and, to a lesser extent, “error.” The 2000 IOM report defined an adverse event as “an injury caused by medical management, rather than the underlying condition of the patient” (2Institute of MedicineTo err is human: building a health system. National Academies Press, Washington, DC2000Google Scholar). The report also clarified that an AE attributable to error is a “preventable AE.” Although all AEs result from medical management, not all are preventable (ie, not all are attributable to errors). Likewise, not all errors result in AEs. The term “complication” encompasses a myriad of sometimes contradictory definitions and is not specific to medical management. For instance, ascites may be a complication of untreated cirrhosis but is not an AE in this situation. Ascites may also be a complication of hepatic radioembolization, where it is also an AE. Therefore, SIR and the Journal of Vascular and Interventional Radiology recommend using the more specific term “AE” rather than “complication” when reporting outcomes of interventions. It should be reiterated that AEs do not on their own imply fault or any element of negligence, incompetence, or malpractice, and the SIR AE classification system does not assess an operator's performance. For example, percutaneous lung biopsies carry an expected pneumothorax rate of 12%–45% and an expected rate of severe pneumothorax requiring chest tube drainage of 2%–15% (12Gupta S. Wallace M.J. Cardella J.F. et al.Quality improvement guidelines for percutaneous needle biopsy.J Vasc Interv Radiol. 2010; 21: 969-975Abstract Full Text Full Text PDF PubMed Scopus (230) Google Scholar). Similarly, percutaneous ablation of lung tumors carries an expected rate of pneumothorax requiring chest tube drainage of 7%–47% (13Genshaft S.J. Suh R.D. Abtin F. et al.Society of Interventional Radiology Quality Improvement Standards on percutaneous ablation of non-small cell lung cancer and metastatic disease to the lungs.J Vasc Interv Radiol. 2021; 32: 1242.e1-1242.e10Abstract Full Text Full Text PDF PubMed Google Scholar). Poor performance of these procedures may result in preventable AEs, but pneumothorax may occur even when standard of care is provided. In addition, AEs may be related to the procedure or the device, rather than the proceduralist. For instance, transjugular placement of an inferior vena cava filter may result in cardiac ectopy from traversal of the right atrium with guide wires and devices, an AE intrinsic to the procedure. Fracture, penetration, or migration of the filter may be intrinsically related to the device. In summary, the modification to the SIR AE classification system proposed in 2017 (7Khalilzadeh O. Baerlocher M.O. Shyn P.B. et al.Proposal of a new adverse event classification by the Society of Interventional Radiology Standards of Practice Committee.J Vasc Interv Radiol. 2017; 28: 1432-1437.e3Abstract Full Text Full Text PDF PubMed Scopus (331) Google Scholar) reflected a considerable improvement in comprehensiveness, reproducibility of stratification, instructive capacity, and compatibility with other classification systems when compared with the initial proposal from 2003. Its implementation in the last 5 years has met with general approval, with improved standardization of reporting. Because it was developed of, for, and by interventional radiologists, its use in clinical practice and research in the IR field should be considered the current standard, and it should be considered the default system for studies submitted to and published in the Journal of Vascular and Interventional Radiology.

Adverse Event Classification: Clarification and Validation of the Society of Interventional Radiology Specialty–Specific System