34th Annual Scientific Meeting proceedings

Introduction
Despite good surgical technique and the presence of skilled surgeons, post-surgical complications remain one of the most difficult parts of patient management, and as such, are often an emotive topic. However, postoperative complications are important outcome measures in studies of surgical procedures. The demand for improvement in veterinary healthcare delivery has been consistently increasing, with a proportionately expanding focus on accurate reporting, shared decision-making and informed client consent. This renders it critical that a standardised method allowing quality assessment of data is developed, which will also allow comparison between various institutions over time.

The levels of evidence were originally described in a report by the Canadian Task Force on the Periodic Health Examination in 1979, but these have been progressively modified over time.  The most recent modification, by the Centre for Evidence Based Medicine places systematic reviews (+/- meta-analyses) of randomised controlled trials at the top of this table. While randomised controlled trials may not be as commonly performed in veterinary medicine as in the human field, it is noteworthy that when cohort studies make their appearance in this table, still, the level of evidence is highest when a systematic review +/- meta-analysis of cohort studies is performed. The same trend is true for case-control studies. Meta-analyses take their place at the top of the pyramid of evidence due to their ability to consolidate previous evidence published in multiple previous reports. They act as powerful tools to cumulate and summarise knowledge.

Consistent reporting of primary studies is essential for a high-quality and reliable meta-analysis. It ensures that the necessary data is readily available and understandable, allowing for effective synthesis and analysis of the existing research evidence. As most of this audience will understand, comparing results across different studies where a variety of methods of reporting have been used, can become incredibly difficult, and likely, inaccurate.

In the human field, many attempts were made to classify surgical complications before 1990 however, none of those attempts gained popularity and acceptance. A standardised method of classification of surgical complications was proposed by Clavien et al in 1992 which is known as the T92 system or Clavien classification of surgical complications (Dindo et al 2004). In 2004, Clavien, along with Dindo, revised the basic T92 model which was later named as the “Clavien-Dindo Classification” or CDC. In 2012, Sink adapted the Clavien-Dindo system for use in hip-preservation surgery (Sink et al 2012). They used five grades, based on the treatment that the complication required and its long-term morbidity, and included specific examples of hip-related complications for each grade. The Clavien-Dindo-Sink system demonstrated high interrater and intrarater reliability for grading complications following hip-preservation surgery. That system has routinely been used in studies evaluating complications following hip-preservation surgery and has been applied to total knee arthroplasty. A modified version of the Clavien-Dindo-Sink classification system has also been shown to have good interrater and excellent intrarater reliability for the evaluation of complications more generally, such as following pediatric orthopedic upper extremity, lower extremity, and spine surgery (Dodwell et al 2018). Martin then made minor modifications to the Clavien-Dindo Classification (CDC) system, which came to be known as the Memorial Sloan Kettering (MSKCC) Severity Grading System (Strong et al 2015).

The Accordion Severity Grading System of surgical complications was described by Strasberg et al. in 2009. The grading system is complex in nature and can expand the range of complications in complex studies. The contracted classification had four levels, whereas the expanded classification had six levels. The proposed time horizon for recording complications was extended to 100 days after the surgical procedure (Strasberg et al 2009). The comprehensive complication index (CCI) was defined in 2013 by Slankamenac (2013). The authors focused on the fact that the Clavien-Dindo classification system only graded the single most severe complication that occurred in the patient, thus ignoring the less severe events. This fails to represent the true overall “morbidity” after surgery. The authors thus adopted the “operation risk index” approach for developing the mathematical formula of CCI. They combined the complications according to the severity into a single score from 0 to 100. This helps to measure a cluster of complications at a given period of time (Slankamenac et al 2013). In 2015, the “Japan Clinical Oncology Group” aimed to standardise the terms for defining adverse events as per the Clavien-Dindo Classification system. The criteria were defined based on extensive research, done by nine surgical specialties, in which they specified the complications commonly experienced in their field (Katayama et al 2016). Every classification system has its own advantages and disadvantages.

Within the veterinary field, only three postoperative complication classification schemes have been used with any frequency or evaluated. These include the Cook classification system (Cook et al 2010), a modified Clavien-Dindo classification (Barrett et al 2023), and the simple classification of complications as major or minor based upon the requirement for revision surgery. One of the major reasons to consider the use of the modified Clavien-Dindo classification is the ability of this scheme to distinguish complications from outcomes, however, the inclusion of these has been shown to reduce the reliability of this system when it is employed in the veterinary field (Barrett et al 2023). When outcomes including “sequalae” and “failure to cure” were excluded, this system was more reliable than the Cook classification, but then this is removing one of the key advantages. None of these schemes have been universally adopted, nor was the veterinary surgery community at large given an opportunity to contribute to the development of these. As such, it appears that further work is necessary to identify a scheme that will be accepted by all.  

This represents only a very brief summary of the research within the human and veterinary fields on this topic and serves to show that it will likely not be a straightforward process to identify a classification scheme that will be appropriate for all studies and appreciated by all individuals. However, adoption of a reproducible, reliable system as a standard of reporting complications in surgery could be a valuable tool for improving surgical practices and, most importantly, patient outcomes. Given the potential advantages that a consistent classification system could have, a group of surgeons decided to take the first steps in a process that we hope others will join, in creating a consistent scheme that can be tailored to individual species and disciplines while still ensuring consistency of reporting and the iterative improvement of the veterinary evidence base over time. 

Methodology
The specific aims of this study were:

• To establish perceptions regarding the most commonly used postoperative complication classification scheme
• To establish perceptions of how minor, major and catastrophic postoperative complications should be defined
• To obtain perspectives on whether additional subcategories of complications should be included, and why
• To survey opinion as to whether veterinary surgeons would support the enforcement of use of a newly established postoperative complication classification scheme

Participant Recruitment
The study cohort consisted of both ECVS and ACVS practicing surgeons and residents, or those that had previously been in practice. Participation was voluntary. An introductory email was sent to all registered ECVS surgeons and residents including a link to the questionnaire. The same introductory text and link was placed on the ACVS Facebook page and was also distributed via ortholistserv. The researchers were blinded to participant identity.

Questionnaires
Quantitative data were collected through multiple choice questions, while qualitative data were collected through a series of short-answer questions. A total of 10 questions were asked.

Quantitative Analysis
Quantitative results were presented as percentages out of the number of individuals that responded to that particular question.

Thematic Analysis
The answers to the short answer questions were analysed using the principles of thematic analysis from the standpoint of Braun and Clarke (2006). The data was analysed from an essentialist perspective. Analysis was theoretical, meaning that it was driven by the theoretical or analytic interest in the area aiming to give a detailed analysis of themes which resemble the research question.

Results and Discussion

Quantitative Analysis
The total number of responses was 207. The percentage of respondents that answered each question ranged from 59% to 100%.

ECVS/ACVS residents represented 53/207 respondents (25.6%) while the remainder were diplomats or residency-trained surgeons.

When asked which complication scheme respondents currently used, 82/207 (39.61%) stated that they used the Cook classification scheme (2010), 56/207 (27.05%) reported that they classified complications as major or minor depending upon the requirement for revision surgery and 32/207 (15.46%) reported that they used variable schemes depending upon the associated manuscript and results. Twenty-eight out of 207 respondents (13.53%) stated that they did not use a classification scheme.

Qualitative Analysis
Theoretical saturation appeared to have been reached as for all short-answer questions, during qualitative analysis, no new themes or insights emerged from the last 10 responses received.

Seven themes were identified through analysis:

1. Benefits associated with a widely accepted classification system are widely, but not universally, appreciated
2. Limitations and lack of consensus associated with the Cook Classification
3. Importance of Education
4. While additional stratification is largely considered beneficial, there were also concerns that this could impact on widespread use and consistency of use
5. Specificity will be key
6. Limitations of subjective language and their impact on reliability
7. Importance of adopting a respected process to establishing any new scheme and involving all key stakeholders

In the presentation we will discuss these themes in the context of the available literature, illustrate them with salient quotations and identify proposed next steps in this important process.

References

1. The periodic health examination. Canadian Task Force on the Periodic Health Examination. Can Med Assoc J 1979;121:1193–1254. 
2. Centre for Evidence Based Medicine. [Accessed December 17, 2010]; Available at  http://www.cebm.net
3. Dindo D, Demartines N, Clavien PA: Classification of surgical complications: a new proposal with evaluation in a cohort of 6336 patients and results of a survey. Ann Surg 2004, 240:205-213.
4. Sink EL, Leunig M, Zaltz I, Gilbert JC, Clohisy J; Academic Network for Conservational Hip Outcomes Research Group. Reliability of a complication classification system for orthopaedic surgery. Clin Orthop Relat Res 2012 Aug;470(8):2220-6. 
5. Dodwell ER, Rubini P, Widmann RF, Green DW, Scher DM, et al. Reliability of the modified Clavien-Dindo-Sink Complication Classification System in Pediatric Orthopaedic Surgery. JBJS Open Access 2018;3(4):p e0020.
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11. Barrett FM, Bleedorn, JA, Hutcheson KD, Torres BT, Fox DB. Comparison of two postoperative complication grading systems after treatment of stifle and shoulder instability in 68 dogs. Vet Surg 2023;52:98-105.
12. Braun V, Clarke V. Using thematic analysis in psychology. Qualitative Research in Psychology 2006;3:77-101.