Skip to content

Modified Clavien Dindo Classification Essay

1. Herrmann TR, Bach T, Imkamp F, et al. Thulium laser enucleation of the prostate (ThuLEP): transurethral anatomical prostatectomy with laser support. Introduction of a novel technique for the treatment of benign prostatic obstruction. World J Urol. 2010;28:45–51. doi: 10.1007/s00345-009-0503-0.[PubMed][Cross Ref]

2. Mishriki SF, Grimsley SJ, Nabi G, Cohen NP. Partners agree that the treatment of LUTS reduces patients’ bother and improves their quality of life: prospective 12 years follow-up study. World J Urol. 2010;28:123–132. doi: 10.1007/s00345-009-0449-2.[PubMed][Cross Ref]

3. Lourenco T, Armstrong N, N’Dow J, et al. Systematic review and economic modelling of effectiveness and cost utility of surgical treatments for men with benign prostatic enlargement. Health Technol Assess. 2008;12:1–516.[PubMed]

4. Rassweiler J, Teber D, Kuntz R, Hofmann R. Complications of transurethral resection of the prostate (TURP)-incidence, management, and prevention. Eur Urol. 2006;50:969–980. doi: 10.1016/j.eururo.2005.12.042.[PubMed][Cross Ref]

5. Reich O, Gratzke C, Bachmann A, et al. Morbidity, mortality and early outcome of transurethral resection of the prostate: a prospective multicenter evaluation of 10, 654 patients. J Urol. 2008;180:246–249. doi: 10.1016/j.juro.2008.03.058.[PubMed][Cross Ref]

6. Holtgrewe HL, Valk WL. Factors influencing the mortality and morbidity of transurethral prostatectomy: a study of 2, 015 cases. J Urol. 1962;87:450–459.[PubMed]

7. Melchior J, Valk WL, Foret JD, Mebust WK. Transurethral prostatectomy: computerized analysis of 2, 223 consecutive cases. J Urol. 1974;112:634–642.[PubMed]

8. Mebust WK, Holtgrewe HL, Cockett AT, Peters PC. Transurethral prostatectomy: immediate and postoperative complications. A cooperative study of 13 participating institutions evaluating 3, 885 patients. J Urol. 1989;141:243–247.[PubMed]

9. Clavien PA, Sanabria JR, Strasberg SM. Proposed classification of complications of surgery with examples of utility in cholecystectomy. Surgery. 1992;111:518–526.[PubMed]

10. Dindo D, Demartines N, Clavien PA. Classification of surgical complications: a new proposal with evaluation in a cohort of a 6336 patients and results of a survey. Ann Surg. 2004;240:205–213. doi: 10.1097/01.sla.0000133083.54934.ae.[PMC free article][PubMed][Cross Ref]

11. Morgan M, Smith N, Thomas K, Murphy D. Is Clavien the new standard for reporting urological complications? BJU Int. 2009;4:434–439. doi: 10.1111/j.1464-410X.2009.08516.x.[PubMed][Cross Ref]

12. Mamoulakis C, Trompetter M, la Rosette J. Bipolar transurethral resection of the prostate: the “golden standard” reclaims its leading position. Curr Opin Urol. 2009;19:26–32. doi: 10.1097/MOU.0b013e328320a61a.[PubMed][Cross Ref]

13. Mamoulakis C, Ubbink DT, la Rosette JJ. Bipolar versus monopolar transurethral resection of the prostate: a systematic review and meta-analysis of randomized controlled trials. Eur Urol. 2009;56:798–809. doi: 10.1016/j.eururo.2009.06.037.[PubMed][Cross Ref]

14. Donat SM. Standards for surgical complication reporting in urologic oncology: time for a change. Urology. 2007;69:221–225. doi: 10.1016/j.urology.2006.09.056.[PubMed][Cross Ref]

15. Graefen M. The modified Clavien system: a plea for a standardized reporting system for surgical complications. Eur Urol. 2010;57:387–389. doi: 10.1016/j.eururo.2009.12.020.[PubMed][Cross Ref]

16. Novara G, Ficarra V, D’Elia C, et al. Prospective evaluation with standardized criteria for postoperative complications after robotic-assisted laparoscopic radical prostatectomy. Eur Urol. 2010;57:363–370. doi: 10.1016/j.eururo.2009.11.032.[PubMed][Cross Ref]

17. Carlsson S, Nilsson AE, Schumacher MC et al. (2009) Surgery-related complications in 1253 robot-assisted and 485 open retropubic radical prostatectomies at the Karolinska University Hospital, Sweden. Urology [Epub ahead of print] [PubMed]

18. Constantinides CA, Tyritzis SI, Skolarikos A, et al. Short- and long-term complications of open radical prostatectomy according to the Clavien classification system. BJU Int. 2009;103:336–340. doi: 10.1111/j.1464-410X.2008.08080.x.[PubMed][Cross Ref]

19. Stolzenburg JU, Rabenalt R, Do M, et al. Endoscopic extraperitoneal radical prostatectomy: the University of Leipzig experience of 2000 cases. J Endourol. 2008;22:2319–2325. doi: 10.1089/end.2008.9714.[PubMed][Cross Ref]

20. Pruthi RS, Nielsen ME, Nix J, et al. Robotic Radical Cystectomy for bladder cancer: surgical and pathological outcomes in 100 consecutive cases. J Urol. 2010;183:510–515. doi: 10.1016/j.juro.2009.10.027.[PubMed][Cross Ref]

21. Ng CK, Kauffman EC, Lee MM, et al. A comparison of postoperative complications in open versus robotic cystectomy. Eur Urol. 2010;57:274–282. doi: 10.1016/j.eururo.2009.06.001.[PubMed][Cross Ref]

22. Kauffman EC, Ng CK, Lee MM, et al. Critical analysis of complications after robotic-assisted radical cystectomy with identification of preoperative and operative risk factors. BJU Int. 2009;105:520–527. doi: 10.1111/j.1464-410X.2009.08843.x.[PubMed][Cross Ref]

23. Novara G, Marco V, Aragona M, et al. Complications and mortality after radical cystectomy for bladder transitional cell cancer. J Urol. 2009;182:914–921. doi: 10.1016/j.juro.2009.05.032.[PubMed][Cross Ref]

24. Hautmann RE, Petriconi R, Volkmer BG. Neobladder formation after pelvic irradiation. World J Urol. 2009;27:57–62. doi: 10.1007/s00345-008-0346-0.[PubMed][Cross Ref]

25. Laguna MP, Beemster P, Kumar P, et al. Perioperative morbidity of laparoscopic cryoablation of small renal masses with ultrathin probes: a European multicentre experience. Eur Urol. 2009;56:355–361. doi: 10.1016/j.eururo.2009.05.002.[PubMed][Cross Ref]

26. Wezel F, Mamoulakis C, Rioja J, et al. Two contemporary series of percutaneous tract dilation for percutaneous nephrolithotomy. J Endourol. 2009;23:1655–1661. doi: 10.1089/end.2009.0213.[PubMed][Cross Ref]

27. la Rosette JJ, Zuazu JR, Tsakiris P, et al. Prognostic factors and percutaneous nephrolithotomy morbidity: a multivariate analysis of a contemporary series using the Clavien classification. J Urol. 2008;180:2489–2493. doi: 10.1016/j.juro.2008.08.025.[PubMed][Cross Ref]

28. Tefekli A, Ali Karadag M, Tepeler K, et al. Classification of percutaneous nephrolithotomy complications using the modified Clavien grading system: looking for a standard. Eur Urol. 2008;53:184–190. doi: 10.1016/j.eururo.2007.06.049.[PubMed][Cross Ref]

29. Hemal AK, Mishra S. Retroperitoneoscopic nephrectomy for pyonephrotic nonfunctioning kidney. Urology. 2010;75:585–588. doi: 10.1016/j.urology.2008.07.054.[PubMed][Cross Ref]

30. Rassweiler JJ, Teber D, Frede T, et al. Complications of laparoscopic pyeloplasty. World J Urol. 2008;26:539–547. doi: 10.1007/s00345-008-0266-z.[PubMed][Cross Ref]

3.EVIDENCE SYNTHESIS

3.1.Systems used to report surgical complications

The systematic review of the literature for standardised systems used for reporting and classification of surgical complications revealed five standardised systems (Table 3).

Table 3: Available classification systems for reporting of complications

Classification

Clinical validation

Simplicity

Severity grading

Clavien-Dindo

Yes

Easy

I-V

MSKCC

Yes

Easy

5

Accordion

contracted

extended

No

Easy

4

5

NSQIP

Yes

Complex

Major/minor

NCT-CTC

Yes

Complex

5

MSKCC=Memorial Sloan-Kettering Cancer Centre classification - modification of the original T92 Clavien classification [9,14]; NSQIP=National Surgical Quality Improvement Programme [3]; NCT-CTC=National Cancer Institute Common Toxicity Criteria [15].

In 1992, Clavien et al. proposed a classification for complications of surgery and introduced a severity

grading system called T92 [10], which was based on the main criterion of the intervention needed to resolve the complication. Four grades containing five levels of complications were described. In 2004, Dindo et al. introduced a modification of the T92 classification using five grades containing seven levels (Table 2) [11]. This modification was performed to add further precision and to characterise whether an intervention due to the complication led to general anaesthesia, intensive care unit admission, or organ failure, and again, it was based on the type of therapy required to treat the complication. This modified classification, which is known as the Clavien-Dindo system, was validated and tested for interobserver variation in 10 centres around the world [14]. The Clavien-Dindo system is widely used, with an exponential increase in recent years, especially in general surgery but also in urology (see Fig. 3 and 4). A few authors have adapted both systems to analyse specific procedures such as living donor liver and kidney transplantation, which has led to confusion [14].

A less extensive modification of the T92 system was made by Martin et al. [9,16] and is referred to as the Memorial Sloan-Kettering Cancer Centre (MSKCC) severity grading system. Conceptually, it is very similar to T92 but differs in numbering (for details see Table 1 in Strasberg et al. [17]).

The Accordion classification was introduced in 2009 and represents a flexible system that can be used in studies of different size and complexity [15] (Table 4). It is available on an open Website (http://www.accordionclassification.wustl.edu).

Table 4: Accordion severity classification of postoperative complications: contracted and expanded classification [15]

Contracted classification

Expanded classification

1.Mild complication

Requires only minor invasive procedures that can be done at the bedside, such as insertion of intravenous lines, urinary catheters and nasogastric tubes, and drainage of wound infections. Physiotherapy and the following drugs are allowed: antiemetics, antipyretics, analgesics, diuretics and electrolytes.

2.Moderate complication

Requires pharmacological treatment with drugs other than those allowed for minor complications, for example, antibiotics. Blood transfusions and total parenteral nutrition are also included.

3.Severe complication

All complications requiring endoscopic or interventional radiology or re-operation, as well as complications resulting in failure of one or more organ systems.

4.Death

Postoperative death

1.Mild complication

Requires only minor invasive procedures that can be done at the bedside, such as insertion of intravenous lines, urinary catheters and nasogastric tubes, and drainage of wound infections. Physiotherapy and the following drugs are allowed: antiemetics, antipyretics, analgesics, diuretics and electrolytes.

2.Moderate complication

Requires pharmacological treatment with drugs other than those allowed for minor complications, for example, antibiotics. Blood transfusions and total parenteral nutrition are also included.

3.Severe: invasive procedure without general anaesthesia.

Requires management by an endoscopic, interventional procedure or re-operation* without general anaesthesia.

4.Severe: operation under general anaesthesia

Requires management by an operation under general anaesthesia.

5.Severe: organ system failure †

6.Death

Postoperative death

*An example would be wound re-exploration under conscious sedation and/or local anaesthetic.

†Such complications would normally be managed in an increased acuity setting but in some cases patients with complications of lower severity might also be admitted to an ICU.

The National Surgical Quality Improvement Program was established in 1994 within the US Veterans

Administration (VA) health care system, with the aim of identifying and reporting adverse events as one prerequisite for process improvement in health care [3]. The system is validated, outcome based, and uses data adjusted for patient preoperative risk. It allows comparison of the performance of different hospitals performing major surgery by the ratio of observed to expected (O/E) adverse events. Statistically low (O/E < 1) or high (O/E > 1) outliers are then identified to support continuous quality improvement activities. The annual use of this system has contributed to the improvement of the standard of surgical care and to lower 30-day mortality and morbidity rates for major non-cardiac surgery within the VA.

The National Cancer Institute Common Toxicity Criteria (NCI-CTC) system [15] was first created in 1983, aimed at the recognition and grading of adverse effects of chemotherapy in cancer patients. The system was updated and expanded in 1998 (CTC v2.0), including acute effects of radiotherapy and limited criteria applicable to surgery. In 2003, Common Terminology Criteria for Adverse Events (CTCAE v3.0) was introduced for application to all possible modalities and is organised by organ system categories (all organs are included), with 370 different criteria. An adverse event is defined as any new finding or undesirable event that may not be attributed to treatment. Grading criteria are shown in Table 5. Late and acute effects criteria are merged into a single uniform system and applied without a predetermined time-based designation. The previously used “90-day rule” is not advised currently because each study is unique. The new CTC system was designed to be applied to all possible modalities, and it is organised by organ system categories (all organs are included) with 370

different criteria. The unexpected serious and life-threatening (grades 3 and 4) consequences of surgery are the focus of immediate surgical reporting. CTCAE v3.0 is available on the Cancer Therapy Evaluation Program Website (www.ctep.info.nih.gov).

Table 5: National Cancer Institute Common Toxicity Criteria grading system for the adverse effects of cancer treatment [15]

Grade

Definition of effects

Grade 1

Minimal and usually asymptomatic effects that do not interfere with functional endpoints (interventions or medications are generally not indicated for these minor effects).

Grade 2

Moderate, are usually symptomatic. Interventions such as local treatment or medications may be indicated (they may interfere with specific functions but not enough to impair activities of daily living).

Grade 3

Severe and very undesirable. There are usually multiple, disruptive symptoms (more serious interventions, including surgery or hospitalisation, may be indicated).

Grade 4

Potentially life threatening, catastrophic, disabling, or result in loss of organ, organ function, or limb.

Most recently, the International Urogynecological Association (IUGA) and the International Continence Society (ICS) have established a joint working group on terminology for complications related to the insertion of prostheses and grafts in female pelvic floor surgery [18]. The document proposes definitions of specific complications, distinguishing local complications, complications to surrounding organs, and systemic complications. New terms have been proposed and defined in detail such as contraction, prominence, separation, exposure, extrusion, perforation, dehiscence, and sinus tract formation. The classification is based on category, time, and site of complications, with the aim of summarising any of a large range of possible clinical scenarios into a code using as few as three numerals and three (or four) letters. Lowercase letters can be added, describing the presence and the type of pain. The ICS-IUGA classification appears at first sight to be complex and not immediately mastered, as outlined by the proponents. The main goal is to establish common

language and to promote a homogeneous registry to improve the quality of pelvic floor surgical procedures using prostheses and grafts.

3.2.Attitude of urologists towards reporting complications

A total of 874 eligible papers of 1261 retrieved publications were included in the final analysis. The type of studies reporting complications did not vary between the two time frames selected (1999-2000 vs 2009-2010) (p > 0.1). Most of the papers identified were case studies (Fig. 1). However, a shift could be seen in the number of studies using most of the Martin criteria (Fig. 2), as well as in the number of studies using either standardised criteria or the Clavien-Dindo system to report complications (Fig. 3).

Fig. 1: Comparative distribution of papers reporting complications after urologic procedures by study type and time frame

Fig. 2: Comparative distribution of papers reporting complications after urologic procedures by number of Martin criteria met and time frame

Fig. 3: Comparative distribution of papers reporting complications after urologic procedures by time frame and whether standardised criteria were used (left), and in case they were, whether the Clavien-Dindo system was used (right)

3.3.Assessment of the Clavien-Dindo system for reporting complications after urologic procedures

The literature search identified 204 papers published in:

  • Urology 38
  • Journal of Urology 37
  • Journal of Endourology 35
  • European Urology 34
  • BJU International 19
  • World Journal of Urology 15
  • and several others 26

The number of papers using the Clavien-Dindo system to report complications after urologic surgical

interventions showed an exponential increase (Fig. 4). Most of the studies identified were, again, case series,and 77.9% of the studies fulfilled > 7 of the Martin criteria (range: 3-10; mean: 7.5; standard deviation: 1.5). The vast majority of papers referred to novel technologies (laparoscopy/robot-assisted procedures), whereas only 13.2% of papers discussed open procedures. The Clavien-Dindo system was not properly used in 72 papers (35.3%): Eight times it was also used to report/grade intraoperative complications; six times the authors used their own modification of the Clavien-Dindo system; in 27 studies, the authors grouped complications into major (Clavien-Dindo > 3) and minor without mentioning specific complications; and in 31 papers, the authors did not assign a grade to the complications reported.

Fig. 4: Distribution of studies using the Clavien-Dindo system to report complications after urologic procedures

3.4.Discussion

The definition of surgical complications still lacks standardisation, which hampers the interpretation of surgical performance and quality assessment [5,7,19]. Although many surgeons would argue that their subjective intuition is an appropriate guide to defining what a complication might be, the value of the surgeon’s intuition is unreliable in many situations because it lacks objective criteria and depends heavily on the experience of the individual clinician [4,7,20]. Second, a surgical complication is not a fixed reality. Instead, it depends on the surgeon’s level of skill, the surgeon’s learning curve for the procedure, the patient’s comorbidity and risk factors, and the facilities available. A surgical complication in a Western country may not be perceived or subjectively weighted as a surgical complication in rural or less developed countries. Similarly, a complication

in 2016 may be seen as obsolete in a few years’ time, with a better understanding of the pathophysiology of the underlying malady. As surgical techniques and equipment improve, what were once inevitable negative outcomes may acquire the status of mere surgical complications [2,5,7]. Finally, and paradoxically, the higher the expectation of the surgeon and patient, the more potential surgical complications occur [21,22]. The clinical relevance of reporting surgical complications is primarily related to the fact that the dissemination of technology is very rapid, with current grades of recommendations based on the level of evidence in their corresponding studies. However, in the surgical field, randomised controlled trials with high levels of evidence are uncommon, and this limitation naturally leads to a low number of recommendations. We have to keep in mind that the guidelines can only rely on the surgical evidence. Thus there is a real discrepancy between the reality of daily surgical practice and the relevance of the low-grade recommendations produced in this area. However, the scientific quality of an article is not only related to its level of evidence. The use of more rigorous methodology and the consensus-related complications of surgical techniques will probably improve the quality of the surgical scientific literature. It is likely that this improvement will renew interest in daily clinical practice in the minds of surgeons. In addition, it will allow recommendations that avoid complications, clearly the most

relevant issue in improving patient care.

In defining surgical complications, subjectivity cannot always be avoided, but it should be reduced as much as possible [4]. Additionally, different audiences (e.g. patients, nurses, health care providers, and third-party payers) and different surgical communities (e.g. urologists, orthopaedists, and vascular surgeons) view, define, and perceive complications differently. Currently, no generally accepted standards or definitions exist with regard to the severity of surgical complications. Clavien-Dindo recommended the following definitions of surgical outcomes:

1.Surgical complication: any deviation from the ideal postoperative course that is not inherent in the procedure and does not comprise a failure to cure.

2.Failure to cure: diseases or conditions that remained unchanged after surgery.

3.Sequelae: conditions that are inherent in a procedure and thus would inevitably occur, such as scar formation or the inability to walk after an amputation.

Based on the review of the current literature, and with reference to the Accordion Severity Grading System [17], an appropriate definition of a complication is a combination of the following items: an event unrelated to the purposes of the procedure, an unintended result of the procedure, an event occurring in temporal proximity to the procedure, something causing a deviation from the ideal postoperative course, an event that induces a change in management, or something that is morbid (i.e. causes suffering directly by causing pain, or indirectly, by subjecting the patient to additional interventions).

In contrast to a complication, the sequelae of a procedure should be defined as an after-effect of that

procedure. The risk of sequelae is inherent in the procedure (e.g. diabetes after pancreatic resection, rejection after transplantation, limp after amputation, dyspnoea after pneumonectomy, or impairment of renal function after tumour nephrectomy). Failure to cure should be defined as failure to attain or maintain the purpose of the procedure (e.g. failure to remove all stones during ureteroscopy or percutaneous stone surgery, tumour recurrence, stricture recurrence, or recurrence of patency when the purpose of the procedure is to occlude). Sequelae of procedures and failures to cure should be reported but presented separately from complications [14].

However, a complication that results in lasting disability is considered a sequela of a complication. Stroke or acute renal failure (ARF) occurring after a procedure is considered a complication and should be reported as such. However, long-term aphasia resulting from stroke or chronic renal failure after ARF is considered a sequela of that complication. Therefore, it should be reported in a special section devoted specifically to long term disability.

Patients and their treating physicians do not necessarily mean the same thing when they use the term complication. Several studies have shown substantial discrepancies in the reporting of adverse events and sequelae of a treatment when the estimations of patients and physicians are compared [21]. The usual information on potential complications that patients can obtain before a surgical procedure can be taken from the available literature, the specific information given by the treating centre (i.e. home page or patient information brochures), or from direct discussion with the treating surgeon. This information has the potential to be biased from the definition of what is considered a complication, and a standardised system that is not only used for complication reports in the literature but also for patient counselling is important for a realistic estimation of outcomes. In the present literature, patients often report a higher frequency and severity of adverse events compared with that reported by their physicians [23]. However, in a recent randomised study, Steinsvik et al. showed that several adverse events, such as bowel problems, were overrated by the physician

[24]. Overrating and especially underrating of complications by the treating physician leads to confusion and a discrepancy between patient expectation and reality.

Schroeck et al. evaluated variables associated with satisfaction and regret after open and robotic radical prostatectomy [22]. Patients who underwent robotic-assisted laparoscopic prostatectomy were more likely to be regretful and dissatisfied, which was not necessarily interpreted as caused by a worse outcome but potentially caused by the higher expectation associated with an innovative procedure. The authors therefore suggested that urologists should carefully portray the risks and benefits of new technologies during preoperative counselling to minimise regret and maximise satisfaction.

These examples support the notion that realistic counselling is crucial for the patient’s decision-making process and for satisfaction with the achieved result. However, a standardised reporting system for surgical complications can only try to standardise the reporting of the intraoperative and perioperative morbidity of the procedure itself. Short-, mid- or long-term sequelae of a surgical procedure, such as erectile dysfunction or urinary incontinence following radical prostatectomy, are not covered by this classification and need to be reported with other validated tools.

Standardised classification and severity grading of surgical complications is essential for proper interpretation of surgical outcome data, for comparing the surgical outcomes between institutions or individual surgeons, and for comparing techniques in case randomised trials are either lacking or difficult to perform (i.e. comparison of minimally invasive techniques with open surgery). The urologic community seems to conform to the current demands because recent studies have more often used standardised criteria to report complications (48.3% vs. 35.3%) (Fig. 3). In urologic oncology reports published from January 1995 to December 2005, the corresponding percentage was 33%, with only 19% (6% of the total) using a numerical complication severity grading system [12]. The Clavien-Dindo system has gained wide acceptance both in general surgery [14] and the urologic community (Fig. 3, and Fig. 4). Clinical databases designed and controlled by physicians may underreport complications [25]. Similarly, a disadvantage of the Clavien-Dindo system is its unreliability when recording is performed by residents, although, when captured, grading of complications was correct in 97% of the cases. Consequently, the authors have proposed that dedicated personnel should evaluate surgical outcomes [2]. Special attention should also be paid to proper use of the Clavien-Dindo system because it has not been designed/validated to grade intraoperative complications, and any modifications and revisions can be confusing [14].

Classification and severity grading of surgical complications is important, albeit not the only criterion of quality when reporting surgical outcome. Approximately 40% of general surgery series and trials and 23% of studies reporting surgical complications in urologic oncology [2] fulfil seven or more Martin criteria. Interestingly, 77.9% of the papers that used the Clavien-Dindo system to report complications after urologic procedures fulfilled seven or more criteria, implying that its use contributes to higher quality reports.

Besides the efficiency of an individual surgeon and the function of an institution, surgical care outcomes also depend on the patient’s preoperative risk factors [26]. Thus they should always be defined and used in the analysis and report. A substantial proportion of postoperative complications occur after hospital discharge [27]; extension of the length of postoperative observation may therefore be necessary. Other quality-of-care indicators are readmissions and reoperations [28] and should be included in both preliminary and final reports.

5.REFERENCES

1.Bertges, D.J., et al. Toward optimal recording of surgical complications: concurrent tracking compared to the discharge data set. Surgery, 2007. 141: 19.

http://www.ncbi.nlm.nih.gov/pubmed/17188164

2.Dindo, D., et al. Quality assessment in surgery: riding a lame horse. Ann Surg, 2010. 251: 766.

http://www.ncbi.nlm.nih.gov/pubmed/20224375

3.Fink, A.S., et al. The National Surgical Quality Improvement Program in non-veterans administration hospitals: initial demonstration of feasibility. Ann Surg, 2002. 236: 344.

http://www.ncbi.nlm.nih.gov/pubmed/12192321

4.Clavien, P.A., et al. Surgeon’s intuition: is it enough to assess patients’ surgical risk?
World J Surg, 2007. 31: 1909.

http://www.ncbi.nlm.nih.gov/pubmed/17661189

5.Sokol, D.K., et al. What is a surgical complication? World J Surg, 2008. 32: 942.

http://www.ncbi.nlm.nih.gov/pubmed/18266027

6.Veen, M.R., et al. Recording and classification of complications in a surgical practice.
Eur J Surg, 1999. 165: 421.

http://www.ncbi.nlm.nih.gov/pubmed/10391156

7.Dindo, D., et al. What is a surgical complication? World J Surg, 2008. 32: 939.

http://www.ncbi.nlm.nih.gov/pubmed/18414942

8.Xylinas, E., et al. Evaluation of combined oncologic and functional outcomes after robotic-assisted laparoscopic extraperitoneal radical prostatectomy: trifecta rate of achieving continence, potency and cancer control. Urol Oncol, 2013. 31: 99.

http://www.ncbi.nlm.nih.gov/pubmed/21719321

9.Martin, R.C., et al. Quality of complication reporting in the surgical literature. Ann Surg, 2002. 235: 803.

http://www.ncbi.nlm.nih.gov/pubmed/12035036

10.Clavien, P.A., et al. Proposed classification of complications of surgery with examples of utility in cholecystectomy. Surgery, 1992. 111: 518.

http://www.ncbi.nlm.nih.gov/pubmed/1598671

11.Dindo, D., et al. 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.

http://www.ncbi.nlm.nih.gov/pubmed/15273542

12.Donat, S.M. Standards for surgical complication reporting in urologic oncology: time for a change.
Urology, 2007. 69: 221.

http://www.ncbi.nlm.nih.gov/pubmed/17320654

13.Mitropoulos, D., et al. Reporting and grading of complications after urologic surgical procedures: an ad hoc EAU guidelines panel assessment and recommendations. Eur Urol, 2012. 61: 341.

http://www.ncbi.nlm.nih.gov/pubmed/22074761

14.Clavien, P.A., et al. The Clavien-Dindo classification of surgical complications: five-year experience.
Ann Surg, 2009. 250: 187.

http://www.ncbi.nlm.nih.gov/pubmed/19638912

15.Trotti, A., et al. CTCAE v3.0: development of a comprehensive grading system for the adverse effects of cancer treatment. Semin Radiat Oncol, 2003. 13: 176.

http://www.ncbi.nlm.nih.gov/pubmed/12903007

16.Kooby, D.A., et al. Impact of steatosis on perioperative outcome following hepatic resection.
J Gastrointest Surg, 2003. 7: 1034.

http://www.ncbi.nlm.nih.gov/pubmed/14675713

17.Strasberg, S.M., et al. The accordion severity grading system of surgical complications. Ann Surg, 2009. 250: 177.

http://www.ncbi.nlm.nih.gov/pubmed/19638919

18.Haylen, B.T., et al. An International Urogynecological Association (IUGA)/International Continence Society (ICS) joint terminology and classification of the complications related directly to the insertion of prostheses (meshes, implants, tapes) and grafts in female pelvic floor surgery. Neurourol Urodyn, 2011. 30: 2.

http://www.ncbi.nlm.nih.gov/pubmed/21181958

19.Bruce, J., et al. The measurement and monitoring of surgical adverse events. Health Technol Assess, 2001. 5: 1.

http://www.ncbi.nlm.nih.gov/pubmed/11532239

20.Graefen, M. The modified Clavien system: a plea for a standardized reporting system for surgical complications. Eur Urol, 2010. 57: 387.

http://www.ncbi.nlm.nih.gov/pubmed/20022421

21.Sanda, M.G., et al. Quality of life and satisfaction with outcome among prostate-cancer survivors.
N Engl J Med, 2008. 358: 1250.

http://www.ncbi.nlm.nih.gov/pubmed/18354103

22.Schroeck, F.R., et al. Satisfaction and regret after open retropubic or robot-assisted laparoscopic radical prostatectomy. Eur Urol, 2008. 54: 785.

http://www.ncbi.nlm.nih.gov/pubmed/18585849

23.Litwin, M.S., et al. Quality-of-life outcomes in men treated for localized prostate cancer. JAMA, 1995. 273: 129.

http://www.ncbi.nlm.nih.gov/pubmed/7799493

24.Steinsvik, E.A., et al. Do perceptions of adverse events differ between patients and physicians? Findings from a randomized, controlled trial of radical treatment for prostate cancer. J Urol, 2010. 184: 525.

http://www.ncbi.nlm.nih.gov/pubmed/20620412

25.Gunnarsson, U., et al. Registration and validity of surgical complications in colorectal cancer surgery. Br J Surg, 2003. 90: 454.

http://www.ncbi.nlm.nih.gov/pubmed/12673748

26.Rodkey, G.V., et al. Evaluation of healthcare quality: a tale of three giants. Am J Surg, 2009. 198: S3.

http://www.ncbi.nlm.nih.gov/pubmed/19874932

27.Bilimoria, K.Y., et al. Effect of postdischarge morbidity and mortality on comparisons of hospital surgical quality. Ann Surg, 2010. 252: 183.

http://www.ncbi.nlm.nih.gov/pubmed/20531000

28.Morris, A.M., et al. Reoperation as a quality indicator in colorectal surgery: a population-based analysis. Ann Surg, 2007. 245: 73.

http://www.ncbi.nlm.nih.gov/pubmed/17197968

6.CONFLICT OF INTEREST

All members of the ad hoc EAU Guidelines working panel on Reporting and Grading of Complications after Urologic Surgical Procedures have provided disclosure statements on all relationships that they have that might be perceived to be a potential source of a conflict of interest. This information is publically accessible through the European Association of Urology website: http://www.uroweb.org/guidelines/. This guidelines document was developed with the financial support of the European Association of Urology. No external sources of funding and support have been involved. The EAU is a non-profit organisation, and funding is limited to administrative assistance and travel and meeting expenses. No honoraria or other reimbursements have been provided.