Surgical Complications and Their Repercussions

Abstract

Purpose:

Surgical complications have a significant impact on intended quality of care. The aim of our study was to identify factors that contribute to the propagation of additional postoperative complications.

Materials and Methods:

Over a 1-year period, we prospectively identified and retrospectively reviewed data on all patients who experienced a surgical complication within 30 days of their procedure. A complication was defined as any deviation from the expected postoperative course and was described using the Clavien–Dindo classification. Data reviewed included length of stay (LOS), Clavien grade, readmission status, and management of the complication. Surgeries were stratified into retroperitoneal, pelvic, and endoscopic procedures. The association between complications and Clavien grade was measured using Spearman rank-order correlation. The probability of subsequent complications and readmission was measured using exact logistic regression.

Results:

Of the 4414 patients who underwent a urologic procedure, 191 (4.3%) had at least one complication. One hundred thirty-four (70%) of these patients had more than one complication, 84 (44%) had more than three complications, and 12 (6.3%) had up to a seventh complication. LOS was affected by the severity of the initial complication. Patients with initial Clavien grades 1, 2, 3a, 3b, and 4 had an LOS of 3.75, 4.17, 4.21, 4.94, and 8.58 days, respectively. Variables associated with the risk of developing a second complication included diabetes mellitus, longer operative times (OR 1.83), and greater estimated blood loss (OR 1.32).

Conclusions:

Surgical patients with an initial complication are at higher risk for multiple subsequent postoperative complications. Complications are associated with an extended LOS and higher readmission rates. Diabetes, longer operative time, and greater blood loss were identified as risk factors for multiple complications.

Introduction

Technological and procedural advances in surgery have allowed modern surgeons to perform increasingly complex procedures with minimal added morbidity to patients. Despite these improvements, surgical complications continue to occur and have a deleterious effect on recovery time, quality of life, surgical costs, and potentially obligate patients to further treatment. In attempts to minimize preventable complications and improve postoperative care, standardized perioperative protocols have been implemented. The introduction of evidence-based protocols such as those to minimize wound infections and deep venous thrombosis has demonstrated to be effective.^1,2 In addition, postoperative clinical care pathways are crucial in facilitating recovery by relying on well-established perioperative care and anticipated outcomes.³ Unfortunately, when a patient suffers a complication, the expected clinical course is altered, leading to the development of subsequent complications.

Increased national attention on U.S. hospital safety began following the publication of “To Err is Human” in 2000.⁴ Despite inevitable complications associated with surgical procedures, preventable complications have been the focus of safety initiatives, while complication rates have been used to compare the quality of care of healthcare providers.⁵ Since that time, quality improvement literature has evolved to focus on consequences of surgical complications rather than incidence. The concept of failure to rescue (FTR) was introduced into the quality improvement literature in 1992, aiming to assess how well hospital personnel respond to complications once they have occurred.⁶ Furthermore, recent data suggest that the inpatient FTR mortality rate may be increasing following urologic surgery in the United States.⁷ Efforts have been made in prior reports to clarify the clinical course leading to subsequent complications, and therefore halt the propagation of these complications; however, literature pertaining specifically to urologic patients is limited.⁸ This study was undertaken to catalogue, define, and assess risk factors leading to the propagation of postoperative complications. The incidence, severity, and distribution of complications after urologic surgery at a tertiary care center were analyzed, and data were used to determine the complication rate and risk factors for having multiple subsequent complications.

Materials and Methods

Database

After gaining institutional review board (IRB) approval, data from all individuals who underwent urologic surgery at our institution between December 2011 and December 2012 were prospectively collected and retrospectively reviewed for postoperative complications and/or unplanned readmissions within 30 days of their surgical procedure. All patients' clinical courses were examined in detail as part of quality control. Attempts were made to capture all complications by including those that were identified and treated at other institutions when clinical data were available. Complications were defined as any deviation from the expected clinical course. Care was taken to distinguish surgical complications from failures to cure. The severity of complications were classified based on the Clavien–Dindo grading system for analysis.^9,10 Mortality rate was defined as the death rate from any cause within 30 days following the index procedure. Readmissions within 30 days to any inpatient setting were included in the analysis.

Data collection

The clinical records (electronic and/or paper) of all adult patients who experienced a perioperative complication were reviewed. Clinical parameters included perioperative data, the nature of the procedure, length of stay (LOS), Clavien grade of the complication, the treatment modality used for each complication, the total number of complications, and readmission status within 30 days after the procedure. Procedures were stratified into five groups based on the current procedural terminology codes as follows: renal and retroperitoneal surgeries (open/laparoscopic), pelvic surgery (open/laparoscopic), endourologic surgery, prostate biopsy, and others (extracorporeal shockwave lithotripsy, bladder instillations, partial penectomy, etc.).

Statistical analysis

Descriptive statistics were computed for the overall sample (i.e., frequencies and percentages for categorical variables, and means and medians for continuous variables). Associations between the various postoperative complications were assessed by comparison of Clavien grades for each complication. Correlations between Clavien grades were measured using Spearman rank-order correlation. Exact logistic regression was used to model the probability of enduring subsequent complications and identify potential patient-specific variables predictive of future complications. Exact logistic regression was also used to model the probability of readmission with the first postoperative complication, Clavien grade. All statistical tests were done using statistical analysis software (SAS). Statistical significance was defined as p < 0.05.

Results

General demographics

During the study period, there were 4414 adult urologic procedures performed at our institution. Of these, 191 (4.3% of 4414) patients experienced at least one complication (Table 1). The mean age of the cohort was 64 years (range 54–94) and consisted predominantly of men (n = 122). The average body–mass index of our cohort was 28 (range 18–52). There were 520 total complications among the 191 individuals in the final cohort (Table 2). The percentage of patients who had a total of 1, 2, 3, 4, and 5 complications was 30%, 26%, 18%, 9.9%, and 6.8%, respectively. The most frequent Clavien grades encountered during the study period were Clavien grade 1 and 2 (162 and 167 incidences total) (Table 2). There were a total of 135 readmissions during the study period (71% of patients who experienced a complication). As a final outcome, 162 (84%) patients were discharged home, 19 (9.9%) discharged to a rehabilitation facility, and 10 (5.2%) patients died (Table 1).

Table 1.

Patient Demographics, Including Surgery Performed and Outcome

	N = 191
Age, median (IQR)	64 (54–94)
Gender, n (%)
Men	122 (63.8)
Women	69 (36.1)
BMI, median (IQR)	28 (18–52)
Surgery category, n (%)
Endoscopy	97 (50.8)
Laparoscopic/open kidney/retroperitoneal	36 (18.8)
Laparoscopic/open pelvic	31 (16.2)
Other^a	16 (8.4)
Prostate biopsy	11 (5.8)
Final outcome, n (%)
Home	162 (84.8)
Rehabilitation	19 (9.9)
Death	10 (5.2)
ICU visit, n (%)	51 (26.8)
Days in ICU, median (IQR)	0 (0–20)
Readmission, n (%)	135 (71)

Formalin instillation, penile prosthesis, and extracorporeal shock wave lithotripsy.

Table 2.

Chronologic Distribution of Clavien Grade

	Chronologic order of postoperative complication, n (%)
Clavien grade	First	Second	Third	Fourth	Fifth	Sixth	Seventh	Eighth ^a	Nineth ^a
1	68 (35)	44 (33)	24 (29)	10 (21)	7 (24)	4 (25)	3 (25)	2 (33)	—
2	73 (38)	41 (31)	20 (24)	13 (27)	12 (40)	6 (38)	2 (17)	—	—
3a	6 (3)	17 (13)	13 (15)	8 (17)	5 (17)	4 (25)	2 (17)	1 (17)	—
3b	17 (9)	18 (13)	15 (18)	5 (10)	2 (7)	1 (6)	2 (17)	—	1 (33)
4a	26 (14)	10 (7)	8 (9)	10 (21)	1 (4)	—	2 (17)	3 (50)	—
4b	1 (1)	3 (2)	1 (1)	1 (2)	1 (4)	—	—	—	—
5	—	1 (1)	3 (4)	1 (2)	1 (4)	1 (6)	1 (7)	—	2 (67)
Total	191	134	84	48	29	16	12	6	3

Limited to nine postoperative complications.

Bold refers to most common complication grade.

Perioperative parameters

There were a total of 97 endourologic procedures (21 percutaneous nephrolithotomy, 35 ureteroscopies, 10 cystoscopy and ureteral stent placement or exchange, 7 Transurethral Resection of Prostate, 17 transurethral resection of bladder tumor, 3 cystoscopies, 2 internal urethrotomies, 2 suprapubic tube), 36 renal and retroperitoneal surgeries, 31 pelvic surgeries, 11 prostate needle biopsies, and 16 procedures categorized as other (Table 1).

First complication

The most common initial Clavien grade of complication that occurred was Clavien grade 2 (n = 73) and occurred most frequently on postoperative day 0. The Clavien grade for the first complication had a relatively weak, but significant correlation with the Clavien grade for the second complication (r = 0.33, p = 0.0001). In comparison, the Clavien grade of the first complication had a weaker correlation with the Clavien grade of the last postoperative complication (r = 0.22, p = 0.01). Finally, mean LOS was affected by the severity of the initial complication. Patients with an initial complication of Clavien grade 1, 2, 3a, 3b, and 4 had an LOS of 3.75, 4.17, 4.21, 4.94, and 8.58 days, respectively.

Subsequent complications

Of the 191 patients in the final cohort, 134 had two or more postoperative complications (70%). Among these patients, 84 had greater than three complications (44% of entire cohort) and 48 went on to develop four or more complications (25% of entire cohort). Among subjects with at least one postoperative complication, 12 (6.3%) had a seventh complication (Table 2). The most common Clavien grade for the second complication was “Grade 1” (33%). On univariate analysis, the odds of suffering a second complication were highest in patients who underwent retroperitoneal or pelvic surgeries (OR 9.91, p < 0.001 and OR 3.05, p = 0.044, respectively). Diabetes mellitus was found to be significantly associated with the development of a second complication (OR 3.11, p = 0.08). Patients who had higher estimated blood loss (EBL) and longer operative times also had greater odds of developing a second complication (OR 1.32, p = 1.32 and OR 1.83, p < 0.001, respectively).

Predictors of readmission

Using logistic regression analysis, the Clavien grade for the first complication was significantly associated with the odds of readmission (overall p = 0016). Patients with an initial Clavien grade 1 complication were 3.9 times more likely to be readmitted in comparison to Clavien grade 3b. No other comparisons with Clavien grade 1 were significant for odds of readmission (Clavien 2-4b). Individuals whose clinical course ended in death (10) were excluded from analysis (Table 3).

Table 3.

Odds of Readmission by Clavien Grade of Initial Complication

Complication 1 Clavien grade ^a	P	OR (95% CI)
1	Ref	—
2	1	1.1 (0.43–2.62)
3a	1	1.4 (0.13–70.88)
3b	0.03	0.2 (0.06–0.89)
4a	0.05	0.3 (0.09–1)
4b	1	0.3 (0.01–1)

Ten deaths in cohort excluded for analysis.

Bold refers to statistically significant value.

Mortality

The mortality rate for the 191 patients who experienced a complication was 5.2% (10/191). Among these patients, the median age was 74 years (range 60–92). These individuals had initially undergone laparoscopic nephrectomy (4), robotic cystectomy (1), an endourologic procedure (3), partial penectomy (1), and foley catheter exchange (1). Six patients experienced an intraoperative complication and are listed in Table 4. Three of these patients were readmitted after their index procedure. The average number of postoperative complications before death was 3. The median American Society of Anesthesiologists (ASA) score, intraoperative time, and EBL were 3, 170 minutes, and 130 mL, respectively, in comparison to 3, 97 minutes, and 100 mL, respectively, among the rest of the cohort (p > 0.05).

Table 4.

Intraoperative Complications for Patients Who Expired During the Study Period

	Procedure	Intraoperative complication
1	Partial penectomy	Cardiac arrhythmia (ventricular tachycardia)
2	Nephrectomy (XGP kidney)	Hemorrhagic shock
3	Percutaneous nephrolithotomy	Pneumothorax requiring chest tube
4	Radical cystectomy	Septic shock
5	Transurethral resection of bladder tumor	Extraperitoneal bladder perforation
6	Laparoscopic partial nephrectomy	Hemorrhagic shock

Discussion

In the mid 1980s, Six Sigma was introduced in an effort to minimize errors and reduce variability in manufacturing. The Six Sigma methodology sought to improve the quality of process outputs by identifying and removing the causes of errors, while minimizing variability in manufacturing and business processes.¹¹ Accordingly, those processes that operated with “six sigma quality” over the short term were assumed to produce long-term defect levels below 3.4 defects per million opportunities (99.99966% efficient).

The report on medical errors by the Institute of Medicine (IOM) in 2000 indicated that the extent of the problem lay not in individual mistakes, but rather in basic flaws processes.¹ This report was followed by a second IOM report in 2001, which provided potential solutions to improving the delivery of healthcare in the United States.¹ As such, Six Sigma methodology has been applied as a method of optimizing processes to improve efficiency and outcomes in the delivery of healthcare in the United States. Among the options discussed, increased transparency, reduced waste of resources, and greater coordination of care between surgical and medical specialists are noted to be critical in redesigning the system. Above all, the core principle of the intended overhaul was that “patient safety is a system property,” which can only be achieved by creating systems that help prevent and mitigate complications. Indeed, the application of this approach has already been implemented in many operating rooms where the team runs through a standardized checklist of preoperative assessments and postoperative order sets to ensure accuracy and safety in the delivery of surgical treatment.

To implement mitigation processes, it is first crucial to understand the issues being addressed. Although morbidity information is prevalent in the literature, there are limited data on how a complication generates secondary complications and how often this occurs. Furthermore, few studies detail the exact clinical course leading to subsequent complications. Our study sought to explore surgical morbidity from an initial complication onward to determine the underlying characteristics of individuals who developed additional complications. Similar to the concept of Six Sigma, evaluating and preventing the earliest basic flaws or complications in the delivery of surgical care by minimizing variability could improve quality and efficiency by mitigating subsequent complications. Taken one step further, a better understanding of the germinal factors orchestrating the development of urologic complications may assist surgeons in proactively managing them when they do inevitably occur.

Even in the current era of modern medicine where we are at a pinnacle of operative techniques with a clear understanding of the pertinent anatomy, physiology, and pathology, adverse outcomes still persist. In trying to avoid an unwanted surgical outcome, the first step is to identify the problem. Before 1992, surgeons had no standardized reporting system to classify negative surgical outcomes. It was at this time that Clavien et al. retrospectively reviewed the outcomes of 600 cholecystectomies and developed the first broadly used classification system (T92) for surgical complications.¹² It was based on the intervention used rather than the nature of the complication due to the availability of more accurate documentation for the former. In 2004, this “4 grade-5 level” classification system was critically re-evaluated and updated into a “5 grade-7 level” Clavien–Dindo classification system.⁸ The new system improved upon the preceding one by including more accurate documentation of the type of intervention, such as the requirement for use of general anesthesia for surgical intervention and the need for intensive care unit admission. A recent international survey of this classification system assessed it to be simple, useful, and reproducible,⁶ which has resulted in it now being considered the standard in reporting surgical complications.⁴

A primary metric of our current study was to identify which initial complications were most likely to result in subsequent complications and to establish the process of their development. For instance, undergoing a renal/retroperitoneal procedure or having diabetes mellitus was each highly predictive of developing secondary complications. It also revealed that for each hour in the operating room and each 100 mL of intraoperative blood loss, the odds of having a secondary complication increased by 1.8 and 1.3 times, respectively (Table 5). In addition, individuals with a lower graded initial complication had a shorter overall LOS. However, a higher graded initial complication was less likely to require a subsequent readmission (p < 0.03) (Table 3). This is likely due to more aggressive and critical treatment (returning to operating room under general anesthesia [Clavien 3b] or intensive care unit [Clavien 4a] management of the same) at the discovery of the initial complication, and as such, patients experienced a complication before being discharged from the hospital.

Table 5.

Odds of Subsequent Complications

Variable	P value	OR (95% CI)
Gender (men)	0.761	1.16 (0.58–2.31)
Age, years	0.094	1.02 (1.00–1.04)
Body mass index	0.126	0.96 (0.91–1.01)
Past medical history
Diabetes mellitus	0.008	3.11 (1.30–8.31)
Hyperlipidemia	0.266	1.51 (0.76–3.04)
Hypertension	0.503	1.33 (0.64–2.71)
Peripheral vascular disease	0.119	5.48 (0.77–240.23)
Myocardial Infarction	0.115	5.54 (0.78–242.67)
Congestive Heart failure	1.000	0.85 (0.12–9.68)
Peptic ulcer	1.000	1.29 (0.10–68.97)
Chronic renal insufficiency	0.372	2.52 (0.52–24.18)
COPD	0.823	0.78 (0.25–2.72)
Smoker	0.145	1.74 (0.84–3.64)
Alcohol	0.192	1.66 (0.80–3.52)
Malignancy	0.174	1.70 (0.82–3.65)
Coronary artery disease	0.939	0.54 (0.03–8.64)
Cardiac stent	0.770	0.43 (0.03–6.97)
Preoperative factors
Fever (>100.4 F)	0.970	0.65 (0.07–8.06)
Hemoglobin, mg/dL	0.491	1.06 (0.90–1.25)
Hematocrit, %	0.601	1.02 (0.96–1.08)
Creatinine, mg/dL	0.706	1.11 (0.65–1.88)
Urinary Tract Infection	0.306	0.43 (0.10–1.89)
Procedure Type
Endoscopy	ref	–
Lap/open kidney/RP	<0.001	9.91 (2.30–90.06)
Lap/open pelvic	0.044	3.05 (1.03–11.06)
Prostate biopsy	0.422	0.50 (0.11–2.10)
Intraoperative factors
Surgery time, hours	<0.001	1.83 (1.32–2.55)
Estimated Blood Loss, 100ml	0.002	1.32 (1.11–1.58)
Intravenous fluids, 100ml	1.055	1.06 (1.02–1.09)
Intra Op complication	0.059	4.2 (0.96–39)

The table demonstrates the odds of developing subsequent complications based upon patient specific comorbidities, procedure type, preoperative and postoperative factors.

Bold refers to statistically significant value.

This study further showed that among individuals who develop a primary complication, nearly two out of three individuals (134/191) will go on to develop a secondary complication. Among patients who do develop a secondary complication, nearly two out of three (84/134) will develop a third complication (Table 2). For the majority of our cohort, the severity of the initial complication was minor and heterogeneous among the subjects. Furthermore, once patients had endured multiple complications (>6), the proportion of Clavien grade 3 to 5 complications increased, and thus, there was a trend in the study toward more complex complications. In general, subtle clinical signs preceded the initial complication, for example, increasing drain output, abdominal distention, and pain. Although these subtle signs did not result in immediate compromise of the clinical course, they were early signs that could alert the urologist to further deterioration. For example, the initial fever, nausea, or oliguria treated with antipyretics, antiemetics, or intravenous fluids (Clavien 1) were early signs of urine leak or fluid collection requiring drainage under anesthesia (not under general anesthesia; Clavien 3a). Furthermore, the results of this study highlight the importance of assessing complications methodically and individually to avoid the common error of pooling negative surgical outcomes en bloc and losing the progeny of complications. Finally, this study can be viewed as a foray into the areas of patient safety and urologic complications. Recent evidence suggests that the mortality rate following urologic surgery is on the rise despite a decrease in the mortality rate in other surgical specialties.⁷ Sammon et al. concluded that this phenomenon was due to the increased FTR mortality rate. FTR has been utilized to compare the safety and quality of care by focusing on a healthcare system's effectiveness on recognizing complications and treating patients before an unfavorable outcome.^6
–8 The present study echoes the concerns raised by Sammon et al. In the current cohort, 70% of patients who had an initial postoperative complication developed at least one subsequent postoperative complication.

In their investigation of the American College of Surgeons National Surgical Quality Improvement Program (NSQIP) data, Wakeam et al. determined the rates of 30-day secondary complications and mortality for 890,604 postsurgical patients.⁸ They concluded that index surgical complications significantly increase the risk of secondary complications, and therefore can be used to measure FTR. Furthermore, this study underscores the importance of continuous risk assessment for surgical patients, as their risk for further complications increases after the initial complication. This evidence has led to several systems to help prevent further complications. For example, our institution's surgical intensive care unit has created a team that will continue to evaluate the patients once they are transferred to the wards. This continued care had led to efficient patient handoff and surveillance of postoperative complications before further deterioration in the clinical condition. In response to the results of our study demonstrating a higher likelihood of developing subsequent complications in those patients undergoing retroperitoneal and pelvic procedures, we have incorporated the use of electronic medical record order sets and standardized clinical pathways. These tools have not only helped avoid error in postoperative care but have also aided in recognizing patients straying from the expected postoperative course. Future investigations should be directed at the clinical pathways leading to postoperative complications, facilitating development of protocols to halt the propagation of these complications.

One limitation of our study stems from the inclusion of only two high-volume tertiary care centers, and therefore, our results may not be generalizable to smaller centers or other geographic locales. Second, patient information was retrospectively reviewed using institution-based morbidity and mortality rate data, which are subject to bias. Although patients were not excluded from the study if they were treated at outside institutions, the possibility of underreporting is possible if the surgeon was not contacted. For example, a patient who suffered a complication and presented to an outside institution may not have been included in the analysis if the surgeon was not made aware of the complication. Although patients are contacted after their procedures in our practice, complications occurring outside of the immediate postoperative period also have the potential to be excluded, thus introducing bias. A short study period and resulting low patient population also limited our study. For example, a medical history of peripheral vascular disease, myocardial infarction, and/or renal insufficiency were not significantly associated with an increased likelihood of developing subsequent complications. Although these are significant risk factors, a minority of the population carried these diagnoses. Furthermore, more patients were needed to make powerful comparisons between the group with nonfatal complications and patients who died. For example, when comparing patients' EBL of these groups, the difference of 30 mL was neither statistically nor clinically significant. Despite these shortcomings that may introduce reporting bias, our study is the first that we have encountered evaluating secondary complications specifically in a urologic cohort. Future studies are needed to identify the best interventions to stop the progression of surgical complications and tailor them to the needs of the urologic patient.

Conclusions

Surgical complications continue to have a significant impact on the intended quality of care. Efforts should be made to aggressively manage postoperative complications, irrespective of their severity, and to maintain a high level of vigilance for subsequent complications. Future studies are needed to define postcomplication risk stratification and to develop pathways that impede the propagation of secondary surgical complications.

Footnotes

Author Disclosure Statement

No competing financial interests exist.

Abbreviations Used

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