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Surgical Apgar Score Predicts an Increased Risk of Major Complications and Death after Renal Mass Excision
Surgical Apgar Score Predicts an Increased Risk of Major Complications and Death after Renal Mass Excision Timothy Ito,*,† Philip H. Abbosh,† Reza Mehrazin,† Jeffrey J. Tomaszewski,† Tianyu Li,† Serge Ginzburg,† Daniel J. Canter,‡ Richard E. Greenberg,§ Rosalia Viterbo,† David Y. Chen,† Alexander Kutikov,k Marc C. Smaldone† and Robert G. Uzzo{ From Fox Chase Cancer Center (TI, PHA, JJT, TL, SG, DJC, REG, RV, DYC, AK, MCS, RGU), Philadelphia, Pennsylvania, and the Department of Urology & Oncological Science, Icahn School of Medicine at Mount Sinai (RM), New York, New York
Abbreviations and Acronyms EBL ¼ estimated blood loss ICU ¼ intensive care unit MAP ¼ mean arterial pressure NSQIP ¼ National Surgical Quality Improvement Program SAS ¼ Surgical Apgar Score Accepted for publication November 11, 2014. Supported by Grant P30 CA006927 from the National Cancer Institute. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the National Cancer Institute or the National Institutes of Health. Additional funds were provided by Fox Chase Cancer Center via institutional support of the Kidney Cancer Keystone Program. * Correspondence: 333 Cottman Ave., Philadelphia, Pennsylvania 19111 (telephone: 646339-9633; e-mail: [email protected]). † Nothing to disclose. ‡ Financial interest and/or other relationship with Olympus. § Financial interest and/or other relationship with Endo Pharmaceuticals. k Financial interest and/or other relationship with UrologyMatch.com LLC, Visible Health Inc. and Genomic Health Inc. { Financial interest and/or other relationship with Pfizer and Janssen.
Editor’s Note: This article is the first of 5 published in this issue for which category 1 CME credits can be earned. Instructions for obtaining credits are given with the questions on pages 2160 and 2161.
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Purpose: Tailoring perioperative management to minimize the postoperative complication rates depends on reliable prognostication of patients most at risk. The Surgical Apgar Score is an objective measure of the operative course validated to predict major complications and death after general/vascular surgery. We assessed the ability of the Surgical Apgar Score to identify patients most at risk for postoperative morbidity and mortality after renal mass excision. Materials and Methods: Data for 886 patients undergoing renal mass excision via radical or partial nephrectomy from 2010 to 2013 were extracted from a prospectively collected database. The Surgical Apgar Score was calculated using electronic anesthesia records. Major postoperative complications, readmission and reoperation within 30 days of surgery as well as 90-day mortality were examined. Results: Overall 13.2% of patients experienced major postoperative complications at 30 days. Clavien grade I, II, III, IV and V complications were experienced by 1.7%, 2.9%, 5.8%, 1.9% and 0.9%, respectively. The 90-day all cause mortality rate was 1.4%. The Surgical Apgar Score was significantly lower in patients experiencing major complications (mean 7.3 vs 7.8, p¼0.004) and death (6.3 vs 7.7, p¼0.03). Patients with a Surgical Apgar Score of 4 or less were 3.7 times more likely to experience a major complication (p¼0.01) and 24 times more likely to die within 90 days of surgery (p¼0.0007) compared to patients with a Surgical Apgar Score greater than 8. Conclusions: The Surgical Apgar Score is an easily collected metric that can identify patients at higher risk for major complications and death after renal mass excision. A prospective trial to help further delineate the optimal use of this tool in an adjusted perioperative management approach with patients undergoing renal mass excision is warranted. Key Words: nephrectomy, postoperative complications
THE Surgical Apgar Score is a recently introduced metric for identifying patients with a higher risk of postoperative complication or death.1 The SAS is based on the 3 intraoperative variables of EBL, lowest
heart rate and lowest MAP, with each variable resulting in a point value based on predetermined categories (table 1). The sum of the point values assigned to these variables results in a SAS ranging from 0 to 10. Similar to
0022-5347/15/1936-1918/0 THE JOURNAL OF UROLOGY® © 2015 by AMERICAN UROLOGICAL ASSOCIATION EDUCATION AND RESEARCH, INC.
http://dx.doi.org/10.1016/j.juro.2014.11.085 Vol. 193, 1918-1922, June 2015 Printed in U.S.A.
SURGICAL APGAR SCORE AND RENAL MASS EXCISION COMPLICATIONS
Table 1. Calculation of the SAS EBL (cc) 0 1 2 3 4
Points Point Points Points Points
Greater than 1,000 601e1,000 101e600 100 or Less
Lowest Heart Rate/min
Lowest MAP (mm Hg)
Greater than 85 76e85 66e75 56e65 55 or Less
Less than 40 40e54 55e69 70 or Greater
Point values assigned to each intraoperative variable comprising the SAS are outlined. The sum of the points for each variable results in a SAS ranging from 0 to 10.
the postnatal Apgar score, the higher the SAS, the better the patient outcome. Therefore, the SAS has an inverse relationship with perioperative morbidity and mortality, with a lower score predictive of higher risk of worse outcomes and vice versa. The SAS was generated and initially validated using general and vascular surgery patients.2 It has since been examined in orthopedic, neurosurgical and gynecologic surgery cohorts, and has demonstrated usefulness in each subspecialty.3e6 To date only 2 studies have been published on the performance of the SAS after urological surgery, neither of which specifically examined patients undergoing renal surgery.7,8 Here we examine the ability of the SAS to predict perioperative outcomes in patients undergoing renal mass excision.
MATERIALS AND METHODS A total of 948 patients who underwent radical or partial nephrectomy between January 2010 and December 2013 at a single institution were identified using a prospectively collected database. These surgeries were performed by 1 of 7 urologic oncology fellowship trained urologists. The exclusion of patients without a complete anesthesia record (8 patients), patients who underwent nephrectomy for a reason other than a renal mass (eg mass originating in the retroperitoneum involving the kidney, 19 patients) and patients undergoing other concurrent surgeries at the time of nephrectomy (35 patients) resulted in a final cohort of 886 patients. Preoperative data extracted from the database included age, gender, race, smoking status, ASAÒ classification and body mass index. The SAS was calculated as previously described using electronic anesthesia records.2 Postoperative data extracted from the database included hospital length of stay and postoperative complications. Major complications examined were primarily derived from the initial validation study for the SAS, and included significant hemorrhage requiring transfusion of 4 U or more of packed red blood cells within 72 hours of surgery, cardiac events (myocardial infarction or arrest), pulmonary events (pulmonary embolism, pneumonia, unplanned intubation or ventilator use greater than 48 hours), stroke, wound disruption and infectious complications (deep or organ-space infection, surgical site infection, sepsis).2 Any readmission or reoperation within
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30 days of surgery was classified as a major complication. Significant leaks were classified as major complications if they remained unresolved for longer than 30 days. Acute renal failure was not considered a major complication in this study unless it resulted in the need for unplanned hemodialysis, either temporary or permanent. The 90-day mortality was also examined. Statistical analysis was performed using SASÒ statistical software, version 9.3. Univariate analysis was performed using the Fisher exact test, t-test and ANOVA where appropriate. Multivariate analysis was performed using logistic regression. A threshold of p <0.05 was used for statistical significance.
RESULTS A total of 117 patients (13.2%) experienced a major complication, underwent reoperation and/or were readmitted to the hospital within 30 days. Thirtyday Clavien-Dindo grade I, II, III, IV and V complications were experienced by 1.7%, 2.9%, 5.8%, 1.9% and 0.9% of patients, respectively. In all, 12 patients died within 90 days of surgery (1.4%). Complication rates increased with decreasing SAS (see figure). Mean SAS for the entire cohort was 7.7 (range 1 to 10). Mean SAS was significantly lower in patients experiencing complications (7.3 vs 7.8, p¼0.003) and 90-day mortality (6.3 vs 7.7, p¼0.03). When considering each component of the SAS, mean EBL was significantly higher in patients experiencing complications (459 vs 212 cc, p <0.0001) or death (1,029 vs 234 cc, p¼0.02). Lowest intraoperative MAP was significantly lower in those experiencing major complications (61.8 vs 64.3 mm Hg, p¼0.01) but was not significantly associated with 90-day mortality (63.6 vs 63.9 mm Hg, p¼0.58).
Rate of complications by SAS. Trend toward decreasing rates of complications is apparent with increasing SAS.
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SURGICAL APGAR SCORE AND RENAL MASS EXCISION COMPLICATIONS
Conversely the lowest intraoperative heart rate was significantly higher in patients experiencing 90-day mortality (66 vs 58 beats per minute, p¼0.02) but was not associated with overall major postoperative complications (57 vs 58, p¼0.18). Lower SAS was also associated with longer hospitalization. Patients with a SAS of 4 or less remained in the hospital for a mean of 6.3 days, compared to 4.7 and 3.4 days for patients with a SAS of 5 to 7 and 8 to 10, respectively (p <0.0001). Patients with a SAS of 4 or less were 3.7 times more likely to experience a complication compared to those with a SAS greater than 8 (95% CI 1.42e9.54, p¼0.01). Patients with a SAS of 4 or less were also 24 times more likely to die within 90 days of surgery compared to those with a SAS greater than 8 (95% CI 4.17e137.32, p¼0.0007). Examination of other preoperative and intraoperative characteristics revealed that patients experiencing major complications were significantly older (age 62.0 vs 59.2 years, p¼0.01, table 2). Patients undergoing open surgery also were more likely to experience complications than those undergoing robotic or laparoscopic surgery (21% vs 9% respectively, p <0.0001). Patients undergoing radical nephrectomy experienced a higher 90-day all cause mortality rate (3.5% vs 0.4%, p¼0.001). This is likely a result of worse extent of disease in
patients undergoing radical nephrectomy, as on final pathology the patients who underwent radical nephrectomy vs partial nephrectomy were more likely to have lymph node positive (10.2% vs 0.2%, p <0.0001) or metastatic disease (21.3% vs 0.8%, p <0.0001). All other preoperative and intraoperative variables examined, including ASA classification, were not significantly different between those experiencing and not experiencing postoperative morbidity or mortality. Given the potential for variation in complication rates due to surgeon experience and volume, both of these variables were examined. Overall 7 surgeons were included in this series, all with urologic oncology fellowship training. Complication rates within the first 5 years after fellowship ranged from 9.1% to 20.0% when stratified based on year from completion of fellowship training, with an overall major complication rate in the first 5 years after fellowship of 13.0%. These annual and overall complication rates did not differ significantly from the complication rate seen after partial/radical nephrectomy performed by surgeons with more than 5 years of experience (13.4%). When looking at surgeon volume, 2 surgeons performed more than 100 partial/radical nephrectomies during the study period (range 173 to 477) and 5 performed fewer than 100 (range 13 to 91). There was no significant
Table 2. Comparison of preoperative and operative variables between patients who experienced major complications within 30 days or mortality within 90 days vs those who did not Overall No. pts Mean age Mean kg/m2 body mass index No. gender (%): M F No. race (%): Caucasian Other No. history of smoking (%): Yes No No. ASA classification (%): 1 2 3 4 No. open vs laparoscopic/robotic (%): Open Laparoscopic/robotic No. partial vs radical (%): Partial Radical No. surgical side (%): L R Mean SAS Mean EBL Mean lowest heart rate/min Mean mm Hg lowest MAP Mean days length of stay
886 59.6 30.3
Complications 117 62.0 30.3
No Complications 769 59.2 29.7
p Value 0.01 0.45
Death 12 64.5 30.2
No Death 874 59.5 30.3
p Value 0.14 0.73
573 313
80 (14) 37 (12)
493 (86) 276 (88)
0.41
8 4
(1) (1)
565 309
(99) (99)
1.00
753 133
103 (14) 14 (11)
650 (86) 119 (89)
0.40
11 1
(1) (1)
742 132
(99) (99)
1.00
414 472
51 (12) 66 (14)
363 (88) 406 (86)
0.49
7 5
(2) (1)
465 409
(98) (99)
0.78
26 604 231 4
3 75 37 0
23 529 194 4
0.53
0 8 4 0
(0) (1) (2) (0)
26 596 227 4
(100) (99) (98) (100)
0.83
307 579
65 (21) 52 (9)
242 (79) 527 (91)
<0.0001
3 9
(1) (2)
304 570
(99) (98)
0.56
628 258
77 (12) 40 (15)
551 (88) 218 (85)
0.23
3 (0.4) 9 (3.5)
625 (99.6) 249 (96.5)
0.001
53 (12) 64 (14) 7.3 462 57.4 61.8 7.3
381 (88) 388 (86) 7.8 212 58.5 64.3 3.4
0.43
7 (2) 5 (1) 6.3 1,029 66 63.6 5.8
427 (98) 447 (99) 7.7 234 58.2 63.9 3.9
0.57
434 452 7.71 245 58.3 63.9 3.9
(12) (12) (16) (0)
(88) (88) (84) (100)
0.003 <0.0001 0.18 0.01 <0.0001
0.03 0.02 0.02 0.58 0.49
SURGICAL APGAR SCORE AND RENAL MASS EXCISION COMPLICATIONS
difference seen between higher volume and lower volume surgeons with regard to major complication rates (12.5% vs 15.6%, respectively, p¼0.27) or mortality rates (1.1% vs 2.1%, p¼0.40). Multivariate analysis was performed controlling for variables found to be significant on univariate analysis. On multivariate analysis, controlling for age and surgical approach (open vs radical nephrectomy), lower SAS was an independent predictor of major postoperative complications with each 1-point decrease in SAS resulting in a 14% increase in the odds of a complication (95% CI 0.75e0.98, p¼0.03). Increasing age (OR 1.03, 95% CI 1.01e1.04, p¼0.007) and open surgery (OR 2.45, 95% CI 1.62e3.70, p <0.0001) were also independent predictors of postoperative complications. Lower SAS also remained an independent predictor of 90-day mortality on multivariate analysis controlling for surgery type (OR 0.66, 95% CI 0.48e0.89, p¼0.007). Radical nephrectomy also continued to be an independent predictor of 90-day mortality (OR 5.80, 95% CI 1.51e22.2, p¼0.01).
DISCUSSION The SAS has been increasingly used as an objective and immediate measure of the intraoperative course calculated in the postanesthesia care unit. Whereas typically the intensity and postoperative setting of care is often determined subjectively at the surgeon or anesthesiologist’s recommendation, based on preoperative comorbidities and how the surgery was believed to have gone, use of the SAS allows for the possibility of standardization of the postoperative course based on objective and immediately calculable data. Indeed the success of programs like the NSQIP, which identifies the areas most in need of improvement postoperatively, relies on risk stratification tools like the SAS to implement change efficiently and effectively by distinguishing patients most likely to experience complications and, thus, most likely to benefit from prescribed interventions. There is evidence of the efficacy of this model. To reduce postoperative venous thromboembolic events as reported by the NSQIP, Cassidy et al used the Caprini score to risk stratify patients into 5 groups from lowest to highest risk of venous thromboembolism.9 Each group was assigned a recommended venous thromboembolism prophylaxis regimen for during and after hospitalization with increasing intensity of the regimen correlating with increased risk. This mandated standardized program resulted in an 84% decrease in the rate of postoperative deep vein thrombosis (1.9% to 0.3%, p <0.01) and a 55% decrease in the incidence of pulmonary embolism (1.1% to 0.5%, p <0.01). One can imagine that in a fashion similar to this, standardized assignment of
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patients at highest risk for postoperative morbidity and mortality as per SAS to higher levels of monitoring (ie the ICU), greater involvement of consultants (ie hospitalists) and improved transitions in care might permit decreases in postoperative adverse events. The advantages of the SAS include its ease of collection and its applicability to multiple subspecialties. While the SAS was initially validated in general and vascular surgery cohorts, it has been further tested after orthopedic surgery, neurosurgery and gynecologic surgery. Wuerz et al found that after hip/knee arthroplasty, each SAS point decrease was associated with a 34% increase in the odds of a complication.3 After neurosurgical procedures Ziewacz et al demonstrated a significant association not only between SAS and complication rates, but also between SAS and hospital and ICU length of stay, with lower scores predictive of higher complication rates and longer hospital and ICU stays.6 In gynecologic oncology Zighelboim et al reported that a SAS of 4 or less resulted in a 7.4-fold increased odds of a major complication (95% CI 2.9e18.8, p <0.0001) in patients with stage III/IV ovarian cancer undergoing cytoreductive surgery.5 To date only 2 published studies have examined the use of SAS in urological patient cohorts. Prasad et al reported on the efficacy of the SAS in the prediction of postoperative morbidity and mortality in 155 radical cystectomy cases using a modified scoring system which took into account higher expected EBL.8 They found that 57% of patients with a SAS of 2 to 3 experienced a major complication compared to just 19% and 8% for patients with a SAS of 6 to 7 and 8 to 10, respectively. Reynolds et al examined the ability of the SAS to predict mortality after more than 10,000 urological surgeries.7 Lower SAS was significantly associated with an increased risk of mortality at 30 (OR 0.74, 95% CI 0.63e0.88) and 90 days (OR 0.65, 95% CI 0.59e0.72). Mortality after urological procedures was 1.4% at 90 days in that study, similar to the rate found in the current study, although no breakdown of specific procedures was provided. This study is the first to our knowledge to examine the ability of the SAS to predict major complications or mortality after renal mass excision. We were able to demonstrate a significant association between lower SAS and postoperative complications and mortality. Lower SAS was also shown to be associated with a prolonged hospital stay. Patients with a SAS of 4 or less had a particularly increased risk of significant morbidity and mortality. Based on our findings it is this cohort of patients that should be targeted after radical or partial nephrectomy for more intensive postoperative care algorithms and improved transitions in care.
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SURGICAL APGAR SCORE AND RENAL MASS EXCISION COMPLICATIONS
A limitation of this study is that the complication reporting was based on chart review of available hospital and clinic records. While these data were collected prospectively, due to the limitations of the data source, complications or readmissions occurring at other hospitals may not have been captured. However, the complication rate reported in this study is similar to that reported by Liu et al in a study examining complication rates after radical and partial nephrectomy as reported by the NSQIP (13.2% vs 4.2% to 13%, respectively).10 Our reported complication rate is slightly higher than that seen by Liu et al, likely because NSQIP complication reporting is standardized and does not include procedure specific complications like significant urinary leak. Mortality rates between the 2 studies were also similar (1.4% in our study vs 0.4% to 2.9% for Liu et al).
However, despite this limitation, overall this study provides an important first step toward optimizing postoperative care for patients after renal mass excision by identifying the SAS as a viable, easily calculated tool for risk stratification in the immediate postoperative setting.
CONCLUSIONS The SAS is a simply collected objective measure of the intraoperative course that was demonstrated to be a reliable indicator of patients at higher risk of major postoperative complications or 90-day mortality after radical or partial nephrectomy. A prospective trial using the SAS to risk stratify patients into defined clinical pathways is warranted to establish the optimal use of this tool in postoperative treatment algorithms.
REFERENCES 1. Gawande AA, Kwaan MR, Regenbogen SE et al: An Apgar score for surgery. J Am Coll Surg 2007; 204: 201. 2. Regenbogen SE, Ehrenfeld JM, Lipsitz SR et al: Utility of the Surgical Apgar Score: validation in 4119 patients. Arch Surg 2009; 144: 30. 3. Wuerz TH, Regenbogen SE, Ehrenfeld JM et al: The Surgical Apgar Score in hip and knee arthroplasty. Clin Orthop Relat Res 2011; 469: 1119. 4. Urrutia J, Valdes M, Zamora T et al: An assessment of the Surgical Apgar Score in spine surgery. Spine J 2015; 15: 105.
5. Zighelboim I, Kizer N, Taylor NP et al: “Surgical Apgar Score” predicts postoperative complications after cytoreduction for advanced ovarian cancer. Gynecol Oncol 2010; 116: 370.
8. Prasad SM, Ferreria M, Berry AM et al: Surgical apgar outcome score: perioperative risk assessment for radical cystectomy. J Urol 2009; 181: 1046.
6. Ziewacz JE, Davis MC, Lau D et al: Validation of the surgical Apgar score in a neurosurgical patient population. J Neurosurg 2013; 118: 270.
9. Cassidy MR, Rosenkranz P and McAneny D: Reducing postoperative venous thromboembolism complications with a standardized risk-stratified prophylaxis protocol and mobilization program. J Am Coll Surg 2014; 218: 1095.
7. Reynolds PQ, Sanders NW, Schildcrout JS et al: Expansion of the surgical Apgar score across all surgical subspecialties as a means to predict postoperative mortality. Anesthesiology 2011; 114: 1305.
10. Liu JJ, Leppert JT, Maxwell BG et al: Trends and perioperative outcomes for laparoscopic and robotic nephrectomy using the National Surgical Quality Improvement Program (NSQIP) database. Urol Oncol 2014; 32: 473.
Abbreviations and Acronyms EBL ¼ estimated blood loss ICU ¼ intensive care unit MAP ¼ mean arterial pressure NSQIP ¼ National Surgical Quality Improvement Program SAS ¼ Surgical Apgar Score Accepted for publication November 11, 2014. Supported by Grant P30 CA006927 from the National Cancer Institute. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the National Cancer Institute or the National Institutes of Health. Additional funds were provided by Fox Chase Cancer Center via institutional support of the Kidney Cancer Keystone Program. * Correspondence: 333 Cottman Ave., Philadelphia, Pennsylvania 19111 (telephone: 646339-9633; e-mail: [email protected]). † Nothing to disclose. ‡ Financial interest and/or other relationship with Olympus. § Financial interest and/or other relationship with Endo Pharmaceuticals. k Financial interest and/or other relationship with UrologyMatch.com LLC, Visible Health Inc. and Genomic Health Inc. { Financial interest and/or other relationship with Pfizer and Janssen.
Editor’s Note: This article is the first of 5 published in this issue for which category 1 CME credits can be earned. Instructions for obtaining credits are given with the questions on pages 2160 and 2161.
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www.jurology.com
Purpose: Tailoring perioperative management to minimize the postoperative complication rates depends on reliable prognostication of patients most at risk. The Surgical Apgar Score is an objective measure of the operative course validated to predict major complications and death after general/vascular surgery. We assessed the ability of the Surgical Apgar Score to identify patients most at risk for postoperative morbidity and mortality after renal mass excision. Materials and Methods: Data for 886 patients undergoing renal mass excision via radical or partial nephrectomy from 2010 to 2013 were extracted from a prospectively collected database. The Surgical Apgar Score was calculated using electronic anesthesia records. Major postoperative complications, readmission and reoperation within 30 days of surgery as well as 90-day mortality were examined. Results: Overall 13.2% of patients experienced major postoperative complications at 30 days. Clavien grade I, II, III, IV and V complications were experienced by 1.7%, 2.9%, 5.8%, 1.9% and 0.9%, respectively. The 90-day all cause mortality rate was 1.4%. The Surgical Apgar Score was significantly lower in patients experiencing major complications (mean 7.3 vs 7.8, p¼0.004) and death (6.3 vs 7.7, p¼0.03). Patients with a Surgical Apgar Score of 4 or less were 3.7 times more likely to experience a major complication (p¼0.01) and 24 times more likely to die within 90 days of surgery (p¼0.0007) compared to patients with a Surgical Apgar Score greater than 8. Conclusions: The Surgical Apgar Score is an easily collected metric that can identify patients at higher risk for major complications and death after renal mass excision. A prospective trial to help further delineate the optimal use of this tool in an adjusted perioperative management approach with patients undergoing renal mass excision is warranted. Key Words: nephrectomy, postoperative complications
THE Surgical Apgar Score is a recently introduced metric for identifying patients with a higher risk of postoperative complication or death.1 The SAS is based on the 3 intraoperative variables of EBL, lowest
heart rate and lowest MAP, with each variable resulting in a point value based on predetermined categories (table 1). The sum of the point values assigned to these variables results in a SAS ranging from 0 to 10. Similar to
0022-5347/15/1936-1918/0 THE JOURNAL OF UROLOGY® © 2015 by AMERICAN UROLOGICAL ASSOCIATION EDUCATION AND RESEARCH, INC.
http://dx.doi.org/10.1016/j.juro.2014.11.085 Vol. 193, 1918-1922, June 2015 Printed in U.S.A.
SURGICAL APGAR SCORE AND RENAL MASS EXCISION COMPLICATIONS
Table 1. Calculation of the SAS EBL (cc) 0 1 2 3 4
Points Point Points Points Points
Greater than 1,000 601e1,000 101e600 100 or Less
Lowest Heart Rate/min
Lowest MAP (mm Hg)
Greater than 85 76e85 66e75 56e65 55 or Less
Less than 40 40e54 55e69 70 or Greater
Point values assigned to each intraoperative variable comprising the SAS are outlined. The sum of the points for each variable results in a SAS ranging from 0 to 10.
the postnatal Apgar score, the higher the SAS, the better the patient outcome. Therefore, the SAS has an inverse relationship with perioperative morbidity and mortality, with a lower score predictive of higher risk of worse outcomes and vice versa. The SAS was generated and initially validated using general and vascular surgery patients.2 It has since been examined in orthopedic, neurosurgical and gynecologic surgery cohorts, and has demonstrated usefulness in each subspecialty.3e6 To date only 2 studies have been published on the performance of the SAS after urological surgery, neither of which specifically examined patients undergoing renal surgery.7,8 Here we examine the ability of the SAS to predict perioperative outcomes in patients undergoing renal mass excision.
MATERIALS AND METHODS A total of 948 patients who underwent radical or partial nephrectomy between January 2010 and December 2013 at a single institution were identified using a prospectively collected database. These surgeries were performed by 1 of 7 urologic oncology fellowship trained urologists. The exclusion of patients without a complete anesthesia record (8 patients), patients who underwent nephrectomy for a reason other than a renal mass (eg mass originating in the retroperitoneum involving the kidney, 19 patients) and patients undergoing other concurrent surgeries at the time of nephrectomy (35 patients) resulted in a final cohort of 886 patients. Preoperative data extracted from the database included age, gender, race, smoking status, ASAÒ classification and body mass index. The SAS was calculated as previously described using electronic anesthesia records.2 Postoperative data extracted from the database included hospital length of stay and postoperative complications. Major complications examined were primarily derived from the initial validation study for the SAS, and included significant hemorrhage requiring transfusion of 4 U or more of packed red blood cells within 72 hours of surgery, cardiac events (myocardial infarction or arrest), pulmonary events (pulmonary embolism, pneumonia, unplanned intubation or ventilator use greater than 48 hours), stroke, wound disruption and infectious complications (deep or organ-space infection, surgical site infection, sepsis).2 Any readmission or reoperation within
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30 days of surgery was classified as a major complication. Significant leaks were classified as major complications if they remained unresolved for longer than 30 days. Acute renal failure was not considered a major complication in this study unless it resulted in the need for unplanned hemodialysis, either temporary or permanent. The 90-day mortality was also examined. Statistical analysis was performed using SASÒ statistical software, version 9.3. Univariate analysis was performed using the Fisher exact test, t-test and ANOVA where appropriate. Multivariate analysis was performed using logistic regression. A threshold of p <0.05 was used for statistical significance.
RESULTS A total of 117 patients (13.2%) experienced a major complication, underwent reoperation and/or were readmitted to the hospital within 30 days. Thirtyday Clavien-Dindo grade I, II, III, IV and V complications were experienced by 1.7%, 2.9%, 5.8%, 1.9% and 0.9% of patients, respectively. In all, 12 patients died within 90 days of surgery (1.4%). Complication rates increased with decreasing SAS (see figure). Mean SAS for the entire cohort was 7.7 (range 1 to 10). Mean SAS was significantly lower in patients experiencing complications (7.3 vs 7.8, p¼0.003) and 90-day mortality (6.3 vs 7.7, p¼0.03). When considering each component of the SAS, mean EBL was significantly higher in patients experiencing complications (459 vs 212 cc, p <0.0001) or death (1,029 vs 234 cc, p¼0.02). Lowest intraoperative MAP was significantly lower in those experiencing major complications (61.8 vs 64.3 mm Hg, p¼0.01) but was not significantly associated with 90-day mortality (63.6 vs 63.9 mm Hg, p¼0.58).
Rate of complications by SAS. Trend toward decreasing rates of complications is apparent with increasing SAS.
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SURGICAL APGAR SCORE AND RENAL MASS EXCISION COMPLICATIONS
Conversely the lowest intraoperative heart rate was significantly higher in patients experiencing 90-day mortality (66 vs 58 beats per minute, p¼0.02) but was not associated with overall major postoperative complications (57 vs 58, p¼0.18). Lower SAS was also associated with longer hospitalization. Patients with a SAS of 4 or less remained in the hospital for a mean of 6.3 days, compared to 4.7 and 3.4 days for patients with a SAS of 5 to 7 and 8 to 10, respectively (p <0.0001). Patients with a SAS of 4 or less were 3.7 times more likely to experience a complication compared to those with a SAS greater than 8 (95% CI 1.42e9.54, p¼0.01). Patients with a SAS of 4 or less were also 24 times more likely to die within 90 days of surgery compared to those with a SAS greater than 8 (95% CI 4.17e137.32, p¼0.0007). Examination of other preoperative and intraoperative characteristics revealed that patients experiencing major complications were significantly older (age 62.0 vs 59.2 years, p¼0.01, table 2). Patients undergoing open surgery also were more likely to experience complications than those undergoing robotic or laparoscopic surgery (21% vs 9% respectively, p <0.0001). Patients undergoing radical nephrectomy experienced a higher 90-day all cause mortality rate (3.5% vs 0.4%, p¼0.001). This is likely a result of worse extent of disease in
patients undergoing radical nephrectomy, as on final pathology the patients who underwent radical nephrectomy vs partial nephrectomy were more likely to have lymph node positive (10.2% vs 0.2%, p <0.0001) or metastatic disease (21.3% vs 0.8%, p <0.0001). All other preoperative and intraoperative variables examined, including ASA classification, were not significantly different between those experiencing and not experiencing postoperative morbidity or mortality. Given the potential for variation in complication rates due to surgeon experience and volume, both of these variables were examined. Overall 7 surgeons were included in this series, all with urologic oncology fellowship training. Complication rates within the first 5 years after fellowship ranged from 9.1% to 20.0% when stratified based on year from completion of fellowship training, with an overall major complication rate in the first 5 years after fellowship of 13.0%. These annual and overall complication rates did not differ significantly from the complication rate seen after partial/radical nephrectomy performed by surgeons with more than 5 years of experience (13.4%). When looking at surgeon volume, 2 surgeons performed more than 100 partial/radical nephrectomies during the study period (range 173 to 477) and 5 performed fewer than 100 (range 13 to 91). There was no significant
Table 2. Comparison of preoperative and operative variables between patients who experienced major complications within 30 days or mortality within 90 days vs those who did not Overall No. pts Mean age Mean kg/m2 body mass index No. gender (%): M F No. race (%): Caucasian Other No. history of smoking (%): Yes No No. ASA classification (%): 1 2 3 4 No. open vs laparoscopic/robotic (%): Open Laparoscopic/robotic No. partial vs radical (%): Partial Radical No. surgical side (%): L R Mean SAS Mean EBL Mean lowest heart rate/min Mean mm Hg lowest MAP Mean days length of stay
886 59.6 30.3
Complications 117 62.0 30.3
No Complications 769 59.2 29.7
p Value 0.01 0.45
Death 12 64.5 30.2
No Death 874 59.5 30.3
p Value 0.14 0.73
573 313
80 (14) 37 (12)
493 (86) 276 (88)
0.41
8 4
(1) (1)
565 309
(99) (99)
1.00
753 133
103 (14) 14 (11)
650 (86) 119 (89)
0.40
11 1
(1) (1)
742 132
(99) (99)
1.00
414 472
51 (12) 66 (14)
363 (88) 406 (86)
0.49
7 5
(2) (1)
465 409
(98) (99)
0.78
26 604 231 4
3 75 37 0
23 529 194 4
0.53
0 8 4 0
(0) (1) (2) (0)
26 596 227 4
(100) (99) (98) (100)
0.83
307 579
65 (21) 52 (9)
242 (79) 527 (91)
<0.0001
3 9
(1) (2)
304 570
(99) (98)
0.56
628 258
77 (12) 40 (15)
551 (88) 218 (85)
0.23
3 (0.4) 9 (3.5)
625 (99.6) 249 (96.5)
0.001
53 (12) 64 (14) 7.3 462 57.4 61.8 7.3
381 (88) 388 (86) 7.8 212 58.5 64.3 3.4
0.43
7 (2) 5 (1) 6.3 1,029 66 63.6 5.8
427 (98) 447 (99) 7.7 234 58.2 63.9 3.9
0.57
434 452 7.71 245 58.3 63.9 3.9
(12) (12) (16) (0)
(88) (88) (84) (100)
0.003 <0.0001 0.18 0.01 <0.0001
0.03 0.02 0.02 0.58 0.49
SURGICAL APGAR SCORE AND RENAL MASS EXCISION COMPLICATIONS
difference seen between higher volume and lower volume surgeons with regard to major complication rates (12.5% vs 15.6%, respectively, p¼0.27) or mortality rates (1.1% vs 2.1%, p¼0.40). Multivariate analysis was performed controlling for variables found to be significant on univariate analysis. On multivariate analysis, controlling for age and surgical approach (open vs radical nephrectomy), lower SAS was an independent predictor of major postoperative complications with each 1-point decrease in SAS resulting in a 14% increase in the odds of a complication (95% CI 0.75e0.98, p¼0.03). Increasing age (OR 1.03, 95% CI 1.01e1.04, p¼0.007) and open surgery (OR 2.45, 95% CI 1.62e3.70, p <0.0001) were also independent predictors of postoperative complications. Lower SAS also remained an independent predictor of 90-day mortality on multivariate analysis controlling for surgery type (OR 0.66, 95% CI 0.48e0.89, p¼0.007). Radical nephrectomy also continued to be an independent predictor of 90-day mortality (OR 5.80, 95% CI 1.51e22.2, p¼0.01).
DISCUSSION The SAS has been increasingly used as an objective and immediate measure of the intraoperative course calculated in the postanesthesia care unit. Whereas typically the intensity and postoperative setting of care is often determined subjectively at the surgeon or anesthesiologist’s recommendation, based on preoperative comorbidities and how the surgery was believed to have gone, use of the SAS allows for the possibility of standardization of the postoperative course based on objective and immediately calculable data. Indeed the success of programs like the NSQIP, which identifies the areas most in need of improvement postoperatively, relies on risk stratification tools like the SAS to implement change efficiently and effectively by distinguishing patients most likely to experience complications and, thus, most likely to benefit from prescribed interventions. There is evidence of the efficacy of this model. To reduce postoperative venous thromboembolic events as reported by the NSQIP, Cassidy et al used the Caprini score to risk stratify patients into 5 groups from lowest to highest risk of venous thromboembolism.9 Each group was assigned a recommended venous thromboembolism prophylaxis regimen for during and after hospitalization with increasing intensity of the regimen correlating with increased risk. This mandated standardized program resulted in an 84% decrease in the rate of postoperative deep vein thrombosis (1.9% to 0.3%, p <0.01) and a 55% decrease in the incidence of pulmonary embolism (1.1% to 0.5%, p <0.01). One can imagine that in a fashion similar to this, standardized assignment of
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patients at highest risk for postoperative morbidity and mortality as per SAS to higher levels of monitoring (ie the ICU), greater involvement of consultants (ie hospitalists) and improved transitions in care might permit decreases in postoperative adverse events. The advantages of the SAS include its ease of collection and its applicability to multiple subspecialties. While the SAS was initially validated in general and vascular surgery cohorts, it has been further tested after orthopedic surgery, neurosurgery and gynecologic surgery. Wuerz et al found that after hip/knee arthroplasty, each SAS point decrease was associated with a 34% increase in the odds of a complication.3 After neurosurgical procedures Ziewacz et al demonstrated a significant association not only between SAS and complication rates, but also between SAS and hospital and ICU length of stay, with lower scores predictive of higher complication rates and longer hospital and ICU stays.6 In gynecologic oncology Zighelboim et al reported that a SAS of 4 or less resulted in a 7.4-fold increased odds of a major complication (95% CI 2.9e18.8, p <0.0001) in patients with stage III/IV ovarian cancer undergoing cytoreductive surgery.5 To date only 2 published studies have examined the use of SAS in urological patient cohorts. Prasad et al reported on the efficacy of the SAS in the prediction of postoperative morbidity and mortality in 155 radical cystectomy cases using a modified scoring system which took into account higher expected EBL.8 They found that 57% of patients with a SAS of 2 to 3 experienced a major complication compared to just 19% and 8% for patients with a SAS of 6 to 7 and 8 to 10, respectively. Reynolds et al examined the ability of the SAS to predict mortality after more than 10,000 urological surgeries.7 Lower SAS was significantly associated with an increased risk of mortality at 30 (OR 0.74, 95% CI 0.63e0.88) and 90 days (OR 0.65, 95% CI 0.59e0.72). Mortality after urological procedures was 1.4% at 90 days in that study, similar to the rate found in the current study, although no breakdown of specific procedures was provided. This study is the first to our knowledge to examine the ability of the SAS to predict major complications or mortality after renal mass excision. We were able to demonstrate a significant association between lower SAS and postoperative complications and mortality. Lower SAS was also shown to be associated with a prolonged hospital stay. Patients with a SAS of 4 or less had a particularly increased risk of significant morbidity and mortality. Based on our findings it is this cohort of patients that should be targeted after radical or partial nephrectomy for more intensive postoperative care algorithms and improved transitions in care.
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SURGICAL APGAR SCORE AND RENAL MASS EXCISION COMPLICATIONS
A limitation of this study is that the complication reporting was based on chart review of available hospital and clinic records. While these data were collected prospectively, due to the limitations of the data source, complications or readmissions occurring at other hospitals may not have been captured. However, the complication rate reported in this study is similar to that reported by Liu et al in a study examining complication rates after radical and partial nephrectomy as reported by the NSQIP (13.2% vs 4.2% to 13%, respectively).10 Our reported complication rate is slightly higher than that seen by Liu et al, likely because NSQIP complication reporting is standardized and does not include procedure specific complications like significant urinary leak. Mortality rates between the 2 studies were also similar (1.4% in our study vs 0.4% to 2.9% for Liu et al).
However, despite this limitation, overall this study provides an important first step toward optimizing postoperative care for patients after renal mass excision by identifying the SAS as a viable, easily calculated tool for risk stratification in the immediate postoperative setting.
CONCLUSIONS The SAS is a simply collected objective measure of the intraoperative course that was demonstrated to be a reliable indicator of patients at higher risk of major postoperative complications or 90-day mortality after radical or partial nephrectomy. A prospective trial using the SAS to risk stratify patients into defined clinical pathways is warranted to establish the optimal use of this tool in postoperative treatment algorithms.
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5. Zighelboim I, Kizer N, Taylor NP et al: “Surgical Apgar Score” predicts postoperative complications after cytoreduction for advanced ovarian cancer. Gynecol Oncol 2010; 116: 370.
8. Prasad SM, Ferreria M, Berry AM et al: Surgical apgar outcome score: perioperative risk assessment for radical cystectomy. J Urol 2009; 181: 1046.
6. Ziewacz JE, Davis MC, Lau D et al: Validation of the surgical Apgar score in a neurosurgical patient population. J Neurosurg 2013; 118: 270.
9. Cassidy MR, Rosenkranz P and McAneny D: Reducing postoperative venous thromboembolism complications with a standardized risk-stratified prophylaxis protocol and mobilization program. J Am Coll Surg 2014; 218: 1095.
7. Reynolds PQ, Sanders NW, Schildcrout JS et al: Expansion of the surgical Apgar score across all surgical subspecialties as a means to predict postoperative mortality. Anesthesiology 2011; 114: 1305.
10. Liu JJ, Leppert JT, Maxwell BG et al: Trends and perioperative outcomes for laparoscopic and robotic nephrectomy using the National Surgical Quality Improvement Program (NSQIP) database. Urol Oncol 2014; 32: 473.