Association of overlapping cardiac surgery with short-term patient outcomes

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Association of overlapping cardiac surgery with short-term patient outcomes Gregory Glauser, BS,a Stephen Goodrich, BS,b,c Scott D. McClintock, PhD,c Wilson Y. Szeto, MD,d Pavan Atluri, MD,d Michael A. Acker, MD,d and Neil R. Malhotra, MDa ABSTRACT

Association of Overlapping Cardiac Surgery with Short-Term Patient Outcomes Coarsened Exact Matched Patient Characteristics

Study Cohort

Objective: This study seeks to assess the safety of overlap in cardiac surgery.

Results: A total of 984 patients had any overlap and were matched to similar patients without overlap (n ¼ 1501). For beginning/end overlap, separate matched groups were created (n ¼ 462, n ¼ 329 patients, respectively). Among matched patients, any overlap did not predict unanticipated return to surgery at 30 or 90 days. Any overlap did not predict increased readmission, reoperation, or emergency department visits at 30 or 90 days. Overlap did not predict higher rates of death over follow-up. Beginning/end overlap had results similar to any overlap. Conclusions: Nonconcurrent, overlapping surgery is not associated with an increase in adverse outcomes in a large, matched cardiac surgery population. (J Thorac Cardiovasc Surg 2020;-:1-10)

Any Overlap

No Overlap

4651 cardiac surgical procedures, from 2014-2016, at a single academic medical center

Operative Duration

188 Values Removed for Missing Data

Insurance Provider

Cost of Surgical Supplies/Implants

6.00%

5.40%

6.20%

4.90%

2.20%

1.50%

Mortality within 90 Days

Body Mass Index (BMI) Case Aculty

2962 No Overlap

30 to 90-Day Readmission

Previous Surgeries (lifetime) Previous Surgeries (last 30 days) Median Household Income (MHI)

1501 Any Overlap (matched cohort)

Charlson Comorbidity Index (CCI) score Race

30 to 90-Day Reoperation

Non-inferior patient outcomes also observed for variable timing of overlap.

IMPLICATIONS: Surgical overlap provides comparable outcomes to non-overlapping surgery with regards to safety and patient outcomes. Elucidating the safety of surgical overlap provides key data for surgeons, administrators and patients for maintaining safe and efficient surgical care.

Depiction of patient cohorts, coarsened exact matching, outcomes, and study implications.

CENTRAL MESSAGE

This study suggests that there is no evidence of compromise in safety or short-term outcomes studied with surgical overlap in a large heterogeneous cardiac surgery population.

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Methods: Coarsened exact matching was used to assess the impact of overlap on outcomes among cardiac surgical interventions (n ¼ 4463) over 2 years (20142016). Overlap was categorized as any, beginning, or end overlap. Study subjects were matched 1:1 on 11 variables, including Charlson comorbidity score, surgical costs, body mass index, length of postoperative hospitalization, and race, among others. Serious unanticipated events were studied, including readmission, unplanned return to the operating room, and mortality.

Patient Outcomes

Length of postoperative stay

PERSPECTIVE Overlapping surgery is a long-standing practice that has garnered significant public attention in recent years; however, limited data exist on the safety of this practice. Elucidating the safety of surgical overlap is important for maintaining safe and efficient surgical care. This study provides key data for surgeons, administrators, and patients. See Commentary on page XXX.

Nonconcurrent, overlapping surgery is a long-standing practice; however, the impact of surgical overlap on patient outcome has not been conclusively studied. Surgical

overlap was brought to the forefront after a 2015 publication by the Boston Globe Spotlight Team investigated the practice at a major academic medical center.1 The report

From the aDepartment of Neurosurgery and dDivision of Cardiovascular Surgery, Department of Surgery, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pa; bMcKenna EpiLog Fellowship in Population Health at the University of Pennsylvania, Philadelphia, Pa; and cThe West Chester Statistical Institute and Department of Mathematics, West Chester University, West Chester, Pa. Funding Statement: This research received no specific grant from any funding agency in the public or commercial sectors. Support was received from the Kevin and Bernadette McKenna Family Research Fund. Institutional Review Board (IRB) statement: This study was approved by the IRB at the Hospital of the University of Pennsylvania. IRB number for this study is 831423. All ethical guidelines and rules were followed to protect patient privacy.

Received for publication March 8, 2019; revisions received Nov 14, 2019; accepted for publication Nov 29, 2019. Address for reprints: Neil R. Malhotra, MD, Department of Neurosurgery, Perelman School of Medicine at the University of Pennsylvania, 3rd Floor Silverstein Pavilion, 3400 Spruce St, Philadelphia, PA 19104 (E-mail: Neil.Malhotra@ pennmedicine.upenn.edu). 0022-5223/$36.00 Copyright Ó 2020 Published by Elsevier Inc. on behalf of The American Association for Thoracic Surgery https://doi.org/10.1016/j.jtcvs.2019.11.136

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Abbreviations and Acronyms ACS ¼ American College of Surgeons BMI ¼ body mass index ED ¼ emergency department

Scanning this QR code will take you to the article title page to access supplementary information.

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suggested a potential link between surgical overlap and postoperative complications, which raised concern about patient safety with regard to overlapping surgeries. Heightened concern caused the Senate Finance Committee to query 20 teaching hospitals, the Centers for Medicare & Medicaid Services, and the American College of Surgeons (ACS) on the practice of surgical overlap.2 The ACS Statement on Principles report defined that ‘‘concurrent operations occur when the critical or key components of the procedures for which the primary attending surgeon is responsible are occurring all or in part at the same time,’’ whereas overlapping surgery ‘‘is when the key or critical elements of the first operation have been completed, and there is no reasonable expectation that the primary attending surgeon will need to return to that operation.’’3 The ACS has indicated that overlapping surgery is an acceptable practice when properly managed, but concurrent operations as an inappropriate practice.3 Despite the stance of the ACS report that running concurrent operations is an inappropriate practice, there have been multiple attempts to use departmental and large database information, such as National Surgical Quality Improvement Program, to assess the practice of simultaneous surgery.4,5 Although considered acceptable, the practice of overlapping surgery has not been conclusively studied. Current literature on the subject has continued to grow and largely suggests that surgical overlap can be a safe practice when appropriately applied.4,6-20 However, previous work is prone to confounding selection bias given that nonoverlap patients can be less healthy than overlap patients.20 Thus, there remains a need for further data that assess similar patients such that the primary issue addressed is the presence or absence of overlap. The number of studies on surgical overlap remains small, with no prior peer-reviewed publications evaluating overlap specifically in a cardiac surgery population. Previous work on the topic of overlap suggests that there is a particular need for additional studies to strengthen the current evidence base.19 To that end, this study makes use of coarsened exact matching21 for optimal control of patient 2

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risk profile, which is crucial for examining the impact of surgical overlap. Further, although the senior author and colleagues have previously studied risk related to timing of overlap in a neurosurgical population,9,17 no study has assessed impact of timing of overlap in patients undergoing cardiac surgery. Thus, this investigation seeks to examine the association of overlapping surgery with patient outcomes in a large, heterogeneous cohort of 4463 consecutive cardiac surgical procedures consisting of open and endovascular cardiac and aortic procedures. This analysis was performed over a 2-year period in a major academic healthcare system. At the institution studied here, there have been long-standing guidelines regarding overlapping surgery that evolved after new ACS guidelines were published in 2016. Residents are the primary surgeon when the principal surgeon is not present. The primary surgeon always performs all critical portions of the operations and needs to be immediately available to return to surgery at any time. These are similar to the guidelines set forth by the ACS and state that overlapping surgery is allowed, whereas concurrent surgery is not. However, subsequent to publication of the guidelines, surgeons have been required to identify an appropriate backup surgeon for all cases in which overlap may occur. Analyzing the safety of overlap, in a time period before the ACS report, serves as a useful benchmark as to the safety of management of overlap. The present study focuses on the safety of the practice of overlapping nonconcurrent surgery and assesses the impact of overlap at the beginning or end of the surgery. MATERIALS AND METHODS In this Institutional Review Board–approved study, patients undergoing surgical intervention at a multi-hospital 1659-bed university health system were enrolled retrospectively over 2 years (January 1, 2014, to January 1, 2016). A waiver of informed consent was granted by the Institutional Review Board because this study was considered to be minimal risk to patients. A total of 4463 consecutive adult (patients aged 18 years) cardiac surgical procedures were studied (Figures 1 and E1). Key data were acquired using the EpiLog tool. EpiLog is a nonproprietary data acquisition system built and layered on top of the existing electronic health record architecture (by the senior author and department on the present article) to enhance quality improvement efforts with low cost and minimal employee workflow impact.9,17,22 In an attempt to reduce the confounding bias present in retrospective analyses, the authors opted to use matched patients. The approach to matching that is more readily used in the medical/surgical literature is propensity score matching. Propensity score matching compacts many different data points (the covariates) into 1 value and then matches on that 1 value, ignoring the original covariates. Compacting variables into 1 score may be suboptimal because it results in some degree of information loss. Coarsened exact matching is advantageous in this regard because it uses the actual covariate values, which results in superior matches compared with those generated by propensity score matching. Because additional covariates are included in the matching criteria, the compacting of data becomes increasingly pronounced, as more and more information is lost. For coarsened exact matching, an exact match is defined as a match on every matching variable.

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Cardiac Surgical Procedures, from 1/1/2014-12/31/2015 (n = 4651) Removal of Missing Values Prior to Matching (n = 188) Cardiac Surgical Procedures Prior to Matching (n = 4463)

Procedures Without Overlap Prior to Matching (n = 2962)

Any Overlap Patients (n = 984, 65.56% match rate) → Cohort n = 1501

Beginning Overlap Patients (n = 339, 73.32% match rate) → Cohort n = 462

End Overlap Patients (n = 238, 72.34% match rate) → Cohort n = 329

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Surgical Patient Matched Cohort (n = 1968) FIGURE 1. Flow chart of patient selection. Illustration of how patients were selected and sorted into cohorts for analysis. Patients were segmented into any, beginning, and end overlap cohorts. For each cohort, patients were exact matched with a nonoverlap control. There were 984 any overlap patients for whom a match was available, creating a total matched cohort of 1968 patients. Within this group, 339 patients for whom a matched control was available qualified as having beginning overlap only. Likewise, 238 patients for whom a matched control was available qualified as having end overlap only. Patients were individually matched 1:1 on the following 11 variables: Charlson Comorbidity Index score, surgical supply and implant costs, duration of surgery, length of postoperative hospitalization, patient race, body mass index (BMI), insurance type at the time of surgery, median household income, 23 case acuity (elective/emergency/urgent), number of prior surgeries in the patient’s lifetime, and number of surgeries in the 30 days before the index case. Categoric variables were exact matched, and continuous variables were matched on the basis of relation to central tendency (ie, median household income above or below the median). Procedures were categorized into having overlap with other surgical procedures performed by the same surgeon (with overlap as defined by the ACS and studied hospital system) or no overlap. Patients without overlap served as controls and the source for coarsened exact matching for patients undergoing the study intervention: surgical overlap. Procedures with overlap were further subcategorized to beginning overlap (overlap occurring exclusively within the first 50% of procedure only) and end overlap (overlap occurring exclusively within the last 50% of procedure only) (Figure 2). All cases involving patients aged less than 18 years were excluded. Serious unanticipated events were studied. Unanticipated events analyzed included unanticipated return to surgery, hospital, or emergency department (ED) within 90 days of index surgical intervention. Further, mortality within 90 days of index intervention was assessed. Patient and outcome data were extracted from EpiLog and pushed into defined spreadsheets. For coarsened exact matching, binning of the matching variables and removal of missing values (Table E1) were performed using SAS Version 9.4 (SAS Institute Inc, Cary, NC). Matching was completed using the MatchIt programming package24 in R Statistics (R Core Team, Vienna, Austria, 2017), with subsequent analysis executed through SAS Version 9.4. McNemar’s test was used to compare means

between matched subjects created via coarsened exact matching. Univariate analysis was performed.

RESULTS Patient Demographics and Baseline Characteristics Of 4463 consecutive cardiac surgical procedures, 984 (22.00%) had any overlap, 339 (7.60%) had beginning overlap only, and 238 (5.30%) had end overlap only (Figure 2). For the matched patient cohort, gender data consisted of 35% female in the control group and 32% female in the any overlap cohort (Table 1). Median length of stay was 8.9 days, and median duration of surgery was 230 minutes. The median total cost of surgical supplies and implants was $7000. Insurance coverage consisted of 37.00% private (commercial, managed care, Blue Cross) and 63.00% government (Medicare, Medicaid, self-pay) providers. Regarding BMI, 69.00% of the population were in the normal-overweight range (BMI ¼ 18.529.9 kg/m2), and 31.00% were in the obese category (BMI 30 kg/m2). No matched patients were considered cachectic (BMI <18.5 kg/m2). Patient Outcomes: Any Overlap Presence of overlap was noted in 984 patients for whom an exact match could be uncovered through coarsening

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End Overlap (n = 238) Beginning Overlap (n = 339) Index Case with Any Overlap (n = 984)

Begin Anesthesia

Incision

Midpoint

Begin End Closure Closure

End Anesthesia

Begin End Closure Closure

End Anesthesia

Index Case with no overlap (n = 2962)

Begin Anesthesia

Incision

Midpoint

FIGURE 2. Schematic of variable timing of procedure overlap. Depiction of how beginning and end overlap were defined. Important time points are shown to denote what events are taking place in a typical operation, such as beginning/ending anesthesia, incision (varied depending on type of procedure), and wound closure. Beginning overlap is shown as cases in which overlap occurred during the first 50% of the procedure. End overlap is shown as cases in which overlap occurred during the final 50% of the procedure. After the removal of patients with missing data, 4463 cases were included for analysis. The number of cases in each cohort, after matching, is included. Bottom: the same time points occurring during a case without overlap. This cohort was used as controls.

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(66.00% of patients with any overlap had an exact match among controls). Patients undergoing surgery with any overlap, compared with matched cardiac surgery patients without overlap, had no difference in the assessed metrics of complication (Figure 3, A, and Tables 2 and E2) including readmission, unanticipated return to surgery, ED visits, or mortality. Further, any overlap patients requiring reoperation had no difference in additional return to the operating room within 30 or 90 days. Patient Outcomes: Variable Timing of Procedure Overlap Beginning overlap. Presence of overlap during the beginning of a procedure was noted in 339 patients for whom an exactly matched patient could be uncovered through coarsening (73.00% of patients with beginning overlap had an exact match among controls). Patients undergoing surgery with beginning overlap had no difference in 30- or 90-day readmission, ED visit, unanticipated return to surgery, or mortality rate (Figure 3, B). Beginning overlap patients requiring reoperation had no difference in additional return to the operating room within 30 or 90 days. End overlap. Presence of end overlap was noted in 238 patients for whom an exact match could be uncovered through coarsening (72.00% of patients with end overlap had an exact match among controls). Patients undergoing surgery with end overlap had no difference in 30- or 90-day readmission, ED visit, unanticipated return to surgery, or mortality rate (Figure 3, C). End overlap patients requiring reoperation had no difference in additional return to the operating room within 30 or 90 days. 4

DISCUSSION Patients undergoing overlapping, nonconcurrent cardiac surgery did not demonstrate any significant differences in major indicators of negative outcome when compared with exactly matched patients undergoing procedures without overlap (Figure 4). This study aligns with the few studies examining overlapping surgery that have recently been published. These studies have demonstrated that overlapping surgery is at least noninferior to nonoverlapping surgery at 30-day follow-up with regard to mortality, morbidity, readmission, reoperation, and postoperative complications.4-7,9-14,17,20,25-28 The data presented in this article align with and contribute to the existing literature in several important ways. The results of this study, through the use of exact matching, suggest that patients with similar risk profiles will have similar risk of postoperative complication, as measured by surrogates such as unanticipated return to surgery, ED visits, hospital readmission, and mortality during the 90-day follow-up period. Previous studies have likewise concluded that overlap did not predict negative outcome; however, these studies also noted that patients undergoing overlapping surgery are healthier at baseline with lower mortality risk, American Society of Anaesthesiologists scores, and severity of illness.4,25 Although these prior reports have found overlapping surgery to be a safe practice, their retrospective cohort design limits the ability to isolate how overlap affects outcomes for matched patients of equal baseline health. Thus, when interpreting the results of prior reports, there remains the possibility that some unobserved factors were a driving force of the findings. Through coarsened exact matching, the risk of unobserved factors

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TABLE 1. Matched patient demographics and baseline characteristics Demographic/baseline characteristic

Matched patients with overlap n ¼ 984

Matched patients without overlap n ¼ 984

Standardized difference

Gender Female Male

318 (32.00) 666 (68.00)

342 (35.00) 642 (65.00)

Race White African American Asian Hispanic/Latino American Indian East Indian Pacific Islander Other Unknown

827 (84.00) 66 (6.70) 5 (0.51) 11 (1.10) 1 (0.10) 4 (0.41) 0 (0.00) 23 (2.30) 47 (4.80)

827 (84.00) 73 (7.40) 20 (2.00) 13 (1.30) 0 (0.00) 2 (0.20) 1 (0.10) 16 (1.60) 32 (3.30)

Median duration of surgery, min

250

230

0.18

Median total cost of surgical supplies and implants, dollars

7000.00

7000.00

0.00

14.00 (15.00)

14.00 (14.00)

71,000

70,000

BMI, n (%) Cachectic <18.5 kg/m2 Normal-overweight 18.5-29.9 kg/m2 Obese 30 kg/m2

6 (0.61) 674 (69.00) 304 (31.00)

6 (0.61) 674 (69.00) 304 (31.00)

Insurance type, n (%) Commercial Medicare Medicaid Managed Care Self-Pay Blue Cross

7 (0.71) 577 (59.00) 34 (3.50) 274 (28.00) 7 (0.71) 85 (8.60)

9 (0.91) 563 (57.00) 50 (5.10) 280 (28.00) 5 (0.51) 77 (7.80)

Admission type, n (%) Routine scheduled Emergency Transfer Routine unscheduled Other

655 (67.00) 40 (4.10) 251 (26.00) 37 (3.80) 1 (0.10)

655 (67.00) 47 (4.80) 215 (22.00) 66 (6.70) 1 (0.10)

Charlson Comorbidity Index Score, n (%) 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

42 (4.30) 108 (11.00) 168 (17.00) 179 (18.00) 172 (17.00) 90 (9.20) 83 (8.40) 51 (5.20) 42 (4.30) 28 (2.90) 16 (1.60) 4 (0.41) 1 (0.10) 0 (0.00) 0 (0.00) 0 (0.00)

67 (6.80) 97 (9.90) 175 (18.00) 180 (18.00) 150 (15.00) 99 (10.00) 74 (7.50) 45 (4.60) 36 (3.70) 34 (3.50) 12 (1.20) 6 (0.61) 5 (0.51) 3 (0.30) 0 (0.00) 1 (0.10)

0.08

0.00

Median household income, dollars

0.04 0.02 0.02

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Mean length of stay, d (SD)

0.00

0.00

0.02

(Continued)

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TABLE 1. Continued Demographic/baseline characteristic No. of other surgical interventions within 30 d before surgery, n (%) 0 1

Matched patients with overlap n ¼ 984

Matched patients without overlap n ¼ 984

Standardized difference 0.01

910 (92.00) 74 (7.50)

910 (92.00) 74 (7.50)

No. of other lifetime surgical interventions before surgery, n (%) 0 1

0.01 899 (91.00) 85 (8.60)

899 (91.00) 85 (8.60)

Incision site contaminant status, n (%) Clean Clean contaminated Dirty Unknown

939 (95.00) 36 (3.70) 7 (0.71) 2 (0.20)

939 (95.00) 38 (3.90) 4 (0.41) 3 (0.30)

Case acuity, n (%) Elective Emergency Urgent

776 (79.00) 43 (4.40) 165 (17.00)

776 (79.00) 43 (4.40) 165 (17.00)

Patient class, n (%) Inpatient Outpatient

984 (100.00) 0 (0.00)

984 (100.00) 0 (0.00)

0.00

0.00

0.00

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Standardized differences are included to show variation between the overlap and no overlap cohorts.

affecting study outcomes is reduced by effectively isolating similar patients, such that overlap is being assessed in the ‘‘same’’ patient in both scenarios. The data reported suggest that when patients of comparable health undergo procedures differing only in the presence or absence of overlap, there is no appreciable difference in the outcome metrics studied. To the knowledge of the authors, the impact of overlapping, nonconcurrent surgery on patient outcomes in cardiac surgery specifically has not been previously studied. However, Sun and colleagues,20 in an analysis of overlapping surgery across multiple specialties and 7 procedure types, found that overlap during coronary artery bypass graft surgery was associated with increased in-hospital mortality and complication rates.20 Although the presented data do not differentiate by specific procedure type, this study did not show the aforementioned untoward effects of surgical overlap. It is possible that patient factors, such as medical comorbidities, in the coronary artery bypass graft–specific cohort were confounding factors that contributed to the observed unfavorable patient outcomes. The present study accounts for potential confounding factors through the use of exact-matched patient cohorts; however, the conflicting findings between these studies is interesting and warrants future investigation. The results of this study can be used to inform decision makers while planning for cardiac procedures. Overlapping 6

surgery has long been performed in the United States. Proponents of overlapping surgery suggest that the practice expands the operative autonomous experience of trainees and improves patient access by reducing lag time until surgery. Impact of overlap on outcome has been inadequately studied. The authors add to an increasing body of literature on the management of overlapping surgery. However, this practice had not been explicitly studied, and evidence supporting preservation of patient outcomes was anecdotal. Anecdotal evidence was all that was available to support overlapping surgery before 2015. Thus, this study provides useful and timely data for decision-makers regarding shortterm patient outcomes after cardiac surgery with overlap. In addition, prior work by the senior author of this study and colleagues has shown that, in a neurosurgical population, patient outcomes are not worsened with overlapping surgery regardless of the specific timing of the overlap.9,17 This study builds upon the aforementioned finding by producing a similar result, which fundamentally suggests that the practice of surgical overlap is safe when appropriately managed in a cardiac surgery patient population. Study Limitations This study was conducted in a heterogeneous cardiac surgical population at a single, multi-hospital academic medical center, which limits generalizability. Another limitation of this work is that it does not analyze the impact of overlap

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Any Overlap vs No Overlap 30 Day Return to OR on Index Admission 30 Day ED Evaluation 30 Day Readmission 30 Day Return to Surgery 30 Day Mortality 90 Day Return to OR on Index Admission 30-90 Day ED Evaluation 30-90 Day Readmission 30-90 Day Return to Surgery 90 Day Mortality 0.1 1 10 Odds Ratio <1 Odds Ratio >1

A

Beginning Overlap vs No Overlap 30 Day Return to OR on Index Admission 30 Day ED Evaluation 30 Day Readmission 30 Day Return to Surgery

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30 Day Mortality 90 Day Return to OR on Index Admission 30-90 Day ED Evaluation 30-90 Day Readmission 30-90 Day Return to Surgery 90 Day Mortality 0.1 1 10 Odds Ratio <1 Odds Ratio >1

B

End Overlap vs No Overlap 30 Day Return to OR on Index Admission 30 Day ED Evaluation 30 Day Readmission 30 Day Return to Surgery 30 Day Mortality 90 Day Return to OR on Index Admission 30-90 Day ED Evaluation 30-90 Day Readmission 30-90 Day Return to Surgery 90 Day Mortality

C

0.01 0.1 1 10 100 Odds Ratio <1 Odds Ratio >1

FIGURE 3. A, Impact of overlap on common indicators of outcome. Odds ratios (ORs) and 95% confidence intervals (CIs) for any overlap compared with procedures without overlap (significance set at P ¼ .05). ORs are shown as a central point, with CIs as lines in each direction. These are included for each of the primary end points in this study. Results are considered significant if their CI does not cross over 1. B, Impact of beginning overlap on common indicators of outcome. ORs and 95% CIs for beginning overlap compared with procedures without overlap (significance set at P ¼ .05). ORs are shown as a central point, with CIs as lines in each direction. These are included for each of the primary end points in this study. Results are considered significant if their CI does not cross over 1. C, Impact of end overlap on common indicators of outcome. ORs and 95% CIs for end overlap compared with procedures without overlap (significance set at P ¼ .05). ORs are shown as a central point, with CIs as lines in each direction. These are included for each of the primary end points in this study. Results are considered significant if their CI does not cross over 1. OR, Operating room; ED, emergency department.

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TABLE 2. Patient outcomes and complications Outcome/ complication

End overlap Beginning control (n ¼ 238) overlap control End overlap Any overlap No overlap control Beginning overlap n ¼ (%) (n ¼ 984) n ¼ (%) (n ¼ 984) n ¼ (%) (n ¼ 339) n ¼ (%) (n ¼ 339) n ¼ (%) (n ¼ 238) n ¼ (%)

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30-d readmission

107 (11.00) P ¼ .88

105 (11.00)

24 (7.10) P ¼ .10

36 (11.00)

27 (11.00) P ¼ .45

22 (9.20)

90-d readmission

61 (6.20) P ¼ .20

48 (4.90)

20 (5.90) P ¼ .38

15 (4.40)

10 (4.20) P ¼ .68

13 (5.50)

30-d reoperation

21 (2.10) P ¼ .41

16 (1.60)

8 (2.40) P ¼ .39

4 (1.20)

4 (1.70) P ¼ .38

1 (0.42)

90-d reoperation

22 (2.20) P ¼ .25

15 (1.50)

7 (2.10) P ¼ 1.00

6 (1.80)

2 (0.80) P ¼ .69

4 (1.70)

30-d ED visit

30 (3.10) P ¼ .19

41 (4.20)

7 (2.10) P ¼ .36

12 (3.50)

6 (2.50) P ¼ .61

9 (3.80)

90-d ED visit

23 (2.30) P ¼ .34

17 (1.70)

8 (2.40) P ¼ 1.00

8 (2.40)

8 (3.40) P ¼ .39

4 (1.70)

Unexpected return to operating room within 30 d

133 (13.00) P ¼ .43

144 (15.00)

42 (12.00) P ¼ .32

50 (15.00)

22 (9.24) P ¼ .62

25 (11.00)

Unexpected return to operating room within 90 d

160 (16.00) P ¼ .89

162 (16.00)

49 (14.00) P ¼ .49

55 (16.00)

26 (11.00) P ¼ .54

30 (13.00)

Mortality rate within 30 d

47 (4.80) P ¼ .10

34 (3.50)

15 (4.40) P ¼ .13

7 (2.10)

9 (3.80) P ¼ .39

5 (2.10)

Mortality rate within 90 d

59 (6.00) P ¼ .52

53 (5.40)

15 (4.40) P ¼ 1.00

15 (4.40)

12 (5.00) P ¼ .21

6 (2.50)

P values represent appropriate statistical test comparing respective category of overlap with no overlap. ED, Emergency department.

for individual cardiac conditions or by specific cardiac procedures. Such an analysis would provide surgeons with the data necessary to tailor the use of overlapping surgery in their own practice. However, the present study provides sufficient data to enable the surgeon’s managers (ie, department chiefs/section chairs) to answer questions regarding population management with respect to overlapping surgery. Elements that permit overlapping surgery to be safe or unsafe merits further investigation to permit replication at other centers. Thus, in the future, studies are strongly encouraged at varied medical institutions and surgical departments to evaluate the safety of overlapping surgery in heterogeneous populations and impact of overlap for distinct procedure types. The authors understand there are inherent limitations to using matched patients. Coarsened exact matching results in significant data loss and a reduced number of patients included for analysis. Although information is lost through this process, matching is preferred over unmatched retrospective review because this method offers improved control of potentially confounding factors, the benefit of which outweighs the loss of patient data. Further, although patients were matched on many key criteria, it is possible that in the population being studied there are additional

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criteria that might have resulted in more perfect matches. Although this is possible, we believe appropriate major criteria have been selected on the basis of supporting literature correlating these factors with outcomes. History of previous surgery, evaluated in cervical spine surgery,29 was found to lower surgical success rate and postoperative improvement. Prior investigations on length of surgery have shown that an increase in surgical time leads to increased risk of complication and predicts length of surgical intensive care unit stay.30 Connolly and colleagues31 found that uninsured and Medicaid patients incurred increased odds of postsurgical inpatient mortality. Multiple studies have reported minority race,32 prolonged postoperative stay,33 case acuity,34 and advanced Charlson Comorbidity Index (significant comorbidities)35 as independently associated with increased postoperative morbidity. An additional criticism of this work is that it only addresses major morbidity via surrogates of complication that result in significant alterations in course of care (ie, return to operating room, readmission). This study does not assess minor morbidities that surely have an impact on patient satisfaction, and future work should focus on patient-reported outcome measures and minor morbidities, as well as the major morbidities addressed in this analysis.

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Association of Overlapping Cardiac Surgery with Short-Term Patient Outcomes Coarsened Exact Matched Patient Characteristics

Study Cohort

Patient Outcomes Any Overlap

No Overlap

6.00%

5.40%

6.20%

4.90%

2.20%

1.50%

Length of postoperative stay

188 Values Removed for Missing Data

Operative Duration Cost of Surgical Supplies/Implants

Mortality within 90 Days

Insurance Provider Body Mass Index (BMI) Case Aculty

2962 No Overlap

30 to 90-Day Readmission

Previous Surgeries (lifetime) Previous Surgeries (last 30 days) Median Household Income (MHI) Charlson Comorbidity Index (CCI) score

1501 Any Overlap (matched cohort)

Race

30 to 90-Day Reoperation

Non-inferior patient outcomes also observed for variable timing of overlap.

IMPLICATIONS: Surgical overlap provides comparable outcomes to non-overlapping surgery with regards to safety and patient outcomes. Elucidating the safety of surgical overlap provides key data for surgeons, administrators and patients for maintaining safe and efficient surgical care. FIGURE 4. Depiction of patient cohorts, coarsened exact matching, outcomes, and study implications.

CONCLUSIONS This study suggests that there is no evidence of compromise in safety or short-term outcomes studied with surgical overlap in a large heterogeneous cardiac surgery population composed of open and endovascular cardiac and aortic procedures (Figure 4). These data suggest that surgeons, patients, and administrators are adequately managing the practice of overlap, considering the presence of any overlap was not associated with an increased risk of adverse postoperative complications, as measured by surrogates such as readmission, reoperation, ED visits, and mortality during the follow-up period. Elucidating the safety of surgical overlap is important for maintaining safe and efficient surgical care, and this study provides key data for surgeons, administrators, and patients. Conflict of Interest Statement Authors have nothing to disclose with regard to commercial support. References 1. Abelson J, Saltzman J, Kowalczyk L. Clash in the name of care. The Boston Globe. Available at: https://apps.bostonglobe.com/spotlight/clash-in-the-nameof-care/story/. Accessed October 25, 2015.

2. US Senate Committee of Finance. Concurrent and overlapping surgeries: additional measures warranted. A Senate Finance Committee staff report. Available at: https://www.finance.senate.gov/imo/media/doc/Concurrent%20 Surgeries%20Report%20Final.pdf. Accessed December 6, 2016. 3. American College of Surgeons Statements on Principles. Bull Am Coll Surg. 2016;101:19-34. 4. Zygourakis CC, Lee J, Barba J, Lobo E, Lawton MT. Performing concurrent operations in academic vascular neurosurgery does not affect patient outcomes. J Neurosurg. 2017;127:1089-95. 5. Liu JB, Berian JR, Ban KA, Liu Y, Cohen ME, Angelos P, et al. Outcomes of concurrent operations: results from the American College of Surgeons’ National Surgical Quality Improvement Program. Ann Surg. 2017;266:411-20. 6. Mooney MA, Brigeman S, Bohl MA, Simon ED, Sheehy JP, Chang SW, et al. Analysis of overlapping surgery in patients undergoing microsurgical aneurysm clipping: acute and long-term outcomes from the Barrow Ruptured Aneurysm Trial. J Neurosurg. 2018;129:711-7. 7. Bohl MA, Mooney MA, Sheehy JP, Cantwell AM, Chang SW, Chapple KM, et al. Overlapping surgeries are not associated with worse patient outcomes: retrospective multivariate analysis of 14 872 neurosurgical cases performed at a single institution. Neurosurgery. 2018;83:53-9. 8. Guan J, Karsy M, Brock AA, Couldwell WT, Kestle JRW, Jensen RL, et al. Impact of a more restrictive overlapping surgery policy: an analysis of pre- and postimplementation complication rates, resident involvement, and surgical wait times at a high-volume neurosurgical department. J Neurosurg. 2018;129:515-23. 9. Glauser G, Agarwal P, Ramayya AG, Chen HI, Lee JYK, Schuster JM, et al. Association of surgical overlap during wound closure with patient outcomes amongst neurological surgery patients at a large academic medical center. Neurosurgery. 2019;85:E882-8. 10. Zhang AL, Sing DC, Dang DY, Ma CB, Black D, Vail TP, et al. Overlapping surgery in the ambulatory orthopaedic setting. J Bone Joint Surg Am. 2016;98:1859-67.

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4651 cardiac surgical procedures, from 2014-2016, at a single academic medical center

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11. Morris AJ, Sanford JA, Damrose EJ, Wald SH, Kadry B, Macario A. Overlapping surgery: a case study in operating room throughput and efficiency. Anesthesiol Clin. 2018;36:161-76. 12. Sweeny L, Rosenthal EL, Light T, Grayson J, Petrisor D, Troob SH, et al. Effect of overlapping operations on outcomes in microvascular reconstructions of the head and neck. Otolaryngol Head Neck Surg. 2017;156:627-35. 13. Ponce BA, Wills BW, Hudson PW, Huntley SR, Starnes AC, Watson SL, et al. Outcomes with overlapping surgery at a large academic medical center. Ann Surg. 2019;269:465-70. 14. Hyder JA, Hanson KT, Storlie CB, Madde NR, Brown MJ, Kor DJ, et al. Assessing the safety of overlapping surgery at a children’s hospital. Ann Surg. 2018;268: e24-7. 15. Ravi B, Pincus D, Wasserstein D, Govindarajan A, Huang A, Austin PC, et al. Association of overlapping surgery with increased risk for complications following hip surgery: a population-based, matched cohort study. JAMA Intern Med. 2018;178:75-83. 16. Rangel SJ, Shamberger RC. Overlapping surgery in pediatric surgical care: is it a safe and cost-effective practice? Ann Surg. 2018;268:e28. 17. Agarwal P, Ramayya AG, Osiemo B, Goodrich S, Glauser G, McClintock SD, et al. Association of overlapping neurosurgery with patient outcomes at a large academic medical center. Neurosurgery. 2019;85:E1050-8. 18. Hoyt DB. Overlapping surgery-opportunities in neurosurgery based on new research. JAMA Surg. 2018;153:321. 19. Mello MM, Livingston EH. Managing the risks of concurrent surgeries. JAMA. 2016;315:1563-4. 20. Sun E, Mello MM, Rishel CA, Vaughn MT, Kheterpal S, Saager L, et al. Association of overlapping surgery with perioperative outcomes. JAMA. 2019;321: 762-72. 21. Iacus S, King G, Porro G. Causal inference without balance checking: coarsened exact matching. Polit Anal. 2012;20:1-24. 22. Gawande AA. Why doctors hate their computers. The New Yorker. 2018;62-73. 23. B19013 Median household income in the past 12 months (in 2016 inflationadjusted dollars). US Census Bureau/American FactFinder; 2016. Available at: http://www.census.gov. Accessed February 7, 2019. 24. Ho DE, Imai K, King G, Stuart EA. MatchIt: nonparametric preprocessing for parametric causal inference. J Stat Softw. 2011;42:1-28. 25. Zygourakis CC, Keefe M, Lee J, Barba J, McDermott MW, Mummaneni PV, et al. Comparison of patient outcomes in 3725 overlapping vs 3633 nonover-

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lapping neurosurgical procedures using a single institution’s clinical and administrative database. Neurosurgery. 2017;80:257-68. Howard BM, Holland CM, Mehta CC, Tian G, Bray DP, Lamanna JJ, et al. Association of overlapping surgery with patient outcomes in a large series of neurosurgical cases. JAMA Surg. 2018;153:313-21. Self DM, Ilyas A, Stetler WR. Safety of running two rooms: a systematic review and meta-analysis of overlapping neurosurgical procedures. World Neurosurg. 2018;116:e179-86. Karsy M, Bowers CA, Scoville J, Kundu B, Azab MA, Gee JM, et al. Evaluation of complications and costs during overlapping transsphenoidal surgery in the treatment of pituitary adenoma. Neurosurgery. 2019;84:1104-11. Radcliff K, Jalai C, Vira S, Yang S, Boniello AJ, Bianco K, et al. Two-year results of the prospective spine treatment outcomes study: analysis of postoperative clinical outcomes between patients with and without a history of previous cervical spine surgery. World Neurosurg. 2018;109:e144-9. Chu D, Bakaeen FG, Wang XL, LeMaire SA, Coselli JS, Huh J. Does the duration of surgery affect outcomes in patients undergoing coronary artery bypass grafting? Am J Surg. 2008;196:652-6. Connolly TM, White RS, Sastow DL, Gaber-Baylis LK, Turnbull ZA, Rong LQ. The disparities of coronary artery bypass grafting surgery outcomes by insurance status: a retrospective cohort study, 2007-2014. World J Surg. 2018;42:3240-9. Causey MW, McVay D, Hatch Q, Johnson E, Maykel JA, Champagne B, et al. The impact of race on outcomes following emergency surgery: an American College of Surgeons National Surgical Quality Improvement Program assessment. Am J Surg. 2013;206:172-9. Hassan A, Anderson C, Kypson A, Kindell L, Ferguson TB, Chitwood WR, et al. Clinical outcomes in patients with prolonged intensive care unit length of stay after cardiac surgical procedures. Ann Thorac Surg. 2012;93:565-9. Akbarian-Tefaghi H, Kalakoti P, Sun H, Sharma K, Thakur JD, Patra DP, et al. Impact of hospital caseload and elective admission on outcomes after extracranial-intracranial bypass surgery. World Neurosurg. 2017;108:716-28. Genther DJ, Gourin CG. Effect of comorbidity on short-term outcomes and cost of care after head and neck cancer surgery in the elderly. Head Neck. 2015;37: 685-93.

Key Words: cardiac surgery, concurrent surgery, overlapping surgery, patient safety, simultaneous surgery

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TABLE E1. Missing covariate data, with number and percentages of each covariate that excluded cases from analysis No. affected

% affected

15

0.32%

3

0.07%

2

116

2.50%

BMI >70 kg/m2

7

0.15%

Length of stay

3

0.07%

Admission type

0

0.00%

Insurance type

0

0.00%

Lifetime prior surgery

0

0.00%

30-d prior surgery

0

0.00%

Race

4

0.09%

CCI score

0

0.00%

Wound class

7

0.15%

Case acuity

0

0.00%

Covariate data missing Operative duration Total cost BMI <10 kg/m

Patient class Median income

0

0.00%

40

0.86%

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BMI, Body mass index; CCI, Charlson Comorbidity Index.

TABLE E2. Odds ratios and 95% confidence intervals for patient outcomes Outcome/complication 30-d readmission

Any overlap OR (95% CI)

Beginning overlap OR (95% CI)

1.02 (0.76-1.37)

0.63 (0.36-1.09)

End overlap OR (95% CI) 1.26 (0.69-2.31)

90-d readmission

1.30 (0.87-1.92)

1.36 (0.68-2.71)

0.77 (0.30-1.90)

30-d reoperation

1.31 (0.69-2.52)

2.00 (0.54-9.08)

4.00 (0.40-196.99)

90-d reoperation

1.47 (0.76-2.83)

1.17 (0.34-4.20)

0.50 (0.05-3.49)

30-d ED visit

0.73 (0.45-1.17)

0.58 (0.20-1.61)

0.67 (0.20-2.10)

90-d ED visit

1.35 (0.69-2.70)

1.00 (0.33-3.06)

2.00 (0.54-9.08)

Unexpected return to operating room within 30 d

0.89 (0.67-1.18)

0.78 (0.48-1.27)

0.85 (0.45-1.62)

Unexpected return to operating room within 90 d

0.98 (0.75-1.28)

0.85 (0.54-1.34)

0.83 (0.45-1.52)

30-d mortality

1.52 (0.92-2.52)

2.14 (0.82-6.21)

2.00 (0.54-9.08)

90-d mortality

1.15 (0.75-1.74)

1.00 (0.48-2.10)

2.20 (0.71-8.08)

OR, Odds ratio; CI, confidence interval; ED, emergency department.

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Case Breakdown - Cardiac Surgery Service Other 6%

All Mitral 14% CABG 38% All Aortic 17%

TAVR 25% FIGURE E1. Case breakdown. Illustration of the specific case types, by percentage, of the cardiac surgery service at the institution studied.

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Association of overlapping cardiac surgery with short-term patient outcomes Gregory Glauser, BS, Stephen Goodrich, BS, Scott D. McClintock, PhD, Wilson Y. Szeto, MD, Pavan Atluri, MD, Michael A. Acker, MD, and Neil R. Malhotra, MD, Philadelphia and West Chester, Pa This study suggests that there is no evidence of compromise in safety or short-term outcomes studied with surgical overlap in a large heterogeneous cardiac surgery population.

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000

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