Managing overlapping surgery: an analysis of 1018 neurosurgical and spine cases

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OBJECTIVE

Overlapping surgery—the performance of parts of 2 or more surgical procedures at the same time by a single lead surgeon—has recently come under intense scrutiny, although data on the effects of overlapping procedures on patient outcomes are lacking. The authors examined the impact of overlapping surgery on complication rates in neurosurgical patients.

METHODS

The authors conducted a retrospective review of consecutive nonemergent neurosurgical procedures performed during the period from May 12, 2014, to May 12, 2015, by any of 5 senior neurosurgeons at a single institution who were authorized to schedule overlapping cases. Overlapping surgery was defined as any case in which 2 patients under the care of a single lead surgeon were under anesthesia at the same time for any duration. Information on patient demographics, premorbid conditions, surgical variables, and postoperative course were collected and analyzed. Primary outcome was the occurrence of any complication from the beginning of surgery to 30 days after discharge. A secondary outcome was the occurrence of a serious complication—defined as a life-threatening or life-ending event—during this same period.

RESULTS

One thousand eighteen patients met the inclusion criteria for the study. Of these patients, 475 (46.7%) underwent overlapping surgery. Two hundred seventy-one patients (26.6%) experienced 1 or more complications, with 134 (13.2%) suffering a serious complication. Fourteen patients in the cohort died, a rate of 1.4%. The overall complication rate was not significantly higher for overlapping cases than for nonoverlapping cases (26.3% vs 26.9%, p = 0.837), nor was the rate of serious complications (14.7% vs 11.8%, p = 0.168). After adjustments for surgery type, surgery duration, body mass index, American Society of Anesthesiologists (ASA) physical classification grade, and intraoperative blood loss, overlapping surgery remained unassociated with overall complications (OR 0.810, 95% CI 0.592–1.109, p = 0.189). Similarly, after adjustments for surgery type, surgery duration, body mass index, ASA grade, and neurological comorbidity, there was no association between overlapping surgery and serious complications (OR 0.979, 95% CI 0.661–1.449, p = 0.915).

CONCLUSIONS

In this cohort, patients undergoing overlapping surgery did not have an increased risk for overall complications or serious complications. Although this finding suggests that overlapping surgery can be performed safely within the appropriate framework, further investigation is needed in other specialties and at other institutions.

ABBREVIATIONS ASA = American Society of Anesthesiologists; BMI = body mass index.

The practice of overlapping surgery—in which a single lead surgeon is responsible for 2 cases at the same time—has been brought under intense scrutiny since it was highlighted in the Boston Globe in late 2015.1 Although it is a long-standing and common occurrence in academic medical centers,3 public perception of overlapping surgery has led to heated debate over the safety and ethics of the practice.11,23 Assessment of overlapping surgery is made more difficult by the lack of data on its impact on complications and outcomes. In this study, we examined our institutional experience with overlapping surgery in the neurosurgical population and its effect on complication rates.

Methods

Study Population

With approval from the University of Utah Institutional Review Board, we performed a retrospective chart review of all cases performed between May 12, 2014, and May 12, 2015, by any of 5 neurosurgeons at our institution who were authorized to run overlapping surgeries. Patients younger than 10 years of age were excluded from this study, as were cases performed on weekends since they are essentially never performed in an overlapping fashion. “Emergent” cases were also excluded as these were almost exclusively nonoverlapping and had high rates of adverse events given the patient condition on presentation. In the rare instance in which an emergent case overlapped with an elective or urgent case, the elective or urgent case was also excluded from our analysis.

Data Collection

A comprehensive review of the medical record, including operative reports, inpatient progress notes, discharge summaries, and follow-up clinic notes, was conducted. Patient characteristics such as demographics, comorbidities, operative variables, postoperative course, and complications were recorded for each included case.

Demographic variables consisted of age, sex, race and/or ethnicity, body mass index (BMI), and insurance type (private, Medicaid/self-pay, or Medicare). Assessed comorbidities included the American Society of Anesthesiologists (ASA) physical classification grade; active tobacco, alcohol, or illicit drug use; preoperative corticosteroid use; cardiovascular comorbidities (for example, atrial fibrillation, coronary artery disease); pulmonary comorbidities (for example, obstructive sleep apnea, asthma); hepatobiliary comorbidities (for example, cirrhosis, hepatitis); renal comorbidities (for example, chronic kidney disease); diabetes; and hypertension. Patients were also assessed for neurological comorbidities (for example, stroke, multiple sclerosis), but they were included only if the neurological condition was not the indication for surgical intervention. Finally, patients were assessed for oncological comorbidities (that is, the presence of active cancer or ongoing cancer treatment), but again these were only included if the oncological condition was not the indication for surgical intervention.

Operative variables consisted of surgery type (divided into 1 of 10 subcategories), the attending neurosurgeon (dichotomized based on postresidency practice > or < 20 years), the level of training of the resident or fellow assisting during the operation (dichotomized into “junior” and “senior” assistants, with the latter defined as postgraduate year 7 and above), the start time of the operation (defined based on the start of anesthesia), the duration of surgery (defined based on the start and end time of anesthesia), and intraoperative blood loss. The surgery scheduling category (elective vs urgent) was also recorded. Elective cases at our institution are defined as operations booked more than 24 hours prior to the start of the surgery, whereas urgent cases begin less than 24 hours after being added to the schedule but are not immediately life-threatening in nature. Postoperative course data included length of stay postsurgery and discharge destination.

Each case was dichotomized into overlapping or nonoverlapping, with overlapping defined as any case in which 2 patients under the care of a single lead surgeon were under anesthesia at the same time. For each surgery, the amount of time during which cases overlapped was recorded.

For this study, a complication was defined as any deviation from the expected intraoperative or postoperative course (Table 1).5 Complications were divided into intraoperative, postoperative, and those occurring within 30 days of discharge. Complications were graded in severity based on a modified Clavien-Dindo scale8 as proposed by Landriel Ibañez et al.13 for neurosurgical complications. Briefly, this classification has 4 categories: Grade I, complications that are not life-threatening and do not require invasive treatment; Grade II, events requiring invasive surgical, endoscopic, or endovascular interventions; Grade III, life-threatening events that require intensive care management; and Grade IV, complications resulting in death. For our analysis, Grade 0 signified no identified complications. In patients with multiple complications, the highest-grade complication was recorded.

TABLE 1.

Representative complications and grades

GradeIntraoperativelyPostoperativelyw/in 30 Days of Discharge
IBlood loss requiring blood transfusion; dural tear repaired intraoperatively; venous/visceral tear repaired intraoperativelyAnemia requiring blood transfusion; urinary tract infection treated w/antibiotics; pneumonia treated w/antibioticsNausea/vomiting requiring admission for fluids & antiemetics; urinary tract infection treated w/antibiotics; hyponatremia/syndrome of inappropriate antidiuretic hormone
IIVertebral artery injury necessitating angiogram, no treatment; intraop hypotension leading to case abortion & return to OR at later dateVentricular shunt failure requiring revision in OR; CSF leak requiring CSF diversion; pseudomeningocele requiring CSF diversion/wound revisionVentricular shunt failure requiring revision in OR; CSF leak requiring CSF diversion; wound infection requiring washout in OR
IIICarotid artery injury resulting in stroke; vertebral artery injury necessitating angiogram & endovascular treatment; intraventricular hemorrhageRespiratory failure necessitating reintubation; persistent postop hemiparesis/hemiplegia (>30 days); epidural/subdural/intraparenchymal hemorrhage requiring op evacuationRespiratory failure necessitating reintubation; delayed hydrocephalus necessitating emergent external ventricular drain placement; meningitis/abscess/subdural empyema
IVAneurysm rupture resulting in deathCerebral edema resulting in death; status epilepticus resulting in death; intraparenchymal hemorrhage resulting in deathIntraparenchymal hemorrhage resulting in death; septic shock resulting in death

OR = operating room.

The 3 most common complications for each grade during each time period are listed. In cases in which fewer than 3 complications within a grade occurred during the time period, all complications are listed.

Outcomes

Our primary outcome was the occurrence of any complication from the time of surgery to 30 days after discharge. Our secondary outcome was the occurrence of “serious complications” (Grade II or higher) during this same period. Particular attention was paid to the association between overlapping surgery and each outcome measure in our analysis.

Statistical Analysis

Continuous variables in all cases were analyzed using the Student t-test, whereas categorical variables were analyzed using chi-square analysis. Univariate analysis was first performed on the overlapping surgery variable to assess the differences between groups. We then performed a univariate analysis to determine what factors were associated with any complications during surgery, postoperatively, or in the first 30 days after discharge. Finally, we performed a univariate analysis to determine what factors were associated with life-threatening (Grade II or higher) complications during this period.

Variables with a p < 0.2 on univariate analysis were included in a forward, stepwise, multivariable regression model with an entry cutoff of 0.05 and a removal cutoff of 0.20. A separate model was constructed for both overall complications and serious complications. The overlapping variable was included in both multivariable models regardless of p. In all analyses, p < 0.05 was considered statistically significant. All statistical analysis was performed using SPSS version 20.0 (IBM Corp.).

Results

Of 1101 cases performed by the 5 neurosurgeons during the study period, 1018 (92.5%) met the criteria for inclusion. Forty-four cases were excluded because they were classified as emergent, 33 cases because they occurred on a weekend, 3 cases because the patients were younger than 10 years old at the time of surgery, and 3 cases because they were elective or urgent cases that overlapped with an emergent case.

Overlapping Versus Nonoverlapping Surgery Analysis

Demographically, patients undergoing overlapping surgery were similar in age (52.7 ± 17.0 vs 52.8 ± 16.1 years, p = 0.907), sex (50.3% vs 54.7% male, p = 0.163), rates of private insurance use (50.9% vs 57.6%, p = 0.068), and BMI (28.6 ± 7.1 vs 28.5 ± 6.3 kg/m2, p = 0.754) compared with those having nonoverlapping surgery (Table 2). White patients were more likely to undergo nonoverlapping operations (91.0% vs 86.5%, p = 0.006) than non-whites. In terms of comorbidities, patients in the 2 groups were similar except that overlapping surgery patients had a higher ASA grade (52.2% vs 44.9% with an ASA Grade III and 7.6% vs 5.7% with an ASA Grade IV or V, p = 0.012), a lower rate of alcohol use (29.7% vs 36.3%, p = 0.026), and a higher incidence of neurological comorbidities (18.5% vs 12.5%, p = 0.008).

TABLE 2.

Univariate analyses of overlapping surgery, any complication, and serious complications

VariableNonoverlapping SurgeryOverlapping Surgeryp ValueNo ComplicationAny Complicationp ValueNo Serious Complication*Serious Complication*p Value
No. of cases543475747271884134
Mean age in yrs52.8 ± 16.152.7 ± 17.00.90752.0 ± 16.554.8 ± 16.40.01652.4 ± 16.555.2 ± 16.10.066
Male sex (%)297 (54.7)239 (50.3)0.163384 (51.4)152 (56.1)0.186458 (51.8)78 (58.2)0.167
Race/ethnicity (%)
  White494 (91.0)411 (86.5)0.006671 (89.8)234 (86.3)0.163781 (88.3)124 (92.5)0.838
  Hispanic/Latino17 (3.1)36 (7.6) 38 (5.1)15 (5.5) 49 (5.5)4 (3.0) 
  African American4 (0.7)0 (0) 4 (0.5)0 (0) 4 (0.4)0 (0) 
  Asian6 (1.1)4 (0.8) 7 (0.9)3 (1.1) 9 (1.0)1 (0.7) 
  American Indian5 (0.9)8 (1.7) 8 (1.1)5 (1.8) 12 (1.4)1 (0.7) 
  Hawaiian/Pacific Islander2 (0.4)6 (1.3) 3 (0.4)5 (1.8) 7 (0.8)1 (0.7) 
  Other/unknown15 (2.8)10 (2.1) 16 (2.1)9 (3.3) 22 (2.5)3 (2.2) 
Mean BMI in kg/m228.5 ± 6.328.6 ± 7.10.75428.9 ± 6.627.6 ± 6.70.01028.7 ± 6.627.5 ± 7.10.060
Insurance type (%)
  Private313 (57.6)242 (50.9)0.068419 (56.1)136 (50.2)0.240485 (54.9)70 (52.2)0.772
  Medicaid/self-pay52 (9.6)61 (12.8) 81 (10.8)32 (11.8) 96 (10.8)17 (12.7) 
  Medicare178 (32.8)172 (36.2) 247 (33.1)103 (38.0) 303 (34.3)47 (35.1) 
ASA grade (%)
  I or II268 (49.4)191 (40.2)0.012370 (49.5)89 (32.8)<0.001422 (47.7)37 (27.6)<0.001
  III244 (44.9)248 (52.2) 346 (46.3)146 (53.9) 415 (46.9)77 (57.5) 
  IV or V31 (5.7)36 (7.6) 31 (4.1)36 (13.3) 47 (5.3)20 (14.9) 
Tobacco use (%)61 (11.2)59 (12.4)0.55893 (12.4)27 (10.0)0.277108 (12.2)12 (9.0)0.275
Alcohol use (%)197 (36.3)141 (29.7)0.026260 (34.8)78 (28.8)0.071297 (33.6)41 (30.6)0.492
Illicit drug use (%)30 (5.5)24 (5.1)0.73742 (5.6)12 (4.4)0.45250 (5.7)4 (3.0)0.199
Preop corticosteroid use (%)73 (13.4)71 (14.9)0.492104 (13.9)40 (14.8)0.735122 (13.8)22 (16.4)0.418
Cardiovascular comorbidity (%)84 (15.5)83 (17.5)0.389121 (16.2)46 (17.0)0.768148 (16.7)19 (14.2)0.455
Pulmonary comorbidity (%)177 (32.6)135 (28.4)0.149238 (31.9)74 (27.3)0.164277 (31.3)35 (26.1)0.222
Hepatobiliary comorbidity (%)17 (3.1)17 (3.6)0.69120 (2.7)14 (5.2)0.05130 (3.4)4 (3.0)0.806
Renal comorbidity (%)14 (2.6)7 (1.5)0.21613 (1.7)8 (3.0)0.22918 (2.0)3 (2.2)0.878
Neurological comorbidity (%)68 (12.5)88 (18.5)0.008105 (14.1)51 (18.8)0.062123 (13.9)33 (24.6)0.001
Oncological comorbidity (%)69 (12.7)59 (12.4)0.89186 (11.5)42 (15.5)0.090105 (11.9)23 (17.2)0.085
Diabetes (%)63 (11.6)58 (12.2)0.76584 (11.2)37 (13.7)0.294103 (11.7)18 (13.4)0.553
Hypertension (%)209 (38.5)170 (35.8)0.374275 (36.8)104 (38.4)0.649330 (37.3)49 (36.6)0.865
Surgery category (%)
  Craniotomy for tumor, simple72 (13.2)83 (17.5)<0.001104 (13.9)51 (18.8)<0.001125 (14.1)30 (22.4)<0.001
  Craniotomy for tumor, complex22 (4.0)30 (6.3) 27 (3.6)25 (9.2) 36 (4.1)16 (11.9) 
  Craniotomy for aneurysm/vascular malformation15 (2.8)20 (4.2) 24 (3.2)11 (4.0) 28 (3.2)7 (5.2) 
  Craniotomy for other15 (2.8)30 (6.3) 37 (5.0)8 (3.0) 40 (4.5)5 (3.7) 
  Bur hole craniotomy16 (2.9)18 (3.8) 20 (2.7)14 (5.2) 23 (2.6)11 (8.2) 
  Non-instrumented spine104 (19.2)45 (9.5) 135 (18.1)14 (5.2) 142 (16.1)7 (5.2) 
  Instrumented spine159 (29.3)81 (17.0)<0.001169 (22.6)71 (26.2)<0.001220 (24.9)20 (14.9)<0.001
  Transnasal approach for tumor22 (4.0)46 (9.7) 45 (6.0)23 (8.5) 60 (6.8)8 (6.0) 
  Shunt52 (9.6)54 (11.4) 81 (10.8)25 (9.2) 91 (10.3)15 (11.2) 
  Miscellaneous66 (12.2)68 (14.3) 105 (14.0)29 (10.7) 119 (13.5)15 (11.2) 
Senior attending (%)174 (32.0)273 (57.5)<0.001336 (45.0)111 (41.0)0.253390 (44.1)57 (42.5)0.731
Overlapping surgery (%)0 (0)475 (100)350 (46.8)125 (46.1)0.837405 (45.8)70 (52.2)0.165
Scheduling type (%)
Elective475 (87.5)426 (89.7)0.271668 (89.4)233 (86.0)0.128789 (89.2)112 (83.6)0.055
Urgent68 (12.5)49 (10.3) 79 (10.6)38 (14.0) 95 (10.7)22 (16.4) 
Assistant training level (%)
Junior298 (54.9)241 (50.7)0.186416 (55.7)123 (45.4)0.004475 (53.7)64 (47.8)0.197
Senior245 (45.1)234 (49.3) 331 (44.3)148 (54.6) 409 (46.3)70 (52.2) 
Mean start time9:52 ± 3:1410:29 ± 3:140.00210:14 ± 3:169:56 ± 3:130.19410:09 ± 3:1410:10 ± 3:260.960
Mean duration of surgery in mins276.4 ± 138.4285.4 ± 133.60.294260.9 ± 119.5334.7 ± 162.4<0.001273.0 ± 129.4330.8 ± 166.3<0.001
Mean overlap time in mins0 ± 0197.5 ± 113.491.4 ± 123.994.4 ± 129.40.73588.9 ± 123.1113.7 ± 138.10.033
Mean estimated blood loss in ml224.5 ± 434.6187.9 ± 269.10.112147.2 ± 208.6373.3 ± 591.3<0.001193.1 ± 351.1301.9 ± 449.30.001
Mean length of stay post-surgery in days4.3 ± 4.34.7 ± 4.90.1663.4 ± 3.27.4 ± 6.4<0.0013.8 ± 3.48.9 ± 7.9<0.001
Discharge destination
    Home372 (68.5)321 (67.6)0.744584 (78.2)109 (40.2)<0.001650 (73.5)43 (32.1)<0.001
  Home health20 (3.7)28 (5.9) 32 (4.3)16 (5.9) 38 (4.3)10 (7.5) 
  Acute rehab84 (15.5)71 (14.9) 68 (9.1)87 (32.1) 104 (11.8)51 (38.1) 
  SNF40 (7.4)32 (6.7) 42 (5.6)30 (11.1) 59 (6.7)13 (9.7) 
  LTAC16 (2.9)16 (3.4) 16 (2.1)16 (5.9) 26 (2.9)6 (4.5) 
  Death7 (1.3)4 (0.8) 0 (0)11 (4.0) 0 (0)11 (8.2) 
  Other4 (0.7)3 (0.6) 5 (0.7)2 (0.7) 7 (0.8)0 (0) 
Intraop complications (%)36 (6.6)21 (4.4)0.1260 (0)57 (21.0)38 (4.3)19 (14.2)
Intraop complication grade (%)
  0507 (93.4)454 (95.6)0.099747 (100)214 (79.0)846 (95.7)115 (85.8)
  I32 (5.9)17 (3.6) 0 (0)49 (18.1) 38 (4.3)11 (8.2) 
  II2 (0.4)0 (0) 0 (0)2 (0.7) 0 (0)2 (1.5) 
  III1 (0.2)4 (0.8) 0 (0)5 (1.8) 0 (0)5 (3.7) 
  IV1 (0.2)0 (0) 0 (0)1 (0.4) 0 (0)1 (0.7) 
Postop complications (%)98 (18.0)84 (17.7)0.8800 (0)182 (67.2)90 (10.2)92 (68.7)
Postop complication grade (%)
  0445 (82.0)391 (82.3)0.091747 (100)89 (32.8)794 (89.8)42 (31.3)
  I62 (11.4)37 (7.8) 0 (0)99 (36.5) 90 (10.2)9 (6.7) 
  II8 (1.5)12 (2.5) 0 (0)20 (7.4) 0 (0)20 (14.9) 
  III22 (4.1)31 (6.5) 0 (0)53 (19.6) 0 (0)53 (39.6) 
  IV6 (1.1)4 (0.8) 0 (0)10 (3.7) 0 (0)10 (7.5) 
30-day complications (%)41 (7.6)41 (8.6)0.5270 (0)82 (30.3)30 (3.4)52 (38.8)
30-day complication grade (%)
  0502 (92.4)434 (91.4)0.822747 (100)189 (69.7)854 (96.6)82 (61.2)
  I15 (2.8)16 (3.4)0.8220 (0)31 (11.4)30 (3.4)1 (0.7)
  II17 (3.1)13 (2.7) 0 (0)30 (11.1) 0 (0)30 (22.4) 
  III8 (1.5)10 (2.1) 0 (0)18 (6.6) 0 (0)18 (13.4) 
  IV1 (0.2)2 (0.4) 0 (0)3 (1.1) 0 (0)3 (2.2) 
Any complication (%)146 (26.9)125 (26.3)0.8370 (0)271 (100)137 (15.5)134 (100)
Serious complication (%)*64 (11.8)70 (14.7)0.1680 (0)134 (49.4)0 (0)134 (100)
Worst complication grade (%)
  0397 (73.1)350 (73.7)0.172747 (100)0 (0)747 (84.5)0 (0)
  I82 (15.1)55 (11.6) 0 (0)137 (50.6) 137 (15.5)0 (0) 
  II26 (4.8)22 (4.6) 0 (0)48 (17.7) 0 (0)48 (35.8) 
  III30 (5.5)42 (8.8) 0 (0)72 (26.6) 0 (0)72 (53.7) 
  IV8 (1.5)6 (1.3) 0 (0)14 (5.2) 0 (0)14 (10.4) 

Home health = home with home health care; LTAC = long-term acute care facility; rehab = rehabilitation; SNF = skilled nursing facility; — = not applicable.

Mean values expressed with standard deviation. Boldface type indicates statistical significance (p < 0.05 is considered statistically significant).

Serious complications were Grade II or higher.

Senior attending had 20+ years postresidency experience.

“Junior assistant” indicated that no resident was assisting or that the assistant was postgraduate year 6 or earlier. “Senior assistant” indicated a postgraduate year 7 assistant or a fellow.

Compared with patients having nonoverlapping surgeries, those undergoing overlapping surgery were significantly less likely to be undergoing spinal surgery (either instrumented or non-instrumented) and were more likely to be undergoing a craniotomy or transnasal approach for tumor resection (p < 0.001). Attending physicians with more than 20 years' postresidency experience were more likely to undertake overlapping cases than those with less experience (p < 0.001).

The average start time for overlapping cases was 37 minutes later than that for nonoverlapping cases (p = 0.002), although neither the duration of surgery nor the estimated blood loss differed significantly between the 2 groups. The average overlap time for overlapping cases was 197.5 ± 113.4 minutes (95% CI 187.34–207.73). Regardless of case overlap, patients spent similar periods in the hospital postoperatively, and the majority of patients in both groups were discharged to home.

There were no significant differences in intraoperative, postoperative, or 30-day complication rates when comparing the overlapping and nonoverlapping surgery groups. Neither was the severity of complications significantly different between these 2 groups.

All Complications Analysis

Patients experiencing complications at any point during the intraoperative period, postoperative period, or within the first 30 days after discharge tended to be older (p = 0.016) and to have a lower BMI (p = 0.010) than those who did not have any complications. Moreover, patients with complications also had significantly higher ASA grades (p < 0.001) and were more likely to have had a craniotomy or transnasal approach for tumor resection, a bur hole craniotomy, an instrumented spinal procedure, or a craniotomy for a nonvascular or nonneoplastic pathology than a non-instrumented spinal procedure and shunt procedure (p < 0.001). Patients experiencing complications tended to have significantly longer operative times (p < 0.001) and to lose more blood during the case (p < 0.001). They were also more likely to have a prolonged stay postoperatively (p < 0.001) and to be discharged to a location other than home (p < 0.001). There was no significant difference in the incidence of overlapping surgery between patients with and without complications (46.1% vs 46.8%, p = 0.837).

In our multivariable model (Table 3), surgery type remained significantly associated with the overall complication rate (p = 0.001), as did a longer operative time (OR 1.003, 95% CI 1.001–1.005, p = 0.001), higher intraoperative blood loss (OR 1.001, 95% CI 1.001–1.002, p < 0.001), and higher ASA grade (p < 0.001). Higher BMI was associated with a lower incidence of overall complications (OR 0.957, 95% CI 0.934–0.981, p < 0.001). We were particularly interested in the impact of overlapping surgery. In our multivariate model, overlapping surgery was not associated with the risk of complications (OR 0.810, 95% CI 0.592–1.109, 0.189).

TABLE 3.

Multivariable regression analysis of any complication

VariableOR (95% CI)p Value
Surgery category0.001
  Craniotomy for tumor, simple1.00 (reference)
  Craniotomy for tumor, complex1.170 (0.577–2.373)0.663
  Craniotomy for aneurysm/vascular malformation0.882 (0.380–2.044)0.770
  Craniotomy for other0.578 (0.239–1.396)0.223
  Bur hole craniotomy2.694 (1.164–6.231)0.021
  Non-instrumented spine0.422 (0.210–0.847)0.015
  Instrumented spine0.859 (0.527–1.399)0.541
  Transnasal approach for tumor2.547 (1.302–4.980)0.006
  Shunt1.547 (0.818–2.927)0.180
  Miscellaneous1.323 (0.708–2.472)0.380
Overlapping surgery0.810 (0.592–1.109)0.189
Duration of surgery in mins1.003 (1.001–1.005)0.001
BMI0.957 (0.934–0.981)<0.001
ASA grade<0.001
  I or II1.00 (reference)
  III1.545 (1.100–2.170)0.012
  IV or V4.449 (2.450–8.079)<0.001
Estimated blood loss in ml1.001 (1.001–1.002)<0.001

Boldface type indicates statistical significance (p < 0.05).

To account for the range of overlap times between overlapping surgeries, we ran a supplemental analysis using the overlapping percentage (overlap time divided by total surgery duration) in our multivariable model of overall complications in place of the overlapping surgery variable. This had no influence on the factors significantly associated with the overall complication rate.

Serious Complications Analysis

In our univariate analysis, patients experiencing serious complications had significantly higher ASA grades (p < 0.001) than those who did not and were more likely to have preexisting neurological comorbidities (p = 0.001; Table 2). Serious complications were more frequently seen after craniotomies and bur hole procedures than after other surgical categories (p < 0.001). Patients who had a prolonged operative time (p < 0.001) and those with higher intraoperative blood loss (p = 0.001) also had a higher rate of serious complications. Although patients with an increased period of overlap with another surgery had a higher incidence of serious complications (p = 0.033), this finding may be attributable to the longer overall operative time in these patients. Postoperatively, patients experiencing serious complications tended to have a significantly longer stay (p < 0.001) and were significantly less likely to be discharged home (p < 0.001). There was no significant difference in the incidence of overlapping surgery between patients with and without serious complications (52.2% vs 45.8%, p = 0.165).

In our multivariable model (Table 4), surgery type (p = 0.004) remained significantly associated with the likelihood of serious complications. A longer operative period (OR 1.003, 95% CI 1.002–1.005, p < 0.001), the presence of a preoperative neurological comorbidity (OR 1.629, 95% CI 1.009–2.629, p = 0.046), and a higher ASA grade (p < 0.002) were also risk factors for serious complications. Higher BMI was associated with a lower rate of serious complications (OR 0.969, 95% CI 0.940–0.998, p = 0.038). Once again, overlapping surgery was not associated with a higher rate of serious complications (OR 0.979, 95% CI 0.661–1.449, p = 0.915).

TABLE 4.

Multivariable regression analysis of serious complications

VariableOR (95% CI)p Value
Surgery category0.004
  Craniotomy for tumor, simple1.00 (reference)
  Craniotomy for tumor, complex1.191 (0.550–2.581)0.657
  Craniotomy for aneurysm/vascular malformation0.863 (0.335–2.224)0.761
  Craniotomy for other0.583 (0.206–1.653)0.310
  Bur hole craniotomy2.912 (1.175–7.213)0.021
  Non-instrumented spine0.365 (0.148–0.896)0.028
  Instrumented spine0.414 (0.219–0.783)0.007
  Transnasal approach for tumor1.076 (0.445–2.600)0.871
  Shunt1.155 (0.540–2.469)0.711
  Miscellaneous0.959 (0.450–2.041)0.913
Overlapping surgery0.979 (0.661–1.449)0.915
Duration of surgery in mins1.003 (1.002–1.005)<0.001
BMI0.969 (0.940–0.998)0.038
ASA grade0.008
  I or II1.00 (reference)
  III1.520 (0.971–2.380)0.067
  IV or V2.922 (1.474–5.792)0.002
Neurological comorbidity1.629 (1.009–2.629)0.046

Boldface type indicates statistical significance (p < 0.05).

To account for the range of overlap times between overlapping surgeries, we ran a supplemental analysis using the overlapping percentage (overlap time divided by total surgery duration) in our multivariable model of serious complications in place of the overlapping surgery variable. This had no influence on the factors significantly associated with the serious complication rate.

Finally, we ran a similar analysis of factors associated with mortality (Grade IV complications) in our cohort. The only variables associated with mortality were a higher ASA grade (p = 0.001) and the presence of a preoperative oncological comorbidity (OR 12.033, 95% CI 3.007–48.152, p < 0.001). Overlapping surgery was not associated with mortality in this analysis (OR 0.427, 95% CI 0.118–1.536, p = 0.193).

Discussion

The use of overlapping surgery has recently become a contentious issue and will likely remain so as increased public awareness drives the topic into the realm of legislation.20 The lack of data on the impact of overlapping surgery significantly hinders the ability of patients, physicians, and policy makers to reach informed conclusions. Our study marks the first analysis of the effects of overlapping surgery on complication rates. We found no association between overlapping surgery and rates of intraoperative, postoperative, and early postdischarge complications in our cohort. Furthermore, we found no significant association between overlapping surgery and life-threatening complications or mortality. Variables associated with overall complications and life-threatening complications included higher intraoperative blood loss and higher ASA grade, both of which are known independent predictors of adverse events.7,16,17,22 Although different surgery types, unsurprisingly, had varying complication rates, our multivariable model suggested that the dangers of these procedures are less likely to be associated with their overlapping with another operation and more likely to be associated with the nature of the surgeries themselves. For example, the increased complications noted for the transnasal approach are influenced by the readmission rate for delayed hyponatremia following pituitary surgery, which occurs in approximately 5% of patients undergoing pituitary tumor resection at our institution. Similarly, patients undergoing bur hole craniotomies frequently did so because they were deemed too unstable to undergo formal craniotomy, as evidenced by the fact that the average ASA grade for bur hole patients was significantly higher than for all other patients (3.14 vs 2.55, p < 0.001).

Overlapping surgery has played an important role in academic medicine for decades1,3 but only recently has it become a concern for the general public. Overlapping surgery is important in the training of future surgeons. The experience gained from a modicum of operative autonomy during training—autonomy that is earned through 100s of hours of intense interactions and meted out in a carefully graduated fashion—is crucial to producing safe physicians. Nearly half of the overlapping cases in our cohort were assisted either by residents in their 7th and final year of postgraduate education or by fellows who had already completed their neurosurgical residency. In contrast, fewer than 15% of overlapping cases in our cohort involved residents with any less than half a decade of postgraduate experience. The controlled operative autonomy that overlapping surgery can help to provide is invaluable to those who must one day become independent surgeons. The need to prepare the next generation of surgeons and the overriding primary directive of the practitioner to ensure that the patient receives optimal care often appear in conflict with one another;9 however, with proper discussion, disclosure, and mentorship, resident involvement has been shown to be both safe and acceptable to the public.4,6,18

Fueling the need to train tomorrow's surgeons is the steadily worsening shortage of health care professionals nationwide.10,24,25 This shortage may be especially acute in neurosurgery, with the majority of counties in the United States having no neurosurgeons in practice. Access to highly subspecialized care is even more difficult, with only 13.4% of neurosurgeons identifying as neurooncology specialists, 5.2% as cerebrovascular specialists, and 0.7% as skull base specialists.12 These low percentages contribute to protracted wait times for access to care.19 Of the 5 neurosurgeons in our cohort, all are highly subspecialized and may represent the only source of specialized neurosurgical care for hundreds of miles. Optimizing the use of both surgical expertise and medical facilities is essential to deliver efficient and high-quality care to patients.3 While the 475 overlapping surgeries analyzed in this cohort make up only 10%–20% of the annual neurosurgical procedures performed at our institution, many of these surgeries are highly specialized in nature. The elimination of overlapping surgery would probably have an outsized impact on patient care, possibly leading to higher costs, increased delays from referral to treatment, and a greater proportion of operations starting after-hours.3

Our study has several limitations. The retrospective nature of our analysis introduces a significant risk of confounding, although we attempted to control for as many variables as possible to ameliorate this risk. Any analysis of the association of complications to one particular variable is obscured by the difficulty in analyzing the root cause of the complication. By casting our net broadly and incorporating intraoperative, postoperative, and early postdischarge complications in our analysis, we may have included a large number of events that were unrelated to the practice of overlapping surgery. It is our hope, however, that by doing so we avoided missing significant adverse events. Although certain events such as wrong-site or wrong-side surgery may be more easily attributable to the distraction that can result from running multiple overlapping cases, the incidence of these complications is fortunately very low. Indeed, within our cohort, no wrong-site or wrong-side surgical errors occurred during the study period. The rarity of these complications makes studying them exceedingly difficult, and a dramatically larger cohort of patients would probably be needed to focus on any individual adverse event.

Perhaps the most significant limitation of our study is the restriction to a single center and a single subspecialty. Although we did not find any association with overlapping surgery and complications, it is impossible to broadly generalize our findings, nor do we advocate a laissez-faire approach to running multiple operating rooms.15 The American College of Surgeons recently released new guidelines regarding the topic of overlapping surgery.2 Its statement distinguishes between “overlapping surgery” and “concurrent surgery.” The latter refers to operations in which “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.”2 Overlapping surgery refers to a situation in which there is a clear staggering or separation of the critical components of ongoing surgeries. The guidelines highlight the importance of the surgeon's undivided attention during the critical portion of every procedure, stress the need for discussions with patients regarding the team that will be involved in their care, and emphasize the fact that the “overriding goal is the assurance of patient safety.”

At our institution, regardless of the training level of the assistant, we adhere strictly to the principle that the attending physician of record must be present and actively involved in any critical portion of the case and that he or she frequently remains so throughout the majority of the operation. In addition, specific criteria are in place to determine which attending physicians can perform overlapping surgeries: 1) The lead physician must be an associate professor or above in academic rank; 2) the lead physician must be board certified in neurosurgery; 3) the lead physician must have at least 5 years of experience within the University of Utah Department of Neurosurgery, regardless of prior practice and/or training; 4) the lead physician must be a subspecialist in the area of the overlapping cases; and 5) qualified assistants of the appropriate training level must be available in both rooms.

In addition to adhering to these restrictions, overlapping surgeries are carefully chosen with attention to multiple factors such as case complexity, schedules, patient characteristics, operating room staffing, and resident or fellow experience. During the study period, while conversations regarding the makeup of the operative team occurred routinely, the topic of overlapping surgery was not a formal part of our consent document. Pursuant to the goals of continuously improving care, we recently added this topic to our surgical consent forms and made discussions of overlapping surgery a standard part of the consent process.

Similar to other institutions, the view at our institution is that overlapping surgery should only be performed with such meticulous attention to detail and with full disclosure and discussion with the patient undergoing the procedure.14,21 It is likely that the minimal impact of overlapping surgery on complication rates in our study is attributable to the strict control of the practice within our department. On the other hand, we believe that a ban on overlapping surgery would certainly have a significantly deleterious effect on both resident education and the ability of surgeons to deliver vital care within a reasonable time. Our study shows that with judicious oversight and monitoring, the practice of overlapping surgery is not associated with higher complication rates or a higher incidence of life-threatening adverse events.

Conclusions

In this single-center review of neurosurgical procedures performed by senior surgeons, we were unable to identify an association between overlapping surgery and overall complications or life-threatening complications including death. There remains a significant need for further inquiry into the subject of overlapping surgery and its impact on patient outcomes, preferably in the setting of a prospective, multicenter multispecialty study.

Acknowledgments

Jian Guan, MD, and Richard H. Schmidt, MD, PhD, had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis. Jian Guan, MD, was responsible for data analysis. Kristin Kraus, MSc, provided editorial assistance to the authors. Sarah Leatherman, PhD, and Richard Holubkov, PhD, provided uncompensated statistical assistance.

Disclosures

The authors have no disclosures directly related to the results of the study. Dr. Jensen is a consultant for Medtronic and Pharmocokinesis. Dr. Meic Schmidt is a consultant for Ulrich Medical USA. Dr. Dailey is a consultant for Medtronic, has received royalties and research support from Biomet, and has received speaking fees from AONA.

Author Contributions

Conception and design: Schmidt, Guan. Acquisition of data: Guan. Drafting the article: Schmidt, Guan, Brock, Karsy. Critically revising the article: Schmidt, Couldwell, Schmidt, Kestle, Jensen, Dailey. Reviewed submitted version of manuscript: Schmidt, Guan. Approved the final version of the manuscript on behalf of all authors: Schmidt. Statistical analysis: Guan.

References

  • 1

    Abelson JSaltzman JKowalczyk LAllen S: Clash in the name of care.. Boston Globe. October252015. (https://apps.bostonglobe.com/spotlight/clash-in-the-name-of-care/story

  • 2

    American College of Surgeons: Statement on Principles. April122016. (https://www.facs.org/about-acs/statements/stonprin

  • 3

    Beasley GMPappas TNKirk AD: Procedure delegation by attending surgeons performing concurrent operations in academic medical centers: balancing safety and efficiency. Ann Surg 261:104410452015

  • 4

    Bydon MAbt NBDe la Garza-Ramos RMacki MWitham TFGokaslan ZL: Impact of resident participation on morbidity and mortality in neurosurgical procedures: an analysis of 16,098 patients. J Neurosurg 122:9559612015

  • 5

    Clavien PASanabria JRStrasberg SM: Proposed classification of complications of surgery with examples of utility in cholecystectomy. Surgery 111:5185261992

  • 6

    Cowles RAMoyer CASonnad SSSimeone DMKnol JAEckhauser FE: Doctor-patient communication in surgery: attitudes and expectations of general surgery patients about the involvement and education of surgical residents. J Am Coll Surg 193:73802001

  • 7

    Daley BJCecil WClarke PCCofer JBGuillamondegui OD: How slow is too slow? Correlation of operative time to complications: an analysis from the Tennessee Surgical Quality Collaborative. J Am Coll Surg 220:5505582015

  • 8

    Dindo DDemartines NClavien PA: Classification of surgical complications: a new proposal with evaluation in a cohort of 6336 patients and results of a survey. Ann Surg 240:2052132004

  • 9

    Dutta SDunnington GBlanchard MCSpielman BDaRosa DJoehl RJ: “And doctor, no residents please!”. J Am Coll Surg 197:101210172003

  • 10

    Editorial Board: Bottlenecks in training doctors. New York Times July192014. SR10(http://www.nytimes.com/2014/07/20/opinion/sunday/bottlenecks-in-training-doctors.html

  • 11

    Gordy C: When surgeons multitask: the little-known practice of concurrent surgeries.. ProPublica. November232015. (https://www.propublica.org/podcast/item/when-surgeons-multitask-the-little-known-practice-of-concurrent-surgeries

  • 12

    Health Policy Research Institute: The Surgical Workforce in the United States: Profile and Recent Trends. Chapel Hill, NCAmerican College of Surgeons Health Policy Research Institute2010. (http://www.acshpri.org/documents/ACSHPRI_Surgical_Workforce_in_US_apr2010.pdf

  • 13

    Landriel Ibañez FAHem SAjler PVecchi ECiraolo CBaccanelli M: A new classification of complications in neurosurgery. World Neurosurg 75:7097152011

  • 14

    Langerman A: Concurrent surgery and informed consent. JAMA Surg 151:6016022016

  • 15

    Mello MMLivingston EH: Managing the risks of concurrent surgeries. JAMA 315:156315642016

  • 16

    Prause GOffner ARatzenhofer-Komenda BVicenzi MSmolle JSmolle-Jüttner F: Comparison of two preoperative indices to predict perioperative mortality in non-cardiac thoracic surgery. Eur J Cardiothorac Surg 11:6706751997

  • 17

    Procter LDDavenport DLBernard ACZwischenberger JB: General surgical operative duration is associated with increased risk-adjusted infectious complication rates and length of hospital stay.. J Am Coll Surg 210:606565.e165.e22010

  • 18

    Raval MVWang XCohen MEIngraham AMBentrem DJDimick JB: The influence of resident involvement on surgical outcomes. J Am Coll Surg 212:8898982011

  • 19

    Rosman JSlane SDery BVogelbaum MACohen-Gadol AACouldwell WT: Is there a shortage of neurosurgeons in the United States?. Neurosurgery 73:3543553653662013

  • 20

    Saltzman JAbelson J: Overlapping surgeries to face US senate inquiry.. Boston Globe. March132016. (https://www.bostonglobe.com/metro/2016/03/12/senator-launches-inquiry-into-simultaneous-surgeries-hospitals-including-mass-general/wxEsbg5r2poqtk88LkcHQI/story.html

  • 21

    Slavin PLLynch TJ: Our view of overlapping surgery.. Boston Globe. January102016. (http://www.bostonglobe.com/opinion/editorials/2016/01/10/our-view-overlapping-surgery/m0h9GxMsEzziBRWAVhZlvK/story.html

  • 22

    Tiret LHatton FDesmonts JMVourc'h G: Prediction of outcome of anaesthesia in patients over 40 years: a multifactorial risk index. Stat Med 7:9479541988

  • 23

    Twedt S: Senate committee looks at policies on surgeons performing more than one surgery at once. Pittsburgh Post-Gazette. March282016. (http://www.post-gazette.com/business/healthcare-business/2016/03/28/Senate-committtee-looks-at-hospital-policies-regarding-concurrent-surgeries/stories/201603270074

  • 24

    Voelker R: Experts say projected surgeon shortage a “looming crisis” for patient care. JAMA 302:152015212009

  • 25

    Williams KSchneider BLajos PMarin MFaries P: Supply and demand: Will we have enough vascular surgeons by 2030?. Vascular 24:4144202016

Article Information

Correspondence Richard H. Schmidt, Department of Neurosurgery, Clinical Neurosciences Center, University of Utah, 175 N Medical Dr. East, Salt Lake City, UT 84132. email: richard.schmidt@hsc.utah.edu.

INCLUDE WHEN CITING Published online December 2, 2016; DOI: 10.3171/2016.8.JNS161226.

Disclosures The authors have no disclosures directly related to the results of the study. Dr. Jensen is a consultant for Medtronic and Pharmocokinesis. Dr. Meic Schmidt is a consultant for Ulrich Medical USA. Dr. Dailey is a consultant for Medtronic, has received royalties and research support from Biomet, and has received speaking fees from AONA.

© AANS, except where prohibited by US copyright law."

Headings

References

1

Abelson JSaltzman JKowalczyk LAllen S: Clash in the name of care.. Boston Globe. October252015. (https://apps.bostonglobe.com/spotlight/clash-in-the-name-of-care/story

2

American College of Surgeons: Statement on Principles. April122016. (https://www.facs.org/about-acs/statements/stonprin

3

Beasley GMPappas TNKirk AD: Procedure delegation by attending surgeons performing concurrent operations in academic medical centers: balancing safety and efficiency. Ann Surg 261:104410452015

4

Bydon MAbt NBDe la Garza-Ramos RMacki MWitham TFGokaslan ZL: Impact of resident participation on morbidity and mortality in neurosurgical procedures: an analysis of 16,098 patients. J Neurosurg 122:9559612015

5

Clavien PASanabria JRStrasberg SM: Proposed classification of complications of surgery with examples of utility in cholecystectomy. Surgery 111:5185261992

6

Cowles RAMoyer CASonnad SSSimeone DMKnol JAEckhauser FE: Doctor-patient communication in surgery: attitudes and expectations of general surgery patients about the involvement and education of surgical residents. J Am Coll Surg 193:73802001

7

Daley BJCecil WClarke PCCofer JBGuillamondegui OD: How slow is too slow? Correlation of operative time to complications: an analysis from the Tennessee Surgical Quality Collaborative. J Am Coll Surg 220:5505582015

8

Dindo DDemartines NClavien PA: Classification of surgical complications: a new proposal with evaluation in a cohort of 6336 patients and results of a survey. Ann Surg 240:2052132004

9

Dutta SDunnington GBlanchard MCSpielman BDaRosa DJoehl RJ: “And doctor, no residents please!”. J Am Coll Surg 197:101210172003

10

Editorial Board: Bottlenecks in training doctors. New York Times July192014. SR10(http://www.nytimes.com/2014/07/20/opinion/sunday/bottlenecks-in-training-doctors.html

11

Gordy C: When surgeons multitask: the little-known practice of concurrent surgeries.. ProPublica. November232015. (https://www.propublica.org/podcast/item/when-surgeons-multitask-the-little-known-practice-of-concurrent-surgeries

12

Health Policy Research Institute: The Surgical Workforce in the United States: Profile and Recent Trends. Chapel Hill, NCAmerican College of Surgeons Health Policy Research Institute2010. (http://www.acshpri.org/documents/ACSHPRI_Surgical_Workforce_in_US_apr2010.pdf

13

Landriel Ibañez FAHem SAjler PVecchi ECiraolo CBaccanelli M: A new classification of complications in neurosurgery. World Neurosurg 75:7097152011

14

Langerman A: Concurrent surgery and informed consent. JAMA Surg 151:6016022016

15

Mello MMLivingston EH: Managing the risks of concurrent surgeries. JAMA 315:156315642016

16

Prause GOffner ARatzenhofer-Komenda BVicenzi MSmolle JSmolle-Jüttner F: Comparison of two preoperative indices to predict perioperative mortality in non-cardiac thoracic surgery. Eur J Cardiothorac Surg 11:6706751997

17

Procter LDDavenport DLBernard ACZwischenberger JB: General surgical operative duration is associated with increased risk-adjusted infectious complication rates and length of hospital stay.. J Am Coll Surg 210:606565.e165.e22010

18

Raval MVWang XCohen MEIngraham AMBentrem DJDimick JB: The influence of resident involvement on surgical outcomes. J Am Coll Surg 212:8898982011

19

Rosman JSlane SDery BVogelbaum MACohen-Gadol AACouldwell WT: Is there a shortage of neurosurgeons in the United States?. Neurosurgery 73:3543553653662013

20

Saltzman JAbelson J: Overlapping surgeries to face US senate inquiry.. Boston Globe. March132016. (https://www.bostonglobe.com/metro/2016/03/12/senator-launches-inquiry-into-simultaneous-surgeries-hospitals-including-mass-general/wxEsbg5r2poqtk88LkcHQI/story.html

21

Slavin PLLynch TJ: Our view of overlapping surgery.. Boston Globe. January102016. (http://www.bostonglobe.com/opinion/editorials/2016/01/10/our-view-overlapping-surgery/m0h9GxMsEzziBRWAVhZlvK/story.html

22

Tiret LHatton FDesmonts JMVourc'h G: Prediction of outcome of anaesthesia in patients over 40 years: a multifactorial risk index. Stat Med 7:9479541988

23

Twedt S: Senate committee looks at policies on surgeons performing more than one surgery at once. Pittsburgh Post-Gazette. March282016. (http://www.post-gazette.com/business/healthcare-business/2016/03/28/Senate-committtee-looks-at-hospital-policies-regarding-concurrent-surgeries/stories/201603270074

24

Voelker R: Experts say projected surgeon shortage a “looming crisis” for patient care. JAMA 302:152015212009

25

Williams KSchneider BLajos PMarin MFaries P: Supply and demand: Will we have enough vascular surgeons by 2030?. Vascular 24:4144202016

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