e131(1) C OPYRIGHT Ó 2014
BY
T HE J OURNAL
OF
B ONE
AND J OINT
S URGERY, I NCORPORATED
Topics in Training Impact of Resident Involvement on Orthopaedic Surgery Outcomes: An Analysis of 30,628 Patients from the American College of Surgeons National Surgical Quality Improvement Program Database Adam I. Edelstein, MD, Francis C. Lovecchio, BA, Sujata Saha, BS, Wellington K. Hsu, MD, and John Y.S. Kim, MD Investigation performed at the Departments of Orthopaedic Surgery and Surgery, Northwestern University, Feinberg School of Medicine, Chicago, Illinois
Background: Operative procedural training is a key component of orthopaedic surgery residency. The influence of intraoperative resident participation on the outcomes of surgery has not been studied extensively using large, populationbased databases. Methods: We identified 30,628 patients who underwent orthopaedic procedures from the 2011 American College of Surgeons National Surgical Quality Improvement Program. Outcomes as measured by perioperative complications, readmission rates, and mortality within thirty days were compared for cases with and without intraoperative resident involvement. Results: Logistic regression with propensity score analysis revealed that intraoperative resident participation was associated with decreased rates of overall complications (odds ratio, 0.717 [95% confidence interval, 0.657 to 0.782]), medical complications (odds ratio, 0.723 [95% confidence interval, 0.661 to 0.790]), and mortality (odds ratio, 0.638 [95% confidence interval, 0.427 to 0.951]). Resident presence in the operating room was not predictive of wound complications (odds ratio, 0.831 [95% confidence interval, 0.656 to 1.053]), readmission (odds ratio, 0.962 [95% confidence interval, 0.830 to 1.116]), or reoperation (odds ratio, 0.938 [95% confidence interval, 0.758 to 1.161]). A second analysis by propensity score stratification into quintiles grouped by similar probability of intraoperative resident presence showed resident involvement to correlate with decreased rates of overall and medical complications in three quintiles, but continued Peer Review: This article was reviewed by the Editor-in-Chief and one Deputy Editor, and it underwent blinded review by two or more outside experts. It was also reviewed by an expert in methodology and statistics. The Deputy Editor reviewed each revision of the article, and it underwent a final review by the Editor-in-Chief prior to publication. Final corrections and clarifications occurred during one or more exchanges between the author(s) and copyeditors.
Disclosure: None of the authors received payments or services, either directly or indirectly (i.e., via his or her institution), from a third party in support of any aspect of this work. One or more of the authors, or his or her institution, has had a financial relationship, in the thirty-six months prior to submission of this work, with an entity in the biomedical arena that could be perceived to influence or have the potential to influence what is written in this work. No author has had any other relationships, or has engaged in any other activities, that could be perceived to influence or have the potential to influence what is written in this work. The complete Disclosures of Potential Conflicts of Interest submitted by authors are always provided with the online version of the article. Disclaimer: The American College of Surgeons National Surgical Quality Improvement Program and the hospitals participating in the ACS NSQIP are the source of the data used herein; they have not verified and are not responsible for the statistical validity of the data analysis or the conclusions derived by the authors.
J Bone Joint Surg Am. 2014;96:e131(1-11)
d
http://dx.doi.org/10.2106/JBJS.M.00660
e131(2) TH E JO U R NA L O F B O N E & JO I N T SU RG E RY J B J S . O RG V O L U M E 96-A N U M B E R 15 A U G U S T 6, 2 014 d
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I M PA C T O F R E S I D E N T I N VO LV E M E N T O N O RT H O PA E D I C S U R G E RY O U T C O M E S : A N A LY S I S O F ACS-NSQIP D ATA B A S E
increased rates of overall and medical complications in one quintile. All other outcomes were equivalent across quintiles.
Conclusions: Orthopaedic resident involvement during surgical procedures is associated with lower risk of perioperative complications and mortality in the National Surgical Quality Improvement Program database. The results support resident participation in the operative care of orthopaedic patients. Level of Evidence: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.
The principal goal of an orthopaedic surgery residency program is to prepare trainees for independent practice. As such, teaching hospitals integrate residents in a graduated fashion into all aspects of patient care including ambulatory, inpatient, and operative settings. With the health-care reform process focused on quality measures, the impact of intraoperative resident involvement on the results of surgery has come under increased scrutiny1-3. Concern over duty-hour restrictions and resident inexperience has even sparked reluctance among patients to have residents involved in their care4,5. Several studies have demonstrated an increased rate of complications and prolonged operating room times for general and vascular surgery cases involving residents6-12. Some studies have stratified complication rates by resident postgraduate year with mixed results7,13-15. To our knowledge, the relationship between orthopaedic surgery outcomes and resident involvement in the operating room has not been studied on a large scale. The American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) is a validated, prospective, multicenter clinical database that collects surgical outcomes data from more than 250 institutions. Both teaching and nonteaching hospitals participate at their discretion. At each institution, 240 separate data points are closely tracked for a set of systematically sampled cases. The tracked variables include patient demographic characteristics, preoperative comorbidities, intraoperative metrics, and postoperative clinical outcomes. Using this data set, this study aimed to assess the impact of intraoperative orthopaedic resident participation on an array of surgical outcomes. Materials and Methods Data Description and Acquisition 16,17
Details of the NSQIP database have been described previously . In brief, the program employs clinical reviewers at each participating site to collect detailed surgical data in a standardized, audited process. All patient data are de-identified to comply with the Health Insurance Portability and Accountability Act of 1996 (HIPAA). The rigorous data collection procedures have resulted in a well-validated 18-20 database that demonstrates high inter-rater reliability . The 2011 NSQIP database was queried for patients who underwent a procedure in which orthopaedics was listed as the primary service. Of note, the database excludes the following patients: those who enter the hospital as a result of acute trauma, those who are less than eighteen years of age, and those who do not receive general, spinal, or epidural anesthesia. The presence or absence of a resident scrubbed into the case is tracked as a variable in the database. However, it should be noted that the database does not detail the intraoperative level of involvement of the resident, nor does it indicate resident involvement in perioperative care. All patients who had missing data on intraoperative resident presence
were also excluded. The sample was stratified into two cohorts based on the presence or absence of a resident scrubbed into the case. All variables were used as defined in the NSQIP user guide, and all 17 outcomes were tracked for thirty days following the primary operation . The primary outcomes of interest consisted of unplanned reoperation, unplanned readmission, mortality, medical complications, wound complications, overall complications, and length of stay. Unplanned reoperation was defined as any unanticipated return to the operating room for surgical intervention within thirty days that was related to the index procedure. Unplanned readmissions included any readmission within thirty days after the primary operation that was likely related to the principal surgical procedure and was not planned at the time of surgery. Length of stay was defined as the time from surgery to discharge. Complications were grouped into wound complications and medical complications. Wound complications consisted of surgical site infection (subdivided into superficial, deep, and organ space) and wound dehiscence. Medical complications consisted of pneumonia, unplanned intubation, pulmonary embolism, ventilation for more than forty-eight hours, acute renal failure (an increase in creatinine of >2 mg/dL above baseline), urinary tract infection, stroke, coma (lasting more than twenty-four hours), peripheral nerve injury (only motor deficits), cardiac arrest (requiring resuscitation), myocardial infarction, blood transfusion within seventy-two hours of the procedure, deep venous thrombosis, and sepsis or septic shock. Demographic variables included age, sex, race, and body mass index (BMI). Comorbidities included recent unintended weight loss (>10% decrease in body weight in the previous six months), diabetes mellitus, smoking, alcohol use (more than two drinks per day in the previous two weeks), chronic obstructive pulmonary disease, congestive heart failure, previous myocardial infarction, previous cardiac intervention, peripheral vascular disease, previous stroke, dialysis, corticosteroid use, bleeding disorder (any condition posing a risk of excessive bleeding due to the deficiency of clotting elements), open wound (includes surgical wounds, with or without infection), chemotherapy (in the previous thirty days), radiation therapy (in the previous ninety days), prior operation (in the previous thirty days), dyspnea, hypertension, and preoperative sepsis. Operative variables included American Society of Anesthesiologists (ASA) class, preoperative blood transfusion (more than four units of packed red blood cells within seventy-two hours of surgery), preoperative hospital stay of more than twenty-four hours, duration of surgery, and total relative value units. The total relative value units for each case were 18,21 included to account for cases that involved multiple procedures .
Statistical Analysis Demographic variables, comorbidities, operative characteristics, and unadjusted complication rates were compared between the group with the resident present and the group with no resident present with use of the Pearson chi-square test for categorical variables and the Mann-Whitney U test for continuous variables. A multivariate model was then created with a threshold of p < 0.1 used to identify covariates for inclusion. Screened variables included age, sex, race, BMI class, operative time, total relative value units, preoperative stay longer than twenty-four hours, and length of stay. Additionally, all comorbidities listed in the NSQIP user guide were screened for an association with the 17 outcomes of interest to determine their inclusion in the multivariate models . 22 Factors with less than ten occurrences were excluded .
e131(3) TH E JO U R NA L O F B O N E & JO I N T SU RG E RY J B J S . O RG V O L U M E 96-A N U M B E R 15 A U G U S T 6, 2 014 d
d
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I M PA C T O F R E S I D E N T I N VO LV E M E N T O N O RT H O PA E D I C S U R G E RY O U T C O M E S : A N A LY S I S O F ACS-NSQIP D ATA B A S E
TABLE I Most Common Procedures Included in Analysis* Current Procedural Terminology Code
Cases†
Total knee arthroplasty
27447
5638 (18.4%)
Total hip arthroplasty
27130
3577 (11.7%)
Arthroscopic medial or lateral meniscectomy
29881
1828 (6%)
Procedure
Arthroscopic rotator cuff repair
29827
874 (2.9%)
Arthroscopic medial and lateral meniscectomy
29880
653 (2.1%)
Arthroscopic subacromial decompression
29826
651 (2.1%)
Open treatment of femoral neck fracture
27236
607 (2%)
Arthroscopically aided anterior cruciate ligament reconstruction
29888
583 (1.9%)
Intramedullary implant for intertrochanteric, peritrochanteric, or subtrochanteric femoral fracture
27245
578 (1.9%)
Total shoulder arthroplasty
23472
543 (1.8%)
*Numerous spine, hand, and foot or ankle procedures are included in the analysis but do not appear in the list in the table. †The values are given as the number of cases, with the percentage in parentheses.
A propensity score was then introduced as an additional method to reduce 23,24 confounding between the cohorts, as described elsewhere . In brief, the propensity score is a computed probability of intraoperative resident presence assigned to each patient on the basis of a comparison of that patient’s characteristics with the distributions of patient characteristics in the two cohorts. Once a propensity score is generated, three forms of analysis are described to adjust for confounders: matching, stratification, and logistic regression. Our analysis utilized propensity scores in stratification and logistic regression analyses. The multivariate model was then used in a logistic regression analysis involving the screened covariates and the propensity scores. Adjusted odds ratios with 95% confidence intervals (95% CIs) were generated for the outcomes of interest: reoperation, readmission, mortality, medical complications, wound complications, and overall complications. Lastly, a separate propensity score stratification analysis was performed by grouping cases into quintiles by propensity score. The first quintile included patients with characteristics least associated with intraoperative resident presence, whereas the fifth quintile included patients with characteristics most associated with resident presence. Each quintile was then divided into a cohort with the resident present and a cohort with no resident present, and demographic characteristics, comorbidities, operative factors, and unadjusted outcomes were compared within the quintiles. Quintile stratification has been shown to effectively adjust for baseline differences between cohorts to minimize bias secondary to nonrandom assign23 ment . C-statistics were computed for each model to determine discriminative 25-27 ability . The level of significance was set at p < 0.05.
Source of Funding No external funding was used in this study.
Results Our query of the 2011 ACS-NSQIP database identified 63,326 patients with the primary service listed as orthopaedics. After exclusion of cases for which the intraoperative resident presence data point was left null, 30,628 cases were included in the final analysis. Of these, 19,557 cases (63.9%) did not involve residents, and 11,071 cases (36.1%) did involve residents. The most common procedures are listed in Table I. Demographic characteristics and preoperative comorbidities for patients within each group are listed in Table II.
Orthopaedic procedures with a resident present had a significantly higher percentage of patients who were on dialysis; had a history of corticosteroid or alcohol use; had a bleeding disorder or had received preoperative blood transfusion; had an open wound, wound infection, or systemic sepsis; had received chemotherapy or radiotherapy; had undergone a prior operation within thirty days; or had been admitted more than twenty-four hours prior to operation. Patients who underwent surgery without resident participation were significantly more likely to have a higher BMI and be diabetic, dyspneic, and hypertensive. Comparison of Outcomes Unadjusted rates of postoperative complications, reoperation, readmission, mortality, length of stay, operative time, and total relative value units for the two groups were compared (Table III). When cases with intraoperative resident participation were compared with cases with no intraoperative resident participation, there were significantly higher unadjusted rates of overall complications (17.50% for intraoperative resident participation and 16.12% for no intraoperative resident participation; p = 0.002), medical complications (16.30% for intraoperative resident participation and 14.86% for no intraoperative resident participation; p = 0.001), and reoperation (2.34% for intraoperative resident participation and 1.74% for no intraoperative resident participation; p < 0.001). Specific medical complications associated with resident involvement in the unadjusted analysis were unplanned intubation (0.41% for intraoperative resident participation and 0.25% for no intraoperative resident participation; p = 0.018), ventilator dependence of more than forty-eight hours (0.42% for intraoperative resident participation and 0.19% for no intraoperative resident participation; p < 0.001), blood transfusion (13.60% for intraoperative resident participation and 12.39% for no intraoperative resident participation; p = 0.002), and sepsis or septic shock
e131(4) TH E JO U R NA L O F B O N E & JO I N T SU RG E RY J B J S . O RG V O L U M E 96-A N U M B E R 15 A U G U S T 6, 2 014 d
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I M PA C T O F R E S I D E N T I N VO LV E M E N T O N O RT H O PA E D I C S U R G E RY O U T C O M E S : A N A LY S I S O F ACS-NSQIP D ATA B A S E
TABLE II Patient Characteristics by Resident Presence No Resident Present (N = 19,557)
Resident Present (N = 11,071)
P Value*
61 (49 to 71)
0.077
Demographics Age† (yr)
61 (49 to 72)
Sex‡
0.067
Male
8721 (44.59%)
5067 (45.77%)
10,817 (55.31%)
5998 (54.18%)
White
14,869 (76.03%)
7012 (63.34%)
Black
1200 (6.14%)
729 (6.58%)
Asian
245 (1.25%)
138 (1.25%)
Other
176 (0.90%)
28 (0.25%)
289 (1.48%)
150 (1.35%)
Female Race‡
BY
T HE J OURNAL
OF
B ONE
AND J OINT
S URGERY, I NCORPORATED
Topics in Training Impact of Resident Involvement on Orthopaedic Surgery Outcomes: An Analysis of 30,628 Patients from the American College of Surgeons National Surgical Quality Improvement Program Database Adam I. Edelstein, MD, Francis C. Lovecchio, BA, Sujata Saha, BS, Wellington K. Hsu, MD, and John Y.S. Kim, MD Investigation performed at the Departments of Orthopaedic Surgery and Surgery, Northwestern University, Feinberg School of Medicine, Chicago, Illinois
Background: Operative procedural training is a key component of orthopaedic surgery residency. The influence of intraoperative resident participation on the outcomes of surgery has not been studied extensively using large, populationbased databases. Methods: We identified 30,628 patients who underwent orthopaedic procedures from the 2011 American College of Surgeons National Surgical Quality Improvement Program. Outcomes as measured by perioperative complications, readmission rates, and mortality within thirty days were compared for cases with and without intraoperative resident involvement. Results: Logistic regression with propensity score analysis revealed that intraoperative resident participation was associated with decreased rates of overall complications (odds ratio, 0.717 [95% confidence interval, 0.657 to 0.782]), medical complications (odds ratio, 0.723 [95% confidence interval, 0.661 to 0.790]), and mortality (odds ratio, 0.638 [95% confidence interval, 0.427 to 0.951]). Resident presence in the operating room was not predictive of wound complications (odds ratio, 0.831 [95% confidence interval, 0.656 to 1.053]), readmission (odds ratio, 0.962 [95% confidence interval, 0.830 to 1.116]), or reoperation (odds ratio, 0.938 [95% confidence interval, 0.758 to 1.161]). A second analysis by propensity score stratification into quintiles grouped by similar probability of intraoperative resident presence showed resident involvement to correlate with decreased rates of overall and medical complications in three quintiles, but continued Peer Review: This article was reviewed by the Editor-in-Chief and one Deputy Editor, and it underwent blinded review by two or more outside experts. It was also reviewed by an expert in methodology and statistics. The Deputy Editor reviewed each revision of the article, and it underwent a final review by the Editor-in-Chief prior to publication. Final corrections and clarifications occurred during one or more exchanges between the author(s) and copyeditors.
Disclosure: None of the authors received payments or services, either directly or indirectly (i.e., via his or her institution), from a third party in support of any aspect of this work. One or more of the authors, or his or her institution, has had a financial relationship, in the thirty-six months prior to submission of this work, with an entity in the biomedical arena that could be perceived to influence or have the potential to influence what is written in this work. No author has had any other relationships, or has engaged in any other activities, that could be perceived to influence or have the potential to influence what is written in this work. The complete Disclosures of Potential Conflicts of Interest submitted by authors are always provided with the online version of the article. Disclaimer: The American College of Surgeons National Surgical Quality Improvement Program and the hospitals participating in the ACS NSQIP are the source of the data used herein; they have not verified and are not responsible for the statistical validity of the data analysis or the conclusions derived by the authors.
J Bone Joint Surg Am. 2014;96:e131(1-11)
d
http://dx.doi.org/10.2106/JBJS.M.00660
e131(2) TH E JO U R NA L O F B O N E & JO I N T SU RG E RY J B J S . O RG V O L U M E 96-A N U M B E R 15 A U G U S T 6, 2 014 d
d
d
I M PA C T O F R E S I D E N T I N VO LV E M E N T O N O RT H O PA E D I C S U R G E RY O U T C O M E S : A N A LY S I S O F ACS-NSQIP D ATA B A S E
increased rates of overall and medical complications in one quintile. All other outcomes were equivalent across quintiles.
Conclusions: Orthopaedic resident involvement during surgical procedures is associated with lower risk of perioperative complications and mortality in the National Surgical Quality Improvement Program database. The results support resident participation in the operative care of orthopaedic patients. Level of Evidence: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.
The principal goal of an orthopaedic surgery residency program is to prepare trainees for independent practice. As such, teaching hospitals integrate residents in a graduated fashion into all aspects of patient care including ambulatory, inpatient, and operative settings. With the health-care reform process focused on quality measures, the impact of intraoperative resident involvement on the results of surgery has come under increased scrutiny1-3. Concern over duty-hour restrictions and resident inexperience has even sparked reluctance among patients to have residents involved in their care4,5. Several studies have demonstrated an increased rate of complications and prolonged operating room times for general and vascular surgery cases involving residents6-12. Some studies have stratified complication rates by resident postgraduate year with mixed results7,13-15. To our knowledge, the relationship between orthopaedic surgery outcomes and resident involvement in the operating room has not been studied on a large scale. The American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) is a validated, prospective, multicenter clinical database that collects surgical outcomes data from more than 250 institutions. Both teaching and nonteaching hospitals participate at their discretion. At each institution, 240 separate data points are closely tracked for a set of systematically sampled cases. The tracked variables include patient demographic characteristics, preoperative comorbidities, intraoperative metrics, and postoperative clinical outcomes. Using this data set, this study aimed to assess the impact of intraoperative orthopaedic resident participation on an array of surgical outcomes. Materials and Methods Data Description and Acquisition 16,17
Details of the NSQIP database have been described previously . In brief, the program employs clinical reviewers at each participating site to collect detailed surgical data in a standardized, audited process. All patient data are de-identified to comply with the Health Insurance Portability and Accountability Act of 1996 (HIPAA). The rigorous data collection procedures have resulted in a well-validated 18-20 database that demonstrates high inter-rater reliability . The 2011 NSQIP database was queried for patients who underwent a procedure in which orthopaedics was listed as the primary service. Of note, the database excludes the following patients: those who enter the hospital as a result of acute trauma, those who are less than eighteen years of age, and those who do not receive general, spinal, or epidural anesthesia. The presence or absence of a resident scrubbed into the case is tracked as a variable in the database. However, it should be noted that the database does not detail the intraoperative level of involvement of the resident, nor does it indicate resident involvement in perioperative care. All patients who had missing data on intraoperative resident presence
were also excluded. The sample was stratified into two cohorts based on the presence or absence of a resident scrubbed into the case. All variables were used as defined in the NSQIP user guide, and all 17 outcomes were tracked for thirty days following the primary operation . The primary outcomes of interest consisted of unplanned reoperation, unplanned readmission, mortality, medical complications, wound complications, overall complications, and length of stay. Unplanned reoperation was defined as any unanticipated return to the operating room for surgical intervention within thirty days that was related to the index procedure. Unplanned readmissions included any readmission within thirty days after the primary operation that was likely related to the principal surgical procedure and was not planned at the time of surgery. Length of stay was defined as the time from surgery to discharge. Complications were grouped into wound complications and medical complications. Wound complications consisted of surgical site infection (subdivided into superficial, deep, and organ space) and wound dehiscence. Medical complications consisted of pneumonia, unplanned intubation, pulmonary embolism, ventilation for more than forty-eight hours, acute renal failure (an increase in creatinine of >2 mg/dL above baseline), urinary tract infection, stroke, coma (lasting more than twenty-four hours), peripheral nerve injury (only motor deficits), cardiac arrest (requiring resuscitation), myocardial infarction, blood transfusion within seventy-two hours of the procedure, deep venous thrombosis, and sepsis or septic shock. Demographic variables included age, sex, race, and body mass index (BMI). Comorbidities included recent unintended weight loss (>10% decrease in body weight in the previous six months), diabetes mellitus, smoking, alcohol use (more than two drinks per day in the previous two weeks), chronic obstructive pulmonary disease, congestive heart failure, previous myocardial infarction, previous cardiac intervention, peripheral vascular disease, previous stroke, dialysis, corticosteroid use, bleeding disorder (any condition posing a risk of excessive bleeding due to the deficiency of clotting elements), open wound (includes surgical wounds, with or without infection), chemotherapy (in the previous thirty days), radiation therapy (in the previous ninety days), prior operation (in the previous thirty days), dyspnea, hypertension, and preoperative sepsis. Operative variables included American Society of Anesthesiologists (ASA) class, preoperative blood transfusion (more than four units of packed red blood cells within seventy-two hours of surgery), preoperative hospital stay of more than twenty-four hours, duration of surgery, and total relative value units. The total relative value units for each case were 18,21 included to account for cases that involved multiple procedures .
Statistical Analysis Demographic variables, comorbidities, operative characteristics, and unadjusted complication rates were compared between the group with the resident present and the group with no resident present with use of the Pearson chi-square test for categorical variables and the Mann-Whitney U test for continuous variables. A multivariate model was then created with a threshold of p < 0.1 used to identify covariates for inclusion. Screened variables included age, sex, race, BMI class, operative time, total relative value units, preoperative stay longer than twenty-four hours, and length of stay. Additionally, all comorbidities listed in the NSQIP user guide were screened for an association with the 17 outcomes of interest to determine their inclusion in the multivariate models . 22 Factors with less than ten occurrences were excluded .
e131(3) TH E JO U R NA L O F B O N E & JO I N T SU RG E RY J B J S . O RG V O L U M E 96-A N U M B E R 15 A U G U S T 6, 2 014 d
d
d
I M PA C T O F R E S I D E N T I N VO LV E M E N T O N O RT H O PA E D I C S U R G E RY O U T C O M E S : A N A LY S I S O F ACS-NSQIP D ATA B A S E
TABLE I Most Common Procedures Included in Analysis* Current Procedural Terminology Code
Cases†
Total knee arthroplasty
27447
5638 (18.4%)
Total hip arthroplasty
27130
3577 (11.7%)
Arthroscopic medial or lateral meniscectomy
29881
1828 (6%)
Procedure
Arthroscopic rotator cuff repair
29827
874 (2.9%)
Arthroscopic medial and lateral meniscectomy
29880
653 (2.1%)
Arthroscopic subacromial decompression
29826
651 (2.1%)
Open treatment of femoral neck fracture
27236
607 (2%)
Arthroscopically aided anterior cruciate ligament reconstruction
29888
583 (1.9%)
Intramedullary implant for intertrochanteric, peritrochanteric, or subtrochanteric femoral fracture
27245
578 (1.9%)
Total shoulder arthroplasty
23472
543 (1.8%)
*Numerous spine, hand, and foot or ankle procedures are included in the analysis but do not appear in the list in the table. †The values are given as the number of cases, with the percentage in parentheses.
A propensity score was then introduced as an additional method to reduce 23,24 confounding between the cohorts, as described elsewhere . In brief, the propensity score is a computed probability of intraoperative resident presence assigned to each patient on the basis of a comparison of that patient’s characteristics with the distributions of patient characteristics in the two cohorts. Once a propensity score is generated, three forms of analysis are described to adjust for confounders: matching, stratification, and logistic regression. Our analysis utilized propensity scores in stratification and logistic regression analyses. The multivariate model was then used in a logistic regression analysis involving the screened covariates and the propensity scores. Adjusted odds ratios with 95% confidence intervals (95% CIs) were generated for the outcomes of interest: reoperation, readmission, mortality, medical complications, wound complications, and overall complications. Lastly, a separate propensity score stratification analysis was performed by grouping cases into quintiles by propensity score. The first quintile included patients with characteristics least associated with intraoperative resident presence, whereas the fifth quintile included patients with characteristics most associated with resident presence. Each quintile was then divided into a cohort with the resident present and a cohort with no resident present, and demographic characteristics, comorbidities, operative factors, and unadjusted outcomes were compared within the quintiles. Quintile stratification has been shown to effectively adjust for baseline differences between cohorts to minimize bias secondary to nonrandom assign23 ment . C-statistics were computed for each model to determine discriminative 25-27 ability . The level of significance was set at p < 0.05.
Source of Funding No external funding was used in this study.
Results Our query of the 2011 ACS-NSQIP database identified 63,326 patients with the primary service listed as orthopaedics. After exclusion of cases for which the intraoperative resident presence data point was left null, 30,628 cases were included in the final analysis. Of these, 19,557 cases (63.9%) did not involve residents, and 11,071 cases (36.1%) did involve residents. The most common procedures are listed in Table I. Demographic characteristics and preoperative comorbidities for patients within each group are listed in Table II.
Orthopaedic procedures with a resident present had a significantly higher percentage of patients who were on dialysis; had a history of corticosteroid or alcohol use; had a bleeding disorder or had received preoperative blood transfusion; had an open wound, wound infection, or systemic sepsis; had received chemotherapy or radiotherapy; had undergone a prior operation within thirty days; or had been admitted more than twenty-four hours prior to operation. Patients who underwent surgery without resident participation were significantly more likely to have a higher BMI and be diabetic, dyspneic, and hypertensive. Comparison of Outcomes Unadjusted rates of postoperative complications, reoperation, readmission, mortality, length of stay, operative time, and total relative value units for the two groups were compared (Table III). When cases with intraoperative resident participation were compared with cases with no intraoperative resident participation, there were significantly higher unadjusted rates of overall complications (17.50% for intraoperative resident participation and 16.12% for no intraoperative resident participation; p = 0.002), medical complications (16.30% for intraoperative resident participation and 14.86% for no intraoperative resident participation; p = 0.001), and reoperation (2.34% for intraoperative resident participation and 1.74% for no intraoperative resident participation; p < 0.001). Specific medical complications associated with resident involvement in the unadjusted analysis were unplanned intubation (0.41% for intraoperative resident participation and 0.25% for no intraoperative resident participation; p = 0.018), ventilator dependence of more than forty-eight hours (0.42% for intraoperative resident participation and 0.19% for no intraoperative resident participation; p < 0.001), blood transfusion (13.60% for intraoperative resident participation and 12.39% for no intraoperative resident participation; p = 0.002), and sepsis or septic shock
e131(4) TH E JO U R NA L O F B O N E & JO I N T SU RG E RY J B J S . O RG V O L U M E 96-A N U M B E R 15 A U G U S T 6, 2 014 d
d
d
I M PA C T O F R E S I D E N T I N VO LV E M E N T O N O RT H O PA E D I C S U R G E RY O U T C O M E S : A N A LY S I S O F ACS-NSQIP D ATA B A S E
TABLE II Patient Characteristics by Resident Presence No Resident Present (N = 19,557)
Resident Present (N = 11,071)
P Value*
61 (49 to 71)
0.077
Demographics Age† (yr)
61 (49 to 72)
Sex‡
0.067
Male
8721 (44.59%)
5067 (45.77%)
10,817 (55.31%)
5998 (54.18%)
White
14,869 (76.03%)
7012 (63.34%)
Black
1200 (6.14%)
729 (6.58%)
Asian
245 (1.25%)
138 (1.25%)
Other
176 (0.90%)
28 (0.25%)
289 (1.48%)
150 (1.35%)
Female Race‡
