The July Effect: Impact of the Beginning of the Academic Cycle on Cardiac Surgical Outcomes in a Cohort of 70,616 Patients

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1 ADULT CARDIAC The July Effect: Impact of the Beginning of the Academic Cycle on Cardiac Surgical Outcomes in a Cohort of 70,616 Patients Faisal G. Bakaeen, MD, Joseph Huh, MD, Scott A. LeMaire, MD, Joseph S. Coselli, MD, Shubhada Sansgiry, PhD, Prasad V. Atluri, MD, and Danny Chu, MD Division of Cardiothoracic Surgery, Michael E. DeBakey Department of Surgery, Baylor College of Medicine, The Michael E. DeBakey Veterans Affairs Medical Center, and The Texas Heart Institute at St. Luke s Episcopal Hospital, Houston, Texas Background. Because surgical residents level of experience may be at its nadir early in the academic year, academic seasonality or the July effect could affect cardiac surgical outcomes. Methods. Prospectively collected data from the Department of Veterans Affairs Continuous Improvement in Cardiac Surgery Program were used to identify 70,616 consecutive cardiac surgical procedures performed between October 1997 and October Morbidity and mortality rates were compared between early (July 1 to August 31, n 11,975) and late (September 1 to June 30, n 58,641) periods in the academic year. A prediction model was constructed by using stepwise logistic regression modeling. Results. The two patient groups had similar demographic and risk variables. Isolated coronary artery bypass grafting accounted for 76.7% of early-period procedures and 75.8% of later-period procedures (p 0.03). Morbidity rates did not differ significantly between the early (14.0%) and later periods (14.2%; odds ratio [OR], 1.01; 95% confidence interval [CI], 0.96 to 1.07; p 0.67) and operative mortality was similar, 3.7% vs 3.9% (OR, 0.99; 95% CI, 0.89 to 1.11; p 0.90). The early portion of the year was associated with longer cardiac ischemia times (84 40 vs minutes), cardiopulmonary bypass times ( vs minutes), and total surgical times ( vs minutes; p < 0.05 for all). Conclusions. The early part of the academic year was associated with slightly longer operative times; however, risk-adjusted outcomes were similar in both periods. This finding should lessen concerns about the quality of cardiac surgical care at the beginning of the academic year. (Ann Thorac Surg 2009;88:70 5) 2009 by The Society of Thoracic Surgeons Accepted for publication April 9, Address correspondence to Dr Bakaeen, Assistant Professor of Surgery, Department of Cardiothoracic Surgery, Michael E. DeBakey VAMC, OCL 112, 2002 Holcombe Blvd, Houston, TX 77030; fbakaeen@ bcm.edu. The month of July marks the beginning of the academic year and is universally associated with an influx of new or junior residents. Therefore, the level of experience of front-line medical caregivers may not be as high in July as it is later in the academic year. In the academic surgical arena, the surgical and perioperative care skills of the residents are usually at their nadir at the beginning of the academic year. It is therefore logical to theorize that the characteristic cyclic rotation of residents may affect surgical outcomes. In a recent landmark study, Englesbe and colleagues [1] used the American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) to look at seasonal variations in surgical outcomes. The findings suggested a real seasonal discrepancy in outcomes: there was an 18% increase in risk-adjusted surgical morbidity and a 41% increase in risk-adjusted surgical mortality during the months of July and August compared with a later period in the academic year. In contrast, concerns about poor outcomes in the month of July were refuted in various other clinical milieus [2 4], including a recent large, nationwide study in the field of obstetrics [4]. Little is known about the effect of academic seasonality on cardiac surgical outcomes. Cardiac surgery involves complex and high-acuity procedures, which calls into question the validity of any extrapolations made from findings in other surgical specialties. A study from a single-center experience from the United Kingdom showed that periods of change in resident surgical staff were associated with increased risk-adjusted in-hospital mortality after complex cardiac operations [5]. At our hospital, we identified no adverse effect of resident turnover in July on cardiac surgical outcomes [6]. However, such findings may be institution-specific, and no generalized conclusions can be drawn from them. The purpose of this study was to use a large national database to identify any effect the beginning of the academic year might have on cardiac surgical outcomes by The Society of Thoracic Surgeons /09/$36.00 Published by Elsevier Inc doi: /j.athoracsur

2 Ann Thorac Surg BAKAEEN ET AL 2009;88:70 5 THE JULY EFFECT AND CARDIAC SURGERY Patients and Methods We obtained Institutional Review Board approval for the study and waiver of informed consent. We requested and received approval for the study from the Department of Veterans Affairs Surgical Quality Data Use Group (SQDUG). Patients The Veterans Affairs (VA) Continuous Improvement in Cardiac Surgery Program (CICSP) prospectively collects risk and outcomes data on all patients who undergo cardiac operations at any of 44 VA cardiac surgery centers [7 9]. Academic affiliation is one of the requirements for establishing a cardiac surgery program at a VA hospital. We conducted a telephone and electronic mailing survey of the 44 VA cardiac surgery programs, of which 40 (91%) responded and confirmed that medical/ surgical trainees were involved in the care of cardiac surgical patients during the study period. We received de-identified data for all patients who underwent open cardiac surgical procedures at the participating VA hospitals between October 1997 and October Next, we divided the patients into groups: 11,975 underwent an operation early in the academic year (July 1 to August 31), and 58,641 had a procedure later in the year (September 1 to June 30). Residents rotated at various times throughout the year at different centers, but the month of July universally marked the beginning of the academic year, and the choice of the periods that we evaluated was based on a local pilot study [6]. Outcomes Two outcome variables were evaluated separately in this study: perioperative morbidity and 30-day operative mortality. CICSP defines 30-day operative mortality as the number of deaths that occur during the index hospitalization or within 30 days postoperatively, plus any deaths that occur more than 30 days postoperatively that are the direct result of a perioperative surgical complication. Perioperative morbidity is defined as the presence of any of the following major complications, alone or in combination: endocarditis, renal failure necessitating dialysis, mediastinitis, reoperation for bleeding, requiring a ventilator for longer than 48 hours, stroke, coma lasting 71 ADULT CARDIAC Table 1. Patient Demographics and Characteristics by Portion of Academic Cycle Variable a (n 11,975) (n 58,641) Early Later p Value Demographic and noncardiac factors Age, y Male sex 11,839 (99) 57,934 (99) Body mass index, kg/m Chronic obstructive pulmonary disease 3167 (26) 15,733 (27) Peripheral vascular disease 2776 (23) 13,985 (24) Cerebral vascular disease 2594 (22) 12,609 (22) Serum creatinine, mg/dl Diabetes 4212 (35) 20,631 (35) Hypertension b 7148 (87) 35,021 (87) Current use of diuretics 3912 (33) 19,398 (33) Current smoker 3349 (28) 16,158 (28) Pulmonary rales 855 (7) 4443 (8) Preoperative intravenous nitroglycerine 1020 (9) 4764 (8) Functional status: partially or totally dependent 1493 (12) 7768 (13) Cardiac factors Prior myocardial infarction 5672 (47) 27,981 (48) Prior heart surgery 834 (7) 4195 (7) Preoperative use of intra-aortic balloon pump 554 (5) 2896 (5) NYHA class III or IV 3545 (30) 18,259 (31) CCS angina class III or IV 7244 (60) 36,172 (62) Current digoxin use 920 (8) 4777 (8) Left ventricular ejection fraction ,137 (89) 49,217 (88) (11) 6506 (12) Left main coronary artery occlusion 50% 3087 (26) 15,006 (26) a Categoric data are presented as number (%); continuous data are presented as the mean standard deviation. b Data available for 45,928 patients (69%). CCS Canadian Cardiovascular Society; NYHA New York Heart Association.

3 ADULT CARDIAC 72 BAKAEEN ET AL Ann Thorac Surg THE JULY EFFECT AND CARDIAC SURGERY 2009;88:70 5 Table 2. Type and Extent of Operation Variable a (n 11,975) (n 58,641) Early Later p Value Procedure Isolated CABG 9179 (77) 44,474 (76) Aortic valve surgery 1736 (15) 8811 (15) Mitral valve surgery 399 (3) 2050 (3) Great vessel surgery 213 (2) 1202 (2) Cross-clamp time, min b CPB time, min c Surgery duration, h Total operating room time, h Surgical priority Elective 10,162 (85) 49,077 (84) Urgent 1401 (12) 7010 (12) Emergency 411 (3) 2536 (4) a Categoric data are presented as number (%); continuous data are presented as the mean standard deviation. b Data available for 59,295 patients (84%). c Data available for 60,826 patients (86%). CABG coronary artery bypass grafting; bypass. CPB cardiopulmonary longer than 24 hours, and any complication necessitating repeat cardiopulmonary bypass or mechanical circulatory support. This complication assessment uses standard definitions and criteria adopted by the VA Cardiac Surgery Consultants Board. Statistical Analyses The mean standard deviation was computed for continuous variables. After examining the parametric distributions, we used independent t tests to compare the parametric data collected during the early and later parts of the academic year. We used 2 analyses to test for differences in categoric data. Multivariable regression modeling was used to identify significant independent risk factors for perioperative morbidity and mortality. Variables used in the model included demographic, cardiac, and noncardiac risk factors. A prediction model was constructed by using stepwise logistic regression modeling with a significance level of p 0.05 for entry and selection. All statistical analyses were conducted with SAS v9.1 (SAS Institute, Inc, Cary, NC). Results Patients A total of 70,616 cardiac surgical procedures were performed between October 1997 and October Intergroup differences in patient risk factors (Table 1) were small, and most were statistically insignificant. Operations Of the procedures performed in the early and late parts of the academic year (Table 2), about three-quarters involved coronary artery bypass grafting (CABG). Compared with the later part of the academic year, the early portion of the year was associated with slightly longer myocardial ischemia times (84 40 vs minutes), cardiopulmonary bypass times ( vs minutes), operative times ( vs minutes), and total operating room times ( vs minutes; p 0.05 for all). There was also a slightly higher prevalence of emergency procedures in the later part of the academic year than in the earlier part of the year (3% vs 4%; p ). Morbidity There were no differences in the incidences of the major tracked complications between the early and later part of the academic year, except for a slightly higher incidence of perioperative myocardial infarction in the later part of the year (Table 3). The overall unadjusted postoperative morbidity rate was 14.0% for the early part and 14.2% for the later part of the academic year (p 0.6). The mean hospital length of stay was slightly longer in the later part of the academic year than in the earlier part ( vs days; p 0.009). Multivariable logistic regression, performed to control for potential confounding variables, associated several variables with postoperative morbidity (Table 4); however, the early period of the academic year was not one of Table 3. Surgical Outcomes Outcomes a (n 11,975) (n 58,641) Early Late p Value Length of hospital stay, d Endocarditis 16 (0.1) 56 (0.1) Renal failure 201 (1.7) 1000 (1.7) necessitating dialysis Mediastinitis 118 (1.0) 669 (1.1) Reoperation for bleeding 347 (2.9) 1733 (3.0) On ventilator 48 h 1000 (8.4) 4912 (8.4) Tracheostomy b 112 (1.4) 535 (1.3) Coma 75 (0.6) 344 (0.6) Stroke 212 (1.8) 1036 (1.8) Mechanical circulatory 210 (2.6) 993 (2.5) support b Peri-op myocardial 1110 (0.9) 675 (1.2) infarction Cardiac arrest 295 (2.5) 1484 (2.5) necessitating CPR Overall perioperative 1681 (14.0) 8332 (14.2) morbidity Operative mortality 447 (3.7) 2289 (3.9) a Categoric data are presented as number (%); continuous data are presented as the mean standard deviation. b Data available for 48,636 patients (69%). CPR cardiopulmonary resuscitation.

4 Ann Thorac Surg BAKAEEN ET AL 2009;88:70 5 THE JULY EFFECT AND CARDIAC SURGERY Table 4. Risk Factors Significantly Associated with Morbidity and Mortality Risk Factor OR 95% CI p Value Morbidity Age (per 1 yr) Female sex Body mass index (per kg/m 2 ) COPD Current smoker Current use of diuretic Diabetic Pre-op intravenous nitroglycerine Cerebrovascular disease Peripheral vascular disease Serum creatinine (per mg/dl) Pulmonary rales Independent functional status Prior heart surgery Prior myocardial infarction Emergency procedure Intra-aortic balloon pump support ASA class IV or V NYHA class III or IV Isolated CABG vs other procedure Mortality Age (per 1 yr) Female sex Body mass index (per kg/m 2 ) COPD Current use of diuretic Current use of digoxin CCS angina class III or IV Pre-op intravenous nitroglycerine Cerebrovascular disease Peripheral vascular disease Serum creatinine (per mg/dl) Pulmonary rales Independent functional status Prior heart surgery COPD Prior myocardial infarction Emergency procedure Intra-aortic balloon pump support ASA class IV or V NYHA class III or IV Isolated CABG vs other procedure ASA American Society of Anesthesiology; CABG coronary artery bypass grafting; CCS Canadian Cardiovascular Society; CI confidence interval; COPD chronic obstructive pulmonary disease; NYHA New York Heart Association; OR odds ratio. them (odds ratio [OR], 1.01; 95% confidence interval [CI], 0.96 to 1.07; p 0.67). Mortality The (unadjusted) operative mortality rate was 3.7% for the early part and 3.9% for the later part of the academic year (p 0.38). Multivariable logistic regression was performed to control for potential confounding variables; the early period of the academic year was not associated with operative mortality (OR, 0.99; 95% CI, 0.89 to 1.11; p 0.90), although several other variables were (Table 4). Subgroup Analyses The (unadjusted) operative mortality rate for isolated CABG operations was 2.8% for the early part and 2.8% for the later part of the academic year (p 0.99). When multivariable logistic regression was performed to control for potential confounding variables, the early period of the academic year was not associated with operative mortality (OR, 1.03; 95% CI, 0.89 to 1.18; p 0.73). The (unadjusted) operative mortality rate for cardiac surgical procedures other than CABG was 6.8% for the early part and 7.3% for the later part of the academic year (p 0.35). When multivariable logistic regression was performed to control for potential confounding variables, the early period of the academic year was not associated with operative mortality (OR, 0.96; 95% CI, 0.81 to 1.13; p 0.60). Comment Although the July effect may influence outcomes in certain surgical settings, our findings do not support an association between the early part of the academic year and worse outcomes in cardiac surgery. There are three stages of patient care at which residents can influence outcomes: In the preoperative stage, patient selection and preparation for the operation are important steps in optimizing outcomes. In the intraoperative stage, the complex nature of cardiac procedures amplifies the effects of any technical inadequacies or imperfections of the novice trainee; hence, an intraoperative error or suboptimal surgical performance can lead to detrimental outcomes. In the postoperative stage, minor lapses in vigilance or care delivery can translate into serious morbidity or mortality. In contrast, a vigilant resident is a valuable asset that can contribute positively to the care of patients. Our group and others have demonstrated the safety of training residents to perform cardiac surgical procedures [10 17]. Cardiac surgical trainees operative and perfusion times are inversely proportional to the trainees level of surgical experience [11, 12]. Therefore, as expected, despite the similarities in the patients risk profiles and the surgical case mix between the early and late time periods, the operative and perfusion times were slightly longer at the beginning of the academic year than they were later in the year. This slowdown may reflect a decline in the efficiency of surgical care delivery due to the disruptive effect of staff changeover. However, these longer operative times even though significant from a statistical perspective in a large patient cohort such as the one at hand did not translate into adverse outcomes. 73 ADULT CARDIAC

5 ADULT CARDIAC 74 BAKAEEN ET AL Ann Thorac Surg THE JULY EFFECT AND CARDIAC SURGERY 2009;88:70 5 From a practical standpoint, the differences in both ischemia and perfusion times between the two periods were very small ( 2 minutes) and had no significant clinical implications. Indeed, risk-adjusted morbidity and mortality rates for all cardiac surgical procedures were similar in the earlier and later parts of the academic year. This result agrees with our previously reported findings at a local institutional level [6]. Shuhaiber and colleagues [5] found no effect of cardiothoracic resident turnover on mortality rates after isolated CABG but detected an increase in risk-adjusted mortality after more complex cardiac cases that coincided with the periods of resident change. In the present national study, our subgroup analysis did not show any effect of the beginning of the academic year on the outcomes of isolated CABG or other cardiac procedures. Our negative finding verifies that our system of training young surgeons to do complicated and risky operations is sound and protects all patients from potential adverse events related to the educational process. This is a reassuring finding that the cardiac surgical specialty will have to maintain as it incorporates new procedures and technologies. From a faculty standpoint, this era of intense public scrutiny has created tremendous pressure to achieve superior outcomes. In addition, hospital administrators and payers are constantly demanding an increase in efficiency and cuts in cost. Also, academic centers are faced with the challenge of training residents and delegating responsibility without compromising patient safety. Yet the responsibility of training the next generation of cardiac surgeons may pose at least a theoretic risk of compromising outcomes, because cardiothoracic surgery is a highly technical field in which hands-on experience is essential. We believe that the key to achieving good results that are not influenced by resident turnover is close supervision and guidance by more senior members of the team, which is headed by faculty members. Such measures can help offset any deficiencies related to the inexperience of the new resident. In addition, it may be that more robust systems of care, resistant to the effects of the academic cycle, are used in cardiac surgery because of the complexity of the procedures involved and the morbidity burden of the patient population. The care of cardiac patients involves more than one clinical service or specialty. Therefore, maintaining a reliable and predictable mode of care usually requires a multidisciplinary team approach and continuity of care that is not operator-dependent and that has built-in checks and safeguards. Such mechanisms are indeed vital to neutralizing any variability in care introduced by the staff changeovers that take place at various times. The staff heart surgeon, assisted by the more permanent auxiliary support staff, is at the center of a well-rehearsed process of care that is July-proof. Our study has several limitations. Because it is retrospective in nature, it is vulnerable to all the weaknesses and biases associated with such a design. Also, the study spanned a considerable period of time, during which changes occurred in surgical faculty, technology, and care delivery plans. Our data represent the experiences of many centers with different academic setups and timetables, and any resident changeovers that occurred after July were not adjusted for. Resident involvement in the cardiac care plan was verified in 91% of the centers our study examined; however, the level of training of residents and the extent of participation in the care process varied from one program to another. The strengths of our study lie in its use of a large, robust, and validated prospective database and its use of risk-adjusted outcomes. Our study addresses a topic that has been inadequately evaluated: the relationship between the beginning of the academic timetable and cardiac surgical outcomes. In conclusion, our findings show that cardiac surgical care delivery is as safe at the beginning of the academic cycle as it is later in the year. This should reassure patients about the quality of cardiac operations performed in the month of July. Stephen N. Palmer, PhD, ELS, contributed to the editing of this manuscript. The CICSP-X study was initially funded by VA Health Services Research and Development Grant #IHY (Dr Shroyer, Principal Investigator), with ongoing support from the Office of Patient Care Services, VA Central Office, Washington, DC. This project was supported in part by the Offices of Research and Development at the Northport and Eastern Colorado Health Care System Denver Veterans Affairs Medical Centers. Special acknowledgment is given to Randy Johnson, Lisa Schade, and Missy Bell, the team members responsible for the CICSP-X access to care report sections, working under the leadership of Dr Gerald McDonald (VA Central Office). References 1. Englesbe MJ, Pelletier SJ, Magee JC, et al. Seasonal variation in surgical outcomes as measured by the American College of Surgeons-National Surgical Quality Improvement Program (ACS-NSQIP). Ann Surg 2007;246: Barry WA, Rosenthal GE. Is there a July phenomenon? The effect of July admission on intensive care mortality and length of stay in teaching hospitals. J Gen Intern Med 2003;18: Rich EC, Hillson SD, Dowd B, Morris N. Specialty differences in the July phenomenon for Twin Cities teaching hospitals. Med Care 1993;31: Ford AA, Bateman BT, Simpson LL, Ratan RB. Nationwide data confirms absence of July phenomenon in obstetrics: it s safe to deliver in July. J Perinatol 2007;27: Shuhaiber JH, Goldsmith K, Nashef SA. Impact of cardiothoracic resident turnover on mortality after cardiac surgery: a dynamic human factor. Ann Thorac Surg 2008;86:123 30; discussion Dhaliwal AS, Chu D, Deswal A, et al. The July effect and cardiac surgery: the effect of the beginning of the academic cycle on outcomes. Am J Surg 2008;196: Grover FL, Hammermeister KE, Burchfiel C. Initial report of the Veterans Administration Preoperative Risk Assessment Study for Cardiac Surgery. Ann Thorac Surg 1990;50: Grover FL, Johnson RR, Shroyer AL, Marshall G, Hammermeister KE. The Veterans Affairs Continuous Improvement in Cardiac Surgery Study. Ann Thorac Surg 1994;58: Grover FL, Shroyer AL, Hammermeister KE. Calculating risk and outcome: the Veterans Affairs database. Ann Thorac Surg 1996;62:S6 11.

6 Ann Thorac Surg BAKAEEN ET AL 2009;88:70 5 THE JULY EFFECT AND CARDIAC SURGERY 10. Bakaeen FG, Dhaliwal AS, Chu D, et al. Does the level of experience of residents affect outcomes of coronary artery bypass surgery? Ann Thorac Surg 2009;87: Haan CK, Milford-Beland S, O Brien S, et al. Impact of residency status on perfusion times and outcomes for coronary artery bypass graft surgery. Ann Thorac Surg 2007;83: Goodwin AT, Birdi I, Ramesh TP, et al. Effect of surgical training on outcome and hospital costs in coronary surgery. Heart 2001;85: Roberts CS, Bocanegra NR. Comparison of the first 100 coronary bypass patients of a supervised resident with his first 100 as an attending surgeon at the same institution. Am J Surg 1999;178: Guo LR, Chu MW, Tong MZ, et al. Does the trainee s level of experience impact on patient safety and clinical outcomes in coronary artery bypass surgery? J Card Surg 2008;23: Baskett RJ, Buth KJ, Legare JF, et al. Is it safe to train residents to perform cardiac surgery? Ann Thorac Surg 2002;74: Sethi GK, Hammermeister KE, Oprian C, Henderson W. Impact of resident training on postoperative morbidity in patients undergoing single valve replacement. Department of Veterans Affairs Cooperative Study on Valvular Heart Disease. J Thorac Cardiovasc Surg 1991;101: Gulbins H, Pritisanac A, Ennker IC, Ennker J. Safety of a cardiac surgical training program over a twelve-year period. Thorac Cardiovasc Surg 2007;55: ADULT CARDIAC INVITED COMMENTARY This is a timely study by addressing a topic that has not been totally resolved in cardiothoracic surgery [1]. The study centers on differences between early and late times of the year. Unfortunately these threshold dates have been arbitrarily specified. A more meaningful approach might have been to select breakpoints defined by the data alone. Although there is certainly some variation across the country, it does seem that beginning residents do not perform a significant portion of the procedures in the first 2 months of training. The first 2 months may actually be characterized by more staff-level involvement than in the subsequent months. In addition, there has been no account of the resident rotation schedule, which clearly has an impact on the resident contribution to surgical care. The authors are to be commended for investigating this issue, but it should be emphasized that this work is not a study of the influence of resident experience, but rather an examination of different parts of the academic year. Fred H. Edwards, MD Division of Cardiothoracic Surgery West 8th St Shands Jacksonville, University of Florida Jacksonville, FL fred.edwards@jax.ufl.edu Reference 1. Bakaeen FG, Huh J, LeMaire SA, et al. The July effect: impact of the beginning of the academic cycle on cardiac surgical outcomes in a cohort of 70,616 patients. Ann Thorac Surg 2009;88: by The Society of Thoracic Surgeons /09/$36.00 Published by Elsevier Inc doi: /j.athoracsur