Research
Original Investigation
The Relationship Between Timing of Surgical Complications and Hospital Readmission Melanie S. Morris, MD; Rhiannon J. Deierhoi, MPH; Joshua S. Richman, MD, PhD; Laura K. Altom, MD, MSPH; Mary T. Hawn, MD, MPH
IMPORTANCE Readmissions after surgery are costly and may reflect quality of care in the
index hospitalization.
Invited Commentary page 354 CME Quiz at jamanetworkcme.com
OBJECTIVES To determine the timing of postoperative complications with respect to hospital discharge and the frequency of readmission stratified by predischarge and postdischarge occurrence of complications. DESIGN, SETTING, AND PARTICIPANTS This is a retrospective cohort study of national Veterans Affairs Surgical Quality Improvement Program preoperative risk and outcome data on the Surgical Care Improvement Project cohort for operations performed from January 2005 to August 2009, including colorectal, arthroplasty, vascular, and gynecologic procedures. The association between timing of complication with respect to index hospitalization and 30-day readmission was modeled using generalized estimating equations. MAIN OUTCOME AND MEASURE All-cause readmission within 30 days of the index surgical
hospitalization discharge. RESULTS Our study of 59 273 surgical procedures performed at 112 Department of Veterans Affairs (VA) hospitals found an overall complication rate of 22.6% (predischarge complications, 71.9%; postdischarge complications, 28.1%). The proportion of postdischarge complications varied significantly, from 8.7% for respiratory complications to 55.7% for surgical site infection (P < .001). The overall 30-day readmission rate was 11.9%, of which only 56.0% of readmissions were associated with a currently assessed complication. Readmission was predicted by patient comorbid conditions, procedure factors, and the occurrence of postoperative complications. Multivariable generalized estimating equation models of readmission adjusting for patient and procedure characteristics, hospital, and index length of stay found that the occurrence of postdischarge complications had the highest odds of readmission (odds ratio, 7.4-20.8) compared with predischarge complications (odds ratio, 0.9-1.48). CONCLUSIONS AND RELEVANCE More than one-quarter of assessed complications are diagnosed after hospital discharge and strongly predict readmission. Hospital discharge is an insufficient end point for quality assessment. Although readmission is associated with complications, almost half of readmissions are not associated with a complication currently assessed by the Veterans Affairs Surgical Quality Improvement Program.
JAMA Surg. 2014;149(4):348-354. doi:10.1001/jamasurg.2013.4064 Published online February 12, 2014. 348
Author Affiliations: Center for Surgical, Medical Acute Care Research and Transitions (C-SMART), Birmingham Veterans Administration Hospital, Birmingham, Alabama (Morris, Deierhoi, Richman, Altom, Hawn); Section of Gastrointestinal Surgery, Department of Surgery, University of Alabama at Birmingham (Morris, Deierhoi, Richman, Altom, Hawn); Health Services/Comparative Effectiveness Research Training Program, University of Alabama at Birmingham (Altom). Corresponding Author: Mary T. Hawn, MD, MPH, Section of Gastrointestinal Surgery, Department of Surgery, University of Alabama at Birmingham, 1922 Seventh Ave S, Kracke Bldg 428, Birmingham, AL 35294-0016 ([email protected]). jamasurgery.com
Copyright 2014 American Medical Association. All rights reserved.
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Surgical Complications and Hospital Readmission
T
he 2000 Institute of Medicine report increased emphasis and scrutiny of the safety and quality of hospital care.1 For surgical care, postoperative complications lead to increased hospital length of stay, morbidity, and mortality.2-5 Reporting of some postoperative complications is a new mandatory quality initiative for hospitals. However, most hospitals track only events that occur during the hospitalization; thus, postdischarge complications will probably not be included in the hospital reporting. Accurately measuring complications, whether they occur before or after hospital discharge, is necessary to inform efforts to reduce them. The Centers for Medicare & Medicaid Services (CMS) has targeted hospital readmission as a quality metric. As a result of the Patient Protection and Affordable Care Act,6 beginning in fiscal year 2013, CMS reimbursement to hospitals will be decreased for higher-than-expected risk-adjusted 30-day readmission rates after admissions for myocardial infarction, pneumonia, and congestive heart failure. The diagnoses covered will expand by fiscal year 2015, and CMS requires hospitals to collect and report all-cause 30-day readmissions. It is conceivable that reporting of postoperative in-hospital complications and 30-day all-cause readmissions will together enable a comprehensive assessment of surgical quality of care. However, there is currently scant evidence available to assess the contribution of postoperative complications to hospital readmission. To make accurate quality assessments and better inform reimbursement decisions, we need more data to understand the timing and consequences of postoperative complications, as well as which readmissions are unplanned and related to surgical complications. With these goals in mind, the objective of this study is to determine when surgical complications occur in relation to hospital discharge. Our secondary aim is to determine the contribution of predischarge and postdischarge complications to readmission within 30 days of hospital discharge.
Original Investigation Research
Table 1. Description of Postoperative Complications Assessed Complication Type
Types of Complications Included
Cardiac
Myocardial infarction, cardiac arrest, and other cardiac ICD-9 codes
Respiratory
Failure to wean, pneumonia, reintubation, and other respiratory ICD-9 codes
Urinary tract
Renal failure, renal insufficiency, urinary tract infection, and other urinary tract ICD-9 codes
Surgical site infection
Deep wound or superficial surgical site infection
Venous thromboembolism
Deep vein thrombosis or pulmonary embolism
Central nervous system
CVA or stroke, coma >24 h, peripheral nerve injury, and other central nervous system ICD-9 codes
Other
Bleeding requiring >4 U of PRBCs, graft/prosthesis failure, systemic sepsis, return to operating room, and other complications identified by ICD-9 codes
Any complication
≥1 complication listed above
Abbreviations: CVA, cerebrovascular accident; ICD-9, International Classification of Diseases, Ninth Revision; PRBCs, packed red blood cells.
This study protocol was reviewed and approved by the local VA Research and Development Committee and the Institutional Review Board of the Birmingham (Alabama) VA Hospital, as well as by the Surgical Quality Data Use Group and the Office of Informatics and Analytics in the VA Central Office, Washington, DC; a waiver of informed consent was obtained. Our data sources have been published elsewhere.7-9
Patient Population The population for this analysis included patients from the SCIP cohort classified by procedure type, defined according to current procedural terminology code as gastrointestinal (GI), gynecologic, orthopedic, vascular, or other. A total of 59 273 SCIP procedures were identified with matched VASQIP records from January 2005 to August 2009.
Study Variables
Methods This is a retrospective cohort study of national Veterans Affairs Surgical Quality Improvement Program (VASQIP) preoperative risk data for the Department of Veterans Affairs (VA) Surgical Care Improvement Project (SCIP) cohort and hospital discharge date records from the Office of Informatics and Analytics External Peer Review Program from January 2005 to August 2009. We chose the SCIP cohort for this study because it includes common major surgical procedures and has been the focus of surgical quality improvement. The VASQIP collects demographic data, preoperative risk and laboratory data, operative data, and 30-day postoperative morbidity and mortality outcomes in most patients undergoing major surgery in the VA system. Clinical nurse reviewers, trained in clinical medicine and quality assurance, complete in-depth training on the data collection procedures and detailed definitions of each of the variables. A recent study of the quality of the data at a sample of VA medical centers showed that the data were complete and highly reliable.7
The main independent variable was timing of a VASQIPidentified postoperative complication grouped by complication category (Table 1). The dependent variable was readmission within 30 days of discharge from the index hospital stay. Information on readmission within 30 days was obtained from the Corporate Data Warehouse. Patient-level covariates thought to predict readmission were considered in analyses, including demographic variables, lifestyle variables (eg, alcohol and tobacco use), and cardiovascular, pulmonary, renal, hepatobiliary, nutritional, and immune comorbid conditions obtained from VASQIP records. Surgery characteristics included case status, duration of the operation, wound class, surgical specialty, American Society of Anesthesiologists (ASA) status, and surgical complexity, recorded using the resource-based relative value unit (RVU) for each current procedural terminology code.
Statistical Analysis Unadjusted analysis of association between the mentioned characteristics and readmission within 30 days was performed using χ2 and Wilcoxon rank sum tests. Multivariable
jamasurgery.com
JAMA Surgery April 2014 Volume 149, Number 4
Copyright 2014 American Medical Association. All rights reserved.
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349
Research Original Investigation
Surgical Complications and Hospital Readmission
analyses adjusting for patient and operative characteristics known to be independently associated with readmission were performed, with use of generalized estimating equations to adjust for clustering at the facility level. Full models included adjustment for history of congestive heart failure, sex, smoking, alcohol use, work RVUs, diabetes mellitus, renal failure, weight loss, emergent case status, operative duration, wound class,10 ASA classification, body mass index, length of stay, and the occurrence of a postoperative complication. Postoperative complications were categorized as none, predischarge, or postdischarge, and patients with no complications were used as the referent group. Only the first complication experienced by each patient was analyzed. Model building was based on forward selection to obtain the most parsimonious model. Significance was defined at α = .05. All analyses were completed using SAS software (version 9.2; SAS Institute Inc).11
Results Our study of 59 273 major surgical procedures performed at 112 VA hospitals found an overall 30-day complication rate of 22.6% and readmission rate of 11.9%. Index hospitalization length of stay and complication and readmission rates by patient and procedure characteristics are shown in Table 2. Older and male patients had a longer median stay and significantly higher rates of complications and readmission. Complication and readmission rates were increased in patients with congestive heart failure, diabetes, chronic obstructive pulmonary disease, chronic kidney disease, and significant preoperative weight loss (all P < .001). Operative characteristics, including increasing ASA class, emergent surgery, longer operative time, increasing case complexity as measured in RVUs, and increasing wound contamination, were associated with postoperative complications and readmission (all P < .001). Postoperative length of stay and complication and readmission rates differed by procedure type. The timing of postoperative complications in relationship to the index hospitalization is shown in Table 3. Of the 13 408 complications, 9646 (71.9%) occurred before discharge, but these rates varied significantly by complication type, from 44.4% for surgical site infection to 91.3% for respiratory complications (P < .001). Respiratory complications occurred most frequently and were associated with the longest stays but were mostly diagnosed before patients were discharged. More than half of surgical site infections were diagnosed after discharge, as were approximately one-third of urinary tract and venous thromboembolism complications. The occurrence of a predischarge complication was associated with an 18.3% readmission rate (range, 17.4%-19.4%) compared with 58.9% (range, 54.3%-78.4%) for postdischarge complications (P < .001 for all complication categories). Patients who had undergone GI surgery had the highest overall complication rate (37.4%), followed by those who had undergone vascular (30.5%), orthopedic (13.1%), or gynecologic surgery (12.7%) (Table 2). Those who had undergone gynecologic surgery had the shortest median stay (3 days) but the highest proportion of postdischarge complications (55.2%). The 350
longest stay was in patients who had undergone GI surgery, only 21.7% of whose complications were diagnosed after discharge. Patients who had undergone orthopedic or vascular surgery had similar median lengths of stay (5 days), with postdischarge complication rates of 31.0% and 34.3%, respectively (Table 3). The readmission rate for postdischarge complications varied widely by procedure type, from 34.2% for gynecologic to 69.7% for vascular procedures (Table 3). Results of the generalized estimating equations modeling readmission are shown in Table 4. Patient comorbid conditions, including congestive heart failure, diabetes, renal failure, chronic obstructive pulmonary disease, preoperative weight loss, and smoking, were associated with increased readmission rates. Procedure-related factors that increased the risk of readmission were emergent status, longer operative time, increasingly contaminated wound class, and higher ASA class. In the adjusted model, vascular surgery was associated with increased odds of readmission (odds ratio [OR], 1.8; 95% CI, 1.6-2.0) and gynecologic surgery with decreased odds of readmission (OR, 0.65; 95% CI, 0.50-0.85). The occurrence of a predischarge complication is either weakly or not associated with readmission, whereas a postdischarge complication regardless of type was strongly associated with readmission, with ORs ranging from 7.4 to 59.3 (Table 4).
Discussion Our study examined the timing of postoperative complications in relation to hospital discharge and the contribution of these complications to readmission. We found that one-third of all complications and more than half of all surgical site infections were diagnosed after hospital discharge. Complication rates and the timing of their diagnosis differed by surgical specialty and length of stay for the index hospitalization. The occurrence of a postdischarge complication was most strongly associated with increased odds of readmission. However, of all readmissions, only slightly more than half were associated with a currently assessed VASQIP complication, regardless of timing. A significant number of all postoperative complications are diagnosed after hospital discharge. Although the VA surgical cohort includes mostly white men, our results are similar to those of another large study examining the American College of Surgeons National Surgical Quality Improvement Program (NSQIP) data. Their cohort included 329 951 patients at 181 hospitals, with an overall complication rate of 11%. This rate is lower than our overall complication rate of 22.6%, because their study population included a broader range of surgical procedures, such as breast surgery, which had a complication rate of 2%. Complications were diagnosed after discharge in 32.9%, which is consistent with our results. Also consistent with our results, some complications occurred more frequently after discharge, including surgical site infection (66.0%), urinary tract infection (39.4%), pulmonary embolus (42.2%), and deep venous thrombosis (34.5%).12 We observed that surgical site infections are most frequently diagnosed after discharge, consistent with findings of
JAMA Surgery April 2014 Volume 149, Number 4
Copyright 2014 American Medical Association. All rights reserved.
Downloaded From: http://archsurg.jamanetwork.com/ by a University of North Dakota User on 05/20/2015
jamasurgery.com
Surgical Complications and Hospital Readmission
Original Investigation Research
Table 2. Characteristics of Study Population Stratified by Complication Rate and Readmission Postoperative LOS
Complications
Median (IQR), d
P Value
5.0 (3-9)
…
Original Investigation
The Relationship Between Timing of Surgical Complications and Hospital Readmission Melanie S. Morris, MD; Rhiannon J. Deierhoi, MPH; Joshua S. Richman, MD, PhD; Laura K. Altom, MD, MSPH; Mary T. Hawn, MD, MPH
IMPORTANCE Readmissions after surgery are costly and may reflect quality of care in the
index hospitalization.
Invited Commentary page 354 CME Quiz at jamanetworkcme.com
OBJECTIVES To determine the timing of postoperative complications with respect to hospital discharge and the frequency of readmission stratified by predischarge and postdischarge occurrence of complications. DESIGN, SETTING, AND PARTICIPANTS This is a retrospective cohort study of national Veterans Affairs Surgical Quality Improvement Program preoperative risk and outcome data on the Surgical Care Improvement Project cohort for operations performed from January 2005 to August 2009, including colorectal, arthroplasty, vascular, and gynecologic procedures. The association between timing of complication with respect to index hospitalization and 30-day readmission was modeled using generalized estimating equations. MAIN OUTCOME AND MEASURE All-cause readmission within 30 days of the index surgical
hospitalization discharge. RESULTS Our study of 59 273 surgical procedures performed at 112 Department of Veterans Affairs (VA) hospitals found an overall complication rate of 22.6% (predischarge complications, 71.9%; postdischarge complications, 28.1%). The proportion of postdischarge complications varied significantly, from 8.7% for respiratory complications to 55.7% for surgical site infection (P < .001). The overall 30-day readmission rate was 11.9%, of which only 56.0% of readmissions were associated with a currently assessed complication. Readmission was predicted by patient comorbid conditions, procedure factors, and the occurrence of postoperative complications. Multivariable generalized estimating equation models of readmission adjusting for patient and procedure characteristics, hospital, and index length of stay found that the occurrence of postdischarge complications had the highest odds of readmission (odds ratio, 7.4-20.8) compared with predischarge complications (odds ratio, 0.9-1.48). CONCLUSIONS AND RELEVANCE More than one-quarter of assessed complications are diagnosed after hospital discharge and strongly predict readmission. Hospital discharge is an insufficient end point for quality assessment. Although readmission is associated with complications, almost half of readmissions are not associated with a complication currently assessed by the Veterans Affairs Surgical Quality Improvement Program.
JAMA Surg. 2014;149(4):348-354. doi:10.1001/jamasurg.2013.4064 Published online February 12, 2014. 348
Author Affiliations: Center for Surgical, Medical Acute Care Research and Transitions (C-SMART), Birmingham Veterans Administration Hospital, Birmingham, Alabama (Morris, Deierhoi, Richman, Altom, Hawn); Section of Gastrointestinal Surgery, Department of Surgery, University of Alabama at Birmingham (Morris, Deierhoi, Richman, Altom, Hawn); Health Services/Comparative Effectiveness Research Training Program, University of Alabama at Birmingham (Altom). Corresponding Author: Mary T. Hawn, MD, MPH, Section of Gastrointestinal Surgery, Department of Surgery, University of Alabama at Birmingham, 1922 Seventh Ave S, Kracke Bldg 428, Birmingham, AL 35294-0016 ([email protected]). jamasurgery.com
Copyright 2014 American Medical Association. All rights reserved.
Downloaded From: http://archsurg.jamanetwork.com/ by a University of North Dakota User on 05/20/2015
Surgical Complications and Hospital Readmission
T
he 2000 Institute of Medicine report increased emphasis and scrutiny of the safety and quality of hospital care.1 For surgical care, postoperative complications lead to increased hospital length of stay, morbidity, and mortality.2-5 Reporting of some postoperative complications is a new mandatory quality initiative for hospitals. However, most hospitals track only events that occur during the hospitalization; thus, postdischarge complications will probably not be included in the hospital reporting. Accurately measuring complications, whether they occur before or after hospital discharge, is necessary to inform efforts to reduce them. The Centers for Medicare & Medicaid Services (CMS) has targeted hospital readmission as a quality metric. As a result of the Patient Protection and Affordable Care Act,6 beginning in fiscal year 2013, CMS reimbursement to hospitals will be decreased for higher-than-expected risk-adjusted 30-day readmission rates after admissions for myocardial infarction, pneumonia, and congestive heart failure. The diagnoses covered will expand by fiscal year 2015, and CMS requires hospitals to collect and report all-cause 30-day readmissions. It is conceivable that reporting of postoperative in-hospital complications and 30-day all-cause readmissions will together enable a comprehensive assessment of surgical quality of care. However, there is currently scant evidence available to assess the contribution of postoperative complications to hospital readmission. To make accurate quality assessments and better inform reimbursement decisions, we need more data to understand the timing and consequences of postoperative complications, as well as which readmissions are unplanned and related to surgical complications. With these goals in mind, the objective of this study is to determine when surgical complications occur in relation to hospital discharge. Our secondary aim is to determine the contribution of predischarge and postdischarge complications to readmission within 30 days of hospital discharge.
Original Investigation Research
Table 1. Description of Postoperative Complications Assessed Complication Type
Types of Complications Included
Cardiac
Myocardial infarction, cardiac arrest, and other cardiac ICD-9 codes
Respiratory
Failure to wean, pneumonia, reintubation, and other respiratory ICD-9 codes
Urinary tract
Renal failure, renal insufficiency, urinary tract infection, and other urinary tract ICD-9 codes
Surgical site infection
Deep wound or superficial surgical site infection
Venous thromboembolism
Deep vein thrombosis or pulmonary embolism
Central nervous system
CVA or stroke, coma >24 h, peripheral nerve injury, and other central nervous system ICD-9 codes
Other
Bleeding requiring >4 U of PRBCs, graft/prosthesis failure, systemic sepsis, return to operating room, and other complications identified by ICD-9 codes
Any complication
≥1 complication listed above
Abbreviations: CVA, cerebrovascular accident; ICD-9, International Classification of Diseases, Ninth Revision; PRBCs, packed red blood cells.
This study protocol was reviewed and approved by the local VA Research and Development Committee and the Institutional Review Board of the Birmingham (Alabama) VA Hospital, as well as by the Surgical Quality Data Use Group and the Office of Informatics and Analytics in the VA Central Office, Washington, DC; a waiver of informed consent was obtained. Our data sources have been published elsewhere.7-9
Patient Population The population for this analysis included patients from the SCIP cohort classified by procedure type, defined according to current procedural terminology code as gastrointestinal (GI), gynecologic, orthopedic, vascular, or other. A total of 59 273 SCIP procedures were identified with matched VASQIP records from January 2005 to August 2009.
Study Variables
Methods This is a retrospective cohort study of national Veterans Affairs Surgical Quality Improvement Program (VASQIP) preoperative risk data for the Department of Veterans Affairs (VA) Surgical Care Improvement Project (SCIP) cohort and hospital discharge date records from the Office of Informatics and Analytics External Peer Review Program from January 2005 to August 2009. We chose the SCIP cohort for this study because it includes common major surgical procedures and has been the focus of surgical quality improvement. The VASQIP collects demographic data, preoperative risk and laboratory data, operative data, and 30-day postoperative morbidity and mortality outcomes in most patients undergoing major surgery in the VA system. Clinical nurse reviewers, trained in clinical medicine and quality assurance, complete in-depth training on the data collection procedures and detailed definitions of each of the variables. A recent study of the quality of the data at a sample of VA medical centers showed that the data were complete and highly reliable.7
The main independent variable was timing of a VASQIPidentified postoperative complication grouped by complication category (Table 1). The dependent variable was readmission within 30 days of discharge from the index hospital stay. Information on readmission within 30 days was obtained from the Corporate Data Warehouse. Patient-level covariates thought to predict readmission were considered in analyses, including demographic variables, lifestyle variables (eg, alcohol and tobacco use), and cardiovascular, pulmonary, renal, hepatobiliary, nutritional, and immune comorbid conditions obtained from VASQIP records. Surgery characteristics included case status, duration of the operation, wound class, surgical specialty, American Society of Anesthesiologists (ASA) status, and surgical complexity, recorded using the resource-based relative value unit (RVU) for each current procedural terminology code.
Statistical Analysis Unadjusted analysis of association between the mentioned characteristics and readmission within 30 days was performed using χ2 and Wilcoxon rank sum tests. Multivariable
jamasurgery.com
JAMA Surgery April 2014 Volume 149, Number 4
Copyright 2014 American Medical Association. All rights reserved.
Downloaded From: http://archsurg.jamanetwork.com/ by a University of North Dakota User on 05/20/2015
349
Research Original Investigation
Surgical Complications and Hospital Readmission
analyses adjusting for patient and operative characteristics known to be independently associated with readmission were performed, with use of generalized estimating equations to adjust for clustering at the facility level. Full models included adjustment for history of congestive heart failure, sex, smoking, alcohol use, work RVUs, diabetes mellitus, renal failure, weight loss, emergent case status, operative duration, wound class,10 ASA classification, body mass index, length of stay, and the occurrence of a postoperative complication. Postoperative complications were categorized as none, predischarge, or postdischarge, and patients with no complications were used as the referent group. Only the first complication experienced by each patient was analyzed. Model building was based on forward selection to obtain the most parsimonious model. Significance was defined at α = .05. All analyses were completed using SAS software (version 9.2; SAS Institute Inc).11
Results Our study of 59 273 major surgical procedures performed at 112 VA hospitals found an overall 30-day complication rate of 22.6% and readmission rate of 11.9%. Index hospitalization length of stay and complication and readmission rates by patient and procedure characteristics are shown in Table 2. Older and male patients had a longer median stay and significantly higher rates of complications and readmission. Complication and readmission rates were increased in patients with congestive heart failure, diabetes, chronic obstructive pulmonary disease, chronic kidney disease, and significant preoperative weight loss (all P < .001). Operative characteristics, including increasing ASA class, emergent surgery, longer operative time, increasing case complexity as measured in RVUs, and increasing wound contamination, were associated with postoperative complications and readmission (all P < .001). Postoperative length of stay and complication and readmission rates differed by procedure type. The timing of postoperative complications in relationship to the index hospitalization is shown in Table 3. Of the 13 408 complications, 9646 (71.9%) occurred before discharge, but these rates varied significantly by complication type, from 44.4% for surgical site infection to 91.3% for respiratory complications (P < .001). Respiratory complications occurred most frequently and were associated with the longest stays but were mostly diagnosed before patients were discharged. More than half of surgical site infections were diagnosed after discharge, as were approximately one-third of urinary tract and venous thromboembolism complications. The occurrence of a predischarge complication was associated with an 18.3% readmission rate (range, 17.4%-19.4%) compared with 58.9% (range, 54.3%-78.4%) for postdischarge complications (P < .001 for all complication categories). Patients who had undergone GI surgery had the highest overall complication rate (37.4%), followed by those who had undergone vascular (30.5%), orthopedic (13.1%), or gynecologic surgery (12.7%) (Table 2). Those who had undergone gynecologic surgery had the shortest median stay (3 days) but the highest proportion of postdischarge complications (55.2%). The 350
longest stay was in patients who had undergone GI surgery, only 21.7% of whose complications were diagnosed after discharge. Patients who had undergone orthopedic or vascular surgery had similar median lengths of stay (5 days), with postdischarge complication rates of 31.0% and 34.3%, respectively (Table 3). The readmission rate for postdischarge complications varied widely by procedure type, from 34.2% for gynecologic to 69.7% for vascular procedures (Table 3). Results of the generalized estimating equations modeling readmission are shown in Table 4. Patient comorbid conditions, including congestive heart failure, diabetes, renal failure, chronic obstructive pulmonary disease, preoperative weight loss, and smoking, were associated with increased readmission rates. Procedure-related factors that increased the risk of readmission were emergent status, longer operative time, increasingly contaminated wound class, and higher ASA class. In the adjusted model, vascular surgery was associated with increased odds of readmission (odds ratio [OR], 1.8; 95% CI, 1.6-2.0) and gynecologic surgery with decreased odds of readmission (OR, 0.65; 95% CI, 0.50-0.85). The occurrence of a predischarge complication is either weakly or not associated with readmission, whereas a postdischarge complication regardless of type was strongly associated with readmission, with ORs ranging from 7.4 to 59.3 (Table 4).
Discussion Our study examined the timing of postoperative complications in relation to hospital discharge and the contribution of these complications to readmission. We found that one-third of all complications and more than half of all surgical site infections were diagnosed after hospital discharge. Complication rates and the timing of their diagnosis differed by surgical specialty and length of stay for the index hospitalization. The occurrence of a postdischarge complication was most strongly associated with increased odds of readmission. However, of all readmissions, only slightly more than half were associated with a currently assessed VASQIP complication, regardless of timing. A significant number of all postoperative complications are diagnosed after hospital discharge. Although the VA surgical cohort includes mostly white men, our results are similar to those of another large study examining the American College of Surgeons National Surgical Quality Improvement Program (NSQIP) data. Their cohort included 329 951 patients at 181 hospitals, with an overall complication rate of 11%. This rate is lower than our overall complication rate of 22.6%, because their study population included a broader range of surgical procedures, such as breast surgery, which had a complication rate of 2%. Complications were diagnosed after discharge in 32.9%, which is consistent with our results. Also consistent with our results, some complications occurred more frequently after discharge, including surgical site infection (66.0%), urinary tract infection (39.4%), pulmonary embolus (42.2%), and deep venous thrombosis (34.5%).12 We observed that surgical site infections are most frequently diagnosed after discharge, consistent with findings of
JAMA Surgery April 2014 Volume 149, Number 4
Copyright 2014 American Medical Association. All rights reserved.
Downloaded From: http://archsurg.jamanetwork.com/ by a University of North Dakota User on 05/20/2015
jamasurgery.com
Surgical Complications and Hospital Readmission
Original Investigation Research
Table 2. Characteristics of Study Population Stratified by Complication Rate and Readmission Postoperative LOS
Complications
Median (IQR), d
P Value
5.0 (3-9)
…
