SPINE Volume 39, Number 23, pp 1943-1949 ©2014, Lippincott Williams & Wilkins
CLINICAL CASE SERIES
Morbidity, Mortality, and Readmission After Vertebral Augmentation Analysis of 850 Patients From the American College of Surgeons National Surgical Quality Improvement Program Database Jason O. Toy, MD, Bryce A. Basques, BS, and Jonathan N. Grauer, MD
Study Design. Retrospective cohort study. Objective. To identify risk factors for poor short-term outcomes after vertebral augmentation procedures. Summary of Background Data. Vertebral compression fractures are the most common fractures of osteoporosis and are frequently treated with vertebroplasty or kyphoplasty. There is a shortage of information about risk factors for short-term, general health outcomes after vertebral augmentation in the literature. Methods. Patients older than 65 years who underwent vertebroplasty or kyphoplasty in 2011 and 2012 were identified from the American College of Surgeons National Surgical Quality Improvement Program database. Patient characteristics were tested for association with 30-day adverse events, mortality, and readmission using bivariate and multivariate analyses. Results. A total of 850 patients met inclusion criteria. The average age was 78.9 ± 11.7 years (mean ± standard deviation) and females made up 70.8% of the cohort. Of these patients, 9.5% had any adverse event (AAE), and 6.6% had a serious adverse event (SAE). Death occurred in 1.5% of patients, and 10.8% were readmitted within the first 30 postoperative days. On multivariate analysis, AAE and SAE were both significantly associated with American Society of Anesthesiologists class 4 (AAE: odds ratio [OR] = 2.7, P = 0.013; SAE: OR = 2.5, P = 0.040) and inpatient status before procedure (AAE: OR = 2.7, P < 0.001, SAE: OR = 2.4, P = 0.003). Increased postoperative mortality rate was
From the Department of Orthopaedics and Rehabilitation, Yale University School of Medicine, New Haven, CT. Acknowledgment date: June 11, 2014. Revision date: July 17, 2014. Acceptance date: July 28, 2014. The manuscript submitted does not contain information about medical device(s)/drug(s). No funds were received in support of this work. Relevant financial activities outside the submitted work: consultancy, expert testimony, grants. Address correspondence and reprint requests to Jonathan N. Grauer, MD, Department of Orthopaedics and Rehabilitation, Yale University School of Medicine, 800 Howard Ave, New Haven, CT 06510, E-mail: jonathan. [email protected] DOI: 10.1097/BRS.0000000000000563 Spine
associated with American Society of Anesthesiologists class 4 (OR = 6.4, P = 0.024) and the use of nongeneral anesthesia (OR = 4.0, P = 0.022). Readmission was associated with history of pulmonary disease (OR = 2.0, P = 0.005) and inpatient status before procedure (OR = 1.9, P = 0.005). Conclusion. Adverse general health outcomes were relatively common, and the factors identified in the earlier text associated with patient outcomes after vertebral augmentation may be useful for preoperative discussions and counseling. Key words: vertebroplasty, kyphoplasty, morbidity, ACS-NSQIP, ASA. Level of Evidence: 3 Spine 2014;39:1943–1949
V
ertebral compression fractures account for more than 700,000 fractures in the United States per year,1 with a yearly medical cost of 12.2 to 17.9 billion dollars.2 This results in 150,000 hospital admissions3 and 161,000 physician office visits per year.4 Although most patients respond to conservative management, some cannot be easily mobilized or develop chronic pain. For these patients, vertebral augmentation may provide pain relief and quality-of-life improvement.5–7 The most common complication is after cement augmentation procedures that is cement leakage, which has been reported in up to 67% of cases.8–16 However, the majority of these are described as clinically insignificant. Other general health complications, such as pain, pulmonary embolism, infection, and death are generally reported in less than 10% of cases.8–10,12–23 There is little information available in the literature describing risk factors for general health adverse events, mortality, and readmission after vertebral augmentation in the literature. In this study, we aim to identify independent risk factors for adverse events and readmission within 30 days after vertebral augmentation on a large cohort of patients who had vertebral compression fracture using a national database. This information may be useful for preoperative counseling and optimizing postoperative care for patients undergoing these procedures. www.spinejournal.com
1943
Copyright © 2014 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited. SPINE140761_LR 1943
01/10/14 9:44 AM
CLINICAL CASE SERIES MATERIALS AND METHODS Data Source For this study, we used the American College of Surgeons National Surgical Quality Improvement Program (ACSNSQIP) database, which captures data from more than 370 participating US hospitals.24 In the ACS-NSQIP, patients are identified prospectively and randomly sampled at eligible hospitals. Trained clinical reviewers abstract more than 150 patient variables from operative reports, medical records, and patient interviews to assess 30-day adjusted surgical outcomes.25 Clinical data are collected for the entire 30-day postoperative period, regardless of discharge status within this time.
Data Collection Patients 65 years or older who underwent kyphoplasty and vertebroplasty in 2011 and 2012 were identified in the ACSNSQIP database. Patients with kyphoplasty were identified using Current Procedural Terminology codes 22523, 22524, and 22525 and patients with vertebroplasty were identified using Current Procedural Terminology codes 22520, 22521, and 22522. Patients with incomplete perioperative data were excluded from this study. Among the variables available in the ACS-NSQIP database are patient characteristics including sex, age, height, and weight. Body mass index was calculated from each patient’s height and weight. The ACS-NSQIP database also includes information on medical comorbidities. History of smoking was defined as the use of cigarettes within the past year. History of diabetes was defined as having a diagnosis of diabetes mellitus and taking either oral agents or insulin. History of pulmonary disease was defined as a history of dyspnea, severe chronic obstructive pulmonary disease, ventilator-assisted respiration within 48 hours before surgery, or current pneumonia. A history of heart disease was defined as a history of congestive heart failure or angina within 1 month before admission, myocardial infarction within 6 months before admission, cardiac surgery, or percutaneous coronary intervention. American Society of Anesthesiologists (ASA) class 3 or more corresponds to severe systemic disease. Steroid use was defined as requiring regular administration of corticosteroid medications in the 30 days prior to surgery. Functional status was defined as the patient’s ability to perform the activities of daily living within the 30 days prior to surgery, with dependent functional status indicating partial or full dependence on others for activities of daily living. Inpatient status before procedure was defined as the patient having stayed in the hospital 1 day or more prior to the procedure. Anesthesia type was separated into general anesthesia and other types of anesthesia (which included MAC, spinal, and local anesthesia). Discharge destination was also available in the database and was defined as discharge to home or a facility.24
Adverse Events The ACS-NSQIP tracks patients for the occurrence of 23 individual adverse events that occurred within the first 1944
www.spinejournal.com
Vertebral Augmentation Outcomes • Toy et al
30 postoperative days (including while in the hospital as well as after discharge). The occurrence of a serious adverse event (SAE) was defined as the occurrence of any of the following: death, coma more than 24 hours, on ventilator more than 48 hours, unplanned intubation, stroke/cerebrovascular accident, thromboembolic event (deep venous thrombosis or pulmonary embolism), cardiac arrest, myocardial infarction, acute renal failure, sepsis, septic shock, return to the operating room, deep surgical or organ space infection, or graft/prosthesis failure. The occurrence of a minor adverse event was defined as a wound dehiscence, superficial surgical site infection, urinary tract infection, pneumonia, blood transfusion, progressive renal insufficiency, or peripheral nerve injury. Any adverse event (AAE) was defined as the occurrence of any SAE or minor adverse event.
Readmission Readmission was defined as a binary variable that was positive when a patient had an unplanned readmission 1 or more times after the initial postoperative discharge. Readmission is tracked in the ACS-NSQIP for the 30-day period after the operation.
Analysis Statistical analyses were conducted using STATA version 11.2 (StataCorp LP, College Station, TX). All tests were 2-tailed, and the statistical difference was established at a 2-sided α level of 0.05 (P < 0.05). All demographic and comorbidity variables were tested for association with the occurrence of AAE, any SAE, mortality, and readmission using bivariate and multivariate logistic regression. Final multivariate models were constructed using a backwards stepwise process that initially included all potential variables and sequentially excluded variables with the highest P value until only those with P < 0.20 remained. Variables with P value between 0.05 and 0.20 were left in the model to control for potential confounding, but were not considered to be significantly associated with the outcome.
RESULTS Patient Characteristics A total of 850 patients met inclusion criteria. A summary of patient demographics and comorbidities can be found in Table 1. The average age was 78.9 ± 7.4 years (mean ± standard deviation) and average body mass index was 26.3 ± 5.7 kg/m2. It is notable that 89.7% of the patients had kyphoplasty and 10.3% had vertebroplasty. Furthermore, 87.5% of the patients had general anesthesia, and 19.8% were discharged to a facility after their procedure.
Adverse Events AAEs occurred in 81 patients (9.5%), with SAEs occurring in 56 patients (6.6%), and minor adverse events occurring in 31 patients (3.7%) (Table 2). Four specific complications November 2014
Copyright © 2014 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited. SPINE140761_LR 1944
01/10/14 9:44 AM
CLINICAL CASE SERIES
Vertebral Augmentation Outcomes • Toy et al
TABLE 1. Patient Characteristics Overall
No. 850
TABLE 2. Frequency of Outcomes in the Patient
Population
(%) 100.0
Preoperative characteristics
Outcome
No.
(%)
Age
Any adverse event
81
9.5
Serious adverse event
56
6.6
65–74
245
28.8
75–84
379
44.6
Death
13
1.5
≥85
226
26.6
Coma >24 hr
0
0.0
Female sex
602
70.8
Ventilator >48 hr
2
0.2
Unplanned intubation
3
0.4
Body mass index
CLINICAL CASE SERIES
Morbidity, Mortality, and Readmission After Vertebral Augmentation Analysis of 850 Patients From the American College of Surgeons National Surgical Quality Improvement Program Database Jason O. Toy, MD, Bryce A. Basques, BS, and Jonathan N. Grauer, MD
Study Design. Retrospective cohort study. Objective. To identify risk factors for poor short-term outcomes after vertebral augmentation procedures. Summary of Background Data. Vertebral compression fractures are the most common fractures of osteoporosis and are frequently treated with vertebroplasty or kyphoplasty. There is a shortage of information about risk factors for short-term, general health outcomes after vertebral augmentation in the literature. Methods. Patients older than 65 years who underwent vertebroplasty or kyphoplasty in 2011 and 2012 were identified from the American College of Surgeons National Surgical Quality Improvement Program database. Patient characteristics were tested for association with 30-day adverse events, mortality, and readmission using bivariate and multivariate analyses. Results. A total of 850 patients met inclusion criteria. The average age was 78.9 ± 11.7 years (mean ± standard deviation) and females made up 70.8% of the cohort. Of these patients, 9.5% had any adverse event (AAE), and 6.6% had a serious adverse event (SAE). Death occurred in 1.5% of patients, and 10.8% were readmitted within the first 30 postoperative days. On multivariate analysis, AAE and SAE were both significantly associated with American Society of Anesthesiologists class 4 (AAE: odds ratio [OR] = 2.7, P = 0.013; SAE: OR = 2.5, P = 0.040) and inpatient status before procedure (AAE: OR = 2.7, P < 0.001, SAE: OR = 2.4, P = 0.003). Increased postoperative mortality rate was
From the Department of Orthopaedics and Rehabilitation, Yale University School of Medicine, New Haven, CT. Acknowledgment date: June 11, 2014. Revision date: July 17, 2014. Acceptance date: July 28, 2014. The manuscript submitted does not contain information about medical device(s)/drug(s). No funds were received in support of this work. Relevant financial activities outside the submitted work: consultancy, expert testimony, grants. Address correspondence and reprint requests to Jonathan N. Grauer, MD, Department of Orthopaedics and Rehabilitation, Yale University School of Medicine, 800 Howard Ave, New Haven, CT 06510, E-mail: jonathan. [email protected] DOI: 10.1097/BRS.0000000000000563 Spine
associated with American Society of Anesthesiologists class 4 (OR = 6.4, P = 0.024) and the use of nongeneral anesthesia (OR = 4.0, P = 0.022). Readmission was associated with history of pulmonary disease (OR = 2.0, P = 0.005) and inpatient status before procedure (OR = 1.9, P = 0.005). Conclusion. Adverse general health outcomes were relatively common, and the factors identified in the earlier text associated with patient outcomes after vertebral augmentation may be useful for preoperative discussions and counseling. Key words: vertebroplasty, kyphoplasty, morbidity, ACS-NSQIP, ASA. Level of Evidence: 3 Spine 2014;39:1943–1949
V
ertebral compression fractures account for more than 700,000 fractures in the United States per year,1 with a yearly medical cost of 12.2 to 17.9 billion dollars.2 This results in 150,000 hospital admissions3 and 161,000 physician office visits per year.4 Although most patients respond to conservative management, some cannot be easily mobilized or develop chronic pain. For these patients, vertebral augmentation may provide pain relief and quality-of-life improvement.5–7 The most common complication is after cement augmentation procedures that is cement leakage, which has been reported in up to 67% of cases.8–16 However, the majority of these are described as clinically insignificant. Other general health complications, such as pain, pulmonary embolism, infection, and death are generally reported in less than 10% of cases.8–10,12–23 There is little information available in the literature describing risk factors for general health adverse events, mortality, and readmission after vertebral augmentation in the literature. In this study, we aim to identify independent risk factors for adverse events and readmission within 30 days after vertebral augmentation on a large cohort of patients who had vertebral compression fracture using a national database. This information may be useful for preoperative counseling and optimizing postoperative care for patients undergoing these procedures. www.spinejournal.com
1943
Copyright © 2014 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited. SPINE140761_LR 1943
01/10/14 9:44 AM
CLINICAL CASE SERIES MATERIALS AND METHODS Data Source For this study, we used the American College of Surgeons National Surgical Quality Improvement Program (ACSNSQIP) database, which captures data from more than 370 participating US hospitals.24 In the ACS-NSQIP, patients are identified prospectively and randomly sampled at eligible hospitals. Trained clinical reviewers abstract more than 150 patient variables from operative reports, medical records, and patient interviews to assess 30-day adjusted surgical outcomes.25 Clinical data are collected for the entire 30-day postoperative period, regardless of discharge status within this time.
Data Collection Patients 65 years or older who underwent kyphoplasty and vertebroplasty in 2011 and 2012 were identified in the ACSNSQIP database. Patients with kyphoplasty were identified using Current Procedural Terminology codes 22523, 22524, and 22525 and patients with vertebroplasty were identified using Current Procedural Terminology codes 22520, 22521, and 22522. Patients with incomplete perioperative data were excluded from this study. Among the variables available in the ACS-NSQIP database are patient characteristics including sex, age, height, and weight. Body mass index was calculated from each patient’s height and weight. The ACS-NSQIP database also includes information on medical comorbidities. History of smoking was defined as the use of cigarettes within the past year. History of diabetes was defined as having a diagnosis of diabetes mellitus and taking either oral agents or insulin. History of pulmonary disease was defined as a history of dyspnea, severe chronic obstructive pulmonary disease, ventilator-assisted respiration within 48 hours before surgery, or current pneumonia. A history of heart disease was defined as a history of congestive heart failure or angina within 1 month before admission, myocardial infarction within 6 months before admission, cardiac surgery, or percutaneous coronary intervention. American Society of Anesthesiologists (ASA) class 3 or more corresponds to severe systemic disease. Steroid use was defined as requiring regular administration of corticosteroid medications in the 30 days prior to surgery. Functional status was defined as the patient’s ability to perform the activities of daily living within the 30 days prior to surgery, with dependent functional status indicating partial or full dependence on others for activities of daily living. Inpatient status before procedure was defined as the patient having stayed in the hospital 1 day or more prior to the procedure. Anesthesia type was separated into general anesthesia and other types of anesthesia (which included MAC, spinal, and local anesthesia). Discharge destination was also available in the database and was defined as discharge to home or a facility.24
Adverse Events The ACS-NSQIP tracks patients for the occurrence of 23 individual adverse events that occurred within the first 1944
www.spinejournal.com
Vertebral Augmentation Outcomes • Toy et al
30 postoperative days (including while in the hospital as well as after discharge). The occurrence of a serious adverse event (SAE) was defined as the occurrence of any of the following: death, coma more than 24 hours, on ventilator more than 48 hours, unplanned intubation, stroke/cerebrovascular accident, thromboembolic event (deep venous thrombosis or pulmonary embolism), cardiac arrest, myocardial infarction, acute renal failure, sepsis, septic shock, return to the operating room, deep surgical or organ space infection, or graft/prosthesis failure. The occurrence of a minor adverse event was defined as a wound dehiscence, superficial surgical site infection, urinary tract infection, pneumonia, blood transfusion, progressive renal insufficiency, or peripheral nerve injury. Any adverse event (AAE) was defined as the occurrence of any SAE or minor adverse event.
Readmission Readmission was defined as a binary variable that was positive when a patient had an unplanned readmission 1 or more times after the initial postoperative discharge. Readmission is tracked in the ACS-NSQIP for the 30-day period after the operation.
Analysis Statistical analyses were conducted using STATA version 11.2 (StataCorp LP, College Station, TX). All tests were 2-tailed, and the statistical difference was established at a 2-sided α level of 0.05 (P < 0.05). All demographic and comorbidity variables were tested for association with the occurrence of AAE, any SAE, mortality, and readmission using bivariate and multivariate logistic regression. Final multivariate models were constructed using a backwards stepwise process that initially included all potential variables and sequentially excluded variables with the highest P value until only those with P < 0.20 remained. Variables with P value between 0.05 and 0.20 were left in the model to control for potential confounding, but were not considered to be significantly associated with the outcome.
RESULTS Patient Characteristics A total of 850 patients met inclusion criteria. A summary of patient demographics and comorbidities can be found in Table 1. The average age was 78.9 ± 7.4 years (mean ± standard deviation) and average body mass index was 26.3 ± 5.7 kg/m2. It is notable that 89.7% of the patients had kyphoplasty and 10.3% had vertebroplasty. Furthermore, 87.5% of the patients had general anesthesia, and 19.8% were discharged to a facility after their procedure.
Adverse Events AAEs occurred in 81 patients (9.5%), with SAEs occurring in 56 patients (6.6%), and minor adverse events occurring in 31 patients (3.7%) (Table 2). Four specific complications November 2014
Copyright © 2014 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited. SPINE140761_LR 1944
01/10/14 9:44 AM
CLINICAL CASE SERIES
Vertebral Augmentation Outcomes • Toy et al
TABLE 1. Patient Characteristics Overall
No. 850
TABLE 2. Frequency of Outcomes in the Patient
Population
(%) 100.0
Preoperative characteristics
Outcome
No.
(%)
Age
Any adverse event
81
9.5
Serious adverse event
56
6.6
65–74
245
28.8
75–84
379
44.6
Death
13
1.5
≥85
226
26.6
Coma >24 hr
0
0.0
Female sex
602
70.8
Ventilator >48 hr
2
0.2
Unplanned intubation
3
0.4
Body mass index
