Research
Original Investigation
Critical Outcomes in Nonrobotic vs Robotic-Assisted Cardiac Surgery Franz Yanagawa, MD; Martin Perez, MD; Ted Bell, MS; Rod Grim, MA; Jennifer Martin, PhD; Vanita Ahuja, MD, MPH
IMPORTANCE As robotic-assisted cardiac surgical procedures increase nationwide, surgeons
Supplemental content at jamasurgery.com
need to be educated on the safety of the new modality compared with that of open technique. OBJECTIVE To compare complications, length of stay (LOS), actual cost, and mortality between nonrobotic and robotic-assisted cardiac surgical procedures. DESIGN, SETTING, AND PARTICIPANTS Weighted data on cardiac patients who had undergone operations involving the valves or septa and vessels, as well as other heart and pericardium procedures, from January 1, 2008, to December 31, 2011, were obtained from the Nationwide Inpatient Sample via the Healthcare Cost and Utilization Project of the Agency for Healthcare Research and Quality. Propensity score matching was used to match each robotic-assisted case to 2 nonrobotic cases on 14 characteristics. MAIN OUTCOMES AND MEASURES Complications, median LOS, actual cost, and mortality. RESULTS Exploratory analysis found a total of 1 374 653 cardiac cases (1 369 454 [99.6%] nonrobotic and 5199 [0.4%] robotic-assisted cases). After propensity score matching, there were 10 331 (66.5%) nonrobotic cases and 5199 (33.5%) robotic-assisted cases. Cardiac operations included 1630 (10.5%) involving the valves or septa, 6616 (42.6%) involving the vessels, and 7284 (46.9%) other heart and pericardium procedures. Robotic-assisted compared with nonrobotic surgery had a higher median cost ($39 030 vs $36 340; P < .001) but lower LOS (5 vs 6 days; P < .001) and lower mortality (1.0% vs 1.9%; P < .001). Robotic-assisted surgery had significantly fewer complications for all operation types (30.3% vs 27.2%; P < .001). CONCLUSIONS AND RELEVANCE Overall, robotic-assisted surgery has significantly reduced median LOS, complications, and mortality compared with nonrobotic surgery. Results of this study support the contention that robotic-assisted surgery is as safe as nonrobotic surgery and offers the surgeon an additional technique for performing cardiac surgery.
Corresponding Author: Vanita Ahuja, MD, MPH, Department of General Surgery, York Hospital, 1001 S George St, York, PA 17405 ([email protected]).
JAMA Surg. 2015;150(8):771-777. doi:10.1001/jamasurg.2015.1098 Published online June 17, 2015.
S
imilar to laparoscopy, with its advent in the 1980s, progression, and acceptance through the 1990s, robotic-assisted surgery has followed a similar rugged path. Since its conception, the symbiotic relationship between robot and surgeon, allowing smooth and minute movements and 3-dimensional vision, has added greatly to the field of surgery.1 Robotic-assisted surgery attempts to improve on laparoscopic surgery by providing increased intracavity articulation, increased degrees of freedom, and downscaling of motion amplitude, which may reduce the strain on the surgeon.2,3 For these reasons, in general surgery and subspecialties, the use of the robot has increased significantly during the past 5 years. jamasurgery.com
Author Affiliations: Department of General Surgery, York Hospital, York, Pennsylvania (Yanagawa, Perez, Ahuja); Department of Research, York Hospital, York, Pennsylvania (Bell, Grim, Martin).
The biggest growth in robotic-assisted surgery has been seen in the fields of gynecology and urology. Recently, Wright et al4 reported an increase in robotic-assisted hysterectomy from 0.5% of the procedures in 2007 compared with 9.5% in 2010 for benign disease. In their study, robotic-assisted surgery had similar outcomes to laparoscopic surgery; however, robotic-assisted surgery had a higher total cost of $2189 more per case. Similarly, in urologic surgery, Leddy et al5 reported in 2010 that radical prostatectomy remains the biggest use of robotic-assisted surgery in urology, with 1% in 2001 to 40% of all cases in 2006 performed in the United States. Specific to cardiac surgery, as early as 1999, the advantages of the robot in coronary artery bypass grafting and val(Reprinted) JAMA Surgery August 2015 Volume 150, Number 8
Copyright 2015 American Medical Association. All rights reserved.
Downloaded From: http://archsurg.jamanetwork.com/ by a Upstate Medical University User on 08/31/2015
771
Research Original Investigation
Critical Outcomes in Nonrobotic vs Robotic-Assisted Cardiac Surgery
vular operations were demonstrated with increased visualization, ease of harvest, and quality of vascular anastomoses.6-8 Although safety and efficacy of robotic-assisted surgery are supported, given the high cost of the robot itself, longer operating times, and short life of the robotic instruments, it remains to be established whether the robot is cost-effective.9-11 The purpose of the present study was to compare outcomes of complications, length of stay (LOS), actual cost, and mortality between nonrobotic and robotic-assisted cardiac surgical procedures.
Methods Data Source Discharge data from January 1, 2008, to December 31, 2011, were obtained from the Nationwide Inpatient Sample (NIS) via the Healthcare Cost and Utilization Project (HCUP) of the Agency for Healthcare Research and Quality. The NIS consists of a 20% stratified sampling of US community hospital discharges and is the largest source of hospital discharge information in the United States. It compiles various demographics, including admission and discharge data, hospital data, total charges, actual cost, and other characteristics of discharges (http://www .hcup-us.ahrq.gov/nisoverview.jsp). The present study used weighted HCUP data to provide approximate total national statistics. Weighted data also help assure that national estimates of hospitalizations and hospitalization rates are comparable across years despite the varying number of states participating in each year of the HCUP. In addition, using the HCUP-NIS Cost-to-Charge Ratio Files, charges were able to be converted to cost. Charges are the amount that each hospital bills for services, whereas cost is the amount that the services actually cost to provide (http://www.hcup-us.ahrq .gov/db/state/costtocharge.jsp#overview). Using “cost-tocharge ratios allows the translation of total charges into actual costs using a validated conversion factor that provides an estimate of all-payer inpatient costs. Wide variation in hospital prices between different regions makes cost-to-charge adjustments in reported hospital costs necessary.”12(p2320) To this end, actual costs are reported in this article. We completed a data use agreement with HCUP-NIS, and the study was considered exempt by WellSpan Health’s Institutional Review Board.
Study Variables All study variables were initially defined and coded by the NIS. Weighted HCUP-NIS data were from January 1, 2008, to December 31, 2011. Cardiac surgical procedures were identified using International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM), procedure codes; only cardiac cases with ICD-9-CM codes in procedures 1 through 15 were included. Cardiac operations included valves or septa (codes 35.1-35.95), vessels (36.03-36.99), and other heart and pericardium procedures (37.11-37.74). Aortic (3511, 3521, 3522, 3539, 3541, 3551, 3561, and 3571) and mitral (3512, 3523, and 3524) procedures were used for subset analysis. Robotic-assisted cases were identified by using ICD-9-CM procedure codes 17.41, 17.42, 772
17.43 and 17.44; cases were identified as robotic-assisted or nonrobotic procedures as appropriate. Similar to Brunt et al,13 the present study propensity matched robotic-assisted to nonrobotic procedures according to patient characteristics, comorbidities, and hospital characteristics. Regarding comorbidities, the Charlson Comorbidity Index score was the propensity-matched variable; this score takes into account conditions such as myocardial infarction, congestive heart failure, peripheral vascular disease, cerebrovascular disease, dementia, chronic obstructive pulmonary disease, connective tissue disease, peptic ulcer disease, diabetes mellitus, moderate to severe chronic kidney disease, hemiplegia, leukemia, malignant lymphoma, solid tumor liver disease, and AIDS. For the present study, Charlson Comorbidity Index scores were calculated using ICD-9-CM diagnosis codes according to the Charlson et al14 and Deyo et al15 validated and published methods. Propensity score matching was used to compare each robotic-assisted case with 2 nonrobotic cases (ie, a 1:2 ratio to help control for variances resulting from size differences between the 2 groups) on 14 characteristics (age, sex, race, payer, elective vs nonelective surgery, Charlson Comorbidity Index score, hospital bed size, location, region and teaching status, annual income, and the 3 operation subtypes). The matching variables for propensity matching were chosen based on the significant differences between nonrobotic and robotic-assisted surgery (discussed in the Results section). Outcome variables were median LOS, actual cost, and mortality. Complication variables were aggregated into “complication yes or no”16 (yes indicating having 1 or more of any of the complications) and total number of complications (sum of all the complications per patient). Nonparametric analyses were conducted because most outcome variables were not normally distributed; therefore, median complications, LOS, and in-hospital cost were reported. All variables used in the present study, including complications and mortality, are associated with the index admission.
Statistical Analysis Exploratory analyses were conducted using descriptive statistics (frequencies) and χ2 or Fisher exact tests to explore associations between robotic-assisted or nonrobotic surgery and patients’ characteristics. Comparative analysis of outcomes used nonparametric statistics such as Kruskal-Wallis and MannWhitney tests to explore differences between roboticassisted surgery and outcomes. Two multiple regressions were performed to predict cost and mortality using type of surgery (nonrobotic or roboticassisted), sex (male or female), age (
Original Investigation
Critical Outcomes in Nonrobotic vs Robotic-Assisted Cardiac Surgery Franz Yanagawa, MD; Martin Perez, MD; Ted Bell, MS; Rod Grim, MA; Jennifer Martin, PhD; Vanita Ahuja, MD, MPH
IMPORTANCE As robotic-assisted cardiac surgical procedures increase nationwide, surgeons
Supplemental content at jamasurgery.com
need to be educated on the safety of the new modality compared with that of open technique. OBJECTIVE To compare complications, length of stay (LOS), actual cost, and mortality between nonrobotic and robotic-assisted cardiac surgical procedures. DESIGN, SETTING, AND PARTICIPANTS Weighted data on cardiac patients who had undergone operations involving the valves or septa and vessels, as well as other heart and pericardium procedures, from January 1, 2008, to December 31, 2011, were obtained from the Nationwide Inpatient Sample via the Healthcare Cost and Utilization Project of the Agency for Healthcare Research and Quality. Propensity score matching was used to match each robotic-assisted case to 2 nonrobotic cases on 14 characteristics. MAIN OUTCOMES AND MEASURES Complications, median LOS, actual cost, and mortality. RESULTS Exploratory analysis found a total of 1 374 653 cardiac cases (1 369 454 [99.6%] nonrobotic and 5199 [0.4%] robotic-assisted cases). After propensity score matching, there were 10 331 (66.5%) nonrobotic cases and 5199 (33.5%) robotic-assisted cases. Cardiac operations included 1630 (10.5%) involving the valves or septa, 6616 (42.6%) involving the vessels, and 7284 (46.9%) other heart and pericardium procedures. Robotic-assisted compared with nonrobotic surgery had a higher median cost ($39 030 vs $36 340; P < .001) but lower LOS (5 vs 6 days; P < .001) and lower mortality (1.0% vs 1.9%; P < .001). Robotic-assisted surgery had significantly fewer complications for all operation types (30.3% vs 27.2%; P < .001). CONCLUSIONS AND RELEVANCE Overall, robotic-assisted surgery has significantly reduced median LOS, complications, and mortality compared with nonrobotic surgery. Results of this study support the contention that robotic-assisted surgery is as safe as nonrobotic surgery and offers the surgeon an additional technique for performing cardiac surgery.
Corresponding Author: Vanita Ahuja, MD, MPH, Department of General Surgery, York Hospital, 1001 S George St, York, PA 17405 ([email protected]).
JAMA Surg. 2015;150(8):771-777. doi:10.1001/jamasurg.2015.1098 Published online June 17, 2015.
S
imilar to laparoscopy, with its advent in the 1980s, progression, and acceptance through the 1990s, robotic-assisted surgery has followed a similar rugged path. Since its conception, the symbiotic relationship between robot and surgeon, allowing smooth and minute movements and 3-dimensional vision, has added greatly to the field of surgery.1 Robotic-assisted surgery attempts to improve on laparoscopic surgery by providing increased intracavity articulation, increased degrees of freedom, and downscaling of motion amplitude, which may reduce the strain on the surgeon.2,3 For these reasons, in general surgery and subspecialties, the use of the robot has increased significantly during the past 5 years. jamasurgery.com
Author Affiliations: Department of General Surgery, York Hospital, York, Pennsylvania (Yanagawa, Perez, Ahuja); Department of Research, York Hospital, York, Pennsylvania (Bell, Grim, Martin).
The biggest growth in robotic-assisted surgery has been seen in the fields of gynecology and urology. Recently, Wright et al4 reported an increase in robotic-assisted hysterectomy from 0.5% of the procedures in 2007 compared with 9.5% in 2010 for benign disease. In their study, robotic-assisted surgery had similar outcomes to laparoscopic surgery; however, robotic-assisted surgery had a higher total cost of $2189 more per case. Similarly, in urologic surgery, Leddy et al5 reported in 2010 that radical prostatectomy remains the biggest use of robotic-assisted surgery in urology, with 1% in 2001 to 40% of all cases in 2006 performed in the United States. Specific to cardiac surgery, as early as 1999, the advantages of the robot in coronary artery bypass grafting and val(Reprinted) JAMA Surgery August 2015 Volume 150, Number 8
Copyright 2015 American Medical Association. All rights reserved.
Downloaded From: http://archsurg.jamanetwork.com/ by a Upstate Medical University User on 08/31/2015
771
Research Original Investigation
Critical Outcomes in Nonrobotic vs Robotic-Assisted Cardiac Surgery
vular operations were demonstrated with increased visualization, ease of harvest, and quality of vascular anastomoses.6-8 Although safety and efficacy of robotic-assisted surgery are supported, given the high cost of the robot itself, longer operating times, and short life of the robotic instruments, it remains to be established whether the robot is cost-effective.9-11 The purpose of the present study was to compare outcomes of complications, length of stay (LOS), actual cost, and mortality between nonrobotic and robotic-assisted cardiac surgical procedures.
Methods Data Source Discharge data from January 1, 2008, to December 31, 2011, were obtained from the Nationwide Inpatient Sample (NIS) via the Healthcare Cost and Utilization Project (HCUP) of the Agency for Healthcare Research and Quality. The NIS consists of a 20% stratified sampling of US community hospital discharges and is the largest source of hospital discharge information in the United States. It compiles various demographics, including admission and discharge data, hospital data, total charges, actual cost, and other characteristics of discharges (http://www .hcup-us.ahrq.gov/nisoverview.jsp). The present study used weighted HCUP data to provide approximate total national statistics. Weighted data also help assure that national estimates of hospitalizations and hospitalization rates are comparable across years despite the varying number of states participating in each year of the HCUP. In addition, using the HCUP-NIS Cost-to-Charge Ratio Files, charges were able to be converted to cost. Charges are the amount that each hospital bills for services, whereas cost is the amount that the services actually cost to provide (http://www.hcup-us.ahrq .gov/db/state/costtocharge.jsp#overview). Using “cost-tocharge ratios allows the translation of total charges into actual costs using a validated conversion factor that provides an estimate of all-payer inpatient costs. Wide variation in hospital prices between different regions makes cost-to-charge adjustments in reported hospital costs necessary.”12(p2320) To this end, actual costs are reported in this article. We completed a data use agreement with HCUP-NIS, and the study was considered exempt by WellSpan Health’s Institutional Review Board.
Study Variables All study variables were initially defined and coded by the NIS. Weighted HCUP-NIS data were from January 1, 2008, to December 31, 2011. Cardiac surgical procedures were identified using International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM), procedure codes; only cardiac cases with ICD-9-CM codes in procedures 1 through 15 were included. Cardiac operations included valves or septa (codes 35.1-35.95), vessels (36.03-36.99), and other heart and pericardium procedures (37.11-37.74). Aortic (3511, 3521, 3522, 3539, 3541, 3551, 3561, and 3571) and mitral (3512, 3523, and 3524) procedures were used for subset analysis. Robotic-assisted cases were identified by using ICD-9-CM procedure codes 17.41, 17.42, 772
17.43 and 17.44; cases were identified as robotic-assisted or nonrobotic procedures as appropriate. Similar to Brunt et al,13 the present study propensity matched robotic-assisted to nonrobotic procedures according to patient characteristics, comorbidities, and hospital characteristics. Regarding comorbidities, the Charlson Comorbidity Index score was the propensity-matched variable; this score takes into account conditions such as myocardial infarction, congestive heart failure, peripheral vascular disease, cerebrovascular disease, dementia, chronic obstructive pulmonary disease, connective tissue disease, peptic ulcer disease, diabetes mellitus, moderate to severe chronic kidney disease, hemiplegia, leukemia, malignant lymphoma, solid tumor liver disease, and AIDS. For the present study, Charlson Comorbidity Index scores were calculated using ICD-9-CM diagnosis codes according to the Charlson et al14 and Deyo et al15 validated and published methods. Propensity score matching was used to compare each robotic-assisted case with 2 nonrobotic cases (ie, a 1:2 ratio to help control for variances resulting from size differences between the 2 groups) on 14 characteristics (age, sex, race, payer, elective vs nonelective surgery, Charlson Comorbidity Index score, hospital bed size, location, region and teaching status, annual income, and the 3 operation subtypes). The matching variables for propensity matching were chosen based on the significant differences between nonrobotic and robotic-assisted surgery (discussed in the Results section). Outcome variables were median LOS, actual cost, and mortality. Complication variables were aggregated into “complication yes or no”16 (yes indicating having 1 or more of any of the complications) and total number of complications (sum of all the complications per patient). Nonparametric analyses were conducted because most outcome variables were not normally distributed; therefore, median complications, LOS, and in-hospital cost were reported. All variables used in the present study, including complications and mortality, are associated with the index admission.
Statistical Analysis Exploratory analyses were conducted using descriptive statistics (frequencies) and χ2 or Fisher exact tests to explore associations between robotic-assisted or nonrobotic surgery and patients’ characteristics. Comparative analysis of outcomes used nonparametric statistics such as Kruskal-Wallis and MannWhitney tests to explore differences between roboticassisted surgery and outcomes. Two multiple regressions were performed to predict cost and mortality using type of surgery (nonrobotic or roboticassisted), sex (male or female), age (
