minimally invasive surgery was first described by wickham   in 1987 and refers to surgical techniques that are less invasive than open surgery for the same purpose . conventional open , laparoscopic , robot - assisted laparoscopic , and video - assisted minilaparotomy surgery ( vams ) have been performed as minimally invasive renal surgery . this surgical technique was performed through minilaparotomy and patients who underwent it recovered quickly . more than 600 cases of living donor nephrectomy have been conducted successfully , and this technique is also widely used to manage renal malignancy . many studies have compared the cost - effectiveness of laparoscopic and robot - assisted renal surgeries with that of open surgery . compared the costs of open surgery and robot - assisted laparoscopic radical prostatectomy for prostate cancer . they noted that robot - assisted laparoscopic prostatectomy was more expensive than open surgery in terms of medical supply and operation costs . reported that laparoscopic living donor nephrectomy with low complication rates was a cost - effective renal surgery . however , there has been no research on the cost - effectiveness of minilaparotomy kidney surgeries such as vams . therefore , this study aimed to compare the cost - analysis of vams versus open , laparoscopic , and robot - assisted laparoscopic radical nephrectomy ( rn ) surgery under korean medical insurance . twenty patients with suspected renal cell carcinoma who underwent vams , open , laparoscopic , or robot - assisted laparoscopic rn between january 2008 and december 2010 were selected . the patients sampled for this study were treated between 2008 and 2010 while the insurance system applied , and the most recent 20 cases not subject to the exclusion criteria were selected . patients who met the following criteria were excluded : 1 ) those who underwent another surgery apart from rn , 2 ) those who incurred additional medical fees owing to postoperative complications , 3 ) those who underwent rn during hospitalization in another department , and 4 ) those whose final pathological finding was not renal cell carcinoma . patient information ( age , gender , body mass index [ bmi ] , and length of hospital stay ) was retrospectively collected from medical records . tumor stage was based on the american joint committee on cancer tumor , nodes , metastasis staging , 7th edition . four items considered to be related to the surgery were compared from the itemized statements : procedure and operation , anesthesia , laboratory testing , and medical supply fees . items such as room and meal charges and medications , which were regarded as being minimally related to surgery , were excluded . surgery was defined as a medical service directly performed by doctors with their hands or tools . laboratory test fees refer to costs associated with extracting and testing specimens to diagnose a disease or ascertain its progression . anesthesia fees refer to the costs of anesthesia for a surgery or treatment associated with alleviating pain . medical supplies refer to the costs of materials used in a test or a surgery . criteria for insured and uninsured costs were based on benefit coverage criteria prescribed by the health insurance review and assessment service . for laparoscopic rn , routine disposable laparoscopic equipment was used . for robot - assisted laparoscopic rn , the da vinci robot ( intuitive surgical inc . , 18.0 ( ibm co. , armonk , ny , usa ) . to determine the significance of the differences observed between the means of continuous variables , student 's t - test was used . to determine the significance of the differences observed between the rates of categorical variables , fisher 's exact test was used . there was a significant difference in patient age and bmi ( p<0.05 ) between the laparoscopic and the vams group . there was no significant difference in tumor sizes or stage distributions between the vams group and the other three groups ( table 1 ) . patient costs ( meanstandard deviation ) were 2,023,791240,757 , 2,024,246674,859 , 3,603,557870,333 , and 8,021,902330,157 korean won ( krw , the currency of south koea ) for the vams , open , laparoscopic , and robot - assisted rn groups , respectively . among them , the sum of the insured costs was 1,904,627231,957 , 1,798,127645,602 ( p=0.634 ) , 3,039,769711,792 ( p<0.01 ) , and 899,668323,508 ( p<0.01 ) krw in the vams , open , laparoscopic , and robot - assisted rn groups , respectively , whereas the sum of the uninsured costs was 119,16324,581 , 226,119215,009 , 563,788487,798 ( p<0.01 ) , and 7,122,23456,117 ( p<0.01 ) krw , respectively ( table 2 ) . in the vams group , medical supply fees accounted for the highest portion of total costs at 38.63% ( insured costs were 33.43% and uninsured costs were 5.20% ) , followed by procedure and operation fees at 29.99% ( insured costs were 29.99% ) . procedure and operation fees in the open rn group , medical supply fees in the laparoscopic rn group , and procedure and operation fees in the robot - assisted laparoscopic rn group accounted for the largest percent at 33.19% ( insured cost at 33.19% ) , 60.51% ( insured cost at 45.3% and uninsured cost at 15.08% ) , and 88.24% ( insured cost at 0.98% and uninsured cost at 87.26% ) , respectively ( fig . 1 ) . there was a significant difference between the vams and open rn groups in the laboratory test ( insured ) and surgical material fees ( insured and uninsured ; p<0.05 ) . medical supply fees were the item with the greatest difference between the laparoscopic and the vams groups ( p<0.05 ) . there was likewise a significant difference between the groups in terms of laboratory test fees ( insured ; p<0.05 ) . in the robot - assisted laparoscopic rn group , procedure and operation fees had the greatest difference compared with those of the vams group . laboratory test costs ( insured ) and medical supply costs ( insured ) were also significantly different from those of the vams group ( p<0.05 ) . there was no significant difference in total cost between the vams and the open rn groups ( p=0.998 ) . there was a significant difference in the sum of insured costs , uninsured costs , and total costs between the vams and the laparoscopic rn group ( p<0.01 ) . with patients placing importance on quality of life and decreased postoperative pain , demand for minimally invasive surgery is increasing . furthermore , along with the development of imaging and operative equipment , surgical techniques have undergone much improvement . four minimally invasive surgical techniques are being used for kidney surgery in the urological field : laparoscopic surgery , minilaparotomy surgery , robot - assisted laparoscopic surgery , and percutaneous cryotherapy or ablation therapy . in 1990 , clayman et al this surgical technique , compared with conventional open surgery , caused less postoperative pain and required a shorter hospital stay and time to return to normal life . in 2001 , guillonneau et al . subsequently , other studies reported good functional and oncologic outcomes in patients undergoing this surgical technique . for the minilaparotomy technique , yang et al .   reported the first living donor nephrectomy using vams , and since then , data on safety and clinical usefulness from more than 600 cases of nephrectomy have been reported . currently , vams is used for diverse renal surgeries including radical , partial , and living donor nephrectomies . the clinical usefulness of percutaneous techniques has been verified by many reports , but they have limits in that they are applied to selected patient cases only . conventional open , laparoscopic , robot - assisted laparoscopic , and vams have been performed for renal masses . vams is a minilaparotomy technique in which an endoscope is used and a technique of internal traction is applied with a piercing retractor . it leaves minimal operation - related scars owing to the surgical window available through minilaparotomy . for a certain surgical technique to become widely used , it should be associated with advantages in terms of cost - effectiveness , patient benefits , and postoperative outcomes . however , there has been no study on the cost - effectiveness of vams compared with other surgical techniques for rn . for comparison and analysis , we divided patients who were diagnosed with renal cell carcinoma and underwent rn into the open , laparoscopic , robot - assisted laparoscopic , and vams rn groups . to research the cost - effectiveness of surgical techniques , it is necessary to evaluate complications from such procedures , because complications affect total cost . therefore , only four direct cost items related to surgery were compared and analyzed : procedure and operation , anesthesia , laboratory testing , and medical supply costs . in this study , items such as room and meal charges related to the length of stay were excluded from the evaluation of the cost - effectiveness of surgical techniques . in korea , the cost of ward stay is approximately 10,000 krw per day , which is inexpensive and therefore may lead to longer hospital stays . according to our study results , vams was more cost - effective than laparoscopic and robot - assisted laparoscopic rn ( p<0.01 ) ( table 2 ) . the greatest difference in medical supply fees was between the vams and laparoscopic rn groups ( p<0.01 ) . in korea , changes in the benefit coverage criteria of health insurance in 2006 enabled medical supply fees in laparoscopic surgery to be covered by health insurance . however , such a difference between the two groups in medical supply fees was probably due to fees for the disposable device ( e.g. , autosuture multifire endo gia 12 mm [ covidien plc , dublin , ireland ] ) that is currently used and which is expensive ( more than 100,000 krw ) . disposable devices ( e.g. , floseal hemostatic matrix [ baxter healthcare co. , hayward , ca , usa ] , harmonic scalpel [ ethicon endo - surgery , cincinnati , oh , usa ] ) are expensive and are rarely used in open or vams rn . this increases the cost of laparoscopic and robot - assisted laparoscopic rn , making them more expensive compared with the open or vams group . laboratory testing ( insured ) fees were less in the vams group than in the laparoscopic rn group ( p=0.037 ) , which is related to the shorter length of stay in the former group . among the itemized costs , the greatest difference in produced and operation fees ( uninsured ) was between the vams and robot - assisted laparoscopic rn groups . in robot - assisted surgery , many reusable devices ( e.g. , endowrist [ intuitive surgical inc . , sunnyvale , ca , usa ] ) were used . those devices are reusable several times with cleansing and sterilization ; thus , it was not feasible to charge this cost for each surgery . at most hospitals , the maintenance cost for reusable devices is included in the uniform procedure and operation fee . disposable devices were not charged separately , and the cost was also included in the uniform fee . therefore , the cost of medical supplies for the robot - assisted laparoscopic rn group can seem to be lower than the costs for other groups . currently , the price of the da vinci robot ranges from 1.5 to 1.75 million dollars and maintenance costs from 112,000 to 150,000 dollars . this is why procedure and operation fees are more expensive in the robot - assisted laparoscopic rn group than in the vams group . laboratory test fees were greater in the open than in the vams group because of the former group 's longer length of hospital stay . the mean total costs of laboratory tests in the immediate postoperative 5 days were almost the same in all groups ; after that period , the cost increase was proportional to the length of hospital stay . medical supply fees were greater in the vams group than in the open rn group . this is due to the use of an endoscope and a disposable device 12 mm visiport plus ( tyco healthcare , norwalk , usa ) accompanying it . nevertheless , there was no significant difference in the total cost between the open rn and vams groups . judging from the study results thus far , vams seems to be more cost - effective than laparoscopic and robot - assisted laparoscopic surgeries . comparison of vams with open surgery showed no significant differences in costs between them , proving that vams is a competitive modality in renal minimally invasive surgery . in addition to direct costs , hamidi et al .   compared and analyzed social costs after discharge , including costs resulting from complications in laparoscopic donor nephrectomy . when a patient undergoes a surgery , other costs such as medication and room and meal charges are incurred in addition to the direct costs related to the surgery . after discharge , patients may incur indirect costs such as sick leave , copayments for health care , and hiring fees for home work . our study compared only costs directly related with surgery and therefore was unable to predict outcomes resulting from the incurrence of other costs . surgeons who have not yet overcome the associated learning curve tend to have higher complication rates than do experienced surgeons . in this study , the surgeries of the vams group were conducted by experienced surgeons , which suggests that their complication rates would not be significantly different from those of the patients who underwent an open surgery . although the learning curve of vams is not very steep , it is not a common technique ; therefore , a large - scale multi - center study is necessary . finally , this study only examined rn , which does not represent all vams procedures . recent medical advancements , including abdominal ultrasonography , have resulted in increased discovery rates of small renal masses . the standard method for treating small renal masses is shifting from radical to partial nephrectomy . to fully research the cost - effectiveness of vams from different aspects , studies on other surgical techniques such as partial nephrectomy and pyeloplasty in addition to rn are necessary . furthermore , the procedure has cost - effectiveness advantages compared with laparoscopic and robot - assisted laparoscopic rn .
purposethis study aimed to comparatively evaluate the cost - effectiveness of four different types of radical nephrectomy ( rn ) techniques : open , laparoscopic , robot - assisted laparoscopic , and video - assisted minilaparotomy surgery ( vams).materials and methodsamong patients who were diagnosed with renal cell carcinoma and underwent rn , 20 patients were selected who received open , laparoscopic , robot - assisted laparoscopic , or vams rn between january 2008 and december 2010 . 
 their medical fees were divided into four categories : procedure and operation , anesthesia , laboratory test , and medical supply fees . 
 the medical costs of the patients were also divided into insured and uninsured costs.resultsthe total direct cost of vams , open , laparoscopic , and robot - assisted laparoscopic rn were 2,023,791240,757 , 2,024,246674,859 ( p=0.998 ) , 3,603,557870,333 ( p<0.01 ) , and 8,021,902330,157 ( p<0.01 ) 
 korean won ( krw , the currency of south koea ) , respectively . 
 the total insured cost of vams , open , laparoscopic , and robot - assisted laparoscopic rn was 1,904,627231,957 , 1,798,127645,602 ( p=0.634 ) , 3,039,769711,792 ( p<0.01 ) , and 899,668323,508 ( p<0.01 ) krw , respectively . 
 the total uninsured cost of vams , open , laparoscopic , and robot - assisted laparoscopic rn was 119,16324,581 , 226,119215,009 , 563,788487,798 ( p<0.01 ) , and 7,122,23456,117 ( p<0.01 ) krw , respectively . 
 medical supply fees accounted for the largest portion of the costs and amounted to 33.43% of the vams 
 cost.conclusionsvams rn is as cost - effective as open surgery . 
 furthermore , it is comparatively more cost - effective than laparoscopic and robot - assisted laparoscopic rn .