in 2010 , chinese center for disease control and prevention investigated and found that the prevalence rate of diabetes in chinese people > 18 years old reached 9.7% , among whom , over 90% were type 2 diabetes . the average annual growth rate of direct medical expenditure of diabetes in china is 19.90% , which exceeds the growth rate of gross domestic product ( gdp ) and national health expenditure contemporarily , and outpatient expenditure occupied 2/3 of the direct medical fees . the increase in the prevalence of type 2 diabetes not only consumed an enormous amount of money , but also induced tremendous disease burden to both the patient and the society ; therefore , it is necessary to research on how to control the outpatient expenditure of type 2 diabetes . in this study , we analyzed new patterns of medical insurance payment for type 2 diabetes outpatient services , combined with the consideration of features of type 2 diabetes outpatient expenditure and advantages of bundled payment system . we studied the feasibility of implementing bundled payment for type 2 diabetes outpatient services in the urban employee basic medical insurance ( uebmi ) in beijing , so as to come up with suitable payment standards for type 2 diabetes outpatient services . bundled payment  is an approach in which payments to health care providers are related to the predetermined expected costs of a grouping , or  bundle  , of a certain health care service . the intent of bundled payment systems is to decrease health care expenditure while improving or maintaining the quality of care . in 2009 , as an important part of the aca ,  bundled payment  was implemented rapidly across the united states under the guidance of the centers for medicare and medicaid services . in recent years , bundled payment has already become an important strategy for the united states government to control the increase of medical fees . compared to other medical insurance payment modes , such as fee - for - service ( ffs ) , diagnosis - related groups , fee for unit , capitation , etc . it can improve the medical service efficiency and decrease unnecessary medical services ( for instance , add abundant nursing after the operation and reduce duplicated check and unnecessary care ) , control the medical expenditure effectively and reduce the cost of medical insurance , promote the coordination between the medical service providers , and improve the medical care quality . furthermore , it can greatly decrease the occurrence of decomposed hospitalization , repeated hospitalization , and shuffling patients in severe conditions . however , there are also some disadvantages in bundled payment : ( 1 ) researchers said that adoption of the bundled payments approach was slowed by both technical and cultural difficulties . technical issues included deciding what health problems should be subject to bundled payment and providing health providers with the information needed to improve medical care . cultural issues included convincing providers that cost - cutting measures will not reduce the quality of medical care . ( 2 ) in order to maximize the profits , hospitals may decrease the patients ' opportunities to be diagnosed and treated by the experts . ( 3 ) as a medical service provider can outsource one part of the patients ' medical services to another provider , it will be difficult to identify financial responsibility for a specific pay package . ( 4 ) since some kinds of diseases are not suitable for packaging , some patients may have more than one package , among which exists overlapping . since 2009 , the chinese government has launched a new round of health care reform . although some reforms took place in the medical insurance payment patterns , the rapid growth of medical expenditure has not slowed down significantly . at present , in most areas of china , the dominant payment pattern is still ffs . disadvantages of this approach have been revealed during the long - term operation because of the information imbalance , the medical institution has the motivation to provide excessive or expensive medical services , which easily results in supplier - induced demand and excessive medical care . for this reason , chinese medical insurance management department has to make various medical insurance lists and detailed health regulations . in 2011 , the main objectives were : ( 1 ) to study the reform of global budget ; ( 2 ) to explore the reform of capitation payment based on the risk pooling of outpatient services ; and ( 3 ) to investigate the reform of diagnosis related groups payment on the basis of the inpatient and outpatient critical illness insurance program . since then , the payment method in china began to change from single pattern ( ffs ) to a compound multilevel medical insurance payment system , which consists of global budget , diagnosis related groups payment , and capitation payment . in recent years , many of the medical insurance institutions in china have done numerous studies on how to conduct a more effective payment method . some of the cities and areas , represented by beijing , have set up a compound multilevel medical insurance payment system . we can expect the generalization of a compound multilevel medical insurance payment system in the future . although many studies have been conducted on the reform of medical insurance payment patterns in china , rare can be found on bundled payment . therefore , in this study , we explored the feasibility of implementing bundled payment in china through the analysis bundled payment standards of type 2 diabetes outpatient services . this study collected the data of the basic medical insurance for an urban employee from january 1 , 2010 to december 31 , 2012 , in beijing 's secondary and tertiary public general hospitals . the selected data included the basic information of patients diagnosed with type 2 diabetes ( icd-10 code : e11.2e11.9 ) , the diagnosis information and relevant settlement information of outpatient expenditure of medical institutions . meanwhile , patients whose treatment time span < 1 year and who have been hospitalized were excluded . hence , we obtained the cases of 308,500 patients , accounting for 2,396,576 person - times . then , we randomly selected 10% of the cases each year as the sample . in order to ensure the data 's independence between the years , we excluded those who were selected in any of the two years . finally , we obtained a sample of 29,374 patients and 225,786 person - times . all information was searched and gathered by year through sql server 2008 ( microsoft corporation inc . , redmond , wa , usa ) , and individually summarized data were imported into spss 13.0 ( spss inc . , we conducted a descriptive analysis and a single factor analysis on characteristic variables of the patients and the outpatient expenditure , wherein single factor analysis was performed with a rank - sum test of the nonparametric test . wallis h test . because the outpatient expenditure related to the disease which took place within 5 months after the first outpatient visit accounted for 75.14% of the total amount of the outpatient expenditure , showing a strong representativeness , it was regarded as the bundled fees . we used fitting multiple linear regression models to analyze influential factors of outpatient expenditure of type 2 diabetes . chi - square automatic interaction detector ( chaid ) in the decision - making tree was conducted to make case - mix analysis on outpatient expenditure . finally , we established a case - mix model to calculate the standard expenditure and upper limit expenditure of each combination . this study collected the data of the basic medical insurance for an urban employee from january 1 , 2010 to december 31 , 2012 , in beijing 's secondary and tertiary public general hospitals . the selected data included the basic information of patients diagnosed with type 2 diabetes ( icd-10 code : e11.2e11.9 ) , the diagnosis information and relevant settlement information of outpatient expenditure of medical institutions . meanwhile , patients whose treatment time span < 1 year and who have been hospitalized were excluded . hence , we obtained the cases of 308,500 patients , accounting for 2,396,576 person - times . then , we randomly selected 10% of the cases each year as the sample . in order to ensure the data 's independence between the years , we excluded those who were selected in any of the two years . finally , we obtained a sample of 29,374 patients and 225,786 person - times . all information was searched and gathered by year through sql server 2008 ( microsoft corporation inc . , redmond , wa , usa ) , and individually summarized data were imported into spss 13.0 ( spss inc . , we conducted a descriptive analysis and a single factor analysis on characteristic variables of the patients and the outpatient expenditure , wherein single factor analysis was performed with a rank - sum test of the nonparametric test . wallis h test . because the outpatient expenditure related to the disease which took place within 5 months after the first outpatient visit accounted for 75.14% of the total amount of the outpatient expenditure , showing a strong representativeness , it was regarded as the bundled fees . we used fitting multiple linear regression models to analyze influential factors of outpatient expenditure of type 2 diabetes . chi - square automatic interaction detector ( chaid ) in the decision - making tree was conducted to make case - mix analysis on outpatient expenditure . finally , we established a case - mix model to calculate the standard expenditure and upper limit expenditure of each combination . the result indicated that : ( 1 ) the number of male patients was slightly higher than female patients . the 86.56% of patients were retired ; no more than 15.00% were in - service . ( 2 ) more than 90.00% patients had complications , among which , proportions of patients with cardiac - cerebrovascular diseases , neuropathy , and arteriosclerosis in lower extremity were all more than 50.00% ; arteriosclerosis in lower extremity even reached 61.79% . proportions of retinopathy , nephropathy , and diabetic foot were < 40% ; diabetic foot was the least ( 9.84% ) . ( 3 ) the average outpatient expenditure in 3 years was rmb 8397.16 yuan ; 50% patients spent less than rmb 8866.18 yuan . ( 4 ) except gender , all of the distribution variance of each characteristic variable at different levels was statistically significant . for all of the complications , the distribution difference of outpatient expenditure of type 2 diabetes was statistically significant [ tables 1 and 2 ] . univariate analysis of patients outpatient expenditures univariate analysis of outpatient expenditures of patients with or without complications we used a multiple linear regression according to the results of the descriptive analysis and the single factor analysis to analyze the influential factors of outpatient expenditure . this step was to make preparation for case - mix analysis through decision - making tree . influential factors of outpatient expenditure will be used as the grouping node ( predict variables ) . we conducted a multiple linear regression , with outpatient expenditure as the dependent variable and relevant factors as independent variables . since all of the variance inflation factors in the equation were < 5 , no serious co - linearity existed in the equitation . factors in the equation were : gender , age , job status ( in service or not ) , and whether with complications . the results indicated , except gender , the age , job status , and severity of the disease significantly influenced the outpatient expenditure of type 2 diabetes [ table 3 ] . multivariate linear regression analysis of the influential factors of outpatient expenditure a further multiple linear regression analysis was conducted on cases with complications ( mostly clinical chronic complication of type 2 diabetes ) . a multiple linear regression model was introduced with the outpatient expenditure as the dependent factor and whether with various complications as the independent factor . from the model , it can be seen that among patients with complications , as to any complication , after controlling other variables ( complications ) , the outpatient expenditure of patients with this complication was higher than that of patients without this complication [ table 4 ] . multivariate linear regression analysis of outpatient expenditures of patients with complications the significant of the influential factors on the total outpatient expenditure were subsequently ( from high to low ) : whether with complication , age , and job status [ table 3 ] . as to various complications , the significances on outpatient expenditure were subsequently ( from high to low ) : diabetic foot , diabetic nephropathy , cardiac - cerebrovascular disease , arteriosclerosis in lower extremity , neuropathy , and retinopathy successively [ table 4 ] . we used chi - square automatic interaction method to build a decision - making tree . primary decision - making tree analysis was made with the influential factors as the grouping node ( predict variables ) according to the multiple linear regression analysis on the influential factors of outpatient expenditure [ table 5 ] . primary case grouping of outpatient expenditures of type 2 diabetes then , a decision - making tree case grouping was conducted on the outpatient expenditure of patients with complications . we obtained the results of the case grouping using type 2 diabetes outpatient expenditure as the target variable and whether with complications as the predicted variable [ table 6 ] . considering the stability of the classification , the weakened reference value of the standard due to too many grouping , and suitable sample volume in each group , we set up five grouping nodes and ten layers at most to cease the tree every time we made decision - making tree analysis . grouping of outpatient expenditure cases of patients with complication the standard value of outpatient expenditure per year in each case group can be calculated according to the grouping result of outpatient expenditure . combining the consultation opinion of experts , we set the median of the outpatient expenditure in each group as the standard bundled expenditure , and 3/4 of the interior expenditure of each group as the upper limit of the bundled expenditure . in practice , medical insurance management organizations can refer to this to work out reasonable reimbursement standards for type 2 diabetes outpatient expenditure . it can also utilize to discover the record of excessive expenditure in time , which can provide a reference for identifying further expenditure risk . we can see : ( 1 ) the first grouping node was whether with complications , which divided the patients into with complication group and without complication group . ( 2 ) the second grouping node was age , classifying patients with complications into groups : 50 years old , 5170 years old , and > 70 years old . ( 3 ) in the group of patients with complications , diabetic foot showed the highest correlation with the outpatient expenditure . the outpatient expenditure of patients with diabetic food was higher than that of patients without diabetic foot . among patients without diabetic foot , the outpatient expenditure of patients with cardiac - cerebrovascular disease was higher than that of patients without cardiac - cerebrovascular disease . among patients without diabetic nephropathy , the outpatient expenditure of patients with cardiac - cerebrovascular disease was higher than that of patients without cardiac - cerebrovascular disease . among patients without cardiac - cerebrovascular disease , the most significant variable was age . outpatient expenditure of patients > 70 years old was the highest and that of patients < 50 years old was the lowest . ( 4 ) in all the characteristic variables , whether with complications was the best predictive variable . with or without diabetic foot , with or without cardiac - cerebrovascular disease , with or without diabetic nephropathy , age , and with or without neuropathy the outpatient expenditure of patients without complication and 50 years old was the lowest , while that of patients complicated with the diabetic foot was the highest . the result indicated that : ( 1 ) the number of male patients was slightly higher than female patients . the 86.56% of patients were retired ; no more than 15.00% were in - service . ( 2 ) more than 90.00% patients had complications , among which , proportions of patients with cardiac - cerebrovascular diseases , neuropathy , and arteriosclerosis in lower extremity were all more than 50.00% ; arteriosclerosis in lower extremity even reached 61.79% . proportions of retinopathy , nephropathy , and diabetic foot were < 40% ; diabetic foot was the least ( 9.84% ) . ( 3 ) the average outpatient expenditure in 3 years was rmb 8397.16 yuan ; 50% patients spent less than rmb 8866.18 yuan . ( 4 ) except gender , all of the distribution variance of each characteristic variable at different levels was statistically significant . for all of the complications , the distribution difference of outpatient expenditure of type 2 diabetes was statistically significant [ tables 1 and 2 ] . univariate analysis of patients outpatient expenditures univariate analysis of outpatient expenditures of patients with or without complications we used a multiple linear regression according to the results of the descriptive analysis and the single factor analysis to analyze the influential factors of outpatient expenditure . this step was to make preparation for case - mix analysis through decision - making tree . influential factors of outpatient expenditure will be used as the grouping node ( predict variables ) . we conducted a multiple linear regression , with outpatient expenditure as the dependent variable and relevant factors as independent variables . since all of the variance inflation factors in the equation were < 5 , no serious co - linearity existed in the equitation . factors in the equation were : gender , age , job status ( in service or not ) , and whether with complications . the results indicated , except gender , the age , job status , and severity of the disease significantly influenced the outpatient expenditure of type 2 diabetes [ table 3 ] . multivariate linear regression analysis of the influential factors of outpatient expenditure a further multiple linear regression analysis was conducted on cases with complications ( mostly clinical chronic complication of type 2 diabetes ) . a multiple linear regression model was introduced with the outpatient expenditure as the dependent factor and whether with various complications as the independent factor . from the model , it can be seen that among patients with complications , as to any complication , after controlling other variables ( complications ) , the outpatient expenditure of patients with this complication was higher than that of patients without this complication [ table 4 ] . multivariate linear regression analysis of outpatient expenditures of patients with complications the significant of the influential factors on the total outpatient expenditure were subsequently ( from high to low ) : whether with complication , age , and job status [ table 3 ] . as to various complications , the significances on outpatient expenditure were subsequently ( from high to low ) : diabetic foot , diabetic nephropathy , cardiac - cerebrovascular disease , arteriosclerosis in lower extremity , neuropathy , and retinopathy successively [ table 4 ] . we used chi - square automatic interaction method to build a decision - making tree . primary decision - making tree analysis was made with the influential factors as the grouping node ( predict variables ) according to the multiple linear regression analysis on the influential factors of outpatient expenditure [ table 5 ] . primary case grouping of outpatient expenditures of type 2 diabetes then , a decision - making tree case grouping was conducted on the outpatient expenditure of patients with complications . we obtained the results of the case grouping using type 2 diabetes outpatient expenditure as the target variable and whether with complications as the predicted variable [ table 6 ] . considering the stability of the classification , the weakened reference value of the standard due to too many grouping , and suitable sample volume in each group , we set up five grouping nodes and ten layers at most to cease the tree every time we made decision - making tree analysis . the standard value of outpatient expenditure per year in each case group can be calculated according to the grouping result of outpatient expenditure . combining the consultation opinion of experts , we set the median of the outpatient expenditure in each group as the standard bundled expenditure , and 3/4 of the interior expenditure of each group as the upper limit of the bundled expenditure . in practice , medical insurance management organizations can refer to this to work out reasonable reimbursement standards for type 2 diabetes outpatient expenditure . it can also utilize to discover the record of excessive expenditure in time , which can provide a reference for identifying further expenditure risk . we can see : ( 1 ) the first grouping node was whether with complications , which divided the patients into with complication group and without complication group . ( 2 ) the second grouping node was age , classifying patients with complications into groups : 50 years old , 5170 years old , and > 70 years old . ( 3 ) in the group of patients with complications , diabetic foot showed the highest correlation with the outpatient expenditure . the outpatient expenditure of patients with diabetic food was higher than that of patients without diabetic foot . among patients without diabetic foot , the outpatient expenditure of patients with cardiac - cerebrovascular disease was higher than that of patients without cardiac - cerebrovascular disease . among patients without diabetic nephropathy , the outpatient expenditure of patients with cardiac - cerebrovascular disease was higher than that of patients without cardiac - cerebrovascular disease . among patients without cardiac - cerebrovascular disease , the most significant variable was age . outpatient expenditure of patients > 70 years old was the highest and that of patients < 50 years old was the lowest . ( 4 ) in all the characteristic variables , whether with complications was the best predictive variable . with or without diabetic foot , with or without cardiac - cerebrovascular disease , with or without diabetic nephropathy , age , and with or without neuropathy the outpatient expenditure of patients without complication and 50 years old was the lowest , while that of patients complicated with the diabetic foot was the highest . first , in the analysis of the influential factors of type 2 diabetes outpatient expenditure , standardized partial regression coefficients of whether with complication and age were 0.778 and 0.014 , ranking top two among all of the influential factors with statistical significance . second , in the grouping result of outpatient expenditure , whether with complications and age were the first and second grouping nodes of decision - making tree grouping . after recalculation , the group with the highest standard expenditure was the group complicated with diabetic foot . as a whole , the older the patient was , the higher the outpatient expenditure would be . all these indicated that age and whether with complications were the most important factors that influenced the bundled payment for type 2 diabetes outpatient services . therefore , relying on the research on medical insurance big data , when bundling type 2 diabetes outpatient expenditure , this study defined the outpatient expenditure related to the disease within 5 months after the first outpatient visit of patients as the bundled payment . we fully considered the influence of whether with complications and age and regarded whether with complications and age as the important variables for cases grouping as far as possible . in this way , we took the individualized difference of the disease into consideration and made it more reasonable to decrease excessive clinical medical service and control the rapid increase of outpatient expenditure . selection of bundled node of type 2 diabetes outpatient expenditure should take realistic feasibility into consideration . in this study it is noteworthy that one key point to establish chaid decision - making tree is to choose the quantity of grouping nodes and set up the conditions of ceasing the growth of the tree . if there are too few grouping nodes , it will be invalid to group the patients according to differentiated characteristics , and the within - group variance will be too large . if there are too many nodes , it will lead to particularly complex grouping result and over - fitting phenomenon , which will weaken the reference value of the standard . therefore , considering the realistic feasibility , this study set up five grouping nodes and ten layers at most to cease growth of the decision - making tree . in this way the result was acceptable for the clinical doctors and medical insurance institutions . within the group , clinical features were similar , within - group variances were small , and between - group variances were significant . it is reasonable reimbursement standard for the bundled payment of outpatient services that can coordinate the interests among doctors , patients , and the medical insurance organizations as well as control the excessively rapid growth of medical fees . in this study , we set the median of the expenditure of each group as the reference and 3/4 of the intra - group expenditure as the upper limit . although we could not prove its reasonability theoretically , the result showed the outpatient expenditure in the lowest in patients without complication and the age 50 years , but highest in patients with diabetic foot , which was consistent with the results of other researchers . in addition , the reimbursement standard of bundled payment can also be modified with the combination of clinical context pathway and advice from medical institutions , medical insurance management institutions , and experts . we believed that in the future , the reimbursement standard of bundled payment can be more than more precise .
background : in recent years , the prevalence of type 2 diabetes among chinese population has been increasing by years , directly leading to an average annual growth rate of 19.90% of medical expenditure . 
 therefore , it is urgent to work on strategies to control the growth of medical expenditure on type 2 diabetes on the basis of the reality of china . 
 therefore , in this study , we explored the feasibility of implementing bundled payment in china through analyzing bundled payment standards of type 2 diabetes outpatient services.methods:this study analyzed the outpatient expenditure on type 2 diabetes with beijing urban employee 's basic medical insurance from 2010 to 2012 . 
 based on the analysis of outpatient expenditure and its influential factors , we adopted decision tree approach to conduct a case - mix analysis . in the end , we built a case - mix model to calculate the standard expenditure and the upper limit of each combination.results:we found that age , job status , and whether with complication were significant factors that influence outpatient expenditure for type 2 diabetes . through the analysis of the decision tree , we used six variables ( complication , age , diabetic foot , diabetic nephropathy , cardiac - cerebrovascular disease , and neuropathy ) to group the cases , and obtained 
 11 case - mix groups.conclusions:we argued that it is feasible to implement bundled payment on type 2 diabetes outpatient services . 
 bundled payment is effective to control the increase of outpatient expenditure . 
 further improvements are needed for the implementation of bundled payment reimbursement standards , together with relevant policies and measures .