倍差法及其在公共卫生领域中的应用
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摘要
倍差法是针对非均衡组设计提出的统计方法,可解决准实验设计中干预组和对照组不均衡的问题。倍差法不仅可以处理两组基线差异的问题,也可以控制作用于两组的混杂因素的影响,有效地估计干预效应。本文阐述了倍差法的设计原理和统计方法,并以结果为连续变量(甲醛日潜在剂量,mg/d)的实例,拟合一般线性模型,并对结果进行解释。同时,针对结果为二分类变量的设计,也介绍了倍差法logistic回归的分析原理和参数解释。公共卫生干预项目采用非随机化分组的准实验设计较多,采用倍差法处理这些资料,可达到接近随机对照试验的统计效果。随着倍差法技术的普及,其在公共卫生项目评价中的应用将更广泛。
Difference-in-differences(DID) is a statistical method specific to the nonequivalent group design(NEGD) and used to solve the problem of imbalance between the intervention group and control group in quasi-experimental study design.It can be used not only for dealing with the baseline difference between the two groups,but also for controlling the influence of confounding factors to effectively estimate the intervention effect.This paper summarizes the design principle and statistical method of DID,an example with a continuous variable as outcome(potential daily dose of formaldehyde,mg/d) is used to fit a general linear model,and the results are explained.With respect to the binary outcome,a logistic regression model is introduced to explain the statistical theory and parameters of DID.There are a bunch of quasi-experimental study designs with nonrandomized grouping in public health interventions.It is reasonable to handle this kind of data by using DID in order to achieve statistical effects similar to the randomized controlled trial(RCT).Difference-in-differences will be widely applied in the public health program evaluation with all-pervading technique of DID.
Difference-in-differences(DID) is a statistical method specific to the nonequivalent group design(NEGD) and used to solve the problem of imbalance between the intervention group and control group in quasi-experimental study design.It can be used not only for dealing with the baseline difference between the two groups,but also for controlling the influence of confounding factors to effectively estimate the intervention effect.This paper summarizes the design principle and statistical method of DID,an example with a continuous variable as outcome(potential daily dose of formaldehyde,mg/d) is used to fit a general linear model,and the results are explained.With respect to the binary outcome,a logistic regression model is introduced to explain the statistical theory and parameters of DID.There are a bunch of quasi-experimental study designs with nonrandomized grouping in public health interventions.It is reasonable to handle this kind of data by using DID in order to achieve statistical effects similar to the randomized controlled trial(RCT).Difference-in-differences will be widely applied in the public health program evaluation with all-pervading technique of DID.
引文
[1]Ashenfelter O,Card D.Using the longitudinal structure of earnings to estimate the effect of training programs[J].Rev Econ Stat,1985,67(4):648-660.DOI:10.2307/1924810.
[2]Listl S,Jürges H,Watt RG.Causal inference from observational data[J].Commun Dent Oral Epidemiol,2016,44(5):409-415.DOI:10.1111/cdoe.12231.
[3]Bifulco R.Addressing self-selection bias in quasi-experimental evaluations of whole-school reform.A comparison of methods[J].Eval Rev,2002,26(5):545-572.DOI:10.1177/019384102236523.
[4]潘思辰,苏义坤.智慧城市政策对城市智慧水平的影响-基于倾向得分匹配倍差法分析[J].工程管理学报,2017,31(6):55-60.DOI:10.13991/j.cnki.jem.2017.06.011.Pan SC,Su YK.A study of effect of policies on city smart level-based on PSM-DID method[J].J Eng Manage,2017,31(6):55-60.DOI:10.13991/j.cnki.jem.2017.06.011.
[5]Rokicki S,Cohen J,Fink G,et al.Inference with difference-indifferences with a small number of groups:a review,simulation study,and empirical application using share data[J].Med Care,2018,56(1):97-105.DOI:10.1097/MLR.0000000000000830.
[6]李晓松.卫生统计学[M].8版.北京:人民卫生出版社,2017:249-261.Li XS.Health statistics[M].8ht ed.Beijing:People′s Medical Publishing House,2017:249-261.
[7]杨帆,于保荣,杜凯,等.临床路径及按病例支付改革前后县级医院小儿腹股沟疝医疗费用变化研究[J].医学与社会,2013,26(1):8-10.DOI:10.3870/YXYSH.2013.01.003.Yang F,Yu BR,Du K,et al.Study of medical cost change of inpatients with pediatric inguinal hernia before and after introduction of clinical pathway and case-based payment in county hospitals[J].Med Sociol,2013,26(1):8-10.DOI:10.3870/YXYSH.2013.01.003.
[8]薛秦香,苏敏,孙璐鑫.新型农村合作医疗总额预付制对住院受益程度的影响[J].中国卫生经济,2017,36(5):59-64.DOI:10.7664/CHE20170517.Xue QX,Su M,Sun LX.The impact of global budget on the hospitalization beneficial degree under new rural cooperative medical system[J].Chin Health Econ,2017,36(5):59-64.DOI:10.7664/CHE20170517.
[9]卢颖.新农合门诊按人头支付改革对村医处方行为的效果评价[D].济南:山东大学,2014:20-24.Lu Y.Effect of NCMS outpatient capitation payment reform on prescribing behavior of village doctors[D].Ji′nan:Shandong University,2014:20-24.
[10]陈鸣声.基层医疗机构合理用药激励性规制研究--基于信息租金和契约设计的视角[D].上海:复旦大学,2013:34-37.Chen MS.Study on the incentive regulation on the rational medicine use of primary healthcare providers-based on the perspectives of information rent and contract design[D].Shanghai:Fudan University,2013:34-37.
[11]Arsenijevic J,Groot W.Does household help prevent loneliness among the elderly?An evaluation of a policy reform in the Netherlands[J].BMC Public Health,2018,18:1104.DOI:10.1186/s12889-018-6004-6.
[12]郑娟.新农合政策及其变化对居民医疗服务需要、利用及费用负担的影响研究--基于济南市三县区面板数据分析[D].济南:山东大学,2015:60-69.Zheng J.A study on the effect of NCMS policies and its change on residents’medical service need and utilization and cost burdenanalysis of panel data in three counties of Ji′nan[D].Ji′nan:Shandong University,2015:60-69.
[13]Ren Y,Yang M,Li Q,et al.Assessing dose-response effects of national essential medicine policy in China:comparison of two methods for handling data with a stepped wedge-like design and hierarchical structure[J].BMJ Open,2017,7(2):e013247.DOI:10.1136/bmjopen-2016-013247.
[14]赵琨,张振忠,隋宾艳,等.农村医疗机构诊治技术优化和补偿机制改革干预效果的评价:基于倍差法[J].中国卫生经济,2011,30(7):13-16.DOI:10.3969/j.issn.1003-0743.2011.07.003.Zhao K,Zhang ZZ,Sui BY,et al.The outcome evaluation of pilot research on health technology optimization and compensation mechanism in rural health facility:based on the evaluation method of difference-in-differences[J].Chin Health Econ,2011,30(7):13-16.DOI:10.3969/j.issn.1003-0743.2011.07.003.
[15]范涛,曹乾,蒋露露,等.新型农村合作医疗对农民健康自评的影响[J].上海交通大学学报:医学版,2011,31(12):1763-1766.DOI:10.3969/j.issn.1674-8115.2011.12.023.Fan T,Cao Q,Jiang LL,et al.Effects of new rural cooperative medical health policy on self-perceived health of rural residents[J].J Shanghai Univ Commun:Med Vers,2011,31(12):1763-1766.DOI:10.3969/j.issn.1674-8115.2011.12.023.
[16]左雯婕,舒燕.新型农村合作医疗制度对农村居民的健康影响研究[J].卫生软科学,2016,30(12):46-50.DOI:10.3969/j.issn.1003-2800.2016.12.012.Zuo WJ,Shu Y.Study on the influence of new rural cooperative medical care system to rural residents’health[J].Soft Sci Health,2016,30(12):46-50.DOI:10.3969/j.issn.1003-2800.2016.12.012.
[17]于石成,殷大鹏.准实验设计方法在疫苗效果评价中的应用[J].首都公共卫生,2018,12(3):124-125.DOI:10.16760/j.cnki.sdggws.2018.03.004.Yu SC,Yin DP.The application for quasi-experimental design method in the evaluation of vaccine efficacy[J].Capital Public Health,2018,12(3):124-125.DOI:10.16760/j.cnki.sdggws.2018.03.004.
[2]Listl S,Jürges H,Watt RG.Causal inference from observational data[J].Commun Dent Oral Epidemiol,2016,44(5):409-415.DOI:10.1111/cdoe.12231.
[3]Bifulco R.Addressing self-selection bias in quasi-experimental evaluations of whole-school reform.A comparison of methods[J].Eval Rev,2002,26(5):545-572.DOI:10.1177/019384102236523.
[4]潘思辰,苏义坤.智慧城市政策对城市智慧水平的影响-基于倾向得分匹配倍差法分析[J].工程管理学报,2017,31(6):55-60.DOI:10.13991/j.cnki.jem.2017.06.011.Pan SC,Su YK.A study of effect of policies on city smart level-based on PSM-DID method[J].J Eng Manage,2017,31(6):55-60.DOI:10.13991/j.cnki.jem.2017.06.011.
[5]Rokicki S,Cohen J,Fink G,et al.Inference with difference-indifferences with a small number of groups:a review,simulation study,and empirical application using share data[J].Med Care,2018,56(1):97-105.DOI:10.1097/MLR.0000000000000830.
[6]李晓松.卫生统计学[M].8版.北京:人民卫生出版社,2017:249-261.Li XS.Health statistics[M].8ht ed.Beijing:People′s Medical Publishing House,2017:249-261.
[7]杨帆,于保荣,杜凯,等.临床路径及按病例支付改革前后县级医院小儿腹股沟疝医疗费用变化研究[J].医学与社会,2013,26(1):8-10.DOI:10.3870/YXYSH.2013.01.003.Yang F,Yu BR,Du K,et al.Study of medical cost change of inpatients with pediatric inguinal hernia before and after introduction of clinical pathway and case-based payment in county hospitals[J].Med Sociol,2013,26(1):8-10.DOI:10.3870/YXYSH.2013.01.003.
[8]薛秦香,苏敏,孙璐鑫.新型农村合作医疗总额预付制对住院受益程度的影响[J].中国卫生经济,2017,36(5):59-64.DOI:10.7664/CHE20170517.Xue QX,Su M,Sun LX.The impact of global budget on the hospitalization beneficial degree under new rural cooperative medical system[J].Chin Health Econ,2017,36(5):59-64.DOI:10.7664/CHE20170517.
[9]卢颖.新农合门诊按人头支付改革对村医处方行为的效果评价[D].济南:山东大学,2014:20-24.Lu Y.Effect of NCMS outpatient capitation payment reform on prescribing behavior of village doctors[D].Ji′nan:Shandong University,2014:20-24.
[10]陈鸣声.基层医疗机构合理用药激励性规制研究--基于信息租金和契约设计的视角[D].上海:复旦大学,2013:34-37.Chen MS.Study on the incentive regulation on the rational medicine use of primary healthcare providers-based on the perspectives of information rent and contract design[D].Shanghai:Fudan University,2013:34-37.
[11]Arsenijevic J,Groot W.Does household help prevent loneliness among the elderly?An evaluation of a policy reform in the Netherlands[J].BMC Public Health,2018,18:1104.DOI:10.1186/s12889-018-6004-6.
[12]郑娟.新农合政策及其变化对居民医疗服务需要、利用及费用负担的影响研究--基于济南市三县区面板数据分析[D].济南:山东大学,2015:60-69.Zheng J.A study on the effect of NCMS policies and its change on residents’medical service need and utilization and cost burdenanalysis of panel data in three counties of Ji′nan[D].Ji′nan:Shandong University,2015:60-69.
[13]Ren Y,Yang M,Li Q,et al.Assessing dose-response effects of national essential medicine policy in China:comparison of two methods for handling data with a stepped wedge-like design and hierarchical structure[J].BMJ Open,2017,7(2):e013247.DOI:10.1136/bmjopen-2016-013247.
[14]赵琨,张振忠,隋宾艳,等.农村医疗机构诊治技术优化和补偿机制改革干预效果的评价:基于倍差法[J].中国卫生经济,2011,30(7):13-16.DOI:10.3969/j.issn.1003-0743.2011.07.003.Zhao K,Zhang ZZ,Sui BY,et al.The outcome evaluation of pilot research on health technology optimization and compensation mechanism in rural health facility:based on the evaluation method of difference-in-differences[J].Chin Health Econ,2011,30(7):13-16.DOI:10.3969/j.issn.1003-0743.2011.07.003.
[15]范涛,曹乾,蒋露露,等.新型农村合作医疗对农民健康自评的影响[J].上海交通大学学报:医学版,2011,31(12):1763-1766.DOI:10.3969/j.issn.1674-8115.2011.12.023.Fan T,Cao Q,Jiang LL,et al.Effects of new rural cooperative medical health policy on self-perceived health of rural residents[J].J Shanghai Univ Commun:Med Vers,2011,31(12):1763-1766.DOI:10.3969/j.issn.1674-8115.2011.12.023.
[16]左雯婕,舒燕.新型农村合作医疗制度对农村居民的健康影响研究[J].卫生软科学,2016,30(12):46-50.DOI:10.3969/j.issn.1003-2800.2016.12.012.Zuo WJ,Shu Y.Study on the influence of new rural cooperative medical care system to rural residents’health[J].Soft Sci Health,2016,30(12):46-50.DOI:10.3969/j.issn.1003-2800.2016.12.012.
[17]于石成,殷大鹏.准实验设计方法在疫苗效果评价中的应用[J].首都公共卫生,2018,12(3):124-125.DOI:10.16760/j.cnki.sdggws.2018.03.004.Yu SC,Yin DP.The application for quasi-experimental design method in the evaluation of vaccine efficacy[J].Capital Public Health,2018,12(3):124-125.DOI:10.16760/j.cnki.sdggws.2018.03.004.