个关于药物经济学的分析模型的Casestudy.ppt

Development of an Economic Model to Assess the Cost Effectiveness of Asthma Management Strategies,Martin J.Price 1 and Andrew H.Briggs2 1 Global health outcomes, GlaxoSmithKline Research Development, Greenford, Middlesex, United Kingdom 2 Health Economics Research Centre, University of Oxford, Oxford, United Kingdom,Pharmaceconomics 2002;20(3):183-194,Disease,Disease:Asthma 慢性发作性疾病 急性症候（不同严重程度）性发作：wheeze, chest tightness, breathlessness, cough, nacturnal waking Treatment: A:salmeterol/flucticasone propionate combination(SFC,沙美特罗/丙酸氟替卡松联合给药)50/100g B:flucticasone propionate(FP,丙酸氟替卡松)100g 实验条件：一天两次，吸入式给药，持续12周，随机， 双盲的临床实验 Treatment success： Asthma control（defined in world-wide asthma management guidelines and in terms of QALYs） Results： 1, Effectiveness:Proportion of successfully controlled weeks per patient: SFC(66%)FP(47%) 2,Cost:Mean weekly direct asthma management cost: SFC(15.77)FP(11.83) 3, Average incremental cost per successfully controlled week with SFC:20.83 4,PSA(probabilistic sensitivity analysis):ICER(95% uncertainty intervals):- 64.94 to 112.66 if decision maker WTP 45 for an additional successful controlled week, SFC more cost-effective in 80% of the time,Methods：Markov model,Health states： 1,Successful control: table I 2,Hospital-managed exacerbation: hospital 3,Primary-care-managed exacerbation: outpatient 4,Sub-optimal control: between “successful control “ and “exacerbation” 5,Treatment failure : discontinue the study treatment Cycle length:1 week Transition parameters: figure I,Health states： 1,Successful control: table I, well-controlled 代替total control,原因：1，对于一部分病人，不清楚total control 是否是现实的和可以达到的。2，对于某些决策者来说， 2,Hospital-managed exacerbation:哮喘恶化病人在医院接受治疗，一些病人：急救室后回家，另一些病人：住院治疗 3,Primary-care-managed exacerbation:门诊病人接受专业治疗。英国：general practice clinic.美国：urgent care centres 4,Sub-optimal control：成功控制和恶化之间，无法确诊，但又不值得干预 5,Treatment failure ：1，由于时间短，哮喘致死率低，而无法使用death作为markov model的absorbing state， 而是用treatment failure 代替。2，而与一般的markov model 不同，处在treatment failure 的病人还会增加成本和效果，因为他们可能会选择另外的治疗方式。3，故使用B:flucticasone propionate(FP,丙酸氟替卡松)100g的成本效果来代替treatment failure 的成本效果 Cycle length：对于哮喘的周期长度来说，1周是比较合适的。 Transition parameters：定义了健康状态和转变方向，其中任意两个状态是可以相互转化的，只有treatment failure 是absorbing state，是单向的。,Data source,Population: 1,patients with asthma aged 12-70, 2,FEV1(forced expiratory volume in 1 second)40%-85%, 3,receiving treatment corticosteroids (beclomethasone dipropionate (二丙酸倍氯米松）252-420g/day or equivalent) or salmeterol （沙美特罗）42 g/day Grouping： 1, salmeterol/flucticasone propionate combination(SFC,沙美特罗/丙酸氟替 卡松联合给药)50/100g 2, B:flucticasone propionate(FP,丙酸氟替卡松)100g 3, salmeterol(沙美特罗)50g 4,placebo Recording: 1,Patient diary card(symptoms, lung function, nocturnal waking, use of rescue salbutamol(舒喘宁） 2,case report form,Data coding,Assignment to health states Determining transition probabilities Model cost Health outcomes Fitting distributions,Assignment to health states,Successful control(1): well-controlled Hospital-managed exacerbation(2):weekly data examined Primary-care-managed exacerbation(3):weekly data examined Sub-optimal control:not 2 and 3, any of criteria of 1 not met Treatment failure :withdraw from the study for prematurely clinical reasons,Determining transition probabilities(1),1，存在的问题：有些transition 的数量为0，这意味着这些transition很小，而不是不可能发生。 2，采用bayesian methods,Determining transition probabilities(2),Model cost,Medication cost(medication usage, physician time, hospital costs):2000 UK pharmacy prices(taking from MIMS(Monthly Index of Medical Specialities) Cost associated with Primary and secondary exacerbation health states(from a paper published in 1998) Inflation(HCHS(hospital and community health services) inflation index),Hospital-managed exacerbation中，cost采用急救室和住院的平均费用计算，Hoskins et al.,Health outcomes,Outcomes:Proportion of successfully controlled weeks All other states except treatment failure are assigned 0 benefit Costs and Outcomes of Treatment failure states: use FP treatment arm（lacking “usual care” sub-model ),Fitting distributions,Transition probabilities: dirichlet distribution(multinomial equivalent of the -distribution) Costs: 1,drug: no distribution 2,unit costs of primary care consultations and the cost of an inpatient day: normal distribution 3,the length of stay for a hospital-managed exacerbation: log normal distribution 4,costs of primary and secondary care-managed exacerbations: normal distribution Treatment failure: probabilistically(FP arm),Data analysis,Cost-effectiveness PSA(Probabilistic sensitivity analysis),1，控制周数增加比例：0.10.26. 2，成本增加：-10.9717.51每周 3，ICER：-64.94112.66 4，25%SFC处于dominant，75%，SFC效果更好，成本更高 5，WTP=45时，80%SFC的NB0,Discussion,Limitations management exacerbation cost factors usual care