Fenn P, Gray A
The Business School, University of Nottingham, England.
Pharmacoeconomics. 1999 Aug;16(2):165-74. doi: 10.2165/00019053-199916020-00005.
This paper puts forward a proposal for a modelling approach to the estimation of long term cost savings from the treatment of Alzheimer's disease (AD).
In the proposed modelling approach, disease progression is defined in terms of intervals in the Mini-Mental State Exam (MMSE) scale. Clinical trial data are then used to determine the time at which a particular patient moved into a more severe stage of the disease. By comparing these durations across treatment groups, survival analysis is used to measure the impact of treatment in delaying the onset of a more costly stage of the disease.
Patients with varying severity of AD.
The model uses clinical trial data on 1333 patients recruited internationally in 2 studies from 67 centres.
The aim of these clinical studies was to evaluate the safety and efficacy of 2 non-overlapping dose ranges of rivastigmine relative to placebo over a 26-week treatment period in patients with probable AD.
The results indicate that the average cost savings with high-dose rivastigmine at the end of the trial period are quite low (approximately 29 Pounds per patient; 1997 values), but by extrapolating to a projected lifetime of 3 years, they rise to approximately 1100 Pounds per patient. The largest long term cost savings from treatment are obtained from treating those in the mild category (i.e. MMSE > 20). However, if the time horizon over which savings are estimated is short (i.e. if life expectancy is below 2 years), more costs are saved by prioritising patients with moderate AD (i.e. MMSE between 20 and 11).
The model is a possible approach for estimating cost savings with treatment of AD, given the lack of long term data on resource use and drug efficacy. Caution should be used when extrapolating the results beyond the original study parameters.
本文提出一种建模方法的建议，用于估算阿尔茨海默病（AD）治疗的长期成本节约情况。
在所提出的建模方法中，疾病进展根据简易精神状态检查表（MMSE）量表中的区间来定义。然后利用临床试验数据确定特定患者进入疾病更严重阶段的时间。通过比较各治疗组的这些持续时间，采用生存分析来衡量治疗对延缓疾病更昂贵阶段发作的影响。
不同严重程度的AD患者。
该模型使用了来自67个中心的2项国际研究中招募的1333名患者的临床试验数据。
这些临床研究的目的是在26周的治疗期内，评估两种不重叠剂量范围的卡巴拉汀相对于安慰剂在可能患有AD的患者中的安全性和有效性。
结果表明，在试验期结束时，高剂量卡巴拉汀的平均成本节约相当低（约每位患者29英镑；1997年价值），但外推至预计3年的生存期时，成本节约升至约每位患者1100英镑。治疗带来的最大长期成本节约来自治疗轻度患者（即MMSE>20）。然而，如果估算成本节约的时间范围较短（即预期寿命低于2年），优先治疗中度AD患者（即MMSE在20至11之间）可节省更多成本。
鉴于缺乏关于资源使用和药物疗效的长期数据，该模型是估算AD治疗成本节约情况的一种可行方法。将结果外推至超出原始研究参数范围时应谨慎。
