Kim Sun-Young, Goldie Sue J
Program in Health Decision Science, Department of Health Policy and Management, Harvard School of Public Health, Boston, MA 02115, USA.
Pharmacoeconomics. 2008;26(3):191-215. doi: 10.2165/00019053-200826030-00004.
Cost effectiveness is becoming an increasingly important factor for stakeholders faced with decisions about adding a new vaccine into national immunization programmes versus alternative use of resources. Evaluating cost effectiveness, taking into account the relevant biological, clinical, epidemiological and economic factors of a vaccination programme, generally requires use of a model. This review examines the modelling approaches used in cost-effectiveness analyses (CEAs) of vaccination programmes.After overviewing the key attributes of models used in CEAs, a framework for categorising theoretical models is presented. Categories are based on three main attributes: static/dynamic; stochastic/deterministic; and aggregate/individual based. This framework was applied to a systematic review of CEAs of all currently available vaccines for the period of 1976 to May 2007. The systematic review identified 276 CEAs of vaccination programmes. The great majority (83%) of CEAs were conducted in the setting of high-income countries. Only a few vaccines were widely studied, with 57% of available CEAs being focused on the varicella, influenza, hepatitis A, hepatitis B or pneumococcal vaccine. Several time trends were evident, indicating that the number of vaccine CEAs being published is increasing; the main health outcome measures are moving away from the number of cases prevented towards quality-adjusted and unadjusted life-years gained, and more complex models are beginning to be used. The modelling approach was often not adequately described. Of the 208 CEAs that could be categorized according to the framework, around 90% were deterministic, aggregate-level static models. Although a dynamic transmission model is required to account for herd-immunity effects, only 23 of the CEAs were dynamic. None of the CEAs were individual based. To improve communication about the cost effectiveness of vaccination programmes, we believe the first step is for analysts to be more transparent with each other. A clear description of the model type using consistent terminology and justification for the model choice must begin to accompany all CEAs. As a minimum, we urge modellers to provide an explicit statement about the following attributes: static/dynamic; stochastic/deterministic; aggregate/individual based; open/closed. Where relevant, time intervals (discrete/continuous) and (non)linearity should also be described. Enhanced methods of assessing model performance and validity are also required. Our results emphasize the need to improve modelling methods for CEAs of vaccination programmes; specifically, model choice, construction, assessment and validation.
对于面临将新疫苗纳入国家免疫规划还是选择其他资源使用方式决策的利益相关者而言，成本效益正成为一个日益重要的因素。评估成本效益时，考虑到疫苗接种计划的相关生物学、临床、流行病学和经济因素，通常需要使用模型。本综述考察了疫苗接种计划成本效益分析（CEA）中所使用的建模方法。在概述了CEA中使用的模型的关键属性之后，提出了一个对理论模型进行分类的框架。分类基于三个主要属性：静态/动态；随机/确定性；以及基于总体/个体。该框架被应用于对1976年至2007年5月期间所有现有疫苗的CEA进行的系统综述。该系统综述识别出276项疫苗接种计划的CEA。绝大多数（83%）的CEA是在高收入国家的背景下开展的。只有少数几种疫苗得到广泛研究，现有CEA中有57%聚焦于水痘、流感、甲型肝炎、乙型肝炎或肺炎球菌疫苗。有几个时间趋势很明显，表明发表的疫苗CEA数量在增加；主要的健康结果衡量指标正从预防的病例数转向获得的质量调整生命年和未调整生命年，并且开始使用更复杂的模型。建模方法往往没有得到充分描述。在可根据该框架进行分类的208项CEA中，约90%是确定性的、总体水平的静态模型。尽管需要一个动态传播模型来解释群体免疫效应，但只有23项CEA是动态的。没有一项CEA是基于个体的。为了改善关于疫苗接种计划成本效益的沟通，我们认为第一步是分析人员之间要更加透明。所有CEA都必须开始使用一致的术语对模型类型进行清晰描述，并对模型选择给出理由。至少，我们敦促建模人员就以下属性提供明确说明：静态/动态；随机/确定性；基于总体/个体；开放/封闭。在相关情况下，还应描述时间间隔（离散/连续）和（非）线性。还需要改进评估模型性能和有效性的方法。我们的结果强调需要改进疫苗接种计划CEA的建模方法；具体而言，包括模型选择、构建、评估和验证。
