Macintyre C R, Plant A J, Hendrie D
Department of Public Health and Community Medicine, Westmead Hospital, Westmead, Australia.
Health Econ. 2000 Jul;9(5):411-21. doi: 10.1002/1099-1050(200007)9:5<411::aid-hec524>3.0.co;2-9.
The potential cost-effectiveness of screening depends on the risk of tuberculosis (TB) in the population being screened and the rate at which the screening outcome (prevention) is achieved.
To compare the cost-effectiveness of contact screening for TB for: (1) contact screening as it actually occurred in Victoria in 1991 (Model 1); (2) the process which should have occurred had the 1991 contact screening guidelines been followed (Model 2); (3) a hypothetical evidence-based model (Model 3).
Three models were constructed according to the aims. The cost-effectiveness of contact screening is presented as costs to government per unit outcome (in the form of cases prevented, cases found and contacts traced) for each model. Assumptions about disease behaviour were consistent between models. A sensitivity analysis was performed to examine the effect of the assumptions made in Model 3 about rates of referral and treatment of infected contacts, and about the efficacy of isoniazid (INH) in preventing TB.
The total cost of Model 1 was greater than that of the other Models. Model 1 is the least cost-effective, costing $309 065 per case prevented, and Model 3 is the most cost-effective, costing $32 210 per case prevented. The cost of Model 2 was $58 742 per case prevented. The incremental cost-effectiveness of Model 3 compared to Model 2 is $107 per additional contact screened, and $3881 per additional case prevented. Case finding is not as cost-effective as best-practice case prevention, ranging from $231 799 per case found in Model 1 to $205 596 per case found in Model 2. The sensitivity analysis shows that the cost-effectiveness of Model 3 decreases with lower referral rates, lower rates of preventive therapy, and lower efficacy of INH. However, even allowing for reduced programme parameters, Model 3 is most cost-effective.
Costing policy options is an important component of programme delivery, but needs to be considered in the context of the product being purchased, e.g. the prevention of disease, or case finding. Case finding as a product of contact screening is expensive in all three models. Prevention of TB, on the other hand, can be cost-effective, as shown in Model 3. It was least cost-effective in Model 1, largely because prevention was not considered a priority, and few infected contacts actually received preventive therapy. Clear programme aims, adherence to guidelines and high rates of preventive therapy are essential in order to achieve cost-effectiveness.
筛查的潜在成本效益取决于被筛查人群的结核病（TB）风险以及实现筛查结果（预防）的比率。
比较结核病人际接触筛查的成本效益，具体如下：（1）1991年在维多利亚实际开展的接触筛查（模型1）；（2）若遵循1991年接触筛查指南应有的流程（模型2）；（3）一个基于假设证据的模型（模型3）。
根据研究目的构建三个模型。每个模型将接触筛查的成本效益表示为政府每单位结果（以防病病例、发现病例和追踪接触者的形式）的成本。各模型关于疾病行为的假设保持一致。进行敏感性分析，以检验模型3中关于受感染接触者的转诊率和治疗率以及异烟肼（INH）预防结核病疗效的假设的影响。
模型1的总成本高于其他模型。模型1的成本效益最低，每预防一例病例成本为309,065美元，模型3的成本效益最高，每预防一例病例成本为32,210美元。模型2每预防一例病例的成本为58,742美元。与模型2相比，模型3每多筛查一名接触者的增量成本效益为107美元，每多预防一例病例的增量成本效益为3,881美元。发现病例的成本效益不如最佳实践的病例预防，在模型1中每发现一例病例成本为231,799美元，在模型2中每发现一例病例成本为205,596美元。敏感性分析表明，随着转诊率降低、预防性治疗率降低以及INH疗效降低，模型3的成本效益会下降。然而，即使考虑到项目参数降低，模型3仍是成本效益最高的。
对政策选项进行成本核算，是项目实施的一个重要组成部分，但需要结合所购买的产品来考虑，例如疾病预防或病例发现。在所有三个模型中，作为接触筛查结果的病例发现成本都很高。另一方面，正如模型3所示，预防结核病可能具有成本效益。在模型1中成本效益最低，主要是因为预防未被视为优先事项，而且很少有受感染接触者实际接受预防性治疗。为实现成本效益，明确的项目目标、遵循指南以及高预防性治疗率至关重要。
