Spalding James R, Hay Joel
Astellas Pharma US, Deerfield, Illinois, USA.
Pharmacoeconomics. 2006;24(12):1221-32. doi: 10.2165/00019053-200624120-00006.
Rheumatoid arthritis (RA) is an autoimmune disease with an unknown aetiology that results in >9 million physician visits and >250 000 hospitalisations per year in the US. Tumour necrosis factor-alpha (TNFalpha) inhibitors are effective agents in treating RA; however, their cost effectiveness as first-line agents has not been investigated. This study aimed to examine the cost effectiveness of using TNFalpha inhibitors (both as monotherapy and in combination with methotrexate) as first-line agents versus methotrexate (monotherapy) from a payer perspective.
A Markov model was developed utilising a discount rate of 3% per annum, a cycle length of 1 year and a lifetime time-horizon for a hypothetical cohort of US females aged 55-60 years who had been diagnosed with RA. The source of data for predicted probabilities, expected mortality rates and treatment costs in year 2005 US dollars (drug, toxicity, monitoring and hospitalisation) was from the literature. These costs are assigned in 5-year cycles (calculated from initial 1-year estimates) along with the effect on quality-adjusted life-years (QALYs), which were calculated using the Health Assessment Questionnaire score. Univariate sensitivity analyses were conducted on all relevant parameters.
Adalimumab, etanercept, adalimumab plus methotrexate and infliximab plus methotrexate had incremental cost-effectiveness ratios (ICERs) versus methotrexate monotherapy of $US63 769, $US89 772, $US194 589 and $US409 523 per QALY, respectively. When taking into consideration age at diagnosis, the ICER for etanercept ranged from $US84 129 to $US96 225 per QALY. In considering males for the base-case age at diagnosis, the ICER for etanercept versus methotrexate was $US85 100 per QALY. The average lifetime cost across all treatment arms in a woman diagnosed between 55 and 60 years of age was $US211 702.
While these ICERs cannot be used to directly compare one biological agent with another since there are no comparative trials, they do provide a valid comparison versus methotrexate as first-line agents. Depending where the cost-effectiveness threshold is drawn (i.e. whether it is considered to be $US50 000 or $US100 000 per QALY), etanercept and adalimumab may be considered relatively cost-effective first-line treatments for RA compared with methotrexate monotherapy.
类风湿性关节炎（RA）是一种病因不明的自身免疫性疾病，在美国每年导致超过900万人次就诊以及超过25万次住院治疗。肿瘤坏死因子-α（TNFα）抑制剂是治疗RA的有效药物；然而，其作为一线药物的成本效益尚未得到研究。本研究旨在从支付方的角度，探讨将TNFα抑制剂（单药治疗以及与甲氨蝶呤联合使用）作为一线药物与甲氨蝶呤（单药治疗）相比的成本效益。
针对一组假设的年龄在55 - 60岁、已被诊断为RA的美国女性队列，构建了一个马尔可夫模型，采用每年3%的贴现率、1年的周期长度以及终身时间范围。预测概率、预期死亡率和以2005年美元计的治疗成本（药物、毒性、监测和住院费用）的数据来源为文献。这些成本按5年周期分配（根据最初1年的估计计算），同时考虑对质量调整生命年（QALYs）的影响，QALYs使用健康评估问卷得分进行计算。对所有相关参数进行了单因素敏感性分析。
与甲氨蝶呤单药治疗相比，阿达木单抗、依那西普、阿达木单抗联合甲氨蝶呤以及英夫利昔单抗联合甲氨蝶呤的增量成本效益比（ICERs）分别为每QALY 63769美元、89772美元、194589美元和409523美元。考虑诊断时的年龄，依那西普的ICER为每QALY 84129美元至96225美元。在将男性作为诊断时的基础病例年龄进行考虑时，依那西普与甲氨蝶呤相比的ICER为每QALY 85100美元。在55至60岁之间被诊断的女性中，所有治疗组的平均终身成本为211702美元。
虽然由于没有比较试验，这些ICERs不能用于直接比较一种生物制剂与另一种生物制剂，但它们确实提供了与作为一线药物的甲氨蝶呤的有效比较。根据成本效益阈值的设定位置（即是否认为是每QALY 50000美元或100000美元），与甲氨蝶呤单药治疗相比，依那西普和阿达木单抗可能被认为是RA相对具有成本效益的一线治疗药物。
