Cost effectiveness analysis of screening program for colorectal cancer based on the parameters measured in the actual population.

通过随机对照试验，已经确定了使用基于愈创木脂的粪便潜血试验（FOBT）筛查结直肠癌（CRC）的有效性，但其程度还不够。日本采用免疫化学FOBT的筛查项目被认为在降低死亡率方面更有效。本研究旨在根据人群筛查结果获得的参数来衡量成本效益，通过对研究地区1986- 1994年1,145例CRC病例的生存状况、死亡原因和筛查史的分析，死亡病例定义为那些在诊断后未能存活超过5年的病例，在筛查发现的病例和确诊病例中分别为10.3%和26.8%。筛查组和未筛查组死亡病例的平均生存期分别为1.85年和1.54年。O+I期、II期、IIIa期、IIIb期和IV期的分期分布在确诊病例和筛查病例中分别为28.0%、19.7%、28.7%、12.8%和10.8%，在筛查病例中分别为63.6%、13.3%、18.1%、4.2%和0.8%。免疫组化FOBT的敏感性和特异性分别为82.5%和96.6%。该项目每年挽救生命的边际成本为807，287日元。根据年龄组计算，50至59岁、60至69岁和70至79岁的男性（女性）的费用分别约为670，000（870，000）、360，000（900，000）和440，000（650，000）日元。这些结果表明，目前的CRC筛查计划具有很高的成本效益，50岁或以上的个体比40岁或以上的个体是更好的目标人群。

Effectiveness of screening program for colorectal cancer (CRC) using guaiac-based fecal occult blood test (FOBT) has been established through randomized controlled trials, but its magnitude is not sufficient. Japanese screening program using immunochemical FOBT is considered to be more effective in terms of mortality reduction. The present study was intended to measure cost effectiveness based on parameters obtained from results of population screening program.From the analysis of survival status, cause of death, and screening history in 1,145 incident CRC cases during 1986-94 in the study area, fatal cases that were defined as those failed to survive more than 5 years after diagnosis were 10.3% and 26.8% for screen-detected cases and routinely-diagnose cases, respectively. Average duration of survival for fatal cases were 1.85 and 1.54 years in screened group and unscreened group, respectively. Stage distribution of stage O+I, II, IIIa, IIIb, IV were 28.0, 19.7, 28.7 12.8 and 10.8% and 63.6, 13.3, 18.1, 4.2 and 0.8% for routinely-diagnosed and screen-detected cases, respectively. Sensitivity and specificity of immunochemical FOBT were calculated to be 82.5% and 96.6%, respectively. Marginal cost of the program per year of life saved was 807, 287 yen. According to age groups, the costs were calculated to be approximately, 670,000 (870,000), 360,000 (900,000) and 440,000 (650,000) yen for males (females) of 50 to 59, 60 to 69 and 70 to 79 years old, respectively. These results indicate that the present screening program for CRC is highly cost-effective and individuals of 50 years or older is a better target population than those 40 years or older.