[Study on medical economic evaluation methods for metastatic brain tumors therapy]

Treatment design for metastatic brain tumors is required to firstly care about the life and function for which the patient hopes because it is terminal care. Therefore, to discuss the value of the therapy, a viewpoint of the QOL and the socioeconomic factors other than the survival rate is important. However, examination that applies these factors to the therapy needs to be carried out more thoroughly. With this in mind, we discuss cost effectiveness of therapy for metastatic brain tumor, through a pilot study on gamma knife therapy.

We studied 18 patients (mean age 61.6 years old) undergoing therapy for metastatic brain tumors. The health rate QOL was assessed by the profile-type measure SF-36 (Short-Form 36-Item Ver1.2) and the preference-based measure EQ-5D (EuroQoL-5D), before and six months after gamma knife therapy. Cost-utility-analysis (yen/Qaly) was carried out from quality adjusted life years (Qalys) and medical fee claims. In addition, we made a correlation analysis of the irradiation procedure and the gains attained.

The observation by SF-36 for six months was useful for metastatic brain tumor. As a result, the QOL indicators showed increased mental health (MH: p=0.040) and role emotional (RE: p=0.029) with significant difference. In the measurement of EQ-5D, it was added only for one month based on the significant difference (p=0.022) from the pre-therapy QOL. The utilities that were analyzed became 0.052+/-0.175SD (score), and Qalys were 0.135. Because the cost was 721.4+/-5.2SD (thousand yen), the performance of cost-utility-analysis was estimated as 5, 330, 000 (yen/Qaly). In addition, positive correlation (r=0.845/p=0.034) was found between the EQ-5D utility score and the tumor irradiation energy (mJ), etc.

We established a new value over and above mere survival rate concerning metastatic brain tumor therapy. The socioeconomics and efficacy of therapy are more difficult to discuss in this disease than in other diseases. We did this by clarifying the measurement and analysis of QOL as compared with the cost factor. We found that quantitatively, the mental health rate involved in the QOL, had improved. We established that it is appropriate to cover this disease by public insurance, because cost-utility-analysis showed that it was under the threshold line. Our study also suggested that, when guessing the QOL of the prognosis, there should be grades of sensitivity according to the irradiation element involved in the therapy.