Cost-Effectiveness Analysis of FOLFIRI-Based First-Line Regimens for Metastatic Colorectal Cancer Using Clinical Decision Analysis.

OBJECTIVE: Metastatic colorectal cancer with KRAS wild type is treated using a range of drug regimens, including fluorouracil, irinotecan, and Leucovorin(FOLFIRI)plus bevacizumab(Bmab), cetuximab(Cmab), or panitumumab(Pmab). The present study aimed to identify the optimal regimen using a decision analysis method, in combination with clinical and economic evidence. METHOD: A simple Markov model with a monthly cycle time was constructed. Probabilistic variables for input into the model were derived from randomized controlled trials. Direct costs for the drugs, laboratory analyses, and medical staff were calculated and used in the model. RESULTS: The expected survival times and costs of FOLFIRI alone and combination therapies were 20.9 months and 2,299,198 yen for FOLFIRI, 29.9 months and 8,929,888 yen for Bmab, 27.8 months and 11,811,849 yen for Cmab, and 22.6 months and 8,795,622 yen for Pmab. The incremental cost-effectiveness ratios to FOLFIRI were 736,743 yen/month for Bmab, 1,378,645 yen/month for Cmab, and 3,821,426 yen/month for Pmab. CONCLUSIONS: These findings suggested that these regimens were not sufficiently cost-effective, although they have excellent therapeutic efficacy. From the economic point of view, these combination regimens were inferior to FOLFIRI alone.

Relationship between age and occlusal force in adults with natural dentition.

This study aimed to clarify the relationship between age and occlusal force in adults with natural dentition. A total of 385 adults (180 males and 205 females) with natural dentition participated in this study. Subjects were asked to perform maximum clenching for approximately 3 s, and the occlusal forces on both sides and habitual chewing side were calculated using a dental prescale. Regression analysis was performed by sex with occlusal forces on both sides and habitual chewing side as the dependent variable and age as the independent variable. In addition, all subjects were divided into three groups: young group (20-39 years), middle group (40-59 years), and old group (60 years and over), and the occlusal forces on both sides and habitual chewing side were compared among the three groups. The occlusal forces did not differ from 20 to 60 years old for both males and females, and the occlusal forces gradually decreased after 60 years old. The curve of the polynomial equation was the most suitable. The occlusal forces on both sides and the habitual chewing side were similar in the young and middle groups, and the values of the old group were significantly smaller than those of the other two groups. From these results, it was suggested that the occlusal force of adults with natural dentition does not differ from 20 to 60 years old and can be represented by a curve of a cubic polynomial, and it significantly decreases after 60 years old.

Masticatory path pattern and masticatory performance while chewing gummy jelly.

The purpose of this study was to clarify masticatory path pattern and masticatory performance during gummy jelly chewing. A total of 235 healthy adults were asked to chew gummy jelly for 20 s on each side, and the masticatory movement was recorded using a Motion Visi-Trainer (MVT V1). Next, the amount of glucose extraction was measured as a parameter of masticatory performance. The masticatory path was classified into one of five patterns newly devised: normal pattern (N, opening: straight or concave, closing: convex) and abnormal patterns (A1-A4). The number of occurrences of each pattern was investigated and compared by sex and path pattern. Next, masticatory performance was compared between the normal pattern and the abnormal patterns by sex. Pattern N was the most frequently expressed in 346 cases out of 470 cases (73.6%), followed by patterns A1, A4, A2, and A3 in that order. Regarding the number of patterns observed, pattern N was the most common in both sexes, followed by pattern A1, with no significant difference between sexes. The amount of glucose extraction in each pattern was the highest in pattern N for both sexes, followed by A2 and others in that order, and a significant difference was observed between the normal pattern and the abnormal patterns. From these results, the existence of sex difference in masticatory path patterns during gummy jelly chewing was not proven, and that masticatory performance was higher with normal patterns than with abnormal patterns.

Cost-Effectiveness Analysis of Cyclin-Dependent Kinase 4/6 Inhibitor Palbociclib for Inoperable or Recurrent Breast Cancer.

BACKGROUND: Palbociclib and endocrine therapy has been approved to treat hormone receptor-positive/human epidermal growth factor receptor 2-negative inoperable or recurrent breast cancer in Japan. However, this cotherapy imposes an economic burden on both patients and society because of its high cost. In this study, we assessed the cost-effectiveness of cotherapy with palbociclib and fulvestrant compared to fulvestrant monotherapy for inoperable or recurrent breast cancer. METHODS: The three-state Markov model was built by taking into count health stats in inoperable or recurrent breast cancer. The clinical outcomes of the therapies were drawn from published randomized controlled trials. Total regimen cost was calculated from medical receipts of patients at the Yamagata University Hospital. The cost-effectiveness was evaluated by the incremental cost-effectiveness ratio(ICER), in case that it was below 400,000 Yen per month. Markov chain Monte Carlo simulation was performed to assess probability. RESULTS: Acquisition cost of palbociclib and fulvestrant and fulvestrant monotherapy was 6,209,554 JPY and 780,870 JPY, and 25.7 and 22.8 months were achieved, respectively. ICER for the cotherapy was 1,847,721 JPY/quality adjusted life month(QALM)gained. CONCLUSIONS: The palbociclib and fulvestrant therapy provided better health outcomes than conventional fulvestrant monotherapy, but were costly and suggested to be less cost-effective.

Cost-effectiveness analysis of dupilumab among patients with oral corticosteroid-dependent uncontrolled severe asthma in Japan.

BACKGROUND: Asthma is a common, chronic inflammatory airway disorder, with up to 1,177,000 people receiving asthma treatment in Japan. Dupilumab is a first-in-class, monoclonal antibody for the treatment of atopic diseases, including persistent asthma. The objective of this study was to assess the cost-effectiveness of dupilumab, compared with other biologics, as add-on treatment to background therapy in patients aged ≥12 years with uncontrolled, persistent asthma in Japan. METHODS: A life-time Markov cohort model was used to conduct cost-effectiveness analysis from the Japanese healthcare payer perspective with an annual discount rate of 2%. Dupilumab was compared with benralizumab and mepolizumab, and against omalizumab (as a hypothetical scenario). Inputs were informed by dupilumab clinical trials (VENTURE [NCT02528214] and QUEST [NCT02414854] trials), the literature, official Japanese sources and expert opinions. RESULTS: The base case results suggest that treatment with dupilumab leads to fewer severe exacerbations and increased life-years (LYs) and quality-adjusted LYs (QALYs) than benralizumab and mepolizumab. At a willingness-to-pay (WTP) threshold of ¥5,000,000 per QALY gained, dupilumab was the dominant strategy (lower cost, increased QALYs) versus benralizumab, and cost-effective versus mepolizumab with an incremental cost-effectiveness ratio (ICER) of ¥1,010,921 (US$9,190, US$1 = ¥110). Versus omalizumab, dupilumab was not cost-effective (ICER of ¥10,802,368 [US$98,203]). CONCLUSIONS: In Japan, dupilumab, as an add-on to background therapy, is economically dominant compared with benralizumab, and cost-effective versus mepolizumab.

Factors contributing to the ceiling effect of the EQ-5D-5L: an analysis of patients with prostate cancer judged "no-problems".

PURPOSE: The goal of the present study was to determine factors related to a ceiling effect (CE) on the EQ-5D-5L among Japanese patients with prostate cancer (PC). METHODS: An existent cross-sectional observational study dataset was used. Patients were ≥ 20 years of age and diagnosed with PC. For CE determinants on the EQ-5D-5L, we excluded possible "full-health" patients flagged by the EQ-VAS (score = 100) and/or FACT-P (score = 156) instruments. We then divided them into binary variables: A CE group (EQ-5D-5L score = 1) and others (< 1). The associations between CE, sociodemographic and medical characteristics, and FACT-P subscale scores were examined using a multivariate LASSO selection followed by a binomial logistic regression analysis performed to calculate odds ratios (ORs) and 95% confidence intervals (CIs). RESULTS: A total of 362 patients were analyzed. The LASSO selection variables, including all obtained variables, were as follows: age, palliative treatment, FACT-P physical well-being, and PC subscale score. Statistically significant variables predicting CE were palliative treatment (OR 0.23; 95% CI 0.09-0.60), physical well-being (OR 1.54; 95% CI 1.34-1.76), and PC subscale (OR 1.08; 95% CI 1.03-1.14). CONCLUSIONS: This study revealed that palliative treatment and two FACT-P physical well-being and PC subscale scores were positively related to CE on the EQ-5D-5L. To our knowledge, this is the first study to examine predictors of CE on the EQ-5D-5L. The present results may be helpful for facilitating the consideration of "bolt-on" studies from the standpoint of PC patients.

Terahertz and mid-infrared spectroscopy of matrix-isolated clusters and matrix-sublimation ice of D2O.

We have established an apparatus for terahertz and mid-infrared spectroscopy in an ultrahigh vacuum and have measured absorption spectra of D2O clusters trapped in solid Ar. To assign terahertz absorption peaks due to the D2O dimer, trimer, and tetramer, the dependence of the spectrum on the annealing temperature and D2O dilution was analyzed. The assignment was also examined by ab initio calculations with the use of the "our own N-layered integrated molecular orbital and molecular mechanics" method, where the flexibility of surrounding Ar atoms was systematically incorporated. We identified all the intermolecular fundamentals of the dimer and those with significant intensities of the trimer and tetramer, whose structural symmetries were revealed to be broken down. After isolating the D2O clusters in solid Ar, we sublimated only Ar atoms to leave behind matrix-sublimation ice, which was found to be amorphous- or crystal-like depending on the formation conditions: the dilution and sublimation temperature. The crystallinity of matrix-sublimation ice was determined by decomposing its terahertz spectrum into the spectra of amorphous and crystalline ices. Since the crystallinity got higher by raising the dilution and sublimation temperature, the diffusion of the D2O monomer on the surface of sublimating solid Ar was found to be crucial to the crystallization of the sublimation ice.

Cost-utility analysis of aprepitant for patients who truly need it in Japan.

PURPOSE: Neurokinin-1 receptor antagonist (NK1RA) is recommended to prevent chemotherapy-induced nausea and vomiting (CINV) in patients who receive highly or moderately emetogenic chemotherapy (HEC or MEC, respectively). We previously reported that aprepitant, an NK1RA, was needed to control CINV in 43% and 12% of patients who received HEC and MEC, respectively (Support Care Cancer 23:905-912, 2015). To elucidate the cost-effectiveness of aprepitant in these patients, a cost-utility analysis according to the necessity of aprepitant was performed. METHODS: A decision-analytic model was developed according to the necessity of aprepitant and CINV responses in both acute and delayed phases of chemotherapy. Probabilities of health states and medical costs were derived from the results of the abovementioned trial. RESULT: In patients who received HEC and needed aprepitant, the incremental cost-effectiveness ratio (ICER) with aprepitant, relative to the regimen with no aprepitant, was 7912 US dollars (USD) per quality-adjusted life year (QALY) gained, which was far below the commonly accepted threshold of 50,000 USD/QALY. The ICER was 27,457 USD/QALY in patients who received MEC and needed aprepitant. In contrast, in patients who received HEC or MEC but did not need aprepitant, the ICER was 175,959 or 478,844 USD/QALY, respectively. CONCLUSION: Regardless of whether a patient received HEC or MEC, aprepitant use was highly cost-effective for patients who truly needed it. These results warrant further research to predict the necessity of NK1RA treatment before initiating emetogenic chemotherapies.

Spectroscopic determination of interconversion rates among three nuclear spin isomers of methane in crystalline II.

We measured infrared absorption spectra of crystalline II of CH4 and succeeded in detecting a prominent Q(2) peak in the ν3 vibrational region by rapid cooling after annealing as well as previously reported rovibrational and librational-vibrational peaks. The integral intensities of the R(0), R(1), and Q(2) peaks were found to show biexponential dependence on time. This clearly demonstrates the interconversion among the three nuclear-spin isomers occupying low-lying rotational levels. The two relaxation rates obtained by biexponential fitting were (0.48, 2.3), (1.1, 4.1), (2.3, 5.1), and (3.4, 15.3) in units of inverse hour (h-1) at 5.2, 6.0, 6.5, and 7.0 K, respectively.

Cost-effectiveness of aprepitant in Japanese patients treated with cisplatin-containing highly emetogenic chemotherapy.

Chemotherapy-induced nausea and vomiting (CINV) remains a major adverse event in cancer chemotherapy. Although aprepitant is effective in preventing CINV, an increment in financial burden for uniform use of aprepitant is a concern. The aim of the present study was to define the cost-effectiveness of aprepitant from the perspective of the Japanese National Health Insurance system. Based on the results of a randomized phase II trial comparing an aprepitant-containing regimen versus a nonaprepitant regimen in Japanese patients who received cisplatin-containing highly emetogenic chemotherapy, a decision analytic model was developed. The incremental cost-effectiveness ratio (ICER) was calculated both in the outpatient care setting (OCS) and in the inpatient care setting (ICS). The use of the aprepitant-containing regimen was associated with improved quality of life compared with the nonaprepitant regimen, with an increment in quality-adjusted life years (QALY) of 0.0016. The incremental total medical costs associated with the use of the aprepitant regimen were lower in the OCS than in the ICS, 6192 JPY (56.92 USD) and 9820 JPY (90.27 USD), respectively. The ICER was calculated as 3 906 698 JPY (35 910 USD) per QALY gained in the OCS and 6 195 781 JPY (56 952 USD) per QALY gained in the ICS. Cost-effectiveness of the aprepitant-containing antiemetic therapy was limited to the OCS, considering the threshold of willingness-to-pay commonly accepted (5 million JPY [45 960 USD] in Japan and 50 000 USD in the USA). The efficacy of aprepitant offsets the costs for revisiting clinics or rehospitalization added with rescue medications in the OCS.

Cost-effectiveness of the recommended medical intervention for the treatment of dysmenorrhea and endometriosis in Japan.

BACKGROUND AND OBJECTIVE: This study aims to assess the cost-effectiveness of early physician consultation and guideline-based intervention to prevent endometriosis and/or disease progression using oral contraceptive (OC) and progestin compared to follow-up of self-care for dysmenorrhea in Japan. METHODS: A yearly-transmitted Markov model of five major health states with four sub-medical states was constructed. Transition probabilities among health and medical states were derived from Japanese epidemiological patient surveys and converted to appropriate parameters for inputting into the model. The dysmenorrhea and endometriosis-associated direct costs included inpatient, outpatient visit, surgery, and medication (OC agents, over-the-counter drugs), etc. The utility measure for patients with phase I-IV endometriosis comprised a visual analogue scale. We estimated the cost per quality-adjusted life year (QALY) at a time horizon of 23 years. An annual discount rate at 3% for both cost and outcome was considered. RESULTS: The base case outcomes indicated that the intervention would be more cost-effective than self-care, as the incremental cost-effectiveness ratio (ICER) yielded 115,000 JPY per QALY gained from the healthcare payers' perspective and the societal monetary value (SMV) was approximately positive 3,130,000 JPY, favoring the intervention in the cost-benefit estimate. A tornado diagram depicting the stochastic sensitivity analysis of the ICER and SMV from both the healthcare payers' and societal perspectives confirmed the robustness of the base case. A probabilistic analysis resulting from 10,000-time Monte Carlo simulations demonstrated efficiency at willingness-to-pay thresholds in more than 90% of the iterations. CONCLUSIONS: The present analysis demonstrated that early physician consultation and guideline-based intervention would be more cost-effective than self-care in preventing endometriosis and/or disease progression for patients with dysmenorrhea in Japan.

Development of endometrioma after cervical conization.

The association between cervical conization and subsequent development of endometriosis is uncertain. The objective of this study was to estimate the incidence rate of ovarian endometrioma after cervical conization and to determine factors associated with the development of endometrioma. One hundred forty-two patients who underwent cervical conization at the University of Tokyo Hospital between January 2006 and December 2013 were included in the study. Their medical records were retrospectively studied until April 2015. The incidence rate of postconization endometrioma was calculated. Patients' characteristics (age, parity, preoperative and postoperative diagnosis and observation period) were analyzed. Six patients developed endometrioma after the cervical conization, and the incidence rate of endometrioma among patients who underwent cervical conization was 10.8 per 1000 person-year (95%CI 3.6-20.5). Patients' age, percent of nulliparous, postoperative diagnosis and observation period were not associated with the development of postconization endometrioma. A preoperative diagnosis with invasive cancer (p < 0.05) was significantly associated with the development of postconization endometrioma. The incidence rate of endometrioma among patients who underwent cervical conization in the current study was higher than that reported population.

Cervical Cancer Screening With Human Papillomavirus DNA and Cytology in Japan.

OBJECTIVE: The aim of this study was to determine the value of human papillomavirus (HPV) testing for primary cervical cancer screening in Japan. METHODS: In total, 5065 women who underwent primary screening with cytology and HPV between January 2005 and December 2006 were enrolled. In the baseline phase, these women were stratified by age, and the rates of HPV-positive and abnormal cytology were compared between women younger than and older than 30 years. In the follow-up phase, women aged 20 to 69 years and cytology negative for intraepithelial lesions or malignancy at baseline were followed up until December 2011 (n = 2383). Progression to grade 2/3 cervical intraepithelial neoplasia or worse (CIN2+/CIN3+) was compared between the HPV-positive and HPV-negative groups. RESULTS: In the baseline phase, HPV-positive rates were significantly higher in women younger than 30 years at 20.7% (95% confidence interval [CI], 18.4-22.9; 255/1234) compared with women 30 years or older at 7.2% (95% CI, 6.4%-8.0%; 275/3831; P < 0.001). However, there was no statistical difference for high-grade squamous intraepithelial lesion or worse rates between them, at 2.7% (95% CI, 1.8%-3.6%; 33/1234) and 2.4% (95% CI, 1.9%-2.9%; 91/3831), respectively, P = 0.55. In the follow-up phase, the rate of progression to CIN2+/CIN3+ was significantly higher in the HPV-positive group than in the HPV-negative group (P < 0.001). Moreover, relative risk of progression to CIN2+ was 15.9 times higher in the HPV-positive group, and that of progression to CIN3+ was 16.1 times higher in the HPV-positive group. CONCLUSIONS: Human papillomavirus testing is a useful test for predicting progression to CIN and is recommended as a primary screening tool. However, screening with cytology alone is still appropriate for younger women, younger than 30 years, because HPV testing yields more false-positive results in younger women.

[Comparison of the Cost-Effectiveness of the SOX and COX Regimens in Patients with Unresectable Advanced and Recurrent Colorectal Cancer Using a Clinical Decision Analysis Approach].

Phase III clinical trials have comfirmed that the S-1 plus oxaliplatin(SOX)is inferior to the capecitabine plus oxaliplatin (COX)regimen in the treatment of metastatic colorectal cancer.On the basis of these findings, we compared, using a clinical decision analysis-based approach, the cost-effectiveness of the SOX and COX regimens.Herein, we simulated the expected effects and costs of the SOX and COX regimens using the markov model.Clinical data were obtained from Hong's 2012 report.The cost data comprised the costs for pharmacist labor, material, inspection, and treatment for adverse event, as well as the total cost of care at the advanced stage.The result showed that the expected cost of the SOX and COX regimen was 1,538,330 yen, and 1,429,596 yen, respectively, with an expected survival rate of 29.18 months, and 28.63 months, respectively.The incremental cost-effectiveness ratio of the SOX regimen was 197,698 yen/month; thus, the SOX regimen was found to be more cost-effective that the COX regimen.

Infrared spectroscopic investigation of nuclear spin conversion in solid CH4.

Infrared spectra of solid CH4 were studied in the ν3 and ν4 vibrational regions. The phase I crystal around 30 K showed broad absorption bands, whereas the phase II crystal at 6.9-10.3 K exhibited splitting of these bands after annealing above 20 K. The split peaks were assigned to the librating and almost freely rotating molecules in phase II on the basis of the peak spacings and time evolution of the peak intensities. From the quantitative analysis of the temporal changes of the R(0) and R(1) peak intensities, the relaxation rates of the numbers of molecules with J = 0 (I = 2) and J = 1 (I = 1) were determined in the temperature range of 6.9-10.3 K. We fitted the function resulting from a combination of direct and indirect relaxation processes mediated by phonons to the temperature dependence of these rates and obtained the activation energies of the indirect process: C ≃ 36 K. Since this value is higher than the energies of perturbed J = 2 states relative to the J = 1 state, we argue that the nuclear spin conversion through the J = 3 state also takes place.

[Pharmacoeconomic evaluation of combination therapy with dutasteride and α1 blocker for treatment of benign prostatic hyperplasia in Japan].

The cost-effectiveness of combination therapy with an α1 blocker and dutasteride in benign prostatic hyperplasia (BPH) was analyzed in comparison with α1 blocker monotherapy. A Markov model with seven health states related to BPH was constructed with 4-year and 10-year time horizons and from the entire payers perspective. The transition probabilities among different health states input into the model were mainly derived from CombAT Study data, while cost parameters were estimated from a clinical database including DPC claims. Effectiveness was defined as quality adjusted life year (QALY). The cost-effectiveness of combination therapy was assessed by the incremental cost-effectiveness ratio (ICER) threshold (6 to 7 million Japanese yen (JPY)/QALY gained). For a base-case analysis, combination therapy produced an incremental effectiveness versus monotherapy of 0.050 and 0.097 QALYs at 4 years and 10 years, respectively, while the concomitant incremental costs were estimated to be 257,172 and 579,908 JPY, respectively. The ICERs for combination therapy versus monotherapy calculated at 4 years and 10 years were 5,119,007 and 5,974,495 JPY/QALY gained, respectively, both below the acceptable ICER threshold. Sensitivity analyses revealed that the ICER tended to decrease with greater BPH severity. These findings suggest that combination therapy with an α1 blocker and dutasteride would be more cost-effective in BPH than α1 blocker monotherapy and more efficient in moderate-to-severe BPH.

[Cephalic hypersensitivity syndrome].

The number of patients suffering from chronic headache accompanied by dizziness and cephalic ringing is gradually increasing. Pathophysiology of migraine has been commonly explained by trigeminovascular theory, although recent studies have suggested that the cause of the migraine stems from cortical hyperexcitability. We measured EEG in 1,000 patients suffering from daily headache accompanied by dizziness and cephalic ringing. Here we defined a new syndrome,"cephalic hypersensitivity syndrome" as a subliminal cortical hyperexcitability which itself is invisible but apparently seen as some symptoms such as dizziness and cephalic ringing. The cephalic hypersensitivity syndrome should be treated to attenuate the excitability by an appropriate triptan medication during attacks so as to exhibit its recurrence.

[Cost-effectiveness of salmeterol/fluticasone combination therapy vs. fluticasone propionate in Japanese asthmatic patients].

We commenced to estimate the economic impact of salmeterol/fluticasone combination (SFC) therapy compared to fluticasone propionate (FP) therapy for asthma control in Japanese patients. A Markov model with five health states, developed by Price in 2002, was used. 1-week transition probabilities among status of asthma management were obtained from literature and epidemiological data from public data base. Direct cost for treatment was estimated from Japan medical fee schedule. Cost and effectiveness were not discounted due to 12-week simulation by the model. Univariate sensitivity analyses were undertaken to examine the main variables affecting cost-effectiveness. Probabilistic analysis was also undertaken to discuss statistical argument and to provide information for decision-making. In this analysis, the model was run over a 12-week period of time using transition probabilities. The results showed that treatment with SFC resulted in a higher proportion of totally controlled weeks per patient than treatment with FP (65.0 vs. 49.5%; incremental effectiveness by 15.5%), and lower mean direct asthma management costs ( yen168 702 vs. yen227 820). Probabilistic sensitivity analysis, conducted to assess robustness of the above base case result, showed that in the 95% of cases SFC was dominant (more effective and less costly) to FP. It suggested that SFC will be the most cost-effective therapy for asthma control. It would, however, be required to further evaluate cost-effectiveness of SFC in long-term observation.

Adjuvant endocrine therapy in post menopausal women: pharmacological evaluation using decision analysis approach in a Japanese hospital setting.

An optimal adjuvant endocrine therapy is yet to be established for post menopausal women with hormone receptor positive breast cancer. The current therapeutic options include initial, switch, and extended adjuvant therapies. We aimed to determine the most cost-effective therapeutic option using the clinical decision analysis method. It was suggested that aromatase inhibitor monotherapy in initial adjuvant therapy is the most cost-effective and optimal adjuvant endocrine therapy for post menopausal women with hormone receptor-positive breast cancer.

A Cost-Effectiveness Analysis of Gemcitabine plus Cisplatin Versus Gemcitabine Alone for Treatment of Advanced Biliary Tract Cancer in Japan.

OBJECTIVES: This study assessed the cost-effectiveness of combination treatment with gemcitabine and cisplatin compared to treatment with gemcitabine alone for advanced biliary tract cancer (BTC) in Japan. METHODS: A monthly transmitted Markov model of three states was constructed based on the Japan BT-22 trial. Transition probabilities among the health states were derived from a trial conducted in Japan and converted to appropriate parameters for our model. The associated cost components, obtained from a receipt-based survey undertaken at the Aichi Medical University Hospital, were those related to inpatient care, outpatient care, and treatment for BTC. Costs for palliative care and treatment of adverse events were obtained from the National Health Insurance price list. We estimated cost-effectiveness per quality-adjusted life year (QALY) at a time horizon of 36 months. An annual discount of 3 % for both cost and outcome was considered. RESULTS: The base case outcomes indicated that combination therapy was less cost-effective than monotherapy when the incremental cost-effectiveness ratio (ICER) was approximately 14 million yen per QALY gained. The deterministic sensitivity analysis of the ICER revealed that the ICER of the base case was robust. A probabilistic analysis conducted with 10,000-time Monte Carlo simulations demonstrated efficacy at the willingness to pay threshold of 6 million yen per QALY gained for approximately 33 % of the population. CONCLUSION: In Japan, combination therapy is less cost-effective than monotherapy for treating advanced BTC, regardless of the statistical significance of the two therapies. Useful information on the cost-effectiveness of chemotherapy is much needed for the treatment of advanced BTC in Japan.