Ataru Igarashi

Dr. Ataru Igarashi


Research Focus & Metrics

Academic Career Length

23Years (2004-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 January 2013 in Cost Effectiveness and Resource Allocation
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Journal Article
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TSTakeru Shiroiwa
Takeru Shiroiwa
AIAtaru Igarashi
Ataru Igarashi
TFTakashi Fukuda
Takashi Fukuda
SIShunya Ikeda
Shunya Ikeda
In economic evaluation, cost per quality-adjusted life year (QALY) is generally used as an indicator for cost-effectiveness. Although JPY 5 million to 6 million (USD 60, 000 to 75,000) per QALY is frequently referred to as a threshold in Japan, do all QALYs have the same monetary value?

20 June 2022 in Hypertension Research
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Journal Article
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ANAkihiro Nomura
Akihiro Nomura
TTTomoyuki Tanigawa
Tomoyuki Tanigawa
KKKazuomi Kario
Kazuomi Kario
AIAtaru Igarashi
Ataru Igarashi
Hypertension increases the risk of cardiovascular and other diseases. Lifestyle modification is a significant component of nonpharmacological treatments for hypertension. We previously reported the clinical efficacy of digital therapeutics (DTx) in the HERB-DH1 trial. However, there is still a lack of cost-effectiveness assessments evaluating the impact of prescription DTx. This study aimed to analyze the cost-effectiveness of using prescription DTx in treating hypertension. We developed a monthly cycle Markov model and conducted Monte Carlo simulations using the HERB-DH1 trial data to investigate quality-adjusted life-years (QALYs) and the cost of DTx for hypertension plus guideline-based lifestyle modification consultation treatment as usual (TAU), comparing DTx + TAU and TAU-only groups with a lifetime horizon. The model inputs were obtained from the HERB-DH1 trial, published or publicly available data, and expert assumptions. The incremental cost-effectiveness ratio (ICER) per QALY was used as the benchmark for cost-effectiveness. We performed probabilistic sensitivity analyses (PSAs) using the Monte Carlo simulation with two million sets. The DTx + TAU strategy produced 18.778 QALYs and was associated with ¥3,924,075 ($34,122) expected costs, compared with 18.686 QALYs and ¥3,813,358 ($33,160) generated by the TAU-only strategy over a lifetime horizon, resulting in an ICER of ¥1,199,880 ($10,434)/QALY gained for DTx + TAU. The monthly cost and attrition rate of DTx for hypertension have a significant impact on ICERs. In the PSA, the probability of the DTx arm being a cost-effective option was 87.8% at a threshold value of ¥5 million ($43,478)/QALY gained. In conclusion, the DTx + TAU strategy was more cost-effective than the TAU-only strategy.

30 January 2021 in Applied Research in Quality of Life
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Journal Article
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TITakaaki Ikeda
Takaaki Ikeda
AIAtaru Igarashi
Ataru Igarashi
SOSatomi Odani
Satomi Odani
MMMasayasu Murakami
Masayasu Murakami
Takahiro TabuchiTakahiro Tabuchi
Takahiro Tabuchi

6 August 2019 in Journal of Medical Economics
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Journal Article
Closed access
AIAtaru Igarashi
Ataru Igarashi
RGRei Goto
Rei Goto
MYMariko Yoneyama-Hirozane
Mariko Yoneyama-Hirozane
Objectives: Theoretically, willingness-to-pay (WTP) for quality-adjusted life years (QALY) can vary depending on social and personal preferences and on ex-ante and ex-post settings. However, empirical investigations into the theoretical differences are lacking. In Japan, setting the threshold has been controversial since a pilot project to implement health technology assessments (HTA) launched in 2016. The study aim is to estimate WTP values for one additional QALY from different perspectives, health statuses, and contexts to confirm the difficulty in setting a uniform price threshold using WTP. Methods: More than 1,000 respondents representing a cross-section of the Japanese population answered each of 9 questionnaire decks in an online panel. WTP values were estimated on three different perspectives (personal, social, and socially inclusive) and on two contexts (ex-ante and ex-post). We primarily used the nonparametric spike model based on double-bounded dichotomous choice (DBDC) settings to obtain the conditional WTP values. Results: WTP per QALY was higher in the severe health status than in the moderate health status from all perspectives. Respondents from the socially inclusive perspective estimated the highest WTP value for a new drug. We also asked about life-threatening diseases in ex-post and ex-ante. The WTP value in ex-ante was higher than in ex-post, and demographic factors affecting the WTP were different in both situations. The various WTP values were obtained from these surveys. Limitations: The analysis was based on data collected from an internet panel, which could be biased. There is also a risk that respondents answered the questionnaire differently if asked in everyday situations. Conclusion: Use of a uniform price threshold may not be appropriate in policy settings, because it may not reflect diverse preferences based on different situations, such as disease type and severity. Setting a price threshold as Japan institutes an HTA system requires further research.

1 January 2009 in PharmacoEconomics
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Journal Article
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AIAtaru Igarashi
Ataru Igarashi
HTHiroki Takuma
Hiroki Takuma
TFTakashi Fukuda
Takashi Fukuda
KTKiichiro Tsutani
Kiichiro Tsutani

23 November 2015 in Applied Health Economics and Health Policy
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Journal Article
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AIAtaru Igarashi
Ataru Igarashi
RGRei Goto
Rei Goto
KSKiyomi Suwa
Kiyomi Suwa
RYReiko Yoshikawa
Reiko Yoshikawa
AWAlexandra J. Ward
Alexandra J. Ward
JMJörgen Moller
Jörgen Moller
Background Smoking cessation medications have been shown to yield higher success rates and sustained abstinence than unassisted quit attempts. In Japan, the treatments available include nicotine replacement therapy (NRT) and varenicline; however, unassisted attempts to quit smoking remain common. Objective The objective of this study was to compare the health and economic consequences in Japan of using pharmacotherapy to support smoking cessation with unassisted attempts and the current mix of strategies used. Methods A discrete-event simulation that models lifetime quitting behaviour and includes multiple quit attempts (MQAs) and relapses was adapted for these analyses. The risk of developing smoking-related diseases is estimated based on the duration of abstinence. Data collected from a survey conducted in Japan were used to determine the interventions selected by smokers initiating a quit attempt and the time between MQAs. Direct and indirect costs are assessed (expressed in 2014 Japanese Yen). Results Using pharmacotherapy (NRT or varenicline) to support quit attempts proved to be dominant when compared with unassisted attempts or the current mix of strategies (most are unassisted). The results of stratified analyses by age imply that smoking cessation improves health outcomes across all generations. Indirect costs due to premature death leading to lost wages are an important component of the total costs, exceeding the direct medical cost estimates. Conclusions Increased utilisation of smoking cessation pharmacotherapy to support quit attempts is predicted to lead to an increase in the number of smokers achieving abstinence, and provide improvements in health outcomes over a lifetime with no additional costs.