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1.  Factors associated with seasonal influenza vaccine uptake among children in Japan 
Seasonal influenza vaccine was once part of the routine immunization schedule that is routinely offered to all children in Japan, but it is now excluded from the schedule. This study aimed to investigate factors influential to parents’ decision to have their children receive seasonal influenza vaccine, as well as types of seasonal influenza vaccine information that is given to parents.
We conducted a cross-sectional online survey of 555 participants who have at least one child younger than 13 years of age. Respondents were asked to categorize the history of influenza vaccination of their youngest child as either ‘annual’ , ‘sometimes’ , or ‘never’. Participants were also asked about potentially influential factors in their decision to have their children receive a seasonal influenza vaccine.
A total of 75% of respondents answered that their youngest child had received a seasonal influenza vaccine, and 57% of respondents answered that their child receives the vaccine every year. The higher income group was more likely than the lowest income group to have a history of influenza vaccine uptake. A recommendation from a pediatrician or school/nursery to have their child vaccinated was also positively associated with a history of influenza vaccine uptake. The most common reason for a pediatrician’s recommendation was ‘it leads to milder symptoms if infected’.
The main finding of the study is a significant association between household income and influenza vaccination of the youngest child in the household. We also found that cost could be a barrier to vaccinating children in low income households and that information from pediatricians and schools/nurseries could motivate parents to have their children vaccinated.
PMCID: PMC4335773
Seasonal influenza vaccine; Self-paid vaccine; Voluntary vaccination; Children
2.  Heat-related mortality risk model for climate change impact projection 
We previously developed a model for projection of heat-related mortality attributable to climate change. The objective of this paper is to improve the fit and precision of and examine the robustness of the model.
We obtained daily data for number of deaths and maximum temperature from respective governmental organizations of Japan, Korea, Taiwan, the USA, and European countries. For future projection, we used the Bergen climate model 2 (BCM2) general circulation model, the Special Report on Emissions Scenarios (SRES) A1B socioeconomic scenario, and the mortality projection for the 65+-year-old age group developed by the World Health Organization (WHO). The heat-related excess mortality was defined as follows: The temperature–mortality relation forms a V-shaped curve, and the temperature at which mortality becomes lowest is called the optimum temperature (OT). The difference in mortality between the OT and a temperature beyond the OT is the excess mortality. To develop the model for projection, we used Japanese 47-prefecture data from 1972 to 2008. Using a distributed lag nonlinear model (two-dimensional nonparametric regression of temperature and its lag effect), we included the lag effect of temperature up to 15 days, and created a risk function curve on which the projection is based. As an example, we perform a future projection using the above-mentioned risk function. In the projection, we used 1961–1990 temperature as the baseline, and temperatures in the 2030s and 2050s were projected using the BCM2 global circulation model, SRES A1B scenario, and WHO-provided annual mortality. Here, we used the “counterfactual method” to evaluate the climate change impact; For example, baseline temperature and 2030 mortality were used to determine the baseline excess, and compared with the 2030 excess, for which we used 2030 temperature and 2030 mortality. In terms of adaptation to warmer climate, we assumed 0 % adaptation when the OT as of the current climate is used and 100 % adaptation when the OT as of the future climate is used. The midpoint of the OTs of the two types of adaptation was set to be the OT for 50 % adaptation.
We calculated heat-related excess mortality for 2030 and 2050.
Our new model is considered to be better fit, and more precise and robust compared with the previous model.
PMCID: PMC3890078  PMID: 23928946
Heat-related mortality; Excess deaths; Climate change; Projection; Adaptation
3.  Association between Combined Lifestyle Factors and Non-Restorative Sleep in Japan: A Cross-Sectional Study Based on a Japanese Health Database 
PLoS ONE  2014;9(9):e108718.
Although lifestyle factors such as cigarette smoking, excessive drinking, obesity, low or no exercise, and unhealthy dietary habits have each been associated with inadequate sleep, little is known about their combined effect. The aim of this study was to quantify the overall impact of lifestyle-related factors on non-restorative sleep in the general Japanese population.
Methods and Findings
A cross-sectional study of 243,767 participants (men, 39.8%) was performed using the Specific Health Check and Guidance System in Japan. A healthy lifestyle score was calculated by adding up the number of low-risk lifestyle factors for each participant. Low risk was defined as (1) not smoking, (2) body mass index<25 kg/m2, (3) moderate or less alcohol consumption, (4) regular exercise, and (5) better eating patterns. Logistic regression analysis was used to examine the relationship between the score and the prevalence of non-restorative sleep, which was determined from questionnaire responses. Among 97,062 men (mean age, 63.9 years) and 146,705 women (mean age, 63.7 years), 18,678 (19.2%) and 38,539 (26.3%) reported non-restorative sleep, respectively. The prevalence of non-restorative sleep decreased with age for both sexes. Compared to participants with a healthy lifestyle score of 5 (most healthy), those with a score of 0 (least healthy) had a higher prevalence of non-restorative sleep (odds ratio, 1.59 [95% confidence interval, 1.29–1.97] for men and 2.88 [1.74–4.76] for women), independently of hypertension, hypercholesterolemia, diabetes, and chronic kidney disease. The main limitation of the study was the cross-sectional design, which limited causal inferences for the identified associations.
A combination of several unhealthy lifestyle factors was associated with non-restorative sleep among the general Japanese population. Further studies are needed to establish whether general lifestyle modification improves restorative sleep.
PMCID: PMC4182544  PMID: 25268956
4.  Population at high-risk of indoor heatstroke: the usage of cooling appliances among urban elderlies in Japan 
Heatstroke due to a heat wave during the summer is one of the commonly known health impacts of climate change in Japan. The elderly are particularly at high-risk of developing indoor heatstroke with poor prognosis. This study aims to describe the population among elderlies at high-risk of indoor heatstroke by focusing on the usage of cooling appliances.
We conducted a web-based household survey in eight urban areas during the winter season of 2011. Households with a person aged 65 and over were selected as samples from panel members of a research firm, and the oldest member of the household was queried about his/her usage of cooling appliances. The population at high-risk of indoor heatstroke is defined as the elderly staying in a room without cooling appliances, or not using the installed cooling appliances, or turning the cooling appliances on only when the room temperature is above 28 °C.
15.4 and 19.1 % of the elderlies living in urban areas of Japan are identified as at high-risk of indoor heatstroke during activity time and sleeping time, respectively, according to the definition of high-risk of indoor heatstroke in this study.
These figures are not negligible since the consequences of heatstroke are grave, but its risk can be eliminated by an appropriate usage of cooling appliances. The preventive interventions are needed to protect the elderlies at high-risk of heatstroke.
PMCID: PMC3650172  PMID: 23160849
Climate change; Cooling appliance; Elderly; Global warming; Heatstroke
5.  Budget impact analysis of chronic kidney disease mass screening test in Japan 
Our recently published cost-effectiveness study on chronic kidney disease mass screening test in Japan evaluated the use of dipstick test, serum creatinine (Cr) assay or both in specific health checkup (SHC). Mandating the use of serum Cr assay additionally, or the continuation of current policy mandating dipstick test only was found cost-effective. This study aims to examine the affordability of previously suggested reforms.
Budget impact analysis was conducted assuming the economic model would be good for 15 years and applying a population projection. Costs expended by social insurers without discounting were counted as budgets.
Annual budget impacts of mass screening compared with do-nothing scenario were calculated as ¥79–¥−1,067 million for dipstick test only, ¥2,505–¥9,235 million for serum Cr assay only and ¥2,517–¥9,251 million for the use of both during a 15-year period. Annual budget impacts associated with the reforms were calculated as ¥975–¥4,129 million for mandating serum Cr assay in addition to the currently used mandatory dipstick test, and ¥963–¥4,113 million for mandating serum Cr assay only and abandoning dipstick test.
Estimated values associated with the reform from ¥963–¥4,129 million per year over 15 years are considerable amounts of money under limited resources. The most impressive finding of this study is the decreasing additional expenditures in dipstick test only scenario. This suggests that current policy which mandates dipstick test only would contain medical care expenditure.
PMCID: PMC4271136  PMID: 24515308
CKD; Budget impact; Dipstick test; Mass screening; Proteinuria; Serum creatinine assay
6.  Demand for pneumococcal vaccination under subsidy program for the elderly in Japan 
Vaccination programs often organize subsidies and public relations in order to obtain high uptake rates and coverage. However, effects of subsidies and public relations have not been studied well in the literature. In this study, the demand function of pneumococcal vaccination among the elderly in Japan is estimated, incorporating effects of public relations and subsidy.
Using a data from a questionnaire survey sent to municipalities, the varying and constant elasticity models were applied to estimate the demand function. The response variable is the uptake rate. Explanatory variables are: subsidy supported shot price, operating years of the program, target population size for vaccination, shot location intensity, income and various public relations tools. The best model is selected by c-AIC, and varying and constant price elasticities are calculated from estimation results.
The vaccine uptake rate and the shot price have a negative relation. From the results of varying price elasticity, the demand for vaccination is elastic at municipalities with a shot price higher than 3,708 JPY (35.7 USD). Effects of public relations on the uptake rate are not found.
It can be suggested that municipalities with a shot price higher than 3,708 JPY (35.7 USD) could subsidize more and reduce price to increase the demand for vaccination. Effects of public relations are not confirmed in this study, probably due to measurement errors of variables used for public relations, and studies at micro level exploring individual’s response to public relations would be required.
PMCID: PMC3470958  PMID: 22970727
Demand; Elderly; Vaccination program; Pneumococcal polysaccharide vaccine (PPV); Price elasticity; Public relations; Subsidy
7.  Growing concern about heatstroke this summer in Japan after Fukushima nuclear disaster 
Heat stroke management will be a major challenge following the Fukushima nuclear plant accident that occurred due to the Great East Japan Earthquake. In this article, a number of actions to meet this challenge are proposed.
PMCID: PMC3156841  PMID: 21833691
Climate change; Electricity shortage; Fukushima nuclear disaster; Global warming; Heatstroke
8.  Prediction of axillary lymph node metastasis in primary breast cancer patients using a decision tree-based model 
The aim of this study was to develop a new data-mining model to predict axillary lymph node (AxLN) metastasis in primary breast cancer. To achieve this, we used a decision tree-based prediction method—the alternating decision tree (ADTree).
Clinical datasets for primary breast cancer patients who underwent sentinel lymph node biopsy or AxLN dissection without prior treatment were collected from three institutes (institute A, n = 148; institute B, n = 143; institute C, n = 174) and were used for variable selection, model training and external validation, respectively. The models were evaluated using area under the receiver operating characteristics (ROC) curve analysis to discriminate node-positive patients from node-negative patients.
The ADTree model selected 15 of 24 clinicopathological variables in the variable selection dataset. The resulting area under the ROC curve values were 0.770 [95% confidence interval (CI), 0.689–0.850] for the model training dataset and 0.772 (95% CI: 0.689–0.856) for the validation dataset, demonstrating high accuracy and generalization ability of the model. The bootstrap value of the validation dataset was 0.768 (95% CI: 0.763–0.774).
Our prediction model showed high accuracy for predicting nodal metastasis in patients with breast cancer using commonly recorded clinical variables. Therefore, our model might help oncologists in the decision-making process for primary breast cancer patients before starting treatment.
PMCID: PMC3407483  PMID: 22695278
Breast cancer; Lymph node metastasis; Data mining; Alternating decision tree
9.  Cost-effectiveness of chronic kidney disease mass screening test in Japan 
Chronic kidney disease (CKD) is a significant public health problem. Strategy for its early detection is still controversial. This study aims to assess the cost-effectiveness of population strategy, i.e. mass screening, and Japan’s health checkup reform.
Cost-effectiveness analysis was carried out to compare test modalities in the context of reforming Japan’s mandatory annual health checkup for adults. A decision tree and Markov model with societal perspective were constructed to compare dipstick test to check proteinuria only, serum creatinine (Cr) assay only, or both.
Incremental cost-effectiveness ratios (ICERs) of mass screening compared with do-nothing were calculated as ¥1,139,399/QALY (US $12,660/QALY) for dipstick test only, ¥8,122,492/QALY (US $90,250/QALY) for serum Cr assay only and ¥8,235,431/QALY (US $91,505/QALY) for both. ICERs associated with the reform were calculated as ¥9,325,663/QALY (US $103,618/QALY) for mandating serum Cr assay in addition to the currently used mandatory dipstick test, and ¥9,001,414/QALY (US $100,016/QALY) for mandating serum Cr assay and applying dipstick test at discretion.
Taking a threshold to judge cost-effectiveness according to World Health Organization’s recommendation, i.e. three times gross domestic product per capita of ¥11.5 million/QALY (US $128 thousand/QALY), a policy that mandates serum Cr assay is cost-effective. The choice of continuing the current policy which mandates dipstick test only is also cost-effective. Our results suggest that a population strategy for CKD detection such as mass screening using dipstick test and/or serum Cr assay can be justified as an efficient use of health care resources in a population with high prevalence of the disease such as in Japan and Asian countries.
PMCID: PMC3328680  PMID: 22167460
Chronic kidney disease; Cost-effectiveness; Dipstick test; Mass screening; Proteinuria; Serum creatinine
10.  The economic burden of TNFα inhibitors and other biologic treatments in Norway 
Costly biologic therapies have improved function and quality of life for patients suffering from rheumatic and inflammatory bowel diseases. In this survey, we aimed to document and analyze the costs.
In 2008, the total costs of tumor necrosis factor alpha inhibitors and other biologic agents in Norway were registered prospectively. In addition to costs, the pattern of use in the four Norwegian health regions was analyzed. The expenses were calculated in Norwegian krone and converted into Euros.
The pattern of use was similar in all four regions, indicating that national guidelines are followed. Whereas the cost was similar in the southeast, western, and central regions, the expenses per thousand inhabitants were 1.56 times higher in the northern region. This indicates that patients in the northern region experienced a lower threshold for access to these drugs. The gap in costs between trusts within northern Norway was about to be closed. The Departments of Rheumatology and Gastroenterology had the highest consumption rates.
The total cost of biologic agents was significant. Northern Norway had among the highest consumption rates worldwide. This can partly be explained. Further exploration calls for a national registry for the use of these drugs.
PMCID: PMC3169971  PMID: 21935335
TNFα inhibitors; biologic agents; Norway; cost

Results 1-10 (10)