Due to recent increases in medical costs and national deficits, effective utilization of limited medical resources is indispensable. Thus, the cost-effective treatment of hypertension is an important social and medical issue, as hypertension treatment consumes the greater part of medical expenditures. The introduction of home blood pressure (HBP) measurement for the diagnosis and treatment of hypertension should lead to a decrease in medical expenditures, since HBP measurements have a stronger predictive power for cardiovascular mortality than casual clinic blood pressure (CBP) measurements.

In this study, we investigated the economic impact of using HBP instead of CBP measurement. To estimate the costs associated with changing from CBP to HBP measurement as the diagnostic tool, we constructed a model using data from the Ohasama study and national database.

As a result, the change from CBP to HBP measurement as a diagnostic tool would result in a decrease in medical costs associated with hypertension by 1013.6 billion yen per year. Most of this is attributable to the reduction of medical costs by avoiding the start of treatment in untreated subjects who are diagnosed as hypertension by CBP but normotension by HBP. Furthermore, it could be expected that adequate BP control mediated by the change in the diagnostic method from CBP to HBP measurement would improve the prognosis foe hypertension. If BP control in half of the hypertensive patients whoes antihypertensive treatment would be reinforced or antihypertensive treatment would be started resulting from the introduction of HBP measurement in diagnosis of hypertension was improved, and their systolic blood pressures were to decrease by 10 mmHg, the prevention of hypertensive complications would result in a reduction of annual medical costs by 3.0 billion yen. In addition, stroke prevention due to adequate BP control based on HBP measurement would lead to the curtailment of chronic care costs as well as medical costs. If we assume that BP control improves, and systolic blood pressure decreases by 10 mmHg in half of patients due to reinforcement of the need for antihypertensive treatment or due to starting antihypertensive treatment because of the use of HBP Measurement, the prevention of hypertensive complications would reduce annual care costs by 4.2 billion yen. Thus, the total reduction of annual medical costs was 1020.9 billion yen. Therefore, we conclude that the introduction of HBP measurement for the diagnosis and treatment of hypertension would be very useful to reduce medical costs. Given the cost savings, extensive application of HBP measurement in the clinical practice of hypertension is expected.

Objectives: Once a prostate cancer screening program using prostate-specific antigen (PSA) has been established and is operational, the issue of the re-screening interval for patients with prior negative PSA results comes into question. In Japan, cancer screenings are mainly provided as public services and designing efficient screening programme is important in terms of resource allocation. We approached this issue using a decision-analytic model in which participants were stratified by initial (baseline) PSA values.

Materials and methods: We established a Markov decision analytic model to evaluate the outcomes of prostate cancer screening programs using PSA measurements at various individual re­screening intervals based on baseline PSA levels. Cost-effectiveness analysis was performed to determine the incremental cost-effectiveness ratio (ICER; costs per quality-adjusted life years) for each strategy.

Results: The most cost-effective strategy is the annual screening with respect to biennial screening in men with PSA≤2.0 ng/ml, The strategies expanding biennial screening from this strategy are dominated. ICERs for annual screening and biennial screening strategies in men with PSA≤1.0 were US＄20,827 and US＄3,495, respectively, with respect to strategies with biennial screening in men with PSA≤2.0 ng/ml. On sensitivity analyses, superiority of the annual screening with respect to biennial screening in men with PSA≤2.0 ng/ml is mostly robust. The only exception was that biennial screening in men with PSA≤1.0 ng/ml was the most cost-effective when the cost of PSA check-up was lower than 10.5＄. It was also observed that ICER for an annual screening strategy is larger in an initial age cohort of men in their 50's and 70's than in their 60's. The most important variable in terms of the change in ICER is the PSA cost.

Conclusions: Using a mathematical model, which well expresses outcomes of PSA-based prostate cancer screening programs, an optimal re-screening strategy based on baseline PSA levels can be created according to clinical variables. Annual screenings for all participants can be safely omitted depending on the rate of participation for secondary biopsy, the cancer detection rate on biopsy and the age of participants.

Health insurance claims commonly contain multiple diagnoses. However, doctors had not been required to specify the primary diagnoses until April 2002. Before then, coders of insurers arbitrarily chose primary diagnoses with no explicit criteria, subject to criticism that such classification may be different from classification by doctors. As part of the fee schedule revision in April 2002, doctors were required to specify a primary diagnosis in claims with more than one diagnosis. The author took advantage of this opportunity and analyzed if the change of classifiers affected the classification on a disease-specific manner using national survey results of claims. Since the number of days per claim and per diem cost were found to follow a log-normal distribution, we adopted the multiplicative model, instead of the regular additive model, in which geometric mean (GM) and geometric standard deviation (GSM) were used instead of arithmetic means and standard deviation, a method commonly used for working environment measurement GSD was calculated using three indices, number of claims classified into a category, number of days per claim and cost per claim for each of the 119 diagnostic categories. Intra-classifier (yearly variance among insurers' coders) GSDs were calculated between the geometric mean (GM) over seven years (1995-2001) and each year. Inter-classifier (variance between coders and doctors) GSDs were calculated between the GM over seven years (1995-2001) and GM over two years (2002-3) for each of 119 diagnostic categories. Inter-classifier GSDs were larger than intra-classifier GSDs in the power of 2.01, signifying that inter-classifier variances were larger than yearly fluctuation among insurers' coders. These findings led one to conclude the change of classifiers did affect the classification. "Pancreatic disease" and "mood disorders" showed the largest discrepancy between doctors and insurers' coders while renal failure and dental diseases showed the least discrepancy, indicating that both doctors and insurers' coders were in agreement in terms of choosing renal failure and dental diseases as primary diagnoses but in disagreement in choosing pancreatic disease or mood disorders. Lack of proper coding skills as well as proliferation of rule-out or diagnoses-for-­convenience might have contributed to such disagreement. The proposed method will have a wide applicability including detection of potential misclassification of DPCs.