Objectives: Total cholesterol (TC) level reduction decreases coronary heart disease (CHD) risk, but it is also associated with an increase in non-CHD mortality rate. Our objectives are to estimate the effect of TC level reduction on total mortality and other mortalities in the Japanese population using published data and to analyze the cost-effectiveness of drug therapy.
Methods: We analyzed three data sets for the estimation. The first data set comprised Japanese mortality rates of cardiac diseases, cerebrovascular/other vascular diseases, malignancy, and all causes according to sex and age. The second data set comprised the distributions of serum TC levels in the Japanese population. The third data set comprised the relative risks of mortality rates for the above causes according to the TC level classified into discrete intervals of 20 mg/dl from an intervention study. We estimated the mortality rates of people aged 30-69, with each TC level classification group on the basis of each cause. On the assumption that TC level decreases from 240-259 mg/dl to 160-179 mg/dl or 180-199 mg/dl with drug therapy, we calculated the differences between the mortalities of the classification. When we found a positive effect of TC level reduction, we performed cost-effectiveness analyses of Number Needed to Treat (NNT).
Results: TC level reduction increased the mortality rates except for that of cardiac diseases, and the NNT for cardiac diseases was in the range of 4,202-17,533. The cost of simvastatin, for example, was 0.25-1.05 billion yen per year.
Conclusions: TC level reduction from 240-259 mg/dl to 160-199 mg/dl leads to an increase in total mortality rate in the Japanese population. The treatment should be reevaluated from both viewpoints of risk benefit and cost-effectiveness.