Shirasaki published a Japanese paper about the relationship between total cholesterol levels and all-cause mortality in Fukui City, Japan. His cholesterol data were not grouped according to ordinal 20mg⁄dL (0.52 mmol⁄L) intervals. In the present study, we re-calculated his data for meta-analysis. The relative risk (RR) of all-cause mortality adjusted for age and sex showed a decreasing trend with total cholesterol levels (p for trend <0.0001).
In order to summarize the relationship between total cholesterol and all-cause mortality, literature describing this relationship in Japan was collected mainly using computer search engines. Literature published before 1995 was excluded. Reports with the total number of study subjects smaller than 5,000 were also excluded. Five reports were found suitable for meta-analysis of cholesterol levels and all-cause mortality. Meta-analysis revealed that the RR in the <160 mg⁄dL (<4.14 mmol⁄L) group [RR=1.71 (1.41, 2.08)] was significantly higher than in the reference group [160-199 mg⁄dL (4.14-5.17 mmol⁄L)], and that the RRs in the 200-239 mg⁄dL (5.18-6.21 mmol⁄L) group [RRs=0.83 (0.74, 0.94)] and ≥240 mg⁄dL (≥6.22 mmol⁄L) group [0.78 (0.65, 0.95)] were significantly lower than in the reference group when both men and women were combined. We suggest that Japanese subjects with cholesterol levels ≥240 mg⁄dL (≥6.22 mmol⁄L) should not be regarded as hypercholesterolemic or dyslipidemic except when having some genetic disorders like familial hypercholesterolemia because they are in the safest ranges in terms of all-cause mortality.