Derivation of gender and age-specific reference intervals from fully normal Japanese individuals and the implications for health screening.

BACKGROUND: With nationwide standardization of laboratory tests among institutions for health screening in Japan, common reference intervals (RIs) were derived from records of 1,500,000 health check attendees. METHODS: Targets were 20 basic laboratory tests including body mass index (BMI) and systolic and diastolic blood pressures (SBP, DBP). Individuals fulfilling the following strict criteria were chosen: SBP<130, DBP<85mmHg, BMI<25kg/m(2), non-smoking, ethanol consumption<20g/day and under no mediation with no remarkable current/past illnesses. The latent abnormal values exclusion (LAVE) method was applied to ensure fully normal results. RIs were derived by parametric method using modified Box-Cox power transformation. RESULTS: Among all attendees, 23% fulfilled the criteria. Application of the LAVE method further reduced the dataset by 40%-50%. Age-related charts of test results differed greatly between genders in almost all tests. Comparison of derived RIs with clinical decision limits (CDLs) revealed that the upper limits of RIs differed from CDLs according to gender and age. CONCLUSIONS: Implementation of gender and age-specific RIs derived from individuals with fully normal health attributes will (1) enable appropriate interpretation of test results in health screening and (2) promote judicious application of CDLs for therapeutic intervention, taking into account gender, age and other health attributes.

Validation of the pepsinogen test method for gastric cancer screening using a follow-up study.

BACKGROUND: Serum pepsinogen (PG) measurement has been used for gastric cancer screening since the 1990s. However, there are no reports comparing the screening validity of the PG test method with that of conventional X-ray examination directly in the same population, using a follow-up study. METHODS: From April 2000 to March 2001, 12 120 residents of Osaka Prefecture, who underwent opportunistic screening at a medical checkup organization in Osaka city (hereafter, "the organization"), were enrolled. They received both a barium meal examination and PG test simultaneously. All the participants were followed up for a 1-year period after the screening. For the participants advised to undergo endoscopic examination, the results of those who were examined at the organization were tallied. The other participants were checked using the Osaka Cancer Registry (hereafter, "the registry"). RESULTS: Of the 12 120 participants, 493 (4.1%) were positive with the PG method and 728 (6.0%) were positive with the X-ray method. Fifty-four (0.4%) were positive for both methods. Thirteen gastric cancer cases were diagnosed by successive esophagogastroduodenoscopies at the organization. Six additional gastric cancer cases were identified by record linkage with the registry. The sensitivity, specificity, and positive predictive values of the PG method with a PGI cutoff level of