Abstract
OBJECTIVES: Special health examinations in Japan lack standardized judgment guidelines, potentially leading to wide variation in outcomes. This study quantified inter-institutional differences in abnormal-finding rates for examinations targeting specified chemical substances and organic solvents, and examined whether institutional judgment criteria are associated with these rates. METHODS: We conducted a cross-sectional questionnaire survey of 115 facilities affiliated with the National Federation of Industrial Health Organizations (Zen-Eiren). Facilities reported abnormal-finding rates for fiscal years 2022-2024. Physicians' judgment criteria were assessed using case vignettes addressing the use of exposure information and biological monitoring. Associations between rates and judgment criteria were evaluated using nonparametric tests (Spearman rank correlation; Wilcoxon rank-sum). RESULTS: Valid responses were obtained from 45 facilities (39.1%). Abnormal-finding rates for specified chemical substances and organic solvent examinations were strongly correlated within facilities. For organic solvent examinations, facilities that did not emphasize the exposure-finding association reported higher abnormal-finding rates than those that did. A similar, but nonsignificant trend was observed for specified chemical substance examinations (P = .066). Abnormal finding rates tended to rise when biological monitoring alone triggered abnormalities and nonoccupational factors were not excluded in both examinations. CONCLUSIONS: Major special health examinations in Japan show substantial inter-institutional variation in abnormal-finding rates, partly explained by differences in judgment criteria-particularly the weight placed on linking clinical findings to workplace exposure. Establishing standardized national guidelines is essential to improve consistency, reliability, and system effectiveness.