PLOS ONE · 8 authors, 4 centres
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In Japan's nationwide health check-up program, 71.7% of eligible adults attended check-ups, but only 35.2% of those identified as high-risk adhered to follow-up health guidance invitations. Older age, more concerning blood pressure or glucose results, and self-reported motivation for lifestyle change were the strongest predictors of adherence. Policy reforms should target younger individuals and those with mild hypertension, diabetes, or dyslipidemia to improve program effectiveness.
**Background:** Japan has conducted a nationwide annual health check-up program (*Tokutei Kenshin*) since 2008, focusing on metabolic syndrome and subsequent health guidance for individuals at high cardiovascular risk. Previous reports suggested low adherence to health guidance invitations, but barriers to adherence were poorly understood. This study aimed to characterize adherence patterns and identify major predictors of adherence to health guidance invitations.
**Methods:** The authors analyzed an anonymized insurer-based database from the Health Insurance Association for Architecture and Civil Engineering companies, one of the largest employer-sponsored insurers in Japan covering over 400,000 individuals. The study included 186,316 adults (aged 40–74 years) eligible for health check-ups at the beginning of fiscal year 2017. High cardiovascular risk was defined as obesity (BMI ≥25 kg/m² or waist circumference ≥85 cm in men or ≥90 cm in women) plus at least one of: SBP ≥130 mmHg or DBP ≥85 mmHg; FBG ≥100 mg/dL or HbA1c ≥5.6%; TG ≥150 mg/dL or HDL ≤40 mg/dL. Individuals already on prescribed medication for hypertension, diabetes, or dyslipidemia were excluded from the health guidance invitation. The primary outcome was receipt of health guidance (lifestyle consultation or clinic visit) within 365 days of the health check-up. Predictors of adherence were evaluated using multivariable logistic regression with multiple imputation (MICE) for missing data. Sensitivity analyses included inverse probability of censoring weighting (IPCW) and complete case analysis.
**Key Results:** In 2017, 71.7% (133,573/186,316) of eligible individuals attended a health check-up. Among those, 25.7% (n=34,294) were already on prescribed medication for hypertension, diabetes, or dyslipidemia, and 23.2% (n=30,979) were invited for health guidance due to high cardiovascular risk. Of those invited, 97.5% (n=30,194) were followed for 365 days, and 35.2% (n=10,614) received health guidance within that period. Sensitivity analyses for 2016 and 2018 showed similar rates (71.2% and 72.4% for check-up attendance; 34.8% and 34.9% for health guidance adherence, respectively).
Among the 30,194 individuals analyzed for predictors, 53% were aged under 50 years, 90% were men, and 62% were non-smokers. Older age was strongly associated with adherence: compared to those aged 40–44, the odds ratios (OR) for adherence were 1.13 (95% CI 1.05–1.22) for ages 50–54, 1.30 (1.19–1.41) for ages 55–59, 1.58 (1.45–1.73) for ages 60–64, 1.80 (1.59–2.03) for ages 65–69, and 2.06 (1.57–2.71) for ages 70–74. More concerning clinical results also predicted higher adherence: individuals receiving employer warnings due to extremely high glucose levels (FBG ≥150 mg/dL or HbA1c ≥8.0%) had an OR of 3.64 (3.08–4.30); those receiving a specific letter for high blood pressure had an OR of 1.53 (1.34–1.73); and those receiving a specific letter for high blood glucose had an OR of 1.90 (1.64–2.20). Self-reported motivation was also significant: those interested in lifestyle change had an OR of 1.24 (1.14–1.34), and those already taking action had an OR of 1.44 (1.28–1.63). Smoking was associated with lower adherence (OR 0.77, 0.73–0.81), as was being an insured family member vs. main insured (OR 0.77, 0.67–0.89). Female sex showed a trend toward lower adherence (OR 0.89, 0.79–1.00). Sensitivity analyses using IPCW and complete case analysis yielded consistent results.
**Clinical Implications:** The study confirms that while two-thirds of eligible adults attend annual cardiovascular risk check-ups, only about one-third of high-risk individuals follow through with recommended health guidance. This represents a major gap in the preventive care cascade. The findings suggest that younger individuals, those with milder abnormalities in blood pressure or glucose, and those lacking motivation for lifestyle change are least likely to adhere. Policy reforms should consider targeted interventions for these groups, such as enhanced communication strategies or employer-based support programs. The study also highlights that employer involvement (triggered by extreme glucose levels) more than doubled adherence, suggesting that workplace-based approaches may be effective. However, generalizability is limited by the study population (architecture and civil engineering workers and their families, 90% male among high-risk invitees) and by the program's unique definition of high risk, which emphasizes waist circumference and excludes elevated LDL cholesterol.