The issues in annual health checkups (human dock system) in Japan to prevent non-communicable diseases

Introduction

Background

Even during the coronavirus disease 2019 (COVID-19) pandemic, the leading causes of death were ischemic heart disease, stroke, and chronic obstructive pulmonary disease (1), so-called non-communicable diseases (NCDs) all over the world. The major risks for the burden of NCD are classified into three categories, modifiable behavioral, metabolic, and environmental risk factors. Among them, metabolic risks such as hypertension, hypercholesterolemia, and diabetes (1) which are without symptoms in the early stage and not diagnosed without measuring blood pressure, blood cholesterol level, and glucose level. These days, home blood pressure monitoring or urinary glucose or blood glucose levels can be measured in some countries at home but it is not widely accepted. So that, only by regular health checkups participants can know their risks.

Rationale and knowledge gap

A recent study aimed at the optimal target blood pressure showed the intensive treatment of blood pressure (systolic blood pressure lower than 120 mmHg) is superior to reducing cardiovascular events and mortality than standard treatment (systolic blood pressure lower than 140 mmHg) (2). In this study, when we calculate the number needed to treat (NNT), it is about 50 patients/3 years. Hypertensive patients are followed for longer than 3 years and if we follow the patients for 30 years, NNT is 5 patients/30 years and it is an acceptable number. However, in this trial, when we calculate NNT in patients with chronic kidney disease (CKD) it is about 1,300 patients/3 years and 130 patients/30 years which is not readily acceptable. This data implies the importance of early detection of risk factors, prevention of development of risk factors, and intensive treatment or risks when the patients have comorbidities. So that health checkups are a good way to screen risks and prevention by educating the participants.

Objective

In this review, we summarized Japanese system for public health checkups and issues to be improved to obtain maximal effect in preventing NCDs.

Historical background

The idea of health checkups was first reported in 1861 by Dr. Horace Dobell (3) and in 1926 G. Scott Willamson and Innes Hope Pearse launched a membership health check service for workers and their families (Pioneer Health Centre). It ensures the members to have access to a doctor (4). In Japan, free regular health checkups started in 1911 to prevent tuberculosis, dysentery, and other communicable disease among factory workers (5). Later on, blood pressure measurements, and urinalysis [1972], electrocardiogram (ECGs), hemoglobin (Hb), aspartate aminotransferase (AST), alanine aminotransferase (ALT), cholesterol [1989], and other exams are included, and finally in 1998 blood glucose is added to this system. By adding these examinations, these checkup systems can be used to screen for risks of cardiovascular diseases and cancers. Besides these free checkups, we developed the “human dock” in the 1950s, which is not covered by insurance but can be checked for multiple risks, and in some occasions, gastric fiber, computed tomography (CT) scan, magnetic resonance imaging (MRI), and ultrasound exam can be done upon the participants’ request.

Until 1964 when automated multiphasic health testing and services were available in California, all the tests were done manually and thereafter automated analysis on blood samples, urine samples, and imaging were available, and checkup could be done in one or two days. These rapid checkups accelerated the number of participants and a lot of companies support the fee for “human dock” of not only their employees but also family members. According to the National Living Infrastructure Survey 2022, about 73% of males and 66% of females above 20 years old undergo annual health checkups in Japan (6).

After the development of the health checkup system (Table 1) and human dock system, in Japan dramatic decline in the mortality rate of stroke, that is mainly hemorrhagic stroke, is observed (Figure 1) (7). It is not solely due to the detection of hypertension, diabetes, or hypercholesterolemia but the development of effective treatment, changes in dietary habits (reduction of salt intake) and other factors. In contrast, cancers, congestive heart failure, and ischemic heart disease are still increasing. The high mortality rate for cancer is partly due to the small number of participants in cancer health checkups in Japan which is not for free and optional examination. In 2022 (8), the highest number of participants was lung cancer screening by chest X-ray (male 53% and female 46%) and the lowest one was colon cancer by fecal occult blood (male 44% and female 38%).

Figure 1 Trends in death rates from leading causes of death, 1950–2019. Modified from the study (7). Mortality due to cerebrovascular diseases declined from 1970s. It is partly due to blood pressure is routinely measured in health checkups since 1972 and blood pressure control rate increased in Japan. In Japan thiazide diuretics (hydrochlorothiazide) is first launched in 1959 but the screening of hypertension was not widely done until 1972.

Accuracy control in laboratory exams in health checkups

Accuracy control in laboratory examination is a critical aspect of ensuring the reliability and validity of laboratory test results. Accurate and precise laboratory test results are essential for making informed clinical decisions, diagnosing medical conditions, monitoring patient health, and conducting medical research. Accredited laboratories either commercial or in hospital follow quality assurance (QA) programs including both internal quality control (IQC) or external quality assessment (EQA), calibrations, standardization, validation, and verification. In addition, documentation that enables tracking the record, training of staff, root cause analysis to implement corrective and preventive action, and continuous improvement are required. Most of the facilities of health checkups or human-dock in Japan follow this QA but some do not. We should inform the status of the laboratory in the facility to participants.

Preanalytical errors

Preanalytical error is mistakes or issues that occur in the laboratory testing process before the actual analysis of a patient’s specimen takes place. These errors can significantly impact the accuracy and reliability of test results. Preanalytical errors can occur at various stages. Among them, specimen collection includes several factors such as mislabeling, inadequate sample volume, hemolysis, contamination, incorrect anticoagulant and patient preparation. In health checkup facilities, when they do not have their own laboratory they transport samples to commercial laboratories and the condition of transportation (temperature, prevention of degradation and contamination) is also an issue. We sometimes experience preanalytical errors in urine examination by mislabeling. A bar-code and patient name labeled sampling cup is handed to each participant and when a participant visit our facility together with his/her partner, they sometimes mix up sampling cups. By examining urinary sediment, we can detect the mix-ups, i.e., the “male” labeled urine shows epithelial cells from the vagina and we know the sample is from his wife.

Analytical errors

Analytical errors refer to mistakes or issues that occur during the actual analysis or testing of a participant’s specimen in a laboratory. These errors also can lead to incorrect or imprecise test results. Analytical errors can arise from various sources and instrumentation and equipment are the most common cause those include malfunctioning, calibration errors, contamination of instruments, inaccurate preparation or handling of reagents and chemicals, and quality control (QC) or QA errors. In addition, interferences by substances in the sample or condition of samples such as pH, sample volume, and others can interfere with the accuracy of the assay. Most of the analytical methods are designed to minimize interference, however, it can still be observed. Urinary protein and albumin are good biomarkers for detecting early stages of CKD and are incorporated with CKD grading by guideline (9). The study shows the urinary albumin level differs from testing kit to kit when comparing liquid chromatography/mass spectrometry (LC/MS) data (10). Although all the kits are accredited, these serious problems remain. We surveyed the urinary protein level and compared the results by dipstick and quantitative evaluation (11). Around 41,000 samples from negative to 4+ in urinary protein by dipstick. It is well known that alkaline urine is a major cause of false positive proteinuria, and in this study, we clarified that a lower specific gravity (SG) sample causes false negative result. In addition, there were sexual differences in SG of urine and females was lower in SG and the sensitivity in trace positive for proteinuria cases was lower in females.

Low-density lipoprotein cholesterol (LDL-C) is a well-acknowledged risk factor for atherosclerosis and it is pivotal to measure LDL-C accurately. These days we use calculation methods and automated direct measurement in health checkups. When triglyceride levels is lower than 400 mg/dL, the Friedwald equation is applicable but higher than 400 mg/dL, there are several methods such as the extended Martin/Hopkins equation or Sampson equation up to 800 mg/dL of triglyceride (12). It is reported that the Martin/Hopkins equation is superior to the Sampson equation (13). It is still required to establish widely and accurately applicable calculation methods. To measure LDL-C directly we have to consider the interference by Lp(a)-C which is composed of apolipoprotein (a) covalently bound to the apolipoprotein B-100 moiety of LDL. The elimination method of Lp(a)-C varies from reagent to reagent and indeed direct measurement kit does not meet the standardization in Japan (14).

What is our next step to reduce cancer and cardiac mortality by utilizing a health checkup and human dock system?

Reducing cancer and cardiac mortality through health checkups and human dock systems involves a multi-faceted approach that integrates early detection, risk assessment, and preventive measures. As I mentioned above, the number of participants is still low for cancer checkups and population and personalized approaches to increase it. We already have accumulated data and they should be analyzed to assess an individual’s risk and provide personalized health recommendations and interventions based upon the individual’s risk profile. To promote a personalized approach, genetic testing both in DNA mutation and epigenetic modification can be applied, however, in health checkups, the tests should be minimally invasive, and somatic mutations cannot be detected unless we biopsy certain organs which is highly invasive. Epigenetic changes also require biopsy, however, kidney diseases can be detected by evaluating DNA methylation in urine sediment cell (15), and also circulating microRNA can be a future candidate for biomarkers to detect disease conditions.

Conclusions

NCD is a big burden on our society especially in low-income societies. Income and NCD relations could be due to the cost of health care, exposure to environmental risks such as smoking, high consumption of alcohol. Management of NCDs includes detecting, screening, and treating these diseases, reducing modifiable risk factors. High-impact essential NCD interventions can be delivered through a regular health checkup to strengthen early detection and timely treatment.

Acknowledgments

Funding: None.

Footnote

Peer Review File: Available at https://jlpm.amegroups.org/article/view/10.21037/jlpm-23-97/prf

Conflicts of Interest: Both authors have completed the ICMJE uniform disclosure form (available at https://jlpm.amegroups.org/article/view/10.21037/jlpm-23-97/coif). T.S. serves as the unpaid Associate Editor-in-Chief of Journal of Laboratory and Precision Medicine from September 2023 to August 2025. The other author has no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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