Entire Japanese Population Research Articles

Allelic frequency of pathogenic α1-antitrypsin variants in the Japanese population: Results from a survey of open Japanese genetic variation databases

α1-antitrypsin deficiency (AATD) is a hereditary disorder with a global prevalence that differs across regions. AATD is highly prevalent in Europe and North America but rarely found in Asian countries, including Japan, possibly because of the founder effect of the pathogenic SERPINA1 variants PI*Z and PI*S. However, AATD remains underdiagnosed even in high-prevalence and low-prevalence regions, possibly because of lack of awareness. In this study, we surveyed open Japanese genetic variation databases to estimate AATD prevalence in Japan. We identified allelic frequencies (AFs) of 5 among the 14 major pathogenic SERPINA1 variants from three datasets, collectively derived from 63,119 Japanese participants. The mean AF was determined to be 8.56 × 10−4 (95% confidence interval [CI]: 6.43 × 10−4 to 1.12 × 10−3). Given that this represents the entire Japanese population, one AATD patient was speculated to be born per 1.37 × 106 births (95% CI: 7.97 × 105 to 2.42 × 106) in Japan. Our results support the prevailing notion that AATD is extremely rare in Japan.

Regional disparities in suicide among patients with cancer: A nationwide population-based study in Japan.

This study aimed to explore prefecture-level differences in suicide risk among patients with cancer in Japan. Data from the National Cancer Registry, which covers the entire Japanese population, were used. Patients diagnosed with cancer between 2016 and 2017 were included. The standardized mortality ratio (SMR) for suicide within 2 years after cancer diagnosis was quantified compared with the general population for each prefecture. Multivariate Poisson regression analysis was conducted to quantify the adjusted relative risk using Hokkaido as the reference. The analysis included 2,133,502 patients. The SMRs were high among patients with cancer residing in certain prefectures, such as the Hokuriku region (the middle and western parts of Japan's main island). These areas also exhibited a significant relative risk in the Poisson regression model. The results demonstrated that patients with cancer in certain prefectures in Japan have a high suicide risk.

Epidemiology of Subarachnoid Hemorrhage in Isolated Islands in Japan: A Population-based Study in the Miyako Islands.

The Miyako Islands (with a population of approximately 50,000) are located in southwestern Japan, with a subtropical oceanic climate. This isolated location permitted a retrospective population-based epidemiological study of subarachnoid hemorrhage. We retrospectively enrolled 110 consecutive patients from 2010 to 2019 using the subarachnoid hemorrhage database at Okinawa Miyako Hospital, which is the only local facility with neurosurgeons. We calculated the incidence of subarachnoid hemorrhage standardized to the entire Japanese population. The seasonal distribution of subarachnoid hemorrhage onset and patients' epidemiological characteristics were also investigated. The standardized annual incidence of subarachnoid hemorrhage was 21.4 per 100,000 population, as reported previously in Japan. The patients' mean age was 62.1 ± 15.4 years, and women constituted 60.9%. Anterior communicating artery aneurysms were most common. The endovascular treatment for ruptured aneurysms was increasing as standard levels in Japan. The rates of symptomatic vasospasm and secondary hydrocephalus requiring additional neurosurgical treatment were 2.7% and 19.1%, respectively. The mortality rate was 23.6%. The percentage of patients with a modified Rankin scale score of 0-2 at discharge was 55.5%. There were no differences in the frequency of subarachnoid hemorrhage associated with seasonal distribution or climatic factors. The incidence, baseline characteristics, and clinical outcomes of subarachnoid hemorrhage in the Miyako Islands were similar to those in other regions of Japan. There are preferable epidemiological backgrounds for further practical clinical research.

Estimation of Real-World Vaccination Effectiveness of mRNA COVID-19 Vaccines against Delta and Omicron Variants in Japan.

A resurgence of COVID-19-positive cases has been observed in many countries in the latter half of 2021. The primary reasons for this resurgence are the waning immunity of vaccination after the second dose of vaccination and the changes in public behavior due to temporal convergence. The vaccination effectiveness for the omicron and delta variants has been reported from some countries, but it is still unclear for several other regions worldwide. Here, we numerically derived the effectiveness of vaccination for infection protection in individuals and populations against viral variants for the entire Japanese population (126 million). The waning immunity of vaccination for the delta variant of Japanese individuals was 93.8% (95% CI: 93.1–94.6%) among individuals <65 years of age and 95.0% (95% CI: 95.6–96.9%) among individuals ≥65 years of age. We found that waning immunity of vaccination in individuals >65 years of age was lower than in those <65 years of age, which may be attributable to human behavior and a higher vaccination rate among individuals >65 years of age. From the reported data of 25,187 positive cases with confirmed omicron variant in Tokyo in January 2022, the effectiveness of vaccination was also estimated at 62.1% (95% CI: 48–66%) compared to that of the delta variant. Derived effectiveness of vaccination would be useful to discuss the vaccination strategy for the booster shot, as well as the status of herd immunity.

Incidence and Clinical Practice of Exudative Age-related Macular Degeneration: A Nationwide Population-Based Cohort Study.

PurposeTo elucidate the incidence and treatment pattern of active exudative age-related macular degeneration (AMD).DesignA population-based cohort study conducted using the National Database of Health Insurance Claims and Specific Health Checkups of Japan (NDB), a national claims database managed by the Japanese Ministry of Health, Labour, and Welfare (MHLW).ParticipantsThe entire Japanese population aged 40 years or older (76 million people).MethodsWith the permission of the MHLW, we accessed the complete NDB dataset and identified patients with newly diagnosed active exudative AMD between 2011 and 2018. The incidence of active exudative AMD was categorized by age and sex per year between 2011 and 2018; moreover, details regarding first-line therapy and number of anti-vascular endothelial growth factor (VEGF) injections per elapsed year since initial treatment were obtained and changes in treatment pattern were investigated.Main Outcome MeasuresIncidence rate of active exudative AMD.ResultsDuring the specified 8-year period, 246 064 incident cases of active exudative AMD were identified; 61.4% of these patients were men. The overall incidence rate was 40.66 per 100 000 person-years (95% confidence interval [CI], 40.49–40.82) in the general population aged 40 years or older, 53.22 (95% CI, 52.95–53.49) in men, and 29.78 (95% CI, 29.60–29.98) in women. Mean age of onset was lower in men than in women (72.51 ± 10.50 years vs. 73.90 ± 10.46 years). Among patients with newly diagnosed active exudative AMD, 92.9% received anti-VEGF injections for initial treatments, whereas 1.8% underwent combination therapy with photodynamic therapy. The number of anti-VEGF injections in the first year (0–12 months), second year (13–24 months), and third year (25–36 months) after the initial injection was 3.66 ± 2.30, 1.39 ± 2.20, and 1.23 ± 2.19, respectively. Patients who received fewer injections in the first year received fewer injections in subsequent years and vice versa.ConclusionsThis is a relatively large population-based study on the detailed epidemiology and actual treatment patterns of active exudative AMD in clinical practice. Our results can be a fundamental information source to ensure healthy eyes and promote well-being for all at all ages.

Dietary exposure to arsenic species in Japan in 2019 using a total diet study based on composite sample with market basket approach at the national level

To estimate the mean dietary exposure to total As (tAs) and some arsenic species [inorganic arsenic (iAs), methylarsonic acid (MMAs) and dimethylarsinic acid (DMAs), and arsenobetaine (AsB)] across the entire Japanese population (≥1 year old), a national total diet study (TDS) based on composite sample with a market-basket approach was conducted in Japan from 10 regions throughout Japan in 2019. Mean dietary exposure to iAs of 0.251 μg kg−1 day−1 showed a slightly lower value compared to the health-based guideline value of 0.30 μg kg−1 day−1. The calculated margin of exposure of 1.2–31.9 were lower or similar to the uncertainty factors of 30. Therefore, the possibility of a risk to Japanese people cannot be excluded. This study indicated that consumption of rice and rice products contributed to 64 % of the dietary exposure to iAs. Furthermore, results showed that dietary exposure to tAs had been increasing gradually since 2004, while that to iAs remained steady since 2014. These data indicate the importance of continuing to survey the dietary exposure to total As and As species.

Retrospective nationwide study on the trends in first-line antidiabetic medication for patients with type 2 diabetes in Japan.

Aims/IntroductionTo investigate the national trend in the prescription of first‐line non‐insulin antidiabetic agents and total medical costs (TMCs) after prescribing the drug in Japanese patients with type 2 diabetes.Materials and MethodsUsing the National Database of Health Insurance Claims and Specific Health Check‐ups of Japan covering almost the entire Japanese population, we calculated the proportion of each antidiabetic drug from 2014 to 2017, and determined the factors associated with drug selection. The TMCs in the first year after starting the drugs were calculated, and factors associated with the costs were also determined.ResultsAmong 1,136,723 new users of antidiabetic agents, dipeptidyl peptidase‐4 inhibitors were the most prescribed (65.1%), followed by biguanides (15.9%) and sodium–glucose cotransporter 2 inhibitors (7.6%). Sodium–glucose cotransporter 2 inhibitor and biguanide use increased during 2014–2017 (2.2%–11.4% and 13.7%–17.2%, respectively), whereas the others decreased. Biguanides were not prescribed at all in 38.2% of non‐Japan Diabetes Society‐certified facilities. The TMCs were the lowest among those who started with biguanides. Fiscal year, age, sex, facility, number of beds and comorbidities were associated with drug choice and TMCs. There were wide regional variations in the drug choice, but not in the TMCs.ConclusionsUnlike in the USA and Europe, dipeptidyl peptidase‐4 inhibitor is the most prescribed first‐line medication for type 2 diabetes patients in Japan, while there is a wide variation in the drug choice by facility‐type and prefecture.

Trends in the co-use of alcohol and tobacco among Japanese adolescents: periodical nationwide cross-sectional surveys 1996–2017

ObjectivesThis study aimed to assess trends in the prevalence of alcohol use depending on smoking behaviours and that of smoking depending on drinking behaviours among Japanese adolescents.DesignThis was a retrospective...

Increase in suicide following an initial decline during the COVID-19 pandemic in Japan

There is increasing concern that the coronavirus disease 2019 (COVID-19) pandemic could harm psychological health and exacerbate suicide risk. Here, based on month-level records of suicides covering the entire Japanese population in 1,848 administrative units, we assessed whether suicide mortality changed during the pandemic. Using difference-in-difference estimation, we found that monthly suicide rates declined by 14% during the first 5 months of the pandemic (February to June 2020). This could be due to a number of complex reasons, including the government's generous subsidies, reduced working hours and school closure. By contrast, monthly suicide rates increased by 16% during the second wave (July to October 2020), with a larger increase among females (37%) and children and adolescents (49%). Although adverse impacts of the COVID-19 pandemic may remain in the long term, its modifiers (such as government subsidies) may not be sustained. Thus, effective suicide prevention-particularly among vulnerable populations-should be an important public health consideration.

A Validation Study of the National Database of Health Insurance Claims and Specific Health Checkups of Japan Regarding the Annual Number of Tooth Extractions Performed Across the Entire Japanese Population.

This report describes a validation study of data in the National Database of Health Insurance Claims and Specific Health Checkups of Japan (NDB) obtained by nationwide surveys on tooth extractions. The following 3 data sources on tooth extractions in Japan were compared: (1) the Nationwide Survey of the Reasons for Permanent Tooth Extractions in Japan (a previous survey conducted by the present authors); (2) the Statistics on Medical Care Activities in Public Health Insurance; and (3) the 4th NDB Open Data Japan. Source 1 was a nationwide survey conducted in 2018; sources 2 and 3 comprised data that are freely available for use by the public. In Source 1, 2,345 of 5,250 dentists approached responded to the questionnaire (recovery rate: 44.8%). The number of extracted teeth among younger age groups (aged 25-50 years) reported in Source 1 was lower than that in the other two sources. In contrast, the number of extracted teeth among older age groups reported in Source 1 was higher than that reported in the other two sources. However, when stratified by age group, all differences across the 3 sources regarding the mean annual number of tooth extractions were <0.05 teeth/year. The present results suggest that the NDB is a reliable resource for data on tooth extractions performed across the entire Japanese population.

1497. Epidemiology of RSV infection in Japan: A nationwide claims database analysis

BackgroundRespiratory syncytial virus (RSV) is the major global cause of hospitalization for bronchiolitis and pneumonia in infancy around the globe. In Japan, the occurrence of RSV infection is monitored under the national pediatric sentinel surveillance system. However, this system does not provide detailed information about patient distribution by month of birth and clinical features. We aimed to describe the national epidemiology and clinical features of RSV infection in children < 24 months of age utilizing a nationwide healthcare claims database in Japan.MethodsWe retrospectively analysed anonymized claims data from the Japan Medical Data Center (JMDC) of medical insurance beneficiaries who had at least one confirmed RSV-related diagnosis by ICD10 codes between January 2017 and December 2018. In children < 24 months of age, the number of patients by age in Japan was estimated using the prevalence of patients in the database and national population data by age.ResultsIn the JMDC database, 9,711 and 8,509 children < 24 months of age had an RSV-related diagnosis in 2017 and 2018, respectively. Of which, 2,473 (25%) and 2,083 (24%) were hospitalized. When extrapolated to the entire Japanese population, an estimated 138,059 and 119,205 RSV-related diagnoses and 33,355 and 27,339 RSV-associated hospitalizations occurred in Japan in 2017 and 2018, respectively. Infants < 6 months of age accounted for between 39% and 42% of total hospitalisations for RSV. A peak in RSV hospitalization was observed at age 2 months. Only 10% of all children < 24 months of age who were hospitalised with an RSV infection had a specific underlying medical condition (preterm infant, bronchopulmonary dysplasia, Down syndrome, chronic heart disease, immunodeficiency). The estimated rate of RSV-associated hospitalization was 35.4 per 1000 population per year among infants < 6 months of age.ConclusionIn conclusion, 3 to 4 out of every 100 Japanese children aged < 6 months were hospitalized for RSV. Ninety percent of children < 24 months of age hospitalised with RSV infection did not have a recognised underlying medical condition. The peak of hospitalization for RSV infection occurred at 2 months of age. Thus, broad-based prevention strategies targeting young infants are needed.DisclosuresYasuhiro Kobayashi, MS, Pfizer (Employee, Shareholder) Kanae Togo, PhD, Pfizer (Employee) Yasmeen Agosti, MD, Pfizer (Employee, Shareholder) John M. McLaughlin, PhD, Pfizer (Employee, Shareholder)

HISTORY OF MEDICAL SERVICE SYSTEM IN UROLOGY

The present paper is a review of the history of the medical service system. Medical treatments were performed mainly as free services until the Edo era. In the Meiji period, the necessity of medical insurance was advocated from the point of view of health care, especially for young males. Around the end of the Taisho period, the health insurance act was established despite incomplete legislation. In 1961, the medical insurance service system was chosen as the health care system for the entire Japanese population and was completed after several revisions. Reimbursements for medical services for urological diseases are shown chronologically from the Edo era until present time and they provide interesting results. Finally, the activities of the JUA health insurance committee are summarized and are demonstrated to have a considerable impact on the present medical insurance system.

Dosimetric Impact of a New Computational Voxel Phantom Series for the Japanese Atomic Bomb Survivors: Children and Adults

One of the largest sources of data on radiation exposure in humans is the study of the atomic bomb survivors at Hiroshima and Nagasaki, Japan performed by the Radiation Effects Research Foundation (RERF). As part of their retrospective dosimetry efforts for the atomic bomb survivors, RERF published two core systems: Dosimetry System 1986 (DS86) and Dosimetry System 2002 (DS02). Due to computing limitations at the time, only three stylized phantoms (an infant, child and adult) were used in DS86 and DS02 to represent the entire Japanese population. In this study, we sought to evaluate the dosimetric differences that should be expected from using an updated and age-expanded phantom series with the survivor cohort. To this end, we developed a new series of hybrid phantoms, based on the Japanese population of 1945, which has greater anatomical realism and improved age resolution over those used by RERF. These phantoms were converted to voxel format and compared to their older counterparts through the calculation of organ dose coefficients using DS02 free-in-air particle fluences at three distances from the bomb hypocenter. From the photon portion of the spectra, organ dose differences of up to nearly 25% are expected between the old and new series, while organ dose differences of up to nearly 70% are expected from the neutron portion. We also compared organ dose coefficients among themselves to determine the accuracy in the use of one organ dose as the epidemiological surrogate to another. Certain organ-surrogate pairs were shown to be inappropriate, such as the use of colon dose for breast risk analyses. Overall, our new series of phantoms provides significant improvements to survivor organ dosimetry, especially to those survivors who were previously misrepresented in body size by their stylized phantom and to those who experienced a highly-directional irradiation field.

Estimates of hip fracture incidence in Japan using the National Health Insurance Claim Database in 2012-2015.

Nationwide registry data on hip fractures have not yet been established in Japan. Using the newly developed National Database of Health Insurance Claims (NDB), which covers the entire Japanese population, we investigated the incidence rates of hip fractures and the associated regional differences. We also assessed the frequency of osteoporosis prescriptions, bone turnover marker (BTM) level, and bone mineral density (BMD) measurements. The annual numbers of hip fractures, osteoporosis prescriptions, and BTM level and BMD measurements by prefecture from 2012 to 2015 were obtained from NDB data. We calculated the standardized claims-data ratio (SCR) in each prefecture. The age-standardized incidence rates from 2012 to 2015 indicated no significant change in females and significant increase in males (p value for trend; 0.920, 0.002, respectively). The fracture risk decreased in females aged 75-84years and indicated no increase in females aged 85-89years during 2012-2015, while the fracture risk indicated no change in males aged 75-84years and increased in males aged 85-89years. The frequency of osteoporosis prescriptions, BTM level measurements, and BMD measurements in the general population in the corresponding period increased with statistical or marginal significance in females and males. West-east regional differences were observed in the incidence rates; the highest SCR values in the western prefectures were approximately double the lowest values in the eastern prefectures. The age-standardized hip fracture incidence rates indicated no significant change in females and significant increase in males in Japan from 2012 to 2015.

METHOD OF THE GLOBAL FITTING OF THE GENERALIZED RADIOGENIC RISK MODELS TO THE JAPANESE COHORT DATA

Research and Technical Center of Radiation-Chemical Safety and Hygiene (RTC RCSH), Moscow, Russia Generalized radiogenic risk models presented in ICRP Publication 103 have a number of attractive features. The models themselves and the corresponding models of background risks are generalized by a single function containing only three parameters specific to the localization of cancer, sex and risk indicator (absolute or relative; mortality or morbidity). However, there are several discrepancies in the values of model parameters for the individual cancer sites and in some predictions based on these models. The aim of this study was to clarify the possibility of refining the parameters of the ICRP models using the LSS cohort data. The method of calculation of the parameters of these models has been developed and verified based on the data on baseline mortality in the cohort and among entire Japanese population. The method consists in the averaging of the local estimates of the parameters calculated based on the values of the rate of the mortality in the ends of different segments of age at exposure and attained age within the entire examined area of change of these variables. The latest published mortality data in the cohort and mortality tables for Japan from the WHO database were used to calculate the mortality rate matrices. Data on the baseline mortality from solid cancers in LSS were in good agreement with statistically more reliable data for the entire Japanese population. Hence, the latter were used for verification of the method.According to the criteria of absolute and relative standard deviation, the ICRP models at whole better approximate baseline and radiogenic mortality from solid cancers in the cohort based on the values of parameters calculated using the proposed method compared to the values from the ICRP. The sets of parameter values for men and women, calculated from LSS data and for the Japanese population differ significantly, while in ICRP models they are almost the same.

Is the default of 2 liters for daily per-capita water consumption appropriate? A nationwide survey reveals water intake in Japan.

Two liters per day is generally applied as the default drinking water intake rate for risk assessments, although evidence supporting this value is insufficient. This study aimed to reveal actual water intakes from tap water and other types of drinks, and to explore the relationships between these intakes. For this purpose, we conducted a nationwide Internet questionnaire survey. Tap water intake negatively correlated with bottled water and soft drink intakes, suggesting a mutually complementary relationship. We propose an index, potential Tap Water Intake (pTWI), calculated by adding soft drinks and bottled water to tap water intake. Mean per-capita tap water intake across the entire Japanese population was estimated at 1.28 L/d, whereas mean pTWI was estimated at 1.65 L/d. Two liters per day corresponds to the 88th percentile of tap water intake and to the 76th percentile of pTWI, and covers the intake of the majority of the population in Japan. This rate should continue being used as the default in the Japanese population, but the rate to cover the tap water intake of almost the entire population would be higher: it was >2.5 L/d.

Whose Life Should Be Reformed?: The Transformation of the Life Reform Movement in Prewar Japan

This paper aims to show that the life reform movement taking place in Japanese cities before the Second World War was not separate from the postwar life reform movement taking place in rural areas; rather, it possessed aspects that were continued after the war. Previous studies have pointed out that life reform movement organizations established in cities in the Taisho period targeted the middle class. However, they have only made fragmentary references to the fact that such organizations instead came to emphasize the importance of farmers, who made up the majority of the population, starting in the late 1920s. This paper is a case study of the activities of the Life Reform League (renamed the Central Association of Life Reform in November 1933), which spearheaded prewar Japan’s life reform movement. The results of this study clarify that the leaders of the life reform movement in the late 1920s and beyond focused on farmers, who made up the majority of the population, as a new target demographic to stop the movement from stagnating. Moreover, they proposed a movement with a foundation consisting not of individuals, but of small, community-based groups. Although many of the organization’s new initiatives never left the planning stages, this change in the organization’s activity policy is nonetheless a clear indication of the process by which the initial principle of “life reform,” concerned with only part of society, transitioned to become a postwar principle concerned with the entire Japanese population.

Secondary sex ratio in regions severely exposed to methylmercury "Minamata disease".

Secondary sex ratio (i.e., male proportion at birth) is considered to function as a sentinel health indicator. Thus, examining this ratio spatially and temporally in regions with severe environmental exposure to compounds such as methylmercury may provide insight into the evolution of exposure. We evaluated spatial and temporal distributions of the secondary sex ratio in Minamata, Japan, and neighboring areas, where severe methylmercury poisoning occurred in the 1950s and 1960s. We selected four areas exposed to methylmercury: Minamata, Ashikita, Goshonoura, and Izumi. After obtaining the number of live births, we conducted descriptive analyses by study area. We observed a reduction in male births in the exposed areas. In particular, a decline in the sex ratio of the Minamata area, where the first patient was officially identified in 1956, was seen around 1955. The ratio during 1955-1959 around Minamata was 0.496 [95% confidence interval (CI) 0.481-0.511]; the 95% CI did not include the value of 0.515 (the secondary sex ratio of the entire Japanese population during the study period). Declines in this ratio were also observed in other exposed areas around 1960, when acetaldehyde production (the origin of methylmercury) reached its peak. These analyses demonstrate that temporal and spatial distributions of the secondary sex ratio reflect the evolution of methylmercury exposure corresponding with the known history of Minamata disease.

The burden and etiology of community-onset pneumonia in the aging Japanese population: a multicenter prospective study.

BackgroundThe increasing burden of pneumonia in adults is an emerging health issue in the era of global population aging. This study was conducted to elucidate the burden of community-onset pneumonia (COP) and its etiologic fractions in Japan, the world’s most aged society.MethodsA multicenter prospective surveillance for COP was conducted from September 2011 to January 2013 in Japan. All pneumonia patients aged ≥15 years, including those with community-acquired pneumonia (CAP) and health care-associated pneumonia (HCAP), were enrolled at four community hospitals on four major islands. The COP burden was estimated based on the surveillance data and national statistics.ResultsA total of 1,772 COP episodes out of 932,080 hospital visits were enrolled during the surveillance. The estimated overall incidence rates of adult COP, hospitalization, and in-hospital death were 16.9 (95% confidence interval, 13.6 to 20.9), 5.3 (4.5 to 6.2), and 0.7 (0.6 to 0.8) per 1,000 person-years (PY), respectively. The incidence rates sharply increased with age; the incidence in people aged ≥85 years was 10-fold higher than that in people aged 15-64 years. The estimated annual number of adult COP cases in the entire Japanese population was 1,880,000, and 69.4% were aged ≥65 years. Aspiration-associated pneumonia (630,000) was the leading etiologic category, followed by Streptococcus pneumoniae-associated pneumonia (530,000), Haemophilus influenzae-associated pneumonia (420,000), and respiratory virus-associated pneumonia (420,000), including influenza-associated pneumonia (30,000).ConclusionsA substantial portion of the COP burden occurs among elderly members of the Japanese adult population. In addition to the introduction of effective vaccines for S. pneumoniae and influenza, multidimensional approaches are needed to reduce the pneumonia burden in an aging society.

Low back pain deprives the Japanese adult population of their quality of life: a questionnaire survey at five healthcare facilities in Japan

To estimate the degree to which low back pain (LBP) deprives the Japanese adult population of their quality of life (QOL) in terms of quality-adjusted life-years (QALYs). A questionnaire survey was conducted among participants of health examinations at five healthcare facilities in Japan. Age- and sex-specific mean values of the EQ-5D score were calculated for (1) those who reported LBP and interference with daily activities (IDA) due to the pain (n = 251), (2) those who reported LBP but no IDA (n = 955), and (3) those who reported no musculoskeletal pain (n = 2887). To estimate the loss of QALYs due to LBP in the Japanese adult population, we multiplied the age- and sex-specific mean differences of the EQ-5D scores between the LBP with (or without) IDA group and the no pain group by the corresponding age- and sex-specific numbers of people with LBP with (or without) IDA in Japan. Among the entire Japanese adult population of 103 million people, 11,800,000 (4,910,000 men and 6,890,000 women) were estimated to suffer from LBP, and 2,403,000 (976,000 men and 1,427,000 women) people were estimated to encounter IDA due to the pain. The loss of QALYs due to LBP in the Japanese adult population was estimated at 947,000 (9.18 per 1000 population). The loss of QALYs due to IDA in the LBP people was estimated at 139,000 (1.35 per 1000 population). The estimated loss of QALYs due to LBP suggests that LBP substantially deprives the Japanese adult population of their QOL.