Smoking and Long-Term Sick Leave in a Japanese Working Population: Findings of the Japan Epidemiology Collaboration on Occupational Health Study.

BACKGROUND: Few studies have investigated the association between tobacco smoking and sick leave (SL) in Japan. METHODS: We followed 70 896 workers aged 20-59 years (60 133 males, 10 763 females) between April 2012 and March 2017. A Cox proportional hazards model was used to investigate the associations between smoking (smoking status and intensity) and long-term SL (ie, SL lasting ≥30 consecutive days). Cause-specific analyses were also conducted. RESULTS: A total of 1777 people took long-term SL during a follow-up of 307 749 person years. Compared with never-smokers, current smokers were at a higher risk of long-term SL (hazard ratio [HR] = 1.32; 95% confidence interval [CI] = 1.19 to 1.48). Cause-specific analyses revealed that current smoking was associated with a higher risk of SL due to all physical disorders (HR = 1.44, 95% CI = 1.22 to 1.69), cancer (HR = 1.49, 95% CI = 1.10 to 2.01), cardiovascular disease (CVD; HR = 2.16, 95% CI = 1.31 to 3.55), and injuries/external causes (HR = 1.83, 95% CI = 1.31 to 2.58). Former smokers were at a higher risk of SL due to cancer at a borderline significance level (HR = 1.38, 95% CI = 0.99 to 1.92). Low-intensity smoking (ie, 1-10 cigarettes smoked per day) was associated with all-cause SL, SL due to CVD, and SL due to injuries/external causes compared with never-smokers. CONCLUSION: In a large cohort of working-age Japanese, smoking was associated with a greater risk of long-term SL. Greater effort is needed to mitigate disease burden associated with smoking at workplace in Japan. IMPLICATIONS: Our study contributes to the literature on the association between smoking and SL in several ways. First, the study was conducted among a Japanese working population. While the association has been extensively studied in Western setting, few attempts have been made elsewhere. Second, cause-specific analyses were undertaken in our study. Third, we paid attention to the effect of low-intensity smoking on SL given that there is growing evidence of an elevated health risk associated with low-intensity smoking.

Importance of Achieving a "Fit" Cardiorespiratory Fitness Level for Several Years on the Incidence of Type 2 Diabetes Mellitus: A Japanese Cohort Study.

BACKGROUND: The "Physical Activity Reference for Health Promotion 2013" provides "fit" reference values for cardiorespiratory fitness (CRF) for good health. The importance of achieving a fit CRF level for several years on the subsequent prevention of type 2 diabetes mellitus (T2DM) remains to be clarified. METHODS: This cohort study was conducted in 2,235 nondiabetic males aged 21 to 59 years, enrolled in April 1986 through March 1987. We calculated the ratio of the area under the curve (AUCratio) for actual measured values and the AUC for the reference values of CRF in each individual during an 8-year measurement period before the baseline. According to whether they met a fit CRF level or not, participants were categorized into groups based on the AUCratio (FitAUC or UnfitAUC) and initial CRF (Fitinitial or Unfitinitial), respectively. T2DM was evaluated on health checkups until March 2010. RESULTS: During the follow-up period, 400 men developed T2DM. After adjustment for confounders, as compared with those in the FitAUC group, the hazard ratio (HR) for those in the UnfitAUC group was 1.33 (95% confidence interval [CI], 1.06-1.65). A combined analysis with the categories of initial value and AUCratio showed that, compared with the Fitinitial and FitAUC group, the HRs of Fitinitial and UnfitAUC, Unfitinitial and FitAUC, and Unfitinitial and UnfitAUC groups were 1.41 (95% CI, 0.99-2.00), 1.18 (95% CI, 0.81-1.70), and 1.40 (95% CI, 1.08-1.83), respectively. CONCLUSION: Achievement of a fit CRF level established in the Japan physical activity guideline for several years was associated with lower subsequent risk of T2DM.

Long-term Impact of Cardiorespiratory Fitness on Type 2 Diabetes Incidence: A Cohort Study of Japanese Men.

BACKGROUND: We sought to examine the association between cardiorespiratory fitness (CRF) and incidence of type 2 diabetes considering the follow-up period in a cohort of Japanese men with a maximum follow-up period of 23 years. METHODS: This study enrolled 7,804 male workers free of diabetes in 1986. CRF was measured using a cycle ergometer, and maximal oxygen uptake was estimated. During 1986-2009, participants were followed for development of type 2 diabetes, which was diagnosed using fasting blood tests, self-administered questionnaires, or oral glucose tolerance tests after urinary tests from annual health checkups. Hazard ratios for the incidence of type 2 diabetes were estimated using Cox proportional hazards models. RESULTS: During the follow-up period, 1,047 men developed type 2 diabetes. In analyses by follow-up periods (1986-1993, 1994-2001, and 2002-2009), there was an inverse dose-response relationship between CRF and the development of type 2 diabetes for all three follow-up periods (P for trend 0.019, <0.001, and 0.001, respectively), and the association between CRF at baseline and the incidence of type 2 diabetes did not weaken with longer follow-up period. Compared with the lowest CRF group, hazard ratios of developing type 2 diabetes were 0.69 (95% confidence interval [CI], 0.49-0.97) for the highest CRF group in 1986-1993, 0.57 (95% CI, 0.42-0.79) for the highest CRF in 1994-2001, and 0.47 (95% CI, 0.30-0.74) for the highest CRF in 2002-2009. CONCLUSION: High CRF is associated with a lower risk of the incidence of type 2 diabetes over an extended period of >20 years among men.

Association between objectively measured physical activity and body mass index with low back pain: a large-scale cross-sectional study of Japanese men.

BACKGROUND: The relationship between the combination of physical activity (PA) and body mass index (BMI) with low back pain (LBP) is unclear. The present study offers a cross-sectional assessment of how combinations of PA and BMI are related to LBP in Japanese men. METHODS: Participants were 4022 Japanese men (mean age = 47) who underwent regular clinical examinations. PA was measured using a uniaxial accelerometer and divided into tertiles (PAhigh, PAmiddle, PAlow). A self-administered questionnaire was used to report on persistent LBP experience, drinking and smoking habits, and any existing lifestyle diseases. After covariance adjustment, a logistic regression model was used to assess how combinations of PA and BMI are related to persistent LBP. RESULTS: 428 of the participants had persistent LBP. A clear negative dose-response relationship was found between PA levels and persistent LBP (P for linearity = 0.012). Regarding BMI, odd ratios were shown to be higher in the overweight/obese category (BMI ≥ 25 kg/m2) than for the normal weight category (BMI < 25 kg/m2). When the PAhigh was taken as the reference in the normal weight category, odds ratios for PAlow and PAmiddle in the normal weight category were shown to be high. Moreover, in the overweight/obese category, odd ratios for every fitness level were also high as for the normal weight category. CONCLUSION: The present study showed that both PA and BMI are related to persistent LBP. Also, the prevalence of persistent LBP became higher when PAlow and high BMI are combined rather than the group of PAhigh and low BMI combination.

Age-, sex-, and diagnosis-specific incidence rate of medically certified long-term sick leave among private sector employees: The Japan Epidemiology Collaboration on Occupational Health (J-ECOH) study.

BACKGROUND: Long-term sick-leave is a major public health problem, but data on its incidence in Japan are scarce. We aimed to present reference data for long-term sick-leave among private sector employees in Japan. METHODS: The study population comprised employees of 12 companies that participated in the Japan Epidemiology Collaboration on Occupational Health Study. Details on medically certified sick-leave lasting ≥30 days were collected from each company. Age- and sex-specific incidence rate of sick-leave was calculated for the period of April 2012 to March 2014. RESULTS: A total of 1422 spells in men and 289 in women occurred during 162,989 and 30,645 person-years of observation, respectively. The three leading causes of sick-leave (percentage of total spells) were mental disorders (52%), neoplasms (12%), and injury (8%) for men; and mental disorders (35%), neoplasms (20%), and pregnancy-related disease (14%) for women. Incidence rate of sick-leave due to mental disorders was relatively high among men in their 20s-40s but tended to decrease with age among women. Incidence rate of sick-leave due to neoplasms started to increase after age 50 in men and after age 40 in women, making neoplasms the leading cause of sick-leave after age 50 for women and after age 60 for men and the second leading cause after age 40 for women and after age 50 for men. Pregnancy-related disease was the second leading cause of sick-leave among women aged 20-39 years. CONCLUSIONS: These results suggest that mental disorder, neoplasms, and pregnancy-related disease are the major causes of long-term sick-leave among private sector employees in Japan.

Obesity and low back pain: a retrospective cohort study of Japanese males.

[Purpose] This study evaluated whether obesity is a risk factor for low back pain, by using body fat percentage (%FAT) and body mass index (BMI) as indices of obesity among Japanese males. [Subjects and Methods] This study included 1,152 males (average age: 28.0 ± 4.6 years). BMI was calculated from subject's height and weight, and %FAT was estimated by the thickness of two parts of skin. Low back pain, drinking and smoking were surveyed using a self-administered questionnaire, and maximal oxygen uptake was measured by a submaximal exercise test using a cycle ergometer. [Results] A significant positive dose-response relationship was shown between %FAT and persistent low back pain prevalence. Similarly, a significant positive dose-response relationship was confirmed between BMI and persistent low back pain. [Conclusion] This study suggests that both high %FAT and BMI are risk factors for persistent low back pain.

[Qualitative analysis of provided information and advice from occupational physicians to attending clinical physicians in supporting an employee's work-treatment balance].

OBJECTIVES: In Japan, the population is aging and there is a declining birth rate. It is an important occupational health issue to support the balance between illness treatment (including nursing care, childcare, etc.) and work. Many patients require mental and financial support to help them with their work-treatment balance. In 2016, the Ministry of Health, Labor and Welfare provided guidelines for supporting employee's work-treatment balance, and in 2018, "Consulting Fee" was approved as an insured medical treatment when clinic doctors supported their patients for continuing to work. The request for the consulting fee requires that the clinician and the occupational physician exchange information on the support necessary for the patient to continue working. Generally, occupational physicians obtain medical information from clinicians to give advice on a worker's employment considerations. However, we do not know what kind of workplace information clinicians hope to know when treating their patients. Therefore, we conducted this survey to clarify how occupational physicians could provide useful information to clinicians. METHODS: We asked approximately 1,500 occupational physicians from the Occupational Health Subcommittee of the Japan Society for Occupational Health to provide us with a letter sent to their clinician to assist workers. From the collected letters, the structural parts of the letters (titles, greetings, acknowledgments, etc.) were removed. We defined a section as a contextual unit that does not impair the meaning. The prepared sections underwent qualitative inductive analysis using the content analysis method of "Berelson, B." RESULTS: A total of 103 cases and 178 documents from 42 people were included in the analysis. Extracting descriptions that could be interpreted as providing information, including descriptions related to treatment, employment, and living environment, and opinions and suggestions from occupational physicians resulted in 596 sections. As a result of the qualitative and inductive classification, the information was classified into three large categories that consisted of information provision, opinions of occupational physicians, and information handling, five middle and eighteen small classifications. In addition, some good practices that were considered significant to clinicians were illustrated. CONCLUSIONS: We analyzed and categorized the information present in the letters sent by occupational physicians to clinicians. The letter does not need to contain all the information in the category table. However, it is important that it should have the necessary and sufficient information considering the case in question. We believe that this category table will aid occupational physicians in writing letters to clinicians.

Objectively Measured Physical Activity and Low Back Pain in Japanese Men.

BACKGROUND: There are several studies on the relationship between low back pain and physical activity. However, the results of these studies vary, and the relationship between them remains unclear. Therefore, we conducted a cross-sectional study to evaluate the association between objectively measured physical activity and low back pain in Japanese men. METHODS: The study included 4022 Japanese men [average age: 47 (10) y]. Daily amount of moderate to vigorous physical activity and step counts were measured using an accelerometer. Low back pain, drinking and smoking, and lifestyle-related diseases were surveyed using a self-administered questionnaire. A logistic regression model was used to evaluate the relationship between physical activity and step counts with persistent low back pain after adjusting for confounders. RESULTS: Persistent low back pain was reported in 428 participants. The multivariable-adjusted odds ratios of presenting persistent low back pain across quartiles of amount of moderate to vigorous physical activity were 1.00 (reference); 0.93 (95% confidence interval, 0.70-1.22); 0.97 (95% confidence interval, 0.74-1.28); and 0.67 (95% confidence interval, 0.50-0.90); P for linearity = .012. CONCLUSION: We found a significant inverse relationship between objectively measured physical activity and persistent low back pain.

Relationship between Cardiorespiratory Fitness and Non-High-Density Lipoprotein Cholesterol: A Cohort Study.

AIM: Recent studies have suggested that non-high-density lipoprotein cholesterol (non-HDL-C) may be a good marker of coronary heart disease and cardiovascular disease risk. Therefore, we investigated the relationship between cardiorespiratory fitness (CRF) and non-HDL-C. METHODS: We evaluated CRF and the incidence of high level of non-HDL-C in 4,067 Japanese men without dyslipidemia. The participants were given a submaximal exercise test, a medical examination, and questionnaires on their health habits in 1986. A cycle ergometer was used to measure the CRF and maximal oxygen uptake was estimated. The incidence of a high level of non-HDL -C (≥170 mg/dL) from 1986 to 2006 was ascertained based on the fasting blood levels. A high level of non-HDL-C was found in 1,482 participants during the follow-up. Cox proportional hazard models were used to obtain the hazard ratios (HRs) and 95% confidence intervals (CIs) for the incidence of a high level of non-HDL-C. RESULTS: Following age adjustment, and using the lowest CRF group (quartile Ⅰ) as reference, the HRs and 95% CIs for quartiles II through IV were: 1.00 (95% CI: 0.87-1.15), 0.87 (95% CI: 0.76-1.00), and 0.70 (95% CI: 0.60-0.81), respectively (P for trend ＜0.001). After additional adjustment for body mass index, systolic blood pressure, smoking, alcohol intake, and family history of dyslipidemia, the HRs and 95% CIs were: 1.05 (95% CI: 0.92-1.21), 0.94 (95% CI: 0.81-1.08), and 0.79 (95% CI: 0.67-0.92), respectively (P for trend=0.001). CONCLUSIONS: These results suggest that there is an inverse relationship between CRF levels and the incidence of a high level of non-HDL-C in Japanese men.

Consistently High Level of Cardiorespiratory Fitness and Incidence of Type 2 Diabetes.

PURPOSE: Although the benefit of high cardiorespiratory fitness (CRF) for the prevention of type 2 diabetes mellitus (T2DM) is widely accepted, whether consistently high CRF is necessary or transiently high CRF is sufficient is unclear. The present study was conducted to examine the hypothesis that consistently high level of CRF is more beneficial than transiently high CRF for the prevention of T2DM. METHODS: This cohort study was conducted in nondiabetic 7158 men age 20 to 60 yr, enrolled from 1986 to 1987. The area under the curve with respect to ground (AUCG) for CRF measurements during an 8-yr measurement period (1979-1987) was calculated as an index of integrated CRF level during the period. The differences (ΔAUCP) between AUCG and peak AUC (peak CRF-measurement period) was also calculated as an index of the presence and the size of a "spike" in CRF. T2DM was defined by fasting blood glucose and a self-reported diagnosis of diabetes for participants with blood tests. For participants without blood tests, T2DM was defined by the result of oral glucose test after a nonfasting urinary test and a self-reported diagnosis of diabetes. T2DM was determined on health checkups until 2009. RESULTS: During the follow-up period, 1495 men developed T2DM. After adjustment for confounders, as compared with the first quartile of AUCG for CRF, the hazard ratio (95% confidence interval) for the second, third, and fourth quartiles were 0.87 (0.76 to 1.00), 0.80 (0.68 to 0.95), and 0.72 (0.58 to 0.89), respectively. For CRF spike, there was no association between ΔAUCP in CRF and the incidence of T2DM. CONCLUSIONS: Consistently higher level of CRF over time was associated with lower risk of T2DM.