Seasonal variations in dietary intake affect the consistency of dietary assessment.

BACKGROUND: Nutritional epidemiology studies are usually based on one dietary assessment without taking into account the season in which the interview is taken or adjusting for the difference in reporting dietary intake in different seasons. The semiquantitative food frequency questionnaire has become the primary questionnaire method for measuring dietary intake in epidemiological studies. The aims of this report were (a) to evaluate the effect of season on dietary intake as measured by a semiquantitative food frequency questionnaire (FFQ) conducted twice: once in summer and a second time in winter; and (b) to assess the effect of the differences in dietary intake on biochemical and anthropometric seasonal related changes, such as serum cholesterol and body mass index (BMI). POPULATION AND METHODS: The study population consisted of 94 male industrial employees who participated in clinical biochemical and physical examinations as well as evaluation of their dietary intake twice a year. Dietary intake was assessed using the semiquantitative FFQ that included 96 items and was conducted by a personal interview. RESULTS: We found a significant increase in the intake of selected nutrients in winter as compared to summer as well as an increased intake of animal fat-containing foods such as meat and dairy products. Significant correlation coefficients were shown between the increase in dietary intake of saturated fat and the increase in BMI, serum total and LDL cholesterol. The increase in dietary cholesterol was significantly and positively correlated with the increase in serum total and LDL cholesterol. CONCLUSION: Although FFQ are designed to assess average yearly food intake, we identified significant seasonal changes in dietary intake as measured by FFQ. These changes have a health impact on our population.

Serum total cholesterol and cardiovascular mortality in Israeli males: the CORDIS Study. Cardiovascular Occupational Risk Factor Determination in Israeli Industry.

BACKGROUND: The degree to which serum total cholesterol predicts cardiovascular disease is uncertain. While most authors have placed TC among the most powerful risk indicators of CVD, some have claimed that it predicted CVD in women only, or even not at all. OBJECTIVE: To determine the predictive value of serum total cholesterol relative to diabetes, smoking, systolic blood pressure and body mass index (kg/m2), for cardiovascular disease mortality in 3,461 occupationally active Israeli males. METHODS: A prospective follow-up was carried out for the years 1987-1998 to determine the effect of age, smoking habits, a history of diabetes, SBP, BMI and TC, at entry, on CVD mortality. RESULTS: There were 84 CVD deaths during a total of 37,174 person-years follow up. The hazard ratios (95% confidence intervals) for CVD mortality with respect to variables at entry were: diabetes 5.2 (2.1-13.2), age 2.2 (1.7-2.9), smoking 1.3 (1.0-1.8), SBP 1.4 (1.1-2.0), TC 1.5 (1.0-2.1) and BMI 1.2 (0.7-2.2). Among non-obese, non-diabetic, normotensive subjects the hazard ratio of TC adjusted for age and smoking was 1.16 (1.09-1.22) per 10 mg/dl. In the remaining subjects it was 1.04 (0.98-1.12) only. There was a significant interaction between TC and diabetes, hypertension or obesity (P = 0.003). CONCLUSIONS: In this population of Israeli males we found an interaction between TC and other risk indicators for CVD. Confirmation is required for the unexpected finding that the predictive value of TC for CVD mortality among non-diabetic, non-obese and normotensive subjects exceeded that among subjects with either of these risk factors.

Summer-winter differences in 24 h variability of heart rate.

OBJECTIVE: To examine possible seasonal changes in heart rate variability (HRV). BACKGROUND: Greater than normal mortality from cardiovascular disease (CVD) in the winter has been reported for many countries and might be partly explained by considering seasonal changes in CVD risk factors. Depression of HRV is an independent predictor of arrhythmic complications and of cardiac death, and it is also among the variables that may be affected by the season of the year. METHODS: We compared pairs of 24 h HRV data of 120 healthy men who were examined once in the summer and once in the winter. Multivariate analyses were performed for each dependent variable (HRV indexes) in separate statistical models with age, resting heart rate, serum level of cholesterol, cigarette smoking, body mass index, sports habits, alcohol consumption, systolic blood pressure, physical activity at work, years of education, consumption of energy, and season as the independent variables. RESULTS: Although there were no seasonal differences in mean R-R interval, all indexes of HRV were found to be lower in the summer than they were during winter. Differences and 95% confidence intervals were standard deviation (SD) of coupling intervals between normal beats 12 ms, 6-17 ms; SD of 5 min mean R-R intervals 14 ms, 8-20 ms; mean of all 5 min SD of R-R intervals 2.0 ms, 0.6-2.5 ms; proportion of adjacent R-R intervals differing by > 50 ms 1.5%, 0.6-2.5% and root mean square of the difference between successive normal intervals 3.1 ms, 1.5-4 ms. Multivariate analyses showed that HRV in the winter was less than that in the summer even after adjustment for age, serum level of cholesterol, systolic blood pressure, and body mass index. CONCLUSIONS: HRV indexes of healthy men vary physiologically by season, with lowest values obtained in the winter. Since low HRV is linked to pathologic conditions, the significance of seasonal changes for those suffering from CVD and their possible contribution to the greater mortality rates in winter have to be considered.

Effect of exposure to lead on postural control in workers.

OBJECTIVES: To examine the effect of lead on postural control of workers who have been exposed to lead. METHODS: 63 Male, lead battery workers mean (SD) age 41.0 (7.4) were compared with 48 age matched male controls after excluding those with acute or chronic diseases. Exposed workers had mean (SD) past blood lead concentrations of 37.5 (9.2) micrograms/dl and 11.2 (5.7) years of employment. Postural control was measured with a computerised postural sway measurement system which measured both sway and total movements. RESULTS: Workers standing straight with eyes open on the bare plates had sway and total movements which were not notably different from controls. On the other hand increased movements were needed in the exposed workers to maintain stability (the general stability quotient 18.2 (5.4) v 15.4 (4.4) in controls, p < 0.01) when standing directly on the foot-plates with closed eyes,, and with the head tilted (15.0 (3.8) v 11.5 (3.0) in controls, p < 0.001). Exposed workers also had a trend for less ability to synchronize anterior posterior and lateral sway in the stress positions (0.0625) than had non-exposed workers. Significant but low correlations were found between the estimate of the chronic internal dose of lead and three of 10 of the postural control measurements, and present lead blood concentrations and only one of the 10 measurements and (r values ranged from 0.21 to 0.31, p < or = 0.03). CONCLUSIONS: These findings suggest that lead affects postural control in asymptomatic workers. Further studies are warranted to find whether workers with decreased postural control are at increased risk of accidents and the relation, if any, of these measurements with subsequent morbidity.

Association of physical activity at work with mortality in Israeli industrial employees: the CORDIS study.

The objective of this study was to evaluate the association of physical activity at work with the risk of all-cause cardiovascular disease and cancer mortality. The cohort consisted of 3488 male, Israeli, industrial employees who participated in an 8-year follow-up study. During this period 129 deaths were recorded: 54 from cardiovascular disease, 47 from cancer, and 28 from other causes. Physical activity at work was assessed at entry on a 4-point scale (none, light, medium, and high). Potential confounding demographic, anthropometric, and socioeconomic variables, and health habits including leisure time physical activity were accounted for. We found that the hazard ratio of all-cause mortality in workers with a high physical workload was 1.82 (95% confidence interval, 1.18 to 2.81) compared with workers having a low workload. A similar trend was noted for cardiovascular disease and cancer mortality. We concluded that a high physical workload is associated with increased mortality rates. Future studies should differentiate between leisure time and work time physical activity.

Circulating natural killer cells in retired asbestos cement workers.

The effect of past exposure to asbestos on natural killer (NK) cell number and activity is uncertain. We measured NK cell number and activity in 1052 retired asbestos workers without symptomatic lung disease, lung cancer, or mesothelioma and with a long latency period from exposure; results were compared with those for 100 healthy age-matched controls. The exposed workers showed a decreased NK cell activity and increased NK cell number, yielding a 10.8 higher odds ratio for low NK activity per cell compared with controls (95% confidence interval 6.4 to 18.4), which was due to both a decrease in NK cell activity and an increase in NK cell number. Asbestos exposure of 10 years or more increased the risk of low NK activity per cell. We conclude that exposure to asbestos is associated with diminished effectiveness of NK cells and a concomitant increase in the number of NK circulating cells.

The association of resting heart rate with cardiovascular, cancer and all-cause mortality. Eight year follow-up of 3527 male Israeli employees (the CORDIS Study)

BACKGROUND: Resting heart rate has frequently been shown to be a predictor of coronary heart disease mortality. Elevated heart rate could also be a marker for the presence of other risk factors, which have not been taken into consideration in previous studies. OBJECTIVE: To evaluate the effect of resting heart rate on the risk of all-cause cardiovascular and cancer mortality, taking into consideration haematological variables. METHOD: The association between resting heart rate and mortality was assessed applying Cox's proportional hazard models to data obtained in an 8 year follow-up of 3527 Israeli male industrial employees. During this period 135 deaths were recorded, 57 from cardiovascular disease and 45 from cancer. Resting heart rate was assessed at entry; potential confounding demographic, anthropometric and socioeconomic variables, haematological data, serum lipid levels and health-related habits were accounted for. RESULTS: We found that the relative risk of all-cause mortality increased with increasing resting heart rate, workers with resting heart rate >90 beats. min(-1)had an adjusted relative risk of 2.23 (95% CI 1.4-3.6) compared with those with a heart rate <70 beats. min(-1). A similar result was achieved for cardiovascular disease mortality (adjusted relative risk 2.02, 95% CI 1.1-4.0). Cancer mortality was not associated with resting heart rate. CONCLUSION: This study found that resting heart rate is associated with all-cause and cardiovascular disease mortality after controlling (in various statistical models) for platelet counts, haemoglobin concentration, white blood cell counts, total protein, and other recognized risk factors.

Referral to occupational medicine clinics and resumption of employment after myocardial infarction.

Rehabilitation after acute myocardial infarction (AMI) consists of education, exercise, and an encouragement to return to work (RTW). This study attempts to (1) determine whether the time interval between AMI and the visit at occupational medicine (OM) clinics predicts resumption of full employment, and (2) estimate the incidence of work-related recurrent AMI after RTW. We followed 216 consecutive AMI patients at a single OM clinic. The independent variables were clinical and personal data, physical workload and time between AMI, and first visit to the OM clinic. The outcome variables were full employment 24 months after the acute event and recurrent AMI during this period. Of all patients, 168 attempted RTW. Of these, 18 stopped working subsequently. Of the remaining 150 patients, 54 returned to part-time work and 96 were employed full-time after 2 years. Logistic regression indicated that a failure to resume full employment was independently associated with diabetes, older age, Q wave AMI, angina before AMI, heavy work, and a late visit to the OM clinic. For each month's delay in referral to the OM clinic, there was a 30% decrease in the chance for full employment 24 months after AMI. Six (4%) of the 150 patients who resumed employment sustained a recurrent AMI, two of them while at work. A delayed referral to the OM clinic was associated with work disability after AMI. Late referrals to OM clinics should receive a more intensive and sustained rehabilitation than early referrals. Whether an earlier referral to OM clinics will result in increased RTW rates is unknown. Patients who attempted to resume employment had a 1.2% risk of a recurrent ischemic event at their workplace.

Healthy volunteer effect in industrial workers.

Volunteers for epidemiological research, have lower mortality rates than non-volunteers, thereby producing a bias referred to as the "healthy volunteer effect" (HVE). Occupationally active persons have been similarly shown to have a reduced mortality relatively to the general population (the "healthy worker effect"). To determine whether a HVE exists in occupationally active persons, we followed for 8 years a cohort of Israeli male industrial employees, of whom 71.6% agreed to participate in 1985 in screening examinations for cardiovascular disease. We calculated standardized mortality ratios (SMRs) of the entire cohort relative to the general population, and compared the mortality among participants with that of the non-participants. Over 8 years follow up, SMRs were 78% for the entire cohort, 71% for participants and 99% for non-participants. Participants were older than non-participants and worked more commonly in smaller factories. A proportional hazard model indicated that after adjusting for these variables, the all cause mortality hazard ratio among participants and non-participants was 0.69 (95% CI = 0.51-0.94). During the first and last two years of the 8-year follow-up there were 39.6 and 30.0 age-adjusted deaths per 10,000 person-years among participants, and 58.6 and 51.5 respectively among non-participants. We conclude that the HVE occurs in occupationally active persons, and that it may persist for up to 8 years follow-up.

Increased serum concentrations of growth factor receptors and Neu in workers previously exposed to asbestos.

OBJECTIVES: Epidermal growth factor receptor (EGFR) and oncogene Neu belong to a family of growth factor receptors which may play a part in carcinogenesis. Although increased serum concentrations of Neu and EGFR have been shown in several patients with asbestosis who later developed cancer, serum concentrations have not been studied in workers exposed in the past to asbestos but without asbestos related diseases. METHODS: Serum concentrations of secreted growth factor receptors were studied in 300 workers exposed in the past to asbestos and the results were compared with those of 70 controls. RESULTS: In the controls 4.3% (3/70) had EGFR values > 912 units/ml, compared with 39% (117/299) of the exposed group (p < 0.001). The difference in high values was even more pronounced for Neu with 4.3% of controls having Neu values > 2580 fmol/ml compared with 72% (216/299) of the exposed workers (p < 0.001). Pleural plaques predicted lower serum concentrations of EGFR but not lower Neu concentrations, and this finding remained significant after adjustment for age, exposure time, smoking, and time from initial exposure. CONCLUSIONS: Enhanced secretion of EGFR and Neu was found in a large cohort of retired asbestos workers with a wide range of exposure and latency periods. They did not have asbestosis or cancer and their EGFR values were higher in those without plaques. Further studies are needed to confirm our results, to determine the source of the secreted growth factor receptors, and to study their possible value as risk factors in the development of cancer.

Seasonal changes in calcitropic hormones in Israeli men.

Seasonal changes in calcitropic hormones might be expected, being that dietary calcium intake may differ with fluctuations in climate and temperature, and vitamin D is diet- and sunlight-dependent. While there are studies on elderly subjects, prospective data on younger men is limited. The objective of this study was to clarify possible seasonal changes in homeostatic regulators of calcium in Israeli men aged 25-64 years. The study was a prospective follow-up analysis of data collected during June-August 1995 and 1996 (summer) and January March 1995 and 1996 (winter). Subjects were ninety-five industrial male employees with and without occupational lead exposure. The main outcome measures were summer and winter serum concentrations of parathyroid hormone (PTH), 25-hydroxyvitamin D (25-OH-D), and 1,25-dihydroxyvitamin D (calcitriol). Summer and winter values of PTH were similar (38.2 and 39.8 ng/l, respectively). 25-OH-D levels were significantly higher in summer (32.8 ng/ml) than in winter (25.4 ng/ml) after controlling for possible confounders (p < 0.0001). Calcitriol levels were significantly higher in summer (79.1 pmol/l) than in winter (73.5 pmol/l) in univariate analyses, but not after controlling for possible confounders. We conclude that healthy men show considerable seasonal changes in 25-OH-D levels even in Israel, a relatively sunny country all the year round. Summer values of 25-OH-D, were 35% higher than in winter. These fluctuations should be taken into account during evaluation of pathological conditions and in research. Given an adequate diet and vitamin D status there are no seasonal variations in PTH or in calcitriol levels.

Adverse work and environmental conditions predict occupational injuries. The Israeli Cardiovascular Occupational Risk Factors Determination in Israel (CORDIS) Study.

This study was designed to test whether the total objective adverse work and environmental conditions, expressed as the ergonomic stress level (ESL), would predict occupational injuries over a 2-year period. The study population consisted of 4,096 men from 21 factories in six industrial sectors who were studied as part of the Israeli Cardiovascular Occupational Risk Factors Determination in Israel (CORDIS) Study, 1985-1987. The ESL (assigned four levels, 1-4) was based on an ergonomic assessment which covered 17 risk factors pertaining to safety hazards, overcrowding, cognitive and physical demands, and environmental stressors. The ESL was found to be a highly reliable measure and stable over a period of 2-4 years. The incidence of injuries among workers in low ESL conditions (level 1) was 10.3%. It increased with higher ESL's: 11.7% in level 2 (relative risk (RR) = 1.13, 95% confidence interval (CI) 0.86-1.50); 21.6% in level 3 (RR = 2.09, 95% CI 1.68-2.62); and 23.8% in level 4 (RR = 2.31, 95% CI 1.85-2.88). After adjustment for age, job experience, educational level, managerial status, and occupational status (white/blue collar), injury occurrence was significantly elevated for those at level 3 (adjusted odds ratio (OR) = 1.46, 95% CI 1.12-1.91) and level 4 (adjusted OR = 1.81, 95% CI 1.39-2.37) but not for level 2 (adjusted OR = 0.87, 95% CI 0.65-1.18). The authors conclude that adverse work and environmental conditions, objectively assessed, can predict occurrence of occupational injuries.

The association between occupational lead exposure and serum cholesterol and lipoprotein levels.

OBJECTIVES: This study sought to clarify the possible associations between blood lead level and serum cholesterol and lipoprotein levels in subjects occupationally exposed to lead. METHODS: Levels of blood lead, serum total cholesterol, high-density lipoprotein (HDL) cholesterol, low-density lipoprotein cholesterol, and triglycerides in 56 male industrial employees who were exposed to lead were compared with those in 87 unexposed employees. RESULTS: Mean blood lead levels were 42.3 (+/- 14.9) micrograms/dL in the exposed group and 2.7 (+/- 3.6) micrograms/dL in the nonexposed group. The exposed subjects had higher mean levels of total cholesterol and HDL cholesterol. CONCLUSIONS: Blood lead levels are positively associated with total and HDL cholesterol.

Changes in dietary intake account for seasonal changes in cardiovascular disease risk factors.

OBJECTIVES: (1) to compare dietary intake in summer and winter time; (2) to measure the change in body mass index (BMI), blood pressure and serum cholesterol between winter and summer; and (3) to determine the relationships between seasonal differences in dietary intake and BMI, blood pressure and serum cholesterol measurements. SUBJECTS AND METHODS: Ninety-four male industrial employees were screened twice in one year, in their work place, at winter and summer time. Workers were recruited from two factories and response rate was 95%. Health-related variables, including dietary intake, blood pressure and serum cholesterol were evaluated at each season and were compared. Correlation coefficients between seasonal differences in dietary intake and in BMI, blood pressure and serum cholesterol were calculated. RESULTS: From summer to winter the mean values of BMI increase from 26.1 kg/cm2 to 26.6 (P=0.038), systolic blood pressure from 119.6 to 121.6 (P=0.025), diastolic blood pressure from 75.2 to 77.2 mmHg (P=0.001), total cholesterol from 200.8 to 208.6 mg/dL (P=0.001), LDL cholesterol from 125.2 to 134.9 (P=0.001) and HDL cholesterol from 42.7 to 44.3 (P=0.0084). Triglycerides levels decrease from 174 to 145 in the winter (P=0.03). Mean dietary intake of fat increases from 99.1 to 106.0 (P=0.0016), saturated fat from 43.6 to 46.3 (P=0.0137), polyunsaturated fat from 25.1 to 28.3 (P=0.0002), cholesterol from 462.0 to 497.9 (P=0.0313), sodium from 5778.5 to 8208.2 (P=0.0035), zinc from 11.6 to 12.3 (P=0.0001), vitamin B1 from 1.4 to 1.5 (P=0.002), vitamin D from 4.3 to 4.9 (P=0.0323) and vitamin E from 11.2 to 12.7 (P=0.0073). Significant correlation was shown between the seasonal increase in saturated fat and the increase in BMI (r=0.37), total cholesterol (r=0.21) and LDL cholesterol (r=0.29). Seasonal change in dietary cholesterol intake was significantly and positively correlated with serum total cholesterol (r=0.24) and LDL cholesterol (r=0.24). Blood pressure was not associated with nutritional intake variables. CONCLUSIONS: Dietary intake in summer and winter is different as well as blood pressure, BMI and serum cholesterol. The seasonal increase in fat and cholesterol intake at winter time is associated with changes in BMI and serum cholesterol.

Smoking cessation and body mass index of occupationally active men: the Israeli CORDIS Study.

OBJECTIVES: This study estimated weight gain after smoking cessation and identified factors attenuating this gain. METHODS: We conducted a prospective follow-up of 1209 male factory workers for 2 to 4 years. The independent variables were smoking habits. age, sports activity, education, alcohol consumption, ethnicity, duration of follow-up, and body mass index (BMI, kg/m2) at entry. The dependent variable was increase in BMI during follow-up. RESULTS: The mean age-adjusted BMI at entry into the study was 26.6 kg/m2 among past smokers and 25.4 kg/m2 among current smokers. There were no differences in BMI between those who quit less than 3 years before entry and those who quit more than 6 years before entry. During follow-up, the average increase in BMI was 0.07 kg/m2 among never smokers, 0.19 kg/m2 among smokers who had stopped smoking before entry, 0.24 kg/m2 among current smokers, and 0.99 kg/m2 among those who stopped smoking after entry. Cessation of smoking after entry predicted an increased gain in BMI; older age, a higher BMI at entry, sports activity, and alcohol consumption attenuated this gain. CONCLUSIONS: The increased rate of weight gain after smoking cessation is transient. However, the weight gained is retained for at least 6 years.

Smoking, diet, and health behaviors among lead-exposed blue-collar workers.

The objectives of the study were to compare dietary intake by smoking levels in blue-collar Israeli workers occupationally exposed to lead and thus identify additional areas for health-enhancing intervention in addition to smoking cessation. One hundred and eighty-seven male industrial employees who were exposed to lead through their work were screened at the worksite to evaluate health status and dietary intake. Smokers had higher intakes of fat, cholesterol, calcium, riboflavin, and vitamin E per day. They were consuming more meat and high-fat dairy products. Dose-response relationships were shown for fat and energy intake by smoking level. Thus, smoking is associated with other adverse health behaviors. When conducting epidemiologic or occupational studies, analyses should include adjustment for the fact that the lifestyles of smokers may also be unhealthy in other ways.

Lead exposure in battery-factory workers is not associated with anemia.

Anemia is a manifestation of lead toxicity. However, there are conflicting reports of its prevalence among lead-exposed workers, and it is uncertain whether they should be monitored by periodic hemoglobin (Hb) examinations. To explore the relationship between Hb and lead exposure, we examined the correlation between Hb, blood lead (PbB), and zinc protoporphyrin (ZPP) levels in 961 blood samples obtained from 94 workers in a lead-acid battery plant in Israel between 1980 and 1993. Blood lead levels exceeded 60 micrograms/dL (2.90 mumol/L) in 105 (14%) of the blood samples. The correlation between PbB and logZPP was 0.594. Hb levels did not correlate with PbB or ZPP. We conclude that (a) periodic Hb determinations are not a useful indicator of lead exposure in Israeli industrial workers; (b) the discrepancies between the reported correlation between PbB and Hb levels remain unexplained and in need of further study; and (c) a finding of anemia in a person with PbB levels of up to 80 micrograms/dL should be considered to be due to lead toxicity only after other causes for anemia have been excluded.

Effect of dietary calcium on blood lead concentrations in occupationally exposed and nonexposed workers.

Workers exposed to lead may benefit from a calcium-rich diet, since calcium competes with lead for intestinal absorption. We studied the effect of dietary calcium on blood lead levels. We assessed blood lead levels, dietary intake of calcium, smoking and alcohol consumption, and anthropometric and demographic data in 56 workers exposed to lead and 90 workers without such exposure. Mean intake of dietary calcium was 775 +/- 370 mg/day in the nonexposed workers and 858 +/- 423 mg/day in the exposed workers. Occupational lead exposure explained nearly 90% of the variance in blood lead levels of the entire cohort. Smoking and alcohol intake also showed significant associations with blood lead levels, but their combined effect was less than 2%. When the exposed and nonexposed workers were considered separately, no association was found between blood lead levels and calcium intake. The amount of calcium in the diet does not influence blood lead levels. Further studies are warranted to determine whether dietary calcium influences blood lead levels in exposed and nonexposed workers in other settings and in subjects with lower intakes of calcium.

Association between somatic symptoms and 24-hour ambulatory blood pressure levels.

OBJECTIVE: To clarify whether somatic complaints in healthy normotensive men are associated with differential 24-hour blood pressure and heart rate measures. METHOD: Twenty-four-hour ambulatory systolic and diastolic blood pressure was monitored in 114 healthy normotensive men, aged 28 to 63 years, engaged in similar physical work. Means were calculated for each hour, for the whole 24-hour period, and for daytime, nighttime, and work time. Subjects were interviewed about somatic complaints, demographic data, and health habits, and body mass index was measured. RESULTS: After controlling for possible confounders, a positive association was found between the somatic complaint score and 24-hour, diurnal, and work-time systolic blood pressure (p = .014, p = .007, and p = .008, respectively). The association with casual systolic blood pressure was of borderline significance (p = .089). There was a positive trend, which did not reach statistical significance, in the relationship between somatic complaint score and all measures of diastolic blood pressure. Diurnal, 24-hour, and work-time heart rates were highest in the subjects with the highest somatic scores (p < .01 for all trends). CONCLUSIONS: In healthy normotensive men, somatic complaints are associated with an increased cardiovascular load. The effects of this increase on long-term cardiovascular morbidity and mortality are uncertain and warrant additional study.

Variation in the ambulatory blood pressure response to daily work load--the moderating role of job control.

OBJECTIVES: This quasi-experimental study tested the ambulatory blood pressure responsivity to daily variation in the work load of the same workers and examined whether this responsivity is moderated by perceived job control. METHODS: The subjects were 79 nonshift, normotensive men who reported nearly almost equal occurrences of low and high work load in a typical workday. Job control was assessed by questionnaire. The workers recorded their situational work load and other parameters at each recording of ambulatory blood pressure. RESULTS: An analysis of covariance showed the main effects of both situational work load and job control on systolic ambulatory blood pressure, as well as a significant work load by job control interaction, even after control for clinic blood pressure, age, and body mass index. A blood pressure response to increased work load was observed only for workers with low job control. These workers also had a higher average systolic ambulatory blood pressure than workers reporting high control. The difference was 6.2 mm Hg (0.82 kPa) during the low workload periods and 10.2 mm Hg (1.36 kPa) during the high workload periods. A further multiple regression analysis confirmed the interaction and the main effect of job control but not that of work load, after control for work-related activities, body position, and hour of examination. CONCLUSIONS: This study showed that ambulatory blood pressure at work can fluctuate with variations in work load but only for workers with low job control. Low job control is independently associated with higher systolic ambulatory blood pressure.