The assessment of the relationship between blood pressure and sodium intake using whole-day, daytime and overnight urine collections.

The usefulness of whole-day, daytime (waking to retiring time) and overnight urine samples for assessing the relationship between blood pressure and sodium intake was examined in 301 male London civil servants, aged from 37 to 58 years old. Systolic blood pressure (SBP)/diastolic blood pressure (DBP) averaged 126/78 mmHg and the 24-h urinary excretion of sodium and potassium was 174 and 73 mmol, respectively. There was poor consistency between day- and night-time urine samples with respect to both sodium and potassium content. The urinary excretion of sodium and potassium was lower (P less than 0.001) in overnight than in daytime samples. After standardization for creatinine, the night: day ratio was 0.79 for sodium output and 0.55 for potassium excretion. Blood pressure, adjusted for age and body mass index, was significantly and positively correlated with overnight sodium excretion (SBP/DBP: slope = 0.061/0.046 mmHg/mmol) whereas the correlations with sodium excretion in daytime (0.010/0.004 mmHg/mmol) and whole-day (0.024/0.016 mmHg/mmol) urine samples were not significant. Blood pressure was significantly correlated with the sodium:potassium ratio in whole-day urine (1.941/1.968 mmHg/unit). As the agreement between daytime and overnight urine samples was low with respect to both sodium and potassium content, and due to the fact that the relationship between blood pressure and sodium in overnight samples may at least partially reflect pressure diuresis, overnight urinary sodium, even if related to sodium intake, cannot be employed to assess the association between salt in the diet and blood pressure.

The relationship between plasma cholesterol concentration and minor psychiatric disturbance in the Department of the Environment Study.

We examined the hypothesis that low plasma cholesterol concentration was associated with minor psychiatric disturbance in a cross-sectional study of 410 male and 138 female civil servants. Psychiatric disturbance was measured using the 30-item General Health Questionnaire (GHQ). Mean GHQ score did not vary significantly with quartile of total cholesterol concentration. After adjustment for confounding variables a significant trend of increasing mean GHQ with increasing cholesterol concentration emerged. In a logistic regression analysis subjects in the highest quartile of cholesterol concentration had an adjusted odds ratio for being a "psychiatric case" of 2.0 (95% confidence interval, 1.1-2.5) compared with those in the lowest quartile. This relationship reversed when using a higher cutoff point to define more severe cases, although the trend was not statistically significant.

Blood cadmium in London civil servants.

Blood cadmium was measured in 466 randomly selected London civil servants not exposed to heavy metals at work. Blood cadmium ranged from 3.6 to 75.6 nmol/L (0.4 to 8.5 micrograms/L) with a geometric mean of 6.4 nmol/L (0.7 micrograms/L) in nonsmokers and 13.6 nmol/L (1.5 micrograms/L) in smokers (p less than 0.001). Blood cadmium was higher in women than in men (9.5 versus 7.8 nmol/L) and was inversely correlated with employment grade (p less than 0.001). The associations with age, body weight and alcohol intake were not significant. After adjusting for gender and the number of cigarettes smoked per day, 36% of the variance of blood cadmium was explained, while the contribution of employment grade was not significant. There was an unexpected negative relationship between serum creatinine and blood cadmium in men (r = -0.16; p less than 0.01). This was not true in women (r = +0.03), but the correlation remained present in men after adjustment for age, body mass index and smoking. In contrast, in the two sexes, the correlations between blood pressure and blood cadmium were weak and not statistically significant. In conclusion, in unexposed subjects, gender and smoking are important determinants of blood cadmium. In addition, a low level of environmental exposure to cadmium is not associated with a deterioration of renal function or an increase in blood pressure.

Predicting death from coronary heart disease using a questionnaire.

The ten-year coronary heart disease (CHD) mortality is reported for 18,322 male civil servants aged 40 to 64 according to questionnaire responses at entry into the Whitehall study. In all 1714 died, 723 from CHD. The predictive power of the questionnaire was examined with a view to its use as a screening tool in population studies. In predicting death from coronary heart disease the greatest specificity (true negative rate) was achieved with men reporting both angina (A) and a history of severe chest pain (possible myocardial infarction, PMI). This strategy (A plus PMI) achieved a specificity of 99% but a sensitivity (true positive rate) of only 7%. In contrast, in men reporting angina and/or PMI, specificity was 90% and sensitivity 29%. If this 'and/or' algorithm was extended to include the report of dyspnoea, diabetes, and/or attending a primary care physician with heart disease or hypertension, then specificity was still 85%, but sensitivity increased to 44%. This combination (11 questions in all) is therefore recommended for screening purposes. Identifying and excluding those who favour positive answers ('yes-set' responders), using questions such as the effect of weather on breathing, led to small increases in specificity but relatively large falls in sensitivity. Among subjects reporting chest pain, those who also complained of non-specific symptoms experienced only half the mortality of those with none of these additional complaints.

Aminophylline toxicity--how many hospital asthma deaths does it cause?

Aminophylline administration was compared in 43 patients who died from asthma and 43 matched controls who were admitted, suffering from acute asthma, to hospitals in the North East Thames Region. A computer program, which used information about individual characteristics, medical history and drug intake, was employed to calculate the serum theophylline levels which were likely to have resulted from the hospital treatment each patient received. Toxic theophylline levels were estimated to have occurred in 21% (9/43) of fatal cases and 7% (3/43) controls. Details of four patients who died when their serum theophylline levels were likely to have been very high are presented. Six fatal cases suffered gastro-intestinal bleeds during their final illness: four of these had theophylline levels which were calculated to have been toxic at the time of bleeding.

Controlled investigation of deaths from asthma in hospitals in the North East Thames region.

One hundred and thirty deaths definitely or potentially due to asthma occurring in hospitals in the North East Thames region over one year were identified from death certificates and Hospital Activity Analysis records. Thirty five of these deaths were considered after independent assessment to have been directly due to asthma. Control patients who left hospital alive after acute asthma attacks were selected and matched with cases for sex, age, and hospital. Management was compared in the two groups. Inadequate monitoring, including failure to monitor arterial blood gas values, and inadequate use of nebulised beta agonists occurred significantly more often in fatal cases. Use of sedation, inadequate treatment with steroids, exposure to potentially toxic doses of aminophylline, and inadequate clinical assessment were more common in cases than controls, but not significantly so. Failure to institute artificial ventilation contributed to seven deaths. Assessors considered important defects in management to have occurred in 83% (29/35) of the cases and 40% (14/35) of the controls. Nevertheless, most of the hospital deaths (19/35) were considered not to have been preventable. Eight other deaths in the region were attributed to the complications of asthma or its treatment. Three of these were associated with gastrointestinal bleeding and one with perforation of a duodenal ulcer. Before considering policies aimed at speeding admission to hospital of patients with acute attacks of asthma it is crucial that the general standard of hospital care offered to all patients with asthma should be improved.

The epidemiology of polycythaemia rubra vera in England and Wales 1968-1982.

The epidemiology of polycythaemia rubra vera (PV) has not been studied extensively in the past. In 1968 PV became subject to cancer registration in England and Wales. The mortality rates and registration rates for PV were abstracted for 1968-1982. The average annual mortality rates were 3.0/million/y (men, 1068 cases) and 2.3/million/y (women, 886 cases), there being no significant increase over the time period. The average annual registration rates were 10.7/million/y (men, 3321 cases) and 6.7/million/y (women, 2207 cases) and showed a large increase from 1968 to 1974 with a stable rate subsequently. This increase was concentrated in the 65+ age groups. The median age of registration was 60--64 y with a peak of mortality and incidence between ages 75 and 84 y. The data suggest some degree of overdiagnosis for PV registrations, however the rates are comparable with those seen in other studies in developed countries. The routine data sources require further validation, but they appear to provide useful information for the study of the epidemiology of PV.

Why do some people look older than they should?

BACKGROUND: As a component of studies on biological age, the age of subjects from their appearance (perceived age) was estimated. OBJECTIVE: To determine the factors associated with looking older. METHODS: Cross sectional study of London civil servants (318 men, 129 women) in the Department of the Environment study. Perceived age was recorded by an observer and the difference between this age and chronological age was analysed according to 20 different variables. RESULTS: Men had an average perceived age of 0.37 years older than their actual age and women a perceived age of 0.54 years younger. In men, looking older was related to greying of the hair, grade of arcus senilis, and grade of baldness. Less expected, looking older was positively related to total serum cholesterol (p=0.03) and blood haemoglobin (p<0.01). In women, looking older was related to greying of the hair, positively to blood erythrocyte sedimentation rate (ESR), and negatively to serum bilirubin (p=0.01). Looking older was not related to alcohol consumption, employment grade, serum high density lipoprotein cholesterol, glucose, albumin, and calcium in either sex. CONCLUSION: The relationships between looking older and total cholesterol and haemoglobin in men and ESR and bilirubin in women, require further investigation.

Prognosis in adult asthma: a national study.

Although one million people consult their general practitioners for asthma each year, data on the prognosis of this disease are scarce, particularly in adults. Mortality was studied among 2547 adult asthmatics attending a national sample of 60 general practices between 1970 and 1976; they were compared with a matched group of non-asthmatic patients. Mortality from all causes was significantly raised in the asthmatic cohort (189 deaths v 112 among controls; relative risk 1.61, 95% confidence interval 1.3 to 2.0), especially in women (92 v 42 deaths; relative risk 2.2 (1.5 to 3.1)), and in the oldest age group (55-59 years). In both sexes the predominant cause of excess mortality was respiratory disease, particularly asthma (25 v 0 deaths) and chronic obstructive airways disease (37 v 4 deaths; relative risk 8.8 (2.8 to 23)). Overall, 94% of the asthmatic cohort survived the mean follow up period of eight years compared with 96% of the controls. In contrast to previous findings, the risk of death due to malignant neoplasms was not significantly reduced overall (34 v 36 deaths), though the risk was significantly reduced among those aged under 45 years (2 v 10 deaths; relative risk 0.2 (0.02 to 0.9)) and there was a significant trend of lowering of relative risk with younger age (p less than 0.01).

Age differences in biochemical and hematological measures during middle age.

Biochemical and hematological measures possibly associated with ageing were measured on a single occasion in 3402 male and 2152 female London Civil Servants aged from 35 to 59 years of age. These included erythrocyte sedimentation rate (ESR), blood hemoglobin and serum albumin, calcium, bilirubin, creatinine, urea, urate, high density lipoprotein (HDL), and total cholesterol. Independently and positively related to age were ESR with an estimated 47% 'increase' in men over the 15 years between ages 40 to 55 and a 40% increase in women; serum urea had a 6%/15-year increase in men and 20% in women; total cholesterol had a 6%/15-year increase in men and 18% in women; serum creatinine 'increased' by 2%/15-years in men and 5% in women. In women, urate, HDL cholesterol and hemoglobin increased with age group. Negatively related to age was serum bilirubin in both sexes (8% and 6% 'fall'/15-years in men and women respectively). Serum albumin and calcium fell with age group in men. The sexes differed in their relationship to aging for total cholesterol and HDL cholesterol (greater increase in women), serum calcium (small decrease in men and small increase in women), urate and hemoglobin (increases in women but not men). Urea increased more in women than men, and albumin decreased more in men than women (p < 0.001 for all comparisons with the exception of HDL cholesterol, p < 0.01). Changes during the menopause were thought to explain some of these findings.

The assessment of biological age: a report from the Department of Environment Study.

Indicators of ageing were measured in 397 male and 130 female London Civil Servants aged from 37 to 58 years of age. Grey hair, skin inelasticity, and arcus senilis were strongly and independently related to chronological age. Also independently related were serum albumin (negatively related in both sexes), baldness, serum creatinine, systolic blood pressure, serum calcium (negatively) and ESR in men, and serum cholesterol in women. Chronological age was regressed on the above variables for men and women separately to provide regression equations. Biological age for an individual was calculated by entering his or her results and calculating the residuals. Biological age in those who stopped smoking tended to be younger than chronological age by an average of 12-13 months in men and 1-4 months in women. Men and women who had never smoked had higher biological than actual ages but not after adjusting for regression dilution bias. Men who currently smoked had higher biological ages of 2-3 months but not women smokers (4-6 months lower). Similarly, men of lower employment grades had an average biological age 13 months older and women 8 months, compared with higher employment grades. These differences between employment grade appeared to be due to ESR, arcus senilis, systolic blood pressure and serum cholesterol. These four measurements may be markers of biological rather than chronological age, and the value of attempting to measure biological age is discussed.

Psycho-emotional stress and salt intake may interact to raise blood pressure.

AIM: This study examined whether work-related aspects of stress, alone or in association with a high salt intake, are associated with a raised blood pressure. METHODS: A total of 384 male civil servants (35-51 years) collected a 24h urine sample and were interviewed using measures of work-related stress. Their blood pressure was taken at a civil-service medical clinic and was self-measured at home. RESULTS: Systolic/diastolic pressure averaged ( +/- SD ) 135 +/- 19/84 +/- 14 mmHg at the clinic and 123 +/- 16/80 +/- 11 mmHG on self-measurements at home. The 24h urinary sodium excretion was 172 +/- 65 mmol. The overall stress score was categorized as low in 98 men, medium in 193 men and high in 93 men. Stress itself was not associated with an elevated pressure. However, in multivariate analyses with adjustments for age and body mass index, a stress-sodium interaction in the determination of the clinic systolic (P = 0.05) and diastolic (P = 0.08) pressure became apparent. At a sodium excretion of 100 mmol/24h (10th percentile), increasing stress from low to high was associated with a fall in pressure, averaging 4.5 mmHg for systolic pressure and 1.4 mmHg for diastolic pressure. By contrast, at 250 mmol/24h (90th percentile) the same stress increase was associated with a rise in pressure of 6.3 mmHg systolic and 5.9 mmHg diastolic. CONCLUSION: The present study suggests that sodium intake and work-related stress may interact to determine blood pressure. This interaction is probably dynamic in nature, so that the contribution of each factor to blood pressure can only be determined if both are measured.

Fibrinogen: a possible link between social class and coronary heart disease.

Mortality from coronary heart disease in civil servants in the lowest grade of employment has been found to be about three times that of men in the highest grade of employment. As part of an investigation of this finding several haemostatic variables were measured in a sample of 29 men in lower grades of employment and 45 men in higher grades. There was a significant difference in plasma fibrinogen concentrations between men in lower grades of employment and those in higher grades (mean 3.39 g/l v 2.95 g/l, respectively; p less than 0.01) but not in other haemostatic variables. Multiple regression analyses showed significant independent associations of fibrinogen concentration with smoking (p less than 0.05) and grade of employment (p less than 0.05). The size of the observed difference between the grades of employment was similar to that between those dying of coronary heart disease or surviving during longitudinal study; it may therefore be an important part of the mechanism underlying social class differences in coronary heart disease. The statistical relation between fibrinogen concentrations and other characteristics that may be concerned in the aetiology of coronary heart disease was examined. A summary measure of job stress was significantly related to fibrinogen concentration (p less than 0.01) and made a substantial contribution to explaining the differences between grades of employment. Behaviour type and a score of physical activity were not significantly related to fibrinogen concentration.

The relationship between both sodium and potassium intake and blood pressure in London Civil Servants. A report from the Whitehall Department of Environment Study.

The relationship was examined in 459 male London Civil Servants between the casual lying systolic and diastolic (phase V) blood pressures measured in the clinic, and 24-hr urinary sodium and potassium excretion collected an average of 6 weeks later. Systolic and diastolic pressures, after adjusting for age and weight, were both negatively associated with the 24 hr potassium excretion (r = -0.17 [p less than 0.001, 95% confidence limits -0.07, -0.27) and r = -0.11 (p less than 0.05, 95% CL 0.00, -0.21) for systolic and diastolic pressure respectively]. Adjusted systolic but not diastolic pressure was also negatively associated with plasma potassium estimated at the time of blood pressure measurement (r = -0.15, p less than 0.001, 95% CL -0.06, -0.24). In 159 female London Civil Servants both systolic and diastolic pressures were negatively correlated with plasma potassium. However, there was no evidence for a negative relationship between urinary potassium excretion and blood pressure in women. Urinary sodium excretion was not related to blood pressure either in men or women. Blood pressure was also measured by the subjects at home over a one week period during which time the urine collection was made. There was no evidence for an association between blood pressure measured at home 6 weeks after the time of drawing blood, and plasma sodium. On the other hand, in men, the negative relationship between blood pressure and urinary potassium excretion was consistent and independent of the time and place of measuring blood pressure. This is consistent with a true effect of diet, a low potassium intake being associated with an increased blood pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood lead concentration, renal function, and blood pressure in London civil servants.

Blood lead concentration was measured in 398 male and 133 female London civil servants not subject to industrial exposure to heavy metals. The relation between blood lead and serum creatinine concentrations and blood pressure were examined. Blood lead concentration ranged from 0.20 to 1.70 mumol/l with a geometric mean concentrations of 0.58 mumol/l in men and 0.46 mumol/l in women (p less than 0.001). In women blood lead concentration increased with age (r = +0.27; p = 0.002). In the two sexes blood lead concentration was positively correlated with the number of cigarettes smoked a day (men r = +0.17 and women r = +0.22; p less than or equal to 0.01), with the reported number of alcoholic beverages consumed a day (men r = +0.34 and women r = 0.23; p less than 0.01), and with serum gamma-glutamyltranspeptidase (men r = +0.23 and women r = +0.14; for men p less than 0.01). Blood lead concentration was not correlated with body weight, body mass index, and employment grade. In men 14% of the variance of blood lead concentration was explained by the significant and independent contributions of smoking and alcohol intake and in women 16% by age, smoking, and alcohol consumption. In men serum creatinine concentration tended to rise by 0.6 mumol/l (95% confidence interval from -0.2 to +1.36 mumol/l) for each 25% increment in blood lead concentration. In men and women the correlations between blood lead concentration and systolic and diastolic blood did not approach statistical significance. In conclusion, in subjects not exposed to heavy metals at work gender, age, smoking, and alcohol intake are determinants of blood lead concentration. At a low level of exposure, lead accumulation may slightly impair renal function, whereas blood pressure does not seem to be importantly influenced. Alternatively, a slight impairment of renal function may give rise to an increase in blood lead concentration.