Influence of Lifestyle, Coping, and Job Stress on Blood Pressure in Men and Women

Lifestyle-related factors such as obesity, drinking habits, diet, and physical inactivity are well established determinants of high blood pressure (BP).¹ In contrast, the role of chronic workplace stress on long-term BP regulation and the predisposition to hypertension remains unclear.² Although various facets of psychosocial job stress have been studied,³⁴⁵ the findings have been inconsistent,⁶⁷⁸ and with few exceptions,⁹¹⁰ previous studies have not considered whether any relationships shown between work stress and BP could be mediated by lifestyle changes such as drinking, eating, and exercise habits known to directly influence BP.¹ So-called lifestyle behaviors are themselves influenced by strategies people use to cope with stress. Some such strategies may be considered “maladaptive” or harmful to health (eg, alcohol/drug abuse, smoking, binge eating, interpersonal withdrawal), whereas others are “adaptive” and conducive to better physical and psychosocial health (eg, exercising, relaxing, seeking external social support, or organizing work time better).

We therefore designed the present study to determine whether there was any direct association between perceived work stress and BP or whether there were indirect effects perhaps mediated by coping mechanisms and their influence on dietary and other lifestyle factors. These two conceptual models are illustrated in the Figure. The study was carried out in a population of male and female tax office workers considered by their employers and unions to be working under relatively high levels of stress.

Methods

Subjects

Volunteers (n=831, 62% of available staff) aged between 17 and 64 years from an Australian government tax office were screened. Ten subjects withdrew after initially consenting, and 41 subjects being treated for hypertension were subsequently excluded. To avoid any confounding effects of ethnic behavior on psychosocial relationships with BP, we excluded a further 126 subjects of non-Caucasian origin (125 Asian and 1 of other ethnic origin) from the analyses, as they showed significant differences in a range of lifestyle factors. Thus, 337 men and 317 women participated in the study.

Measures

Before attending an on-site health screening program, subjects completed two self-report questionnaires. The first measured job-related stress and stress-related coping strategies (Occupational Stress Indicator, or OSI¹¹ ) and was administered in group sittings of 20 to 30 employees during working hours in the workplace. The OSI measure reflecting potential sources of both job and home aspects of pressure¹¹ is derived from previous research that has identified the major sources of occupational stress.^12131415 In the design of the OSI, 61 sources of stress are organized into six subscales (“factors intrinsic to the job,” “the managerial role,” “relationships with other people,” “career and achievement,” “organizational structure and climate,” and “home/work interface”). The respondent is asked to rate each potential source of pressure they perceive using a 6-point Likert-type scale ranging from “very definitely is not a source of pressure” to “very definitely is a source of pressure.”

For the OSI stress-related coping scales, the respondent is asked to rate the use of 28 coping strategies using a 6-point Likert-type scale (ranging from “never used by me” to “very extensively used by me”), with a higher score on each item indicating a more adaptive coping style. In addition to the OSI stress-related coping scales, we included nine items in the current study to explore the extent to which respondents pursued various lifestyle strategies as a means of coping with stress. The items (“exercise,” “eat frequently,” “drink coffee, tea, or smoke,” “have an alcoholic drink,” “take analgesics,” “use tranquilizers or other medicine,” “use humor,” “use relaxation techniques,” and “take positive time out”) were adapted from Hingley and Cooper's¹⁶ coping questionnaire and were scored in a manner similar to that of the OSI items. A second questionnaire that assessed demographic characteristics and health and lifestyle factors was completed by employees at home to remove the association of the workplace environment and to reduce work time lost. These measures were adapted from lifestyle questionnaires that had been extensively used in population¹⁷¹⁸¹⁹ and intervention²⁰²¹ studies and are particularly related to alcohol consumption, smoking habits, physical activity, and prescription and nonprescription drug usage. Five questions assessed the frequency of alcohol consumption, the type of beverage, and the usual amount consumed. Alcohol consumption for beer, wine, or spirits was assessed by a 7-day retrospective diary.²² Beverage consumption was converted to an estimate of milliliters of pure ethanol consumed with the use of the conversion factors for beer, wine, and spirits recommended for use in Australia. Current and past smoking habits were recorded with respect to the type and quantity of tobacco smoked per day. The quantity smoked per day was then converted into grams smoked per week. The subjects were classified as smokers or nonsmokers according to whether they currently smoked at least one cigarette per day. Physical activity was assessed by questions on the frequency of vigorous exercise covering a wide range of activities (and scored as the number of days per week in which any such activity was performed). Respondents rated the frequency of consumption of meat, animal fat, sweets/starch, vegetables, fruit, salt, dairy products, eggs, and fish. A separate question solicited the average component of the total weekly diet consisting of whole foods (whole grains, fresh fruit, vegetables, and salads).

In a standardized screening program, seated BP was measured seven times at 2-minute intervals on two occasions 1 week apart. Subjects rested at least 10 minutes before BP measurements; a Dinamap 1846SX/P oscillometric recorder was used. The ambient room temperature was held constant at around 21°C on both occasions, and measurements were made at approximately the same time of the day (between 8 am and 1 pm) for any individual. BPs were assessed with subjects in a nonfasting state to avoid the stress of hypoglycemia. Subjects were asked to abstain from cigarettes, coffee, tea, and vigorous exercise for at least 2 hours before the BP measurements to minimize the variability of these extraneous influences on BP levels.^18192324 The averages of the sets of seven BP readings from each of the two occasions were used for the analysis.

Body mass index (BMI) was used as a measure of overall obesity. Body weight was measured on both occasions (with subjects in light clothing and without shoes) and BMI calculated as mean weight (kilograms) divided by height (meters squared).

Statistical Analyses

The five OSI subscale scores dealing with job-related stress were averaged to form a single job-stress score, and the home/work interface subscale was retained as a measure of home/work stress (the split half reliability coefficients for job stress were .89 for men and .91 for women and for home/work stress were .81 and .83 for men and women, respectively).

Factor analysis was used for identification of broad dimensions of coping behaviors, as defined by the linear combination of the 37 coping items. Principal components extractions followed by orthogonal Varimax rotation were performed separately for men and women to allow differences in coping strategies to be expressed.^25262728 Preliminary analyses using the default option (ie, eigenvalues ≥1) provided an initial estimate of the maximal number of factors. The 10 factors extracted for men and 8 for women included some factors with only one or two items loading above 0.4, so alternative solutions with fewer factors were tried. More than 5 factors resulted in some trivial factors defined by 2 or fewer items, and fewer than 5 factors resulted in items with split loadings and hence less interpretable factors. Hence, for both men and women, 5-factor solutions were readily interpretable and retained robust factors, with similar definitions for men and women. The number of items comprising the factors ranged between 4 and 10 for men and 4 and 9 for women. Items with structure loading coefficients less than .40 (16% of item variance) were not retained, resulting in factors loading 31 items for men and 29 items for women (the split half reliability coefficients for these scales ranged from .52 to .72 for men and .52 to .79 for women).

Three adaptive and two maladaptive coping dimensions were identified for men and women. The first dimension of coping was considered to represent a rational approach to stress (eg, plan ahead, practice effective time management, reorganize work) and was designated “solution-oriented” coping. The second dimension included coping strategies involving positive external techniques (eg, have stable relationships, resort to hobbies and pastimes, seek as much social support as possible) and was interpreted as “external/social” coping. The third dimension was characterized by drug use for men or drug and food use for women (eg, have an alcoholic drink, eat frequently, drink coffee or tea, or smoke) and was termed “consumption behavior” coping. The fourth dimension was defined more by positive individual internal and external coping techniques (eg, use relaxation techniques, take positive time out, delegate) and was designated as “positive attitudinal” coping. The fifth dimension was characterized by coping strategies that involved denial or a tendency to focus attention away from a stressor (eg, suppress emotions, use distractions to take mind off things, stay busy) and was interpreted as “avoidance/denial” coping. Averaged factor scores were used in subsequent analyses of the effects of coping strategies on BP.

Dietary items were reduced by principal components extraction with Varimax rotation into a relatively more healthy eating pattern (fruit, vegetables, whole foods, and fish) and a less healthy or potentially atherogenic eating pattern (animal fat, meats, sweets/starch, salt, eggs, and dairy products) for men and women separately. The factor loadings showed a similar pattern for men and women, providing a rationale based on statistical grounds for repeating the factor analysis with men and women combined. The two extracted factors accounted for 42% of the total variance of the 10 food items for men and women combined (the split half reliability coefficients for the more healthy eating pattern were .62 for men and .63 for women and for the less healthy eating pattern were .51 for men and .50 for women). Gender differences in BP, job stress, lifestyle factors, and BMI were compared with two-tailed unpaired t tests for continuous variables and the χ² test for categorical variables. Pearson correlation coefficients were calculated for unadjusted associations between lifestyle and job and home/work stress, coping with job and home/work stress, lifestyle and coping, and job and home/work stress with BP. Multiple regression analyses with fixed-order or hierarchical entry were used, with physical measures (age, BMI) entered ahead of lifestyle and psychological measures. One analysis examined whether the association of stress (job stress and home/work stress scores) with age-adjusted BP was mediated by a fixed block of lifestyle factors (alcohol, smoking, exercise, and diet). We also used regression analyses to explore whether the association between stress (job stress and home/work stress scores) and BP was mediated by a fixed block of coping behaviors (solution-oriented, external/social, consumption behavior, positive attitudinal, and avoidance/denial) after adjustment for age. Finally, we constructed multivariate models to examine whether there was an association of stress with age-adjusted BP after including both lifestyle factors and coping behaviors. The fixed block of lifestyle factors was entered before the fixed block of coping behaviors, which in turn was entered before the fixed block of stress variables. Dummy coding was used for smoking status (nonsmoker=0; smoker=1), and a 4-point ordinal scale was used to categorize weekly alcohol consumption. Alternative regression analyses compared the 4-point ordinal scale with dummy variables for alcohol consumption. The results were similar, and the tabled results are for the ordinal scales. For all tests, an α level of .05 was used.

Results

Male and Female Characteristics

Table 1 summarizes gender differences on sample characteristics, lifestyle factors, and job and home/work stress. Average age and BMI levels were similar in men and women. Men had higher average systolic BP (by 8 mm Hg) and higher diastolic BP (by 3 mm Hg) than women. Men reported exercising more than women. Men were more likely to be drinkers, drank more alcohol, and showed higher scores for unhealthy and lower scores for healthy eating patterns. Smoking habits did not differ significantly between men and women.

Examination of the overall job stress or home/work stress scores showed no significant male/female differences.

Correlations of Lifestyle, Coping, and Stress with BP

Table 2 shows simple correlations between BP measures and scores for BMI, lifestyle factors (smoking, alcohol, exercise, and diet), coping behaviors, and job and home/work stress for men and women. Significant univariate relationships are summarized below.

Lifestyle Factors

BMI correlated with BP in both sexes. Exercise was negatively correlated with diastolic BP in both men and women and with systolic BP in women. Average weekly alcohol consumption was significantly correlated with both systolic and diastolic BPs in men.

Job and Home/Work Stress

Overall job stress or home/work stress and unadjusted BP were not significantly correlated in either men or women.

Coping Behaviors

In men, there was a significant negative relationship between external/social behavior and diastolic BP. Women showed significant inverse correlations between positive attitudinal behavior and systolic and diastolic BPs.

Relationships Between Lifestyle, Coping, and Job and Home/Work Stress

There were a number of important relationships between stress, coping mechanisms, and lifestyle (Table 3). In men, both job and home/work stress correlated with drinking status and with consumption coping and avoidance/denial coping. Home/work stress also correlated with unhealthy eating in men. In women, lifestyle factors and sources of stress were not significantly correlated. Avoidance/denial coping behavior was correlated with job stress in women, as for men.

Coping factors were correlated with a number of independent measures of lifestyle (Table 4). In men and women, external/social coping and positive attitudinal coping were positively correlated with exercise habits. Consumption behavior in men and avoidance/denial in women were negatively correlated with exercise. Consumption behavior was also correlated with alcohol intake and inversely related to healthy eating habits. Solution-oriented behavior was related to healthy eating in men and women.

Multiple Regression Analyses

We used multiple regression analyses to determine whether there were independent effects of work-related stress, a block of lifestyle factors (alcohol, smoking, exercise, and diet), and BMI on age-adjusted BP. In separate analyses, we then examined for any additional effect of a block of coping behaviors (solution-oriented, external/social, positive attitudinal, consumption behavior, and avoidance/denial).

Stress, Lifestyle, and BP

Initial multiple regression analysis examined the effects of stress (job and home/work stress scores), BMI, and a block of lifestyle characteristics (alcohol, smoking, exercise, and diet) on BP. The results showed that after adjustment for age, BMI made the largest contribution to the variance of systolic and diastolic BPs in both men (P<.01) and women (P<.01). The block of lifestyle factors independently contributed to the variance of systolic BP (P=.02) in men. There were no independent effects of job or home/work stress on BP.

Stress, Coping, and BP

A second multiple regression analysis examined the effects of stress (job and home/work stress scores) and coping behaviors (solution-oriented, external/social, consumption behavior, positive attitudinal, avoidance/denial). After adjustment for age, the block of coping behaviors contributed to diastolic BP (P=.01) in men. There were no significant associations between job or home/work stress and BP in men or women.

Stress, Lifestyle, Coping, and BP

A third multiple regression analysis examined whether there was any association between work-related stress, coping, and BP after adjustment for age, BMI, and lifestyle (Table 5). After adjustment for age and BMI, the block of lifestyle factors still made a significant contribution to systolic (P=.02) and diastolic (P<.01) BPs in men. The additional block of coping behaviors was significantly associated with diastolic BP (P=.01) in men. Again, there were no significant associations for stress and BP.

Discussion

We designed this study to determine whether work-related stress was directly or indirectly related to resting BP levels in office workers. Although the results provide no evidence for a direct effect of perceived job stress on BP, they do suggest that there may be indirect influences consequent on the strategies used to cope with stress. Thus, measures of job stress were significantly related to a number of coping mechanisms influencing lifestyle factors, such as alcohol consumption, physical inactivity, and dietary habits, that with obesity were the dominant factors associated with BP levels in both men and women. Relationships between job stress and maladaptive or unhealthy coping behaviors were more clearly demonstrated in men than women, particularly with respect to excessive consumption behavior (food, cigarettes, and alcohol) and denial of stress. Men reported higher levels of alcohol consumption and unhealthy eating and lower levels of healthy eating than women. Men also showed significant associations between job stress, drinking status, and unhealthy eating patterns. Hence, if there are any influences of job stress on BP in this population, they are likely to be indirectly mediated through coping mechanisms and associated lifestyle changes, as illustrated in the Figure (B). The data suggest that although obesity and other known lifestyle factors are dominant as regards their effect on BP, coping strategies used to deal with perceived stress are important additional intermediaries and should be targeted in any behavioral change programs.

The workers in this study were all government office employees in predominantly white-collar occupations. The absence of a direct relationship between work-related stress and BP supports some⁷⁸ but not all³⁴⁵ previous investigations. Another study⁶ found no relationship between sources of work stress and casual systolic BP in white- and blue-collar workers from the Australian Taxation Office, Telecom Australia, and Australian Post. However, in a study examining interactions among job stress, lifestyle, and ambulatory BP, Schnall et al²⁹ reported an interaction between alcohol consumption and job demand/decision latitude in North American male workers across a range of occupations, such that BPs were raised only in men in high-demand/low-control situations who were also regular drinkers. Other lifestyle factors were not recorded in such detail as in the present study, but the interaction described may reflect a predominant lifestyle effect (alcohol drinking) resulting from a stress-related coping mechanism rather than a direct work stress affecting neuroendocrine control of BP.

Although the present study was not conceived with the use of the Karasek job-strain model,³⁰³¹³² the questionnaires included two questions that directly assessed perceived job demands relative to decision-making capacity. However, responses to these questions revealed no evidence to support a relation between BP and a high job strain/low decision-making work situation in the present study. With the use of similar abbreviated measures in a 5-year prospective study of the effects of chronic perceived stress on casual BP change among 2634 Australian government employees, Chapman et al³³ could find little support for an effect of the job strain model when using obesity, physical fitness, and alcohol consumption as covariates. Moreover, two other studies³⁴³⁵ that did use Karasek's job strain measures were also unable to find any relation between the interactive effects of job demand relative to job control on BP elevation using casual BP readings.

Resting measures of BP are sufficiently sensitive for the detection of associations with factors stemming from relatively established and stable lifestyle patterns.³⁶ The question asked in the present study was whether perceptions of chronic work stress affected resting BP levels implicitly by an effect on long-term neuroendocrine regulation. We therefore considered it appropriate to use a series of seated BP measurements recorded on 2 separate days as an indication of casual BP, thus providing a more rigorous estimate of BP than single casual pressures frequently used in the classification of hypertension.³⁷ However, the information provided by ambulatory BP readings could yield different but complementary results, both in relation to more acute effects of job stress and in relation to overall BP “load” during working activities, at home, or during sleep.³⁸ However, concurrent physical activity or recent smoking and coffee consumption may also strongly influence ambulatory pressure recordings,^18192324 making the assessment of stress-related effects on resting BP more difficult. In one such study,³⁹ job strain was unrelated to casual office BP measurement but was related to ambulatory BP during work and during the hours at home subsequent to work. Similarly, Light et al⁴⁰ found that in men, high job strain was not correlated to casual BP but was associated with mean ambulatory BP levels taken over an 8-hour work day. Two recent studies seem to indicate that the association between job strain and ambulatory BP seems to be more evident in men than in women.³⁹⁴⁰ Problems in evaluating the role of chronic stress on cardiovascular health are further compounded by difficulties in defining and measuring stress and possible interactions among stress, coping mechanisms, and lifestyle. The present study attempted to deal with these issues by careful evaluation of lifestyle characteristics known to influence BP, the use of rigorously standardized measurement of resting BP, and the use of well-validated multidimensional scales for assessing perceived job stress and coping mechanisms. These scales record perceptions of work stress and their considered approaches to coping with stressful situations. The difficulty in defining and measuring concepts such as stress and coping cannot be underestimated, but the factors defined by the principal components analysis of the coping strategies seem to make sense in the way they related to the measures of job stress and lifestyle.

As mentioned above, most studies of the relationship between job stress and BP have looked for direct effects of perceived stress while ignoring the possible mediating influences of lifestyle factors or coping behaviors. The present study examined in some detail the manner in which people reported coping with stress at work or the home/work interface. Using factor analysis, we were able to characterize five patterns of coping likely to be either beneficial or deleterious to physical or mental health. Men in particular reported a greater use of maladaptive coping behaviors in response to work-related stress in the form of excessive drinking, excessive consumption of a range of foodstuffs and/or cigarettes, and avoidance or denial of stressful work situations. The observation that in multiple regression analysis “coping” remained an independent predictor of diastolic BP in men after adjustment for age and other lifestyle factors may have reflected the adoption of excessive drinking and unhealthy eating habits in response to stress. In women, on the other hand, avoidance/denial coping was positively correlated to job stress, whereas interestingly, the positive attitudinal coping mechanism was inversely related to BP levels. In women, the overall mean scores for job stress and stress at the home/work interface were similar to those in men.

We undertook assessment of stress using the OSI job stress questionnaire, which has been used to comprehensively assess organizational stress and coping.¹¹ The population studied was relatively homogeneous in socioeconomic and cultural terms. As government employees working in a tax department, the subjects were considered by union and management to be working under a high level of stress before and during the 10-week study because of restructuring toward multiskilling and annual tax return deadlines. No OSI data from Australian samples have been reported in the literature, but the present population had higher mean scores (men, 33.5; women, 32.9) on overall job pressure than a sample of either British male middle managers (28.6) or American female bank clerical workers (31.2). Although the results cannot necessarily be extrapolated to other occupational groups or cultures, it is likely that this group of tax office workers was fairly typical of predominantly white-collar public servants in Australia, and there is no reason to believe that the stresses and behaviors would differ greatly in similar occupational groups in Western countries of similar socioeconomic status. The results are also in accord with a recent North American study in which no direct relationship was found between job stress and other cardiovascular risk factors.⁴¹

The present study included measures concerning the effect of work on home life, designated the home/work interface. These showed no relationship with BP. However, a more comprehensive evaluation of the effects of home-related stress on coping mechanisms and lifestyle behaviors could be of importance in light of the positive findings here. Two reports¹²⁴¹ have suggested that home stress may be a factor influencing BP in women, particularly working married women who experience dual work and family roles; this area warrants further examination in different working populations. Furthermore, a major deficiency in research in various facets of psychosocial stress and BP has been the relative paucity of data on women.⁴²⁴³

In summary, the results of this study suggest a conceptual model (see Figure, B) in which resting BP levels are determined not by the direct effects of job stress but may be influenced indirectly by adaptive or maladaptive coping mechanisms that determine dietary and related lifestyle habits known for their direct effects on BP control. Programs designed to prevent hypertension in the workplace should therefore focus not only on the working environment but also on the way individuals perceive and cope with stress insofar as this influences behaviors directly predisposing to hypertension. Gender differences in coping mechanisms should also be addressed. However, workplace stress is likely to be only one determinant of high BP and lifestyle behaviors, with home stress, nurture, culture, and genetics being other, possibly more important, factors in many instances.

Reprint requests to Prof L.J. Beilin, University Department of Medicine, Medical Research Foundation Bldg, GPO Box X 2213, Perth, Western Australia 6000.

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