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.