163 INFLUENCE OF WORK STRESS ON SEASONAL VARIATION OF BLOOD PRESSURE IN MEN-DIFFERENCE BETWEEN NORMOTENSION AND MILD HYPERTENSION

Abstract

Objective: The aim of the study was to examine if 1) seasonal blood pressure variation differ between normotension (NT) and mild hypertension (MH), and if 2) work stress influences such variation. Methods: We studied 114 male hospital employees (38.1 ± 4.4 yrs). Anthropometric parameters, supine blood pressure, heart rate and fasting blood were studied in summer and winter. The difference between winter and summer was defined as seasonal variation. Subjects were classified as NT and MH groups by the cut-off values of 130/85 mmHg. Score of skill underutilization by NIOSH stress questionnaire was used as a measure for work stress. Each group was dichotomized by the median value of work stress. Results: From summer to winter, SBP increased in NT (116.1 ± 6.9 vs. 119.1 ± 10.8 mmHg, p < 0.01) but decreased in MH (138.6 ± 9.2 vs. 133.8 ± 11.6 mmHg, p < 0.05). In MH group, the decrease in SBP was related to an increase in uric acid (p < 0.05) but was not related to any hormonal or anthropometric parameters. The ANCOVA showed that high work stress group showed a smaller reduction in SBP than low work stress group (0.3 ± 3.0 vs. -7.6 ± 0.3 mmHg, p < 0.05). In NT group, the increase in SBP during winter was related only to an increase in body weight and was not influenced by work stress. Conclusions: Systolic blood pressure elevation during winter seen in NT group is counteracted in MH group possibly through volume control mechanism, which may be impaired by work stress.