Association between workplace social capital and systolic blood pressure among 23 173 workers at 367 small-sized and medium-sized enterprises in Japan: a cross-sectional study

Objectives Social capital (SC) has been shown to be inversely associated with elevated blood pressure. While SC in the workplace may also be associated with blood pressure, it has not been extensively studied. We aimed to investigate the association between workplace SC and systolic blood pressure (SBP).Design A cross-sectional study.Setting 367 small-sized and medium-sized companies in Japan.Participants A total of 23 173 participants (15 991 males and 7182 females) aged >= 18 years.Exposure of interest SC was assessed using individual responses to eight 4-point Likert questions used in the Brief Job Stress Questionnaire. Workplace SC was assessed as the mean of individual-level responses to the SC questions from those working in the same company.Outcome measure Systolic blood pressure (SBP)Results A multilevel linear regression model revealed that higher workplace-level SC was linked with lower SBP (coef.=-0.53 per 1SD increment in workplace SC, 95% CI=-1.02 to -0.05) among females in the age-adjusted model, which remained statistically significant after adjusting for other covariates. After adjusting for individual-level SC, this association was attenuated and became non-significant (coef.=-0.41, 95% CI=-0.87 to 0.05), while individual-level SC was inversely associated with SBP (coef.=-0.43, 95% CI=-0.73 to -0.13). Among males, we did not find any evidence of significant inverse associations either in relation to workplace SC (coef.=-0.12, 95% CI=-0.46 to 0.21) or individual-level SC (coef.=0.19, 95% CI=-0.01 to 0.39).Conclusions Our study findings suggested that workplace-level SC can affect SBP differently by sex.