Managerial leadership and ischaemic heart disease among employees: the Swedish WOLF study

Anna Nyberg ^1*, Lars Alfredsson ², Tores Theorell ³, Hugo Westerlund ³, Jussi Vahtera ⁴ and Mika Kivimaki ⁵

¹ Department of Public Health Sciences, Sweden
² Karolinska Institute, Sweden
³ Stress Research Institute, Sweden
⁴ Finnish Institute of Occupational Health, Finland
⁵ University College London, United Kingdom

^* To whom correspondence should be addressed. E-mail: anna.nyberg{at}ki.se.

Accepted 22 August 2008

Abstract

Objective: The aim of this study was to investigate the association between managerial leadership and hard endpoint ischemic heart disease (IHD) among employees.

Methods: Data were drawn from a prospective cohort study (WOLF) and included 3122 Swedish male employees. Baseline screening was carried out in 1992-1995. Managerial leadership behaviours, including the managers' consideration for the individual employee, clarity in goals and role expectations, provision of information and feed-back, ability to carry out changes at work successfully, and promotion of employee participation and control, were rated by subordinates. Records of employees' hospital admissions with a diagnosis of acute myocardial infarction or unstable angina and deaths from ischemic heart disease or cardiac arrest until the end of 2003 were obtained from national registers and were used to ascertain IHD. Cox proportional-hazards analyses were used to calculate hazard ratios for incident IHD per one standard deviation increase in standardized leadership score.

Results: A total of 74 incident IHD events occurred during the mean follow-up of 9.7 years. Higher leadership score was associated with lower IHD risk. The inverse association was stronger the longer the participant had worked at the same workplace [age-adjusted hazard ratio 0.76 (95% CI 0.61-0.96) for at least 1 year employment: 0.77 (0.61-0.97) for 2 years, 0.69 (0.54-0.88) for 3 years, and 0.61 (0.47-0.80) for 4 years], and this association was robust to adjustments for education, social class, income, supervisory status, physical workload, smoking, physical exercise, BMI, blood pressure, lipids fibrinogen and diabetes. The dose-response association between perceived leadership behaviours and IHD was also evident in subsidiary analyses with only acute MI and cardiac death as the outcome.

Conclusion: If the observed associations were causal then workplace interventions should focus on concrete managerial behaviours in order to prevent IHD in employees.