785 Magnusson Hanson LL, et al. Occup Environ Med 2019;76:785–792. doi:10.1136/oemed-2018-105595 ORIGINAL RESEARCH Multicohort study of change in job strain, poor mental health and incident cardiometabolic disease Linda L Magnusson Hanson, 1 Naja Hulvej Rod, 2,3 Jussi Vahtera , 4,5 Paraskevi Peristera, 1 Jaana Pentti, 4 Reiner Rugulies, 2,3,6 Ida Elisabeth Huitfeldt Madsen, 3 Anthony D LaMontagne , 7,8 Allison Milner , 9 Theis Lange, 10 Sakari Suominen, 4,11 Sari Stenholm , 4 Tianwei Xu, 2,3 Mika Kivimäki, 12,13 Hugo Westerlund 1 Workplace To cite: Magnusson Hanson LL, Rod NH, Vahtera J, et al. Occup Environ Med 2019;76:785–792. ► Additional material is published online only. To view, please visit the journal online (http://dx.doi.org/10.1136/ oemed-2018-105595). For numbered affiliations see end of article. Correspondence to Dr Linda L Magnusson Hanson, Stress Research Institute, Stockholm University, Stockholm 106 91, Sweden; linda.hanson@su.se Received 16 November 2018 Revised 2 July 2019 Accepted 21 July 2019 Published Online First 5 September 2019 © Author(s) (or their employer(s)) 2019. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ. Key messages What is already known about this subject? ► Job strain (a combination of high demands and low control at work) has been found a risk factor for both poor mental health and cardiometabolic disease, including cardiovascular disease and diabetes. ► Poor mental health also appears to be a risk factor for cardiometabolic disease. ► However, whether poor mental health is a mediator in the pathway from job strain to cardiometabolic disease has not been tested longitudinally. What are the new findings? ► This study showed that an increase in job strain is associated with risk of poor mental health supporting a temporal precedence of job strain and a causal association. ► However, no clear associations were observed between change in job strain and cardiometabolic disease, or between poor mental health and cardiometabolic disease. ► Hence, the study yielded no support for poor mental health as a mediator in the relationship between job strain and cardiometabolic disease. How might this impact on policy or clinical practice in the foreseeable future? ► The findings suggest that interventions targeting mental health may not be an effective alternative to preventing any effects of job strain on cardiometabolic disease, but support continued policy and practice targeting the psychosocial work environment for mental health promotion. ABSTRACT Objectives Several recent large-scale studies have indicated a prospective association between job strain and coronary heart disease, stroke and diabetes. Job strain is also associated with poorer mental health, a risk factor for cardiometabolic disease. This study investigates the prospective relationships between change in job strain, poor mental health and cardiometabolic disease, and whether poor mental health is a potential mediator of the relationship between job strain and cardiometabolic disease. Methods We used data from five cohort studies from Australia, Finland, Sweden and UK, including 47 757 men and women. Data on job strain across two measurements 1–5 years apart (time 1 (T1)–time 2 (T2)) were used to define increase or decrease in job strain. Poor mental health (symptoms in the top 25% of the distribution of the scales) at T2 was considered a potential mediator in relation to incident cardiometabolic disease, including cardiovascular disease and diabetes, following T2 for a mean of 5–18 years. Results An increase in job strain was associated with poor mental health (HR 1.56, 95% CI 1.38 to 1.76), and a decrease in job strain was associated with lower risk in women (HR 0.70, 95% CI 0.60–0.84). However, no clear association was observed between poor mental health and incident cardiometabolic disease (HR 1.08, 95% CI 0.96–1.23), nor between increase (HR 1.01, 95% CI 0.90–1.14) and decrease (HR 1.08, 95% CI 0.96–1.22) in job strain and cardiometabolic disease. Conclusions The results did not support that change in job strain is a risk factor for cardiometabolic disease and yielded no support for poor mental health as a mediator. INTRODUCTION Work-related stress, one of the major contempo- rary challenges, can be defined in different ways influenced by different theoretical perspectives. Job strain, which refers to a combination of high demands and low control at work according to the job–demand–control model, 1 is one of the most commonly studied indicators of work stress. Several recent large-scale studies have indicated that job strain is associated with a moderately elevated risk of coronary heart disease (CHD) 2 and stroke. 3 Job strain also appears to be a risk factor for type 2 diabetes, 4 but not, for example, cancer, 5 asthma 6 or chronic obstructive lung disease, 7 suggesting that job strain may have some specificity with regard to cardiometabolic disease. 8 Meta-analyses suggest that job strain is also associ- ated with poorer mental health, particularly depres- sion. 9 10 Poor mental health, especially depression, is also associated with a range of cardiometabolic disorders. 11 The relationship between depression and cardiometabolic disease may be bidirectional, 12 on June 3, 2020 by guest. Protected by copyright. http://oem.bmj.com/ Occup Environ Med: first published as 10.1136/oemed-2018-105595 on 5 September 2019. Downloaded from