IPD-Work consortium: pre-defined meta-analyses of individual-participant data strengthen evidence base for a link between psychosocial factors and health

Abstract

Established in 2008 and comprising over 60 researchers, the IPD-Work (individual-participant data metaanalysis in working populations) consortium is a collaborative research project that uses pre-defined meta-analyses of individual-participant data from multiple cohort studies representing a range of countries. The aim of the consortium is to estimate reliably the associations of work-related psychosocial factors with chronic diseases, disability, and mortality. Our findings are highly cited by the occupational health, epidemiology, and clinical medicine research community. However, some of the IPD-Work's findings have also generated disagreement as they challenge the importance of job strain as a major target for coronary heart disease (CHD) prevention, this is reflected in the critical discussion paper by Choi et al (1).In this invited reply to Choi et al, we aim to (i) describe how IPD-Work seeks to advance research on associations between work-related psychosocial risk factors and health; (ii) demonstrate as unfounded Choi et al's assertion that IPD-Work has underestimated associations between job strain and health endpoints; these include the dichotomous measurement of job strain, potential underestimation of the population attributable risk (PAR) of job strain for CHD, and policy implications arising from the findings of the IPD-Work consortium; and (iii) outline general principles for designing evidence-based policy and prevention from good-quality evidence, including future directions for research on psychosocial factors at work and health. In addition, we highlight some problems with Choi et al's approach. What is the IPD-Work consortium?The IPD-Work consortium was established at a meeting of principal investigators and researchers working on European occupational cohort studies in London in 2008. In 2010, we obtained funding from the European Union (new OSH-ERA research program) to cover core activities, harmonization of the data across studies, and statistical analysis. Originally, 17 independent cohort studies from Finland, Sweden, Denmark, the Netherlands, Belgium, France, Germany, and the UK were included (2). This number currently stands at 26 studies, including those from the United States and Australia.Our motivation for establishing the consortium was to advance research on work-related psychosocial factors and health. The most widely studied of these, "job strain", dates back to 1979 (3). The original hypothesis posits that a combination of high psychological demands at work and low job control (ie, job strain) increases the risk of health problems of public health importance, such as CHD (4). Although the concept was well received by both stress researchers and occupational health specialists, for decades, unresolved debates have hampered interpretation of results and research progress. These include the magnitude of the association, the relative importance of high psychological demands versus low job control (whether one is more toxic than the other), and differences in effect by age and sex...

Update of the fractions of cardiovascular diseases and mental disorders attributable to psychosocial work factors in Europe

“…Relative risk (RR) estimates were obtained from the most recent literature reviews or if not available from studies of the IPD-Work consortium (Kivimaki et al 2015b ) that provided pooled RR estimates from various cohort studies from a range of countries. Fifteen literature reviews and IPD-Work consortium studies were used to provide RRs for a number of associations between psychosocial work factors and health outcomes related to cardiovascular diseases and mental disorders.…”

Data sharing—trialists' plans at registration, attitudes, barriers and facilitators: A cohort study and cross‐sectional survey

“…Meta-analyses of observational studies are often subject to substantial heterogeneity (and more so than those of interventional studies) due to a wider range of study designs, methodologies and analytical models, different confounders adjusted for in each study and different measures and cut-offs for exposures. 46,47 These issues can be addressed using IPD-MA and PMA methodologies, and future research and methods development are required to ensure they are sufficiently supported and encouraged. It is likely that many of the barriers and strategies to increase data sharing identified in this manuscript will be applicable to observational studies in addition to interventional trials.…”

Cognitive stimulation at work and dementia

“…The linked study by Kivimäki and colleagues (doi:10.1136/bmj.n1804) is an important piece of work that addresses these gaps in a systematic way 8. Using data from the individual participant data meta-analysis in working populations (IPD-WORK), the largest ongoing multicohort project on work and health,9 these authors conducted three studies combined to investigate the association between cognitive stimulation at work and dementia (assessed in seven cohorts including nearly 108 000 people); cognitive stimulation at work and nearly 5000 plasma proteins—to explore the biological correlates of work stimulation (assessed in >2200 people from one cohort); and plasma proteins and dementia (assessed in >13 500 people from two cohorts).…”