Lucas V. Boersma
Adults who work more than 55 hours per week are at higher risk for developing atrial fibrillation, according to a recent study in the European Heart Journal.
“Although the 2016 European Guidelines for [CVD] prevention acknowledges psychosocial stress at work as a potential risk factor for [CVD], citing evidence that show long working hours to be associated with increased stroke risk, little is known about the role of long working hours as a potential risk factor of atrial fibrillation,” Mika Kivimäki, PhD, of the department of epidemiology at University College London, and colleagues wrote. “In principle, stress and long working hours may enhance functional re-entry, repetitive pulmonary vein and atrial firing, and autonomic nervous system abnormalities, inducing arrhythmia vulnerability.”
Risk and working hours
Kivimäki and colleagues used data from the IPD-Work consortium, which pooled data from eight studies in the United Kingdom, Denmark, Sweden and Finland. The study included 85,494 working adults (mean age, 43 years; 35% men) who were assessed at baseline between 1991 and 2004 for the number of hours worked per week. Working hours were stratified as less than 35 hours per week, 35 to 40 hours per week, 41 to 48 hours per week, 49 to 54 hours per week and at least 55 hours per week.
Participants were free of AF at baseline.
During 10 years of follow-up, 1,061 cases of AF were recorded. Compared with those who worked a normal week (35-40 hours), those who work at least 55 hours per week were 40% more likely to develop AF after adjustment for age, sex and socioeconomic status (HR = 1.42; 95% CI, 1.13-1.8).
This increased risk remained after excluding participants with CHD or stroke (HR = 1.36; 95% CI, 1.05-1.76) and after adjustment for obesity, risky alcohol use and high BP.
In an accompanying editorial, Bakhtawar K. Mahmoodi, MD, PhD, MPH, and Lucas V. Boersma, MD, PhD, FESC, of the cardiology apartment at St. Antonius Hospital in the Netherlands, wrote: “It is worth noting that the individual studies were all underpowered to detect statistically significant associations; the authors should be congratulated for the impressive collaborative effort required to integrate patient-level data from multiple studies to increase the power. However, despite the efforts of the authors to assess the reported association between long working hours and AF thoroughly, there are many inherent limitations of the data that preclude us from definite conclusions on acknowledging long working hours as an independent risk factor for AF.”
Mahmoodi and Boersma raised concerns about the timing of assessment for hours worked per week. Participants were only assessed at baseline and, in some studies, that was as early as the 1990s. Today, jobs with hard physical labor are monitored, and likely, jobs with mental stress, such as higher management and self-employed businesses, may put more strain on health than jobs with direct physical demands, according to the editorial.
“Further research is needed to determine mechanisms underlying the link between long working hours and atrial fibrillation,” Kivimäki and colleagues wrote. “Furthermore, the participants of this study were from the U.K., Denmark, Sweden and Finland. Although there is no reason to assume that the association would be dependent on geographical region, the generalizability of our findings to other countries remains to be confirmed.” – by Cassie Homer
Disclosures: The authors, Boersma and Mahmoodi report no relevant financial disclosures.