Association between sitting time at work and the onset of major depressive episode: a 1-year prospective cohort study using the Bayesian regression

Kazuhiro Watanabe,Norito Kawakami

doi:10.1186/s12889-021-12059-y

Abstract

BackgroundAlthough sedentary behavior is associated with the onset of major depressive disorder, it remains unclear whether sedentary behavior at work increases the risk of depression. The present study used the Bayesian approach to investigate the association between sitting time at work and the onset of major depressive episode (MDE).MethodsA 1-year prospective cohort study was conducted among 233 Japanese workers without MDE (response rate: 4.3%). MDE onset was assessed using the self-reported WHO Composite International Diagnostic Interview version 3.0. A Bayesian Cox proportional hazard model was used to estimate the hazard ratio (HR) between long sitting time at work and MDE onset.ResultsA total of 231 workers were included in the analysis. During the follow-up, 1621 person-months were observed, and six participants experienced MDE onset. Incident rates per months were 0.34, 0.11, and 1.02% in short (< 7.2 h per day), medium (7.2–9.5 h), and long (9.5+ h) sitting time at work, respectively. The estimated median posterior probability distribution of the HR of long sitting time was 3.00 (95% highest density interval [HDI]: 0.73–12.03). The estimated median remained positive after adjustment for physical activity level and other covariates (HR = 2.11, 95% HDI: 0.42–10.22). The 10-base Bayesian factor for H1 (HR = 1.00) compared with the alternatives (H0, HR = 1.00) was 0.68 in the adjusted model. The analysis, which treated sitting time at work as a continuous variable, estimated that the median of the posterior probability distribution of the HR of sitting time was 0.79 (95% HDI: 0.58–1.07. The 10-base Bayesian factor was 2.73 in the linear association.ConclusionsLong sitting time at work (9.5+ h per day) might be associated with MDE onset among workers. However, the linear association indicated conflicting results. Non-linear associations between sitting time and MDE onset might explain this inconsistency. The evidence for an adverse association between sitting time at work and MDE onset remains inconclusive.

Highlights

Sedentary behavior is associated with the onset of major depressive disorder, it remains unclear whether sedentary behavior at work increases the risk of depression
A systematic review and metaanalysis [4] of 24 studies showed that the pooled relative risk (RR) of depression associated with sedentary behavior was 1.25 (95% confidence interval [CI]: 1.16–1.35)
We aimed to investigate prospective associations between sedentary behaviors at work and the onset of major depressive episode (MDE) over a 1-year period, based on the standard diagnostic criteria detailed in the Diagnostic and Statistical Manual of Mental Disorders (DSM)IV/V

Summary

Introduction

Sedentary behavior is associated with the onset of major depressive disorder, it remains unclear whether sedentary behavior at work increases the risk of depression. Sedentary behavior is defined as any waking behavior involving an energy expenditure of 1.5 metabolic equivalents or less while in a sitting or reclining posture [1]. Such behavior has been associated with morbidity and mortality from various non-communicable diseases, even independent of physical inactivity [2, 3]. Sedentary behavior is associated with an increase in the risk of mental disorders. Hallgren et al [5, 6] conducted a 13-year prospective cohort study among Swedish adults with no mental disorder and found that mentally passive sedentary behaviors (e.g., TV watching, listening to music, sitting in the bathtub) were associated with a high risk of major depressive disorder (MDD)

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