Abstract

Objectives

Multimorbidity poses various challenges, and previous research has indicated a causal relation with depression. As multimorbidity is not curable, the underlying mechanisms are of great interest. Positive affect is a major resource for coping with chronic conditions and for the prevention of depression. Long-term multimorbidity, however, may deplete positive affect. The purpose of this paper is to investigate the role of positive affect in the association between multimorbidity and depressive symptoms.

Method

We used four consecutive waves (2008, 2011, 2014, 2017) of the nationally representative German Ageing Survey (DEAS) with a total of 1,558 older adults aged 40 and over. To account for time-varying confounding, exposure-induced mediator-outcome confounding, and reciprocities, we applied the mediational g-formula with inverse-probability weighting techniques. We also tested for exposure-mediator interaction to adjust for differences in mediation across the duration of multimorbidity.

Results

We confirmed a positive longitudinal relation between multimorbidity and depressive symptoms, both of which were negatively associated with while positive affect. The model without interaction indicated a share mediated of ca. 18.3% on the total effect of multimorbidity on depressive symptoms. Addition of interaction led to substantial differences for multimorbidity duration and levels of positive affect. Associations for long-term multimorbidity (at least two survey waves) were more substantial, and the share mediated doubled (>40%). Additionally, the direct effect of multimorbidity on depressive symptoms diminished for short-term multimorbidity.

Conclusion

Strengthening positive affect could reduce depressive symptoms in those facing multimorbidity. This study also discusses methodological challenges in performing longitudinal mediation analysis. We advise researchers to consider the mediational g-formula and exposure-mediator interaction.

摘要

目标

多重疾病带来了各种挑战，以前的研究表明与抑郁症存在因果关系。由于多发病是不可治愈的，因此潜在的机制是非常令人感兴趣的。积极影响是应对慢性病和预防抑郁症的主要资源。然而，长期的多重疾病可能会耗尽积极的影响。本文的目的是研究积极情绪在多发病和抑郁症状之间的关系中的作用。

方法

我们使用了具有全国代表性的德国老龄化调查 (DEAS) 的连续四波（2008 年、2011 年、2014 年、2017 年），共有 1,558 名 40 岁及以上的老年人。为了解释时变混杂、暴露引起的中介结果混杂和互惠，我们应用了具有逆概率加权技术的中介 g 公式。我们还测试了暴露-调解员的相互作用，以调整多发病期间调解的差异。

结果

我们证实了多重疾病和抑郁症状之间的正向纵向关系，这两者都与积极影响呈负相关。没有交互作用的模型表明份额介导的 ca。多重疾病对抑郁症状的总影响为 18.3%。相互作用的增加导致多病持续时间和积极影响水平的显着差异。长期多发病（至少两次调查波）的关联更为显着，并且介导的份额翻了一番（> 40％）。此外，短期多发病对抑郁症状的直接影响减弱。

结论

加强积极影响可以减少那些面临多重疾病的人的抑郁症状。本研究还讨论了进行纵向中介分析的方法学挑战。我们建议研究人员考虑中介 g 公式和暴露-中介相互作用。