Background

Social isolation has been associated with increased risk of coronary heart disease and stroke. However, it is unclear whether the associations differ between fatal and non-fatal events or by the type of isolation (living alone or having few social contacts). We aimed to examine these associations in two large UK prospective cohorts.

Methods

Million Women Study and UK Biobank participants without previous coronary heart disease or stroke who provided data in median year 2010 (IQR 2009–2011) on social contacts were included in this prospective analysis. Participants were followed up to median year 2017 (2017–2017) by electronic linkage to national hospital and death records. Risk ratios (RRs) were calculated using Cox regression for first coronary heart disease and stroke event (overall, and separately for hospital admission as the first event and for death without an associated hospital admission as the first event) by three levels of social isolation (based on living alone, contact with family or friends, and group participation) adjusted for age, sex, study, region, deprivation, smoking, alcohol intake, body-mass index, physical activity, and self-rated health.

Findings

938 558 participants were included in our analyses (mean age 63 years [SD 9]): 481 946 participants from the Million Women Study (mean age 68 years [5]) and 456 612 participants (mean age 57 years [8]) from UK Biobank. During a mean follow-up period of 7 years (2), 42 402 first coronary heart disease events (of which 1834 were fatal without an associated hospital admission) and 19 999 first stroke events (of which 529 were fatal without an associated hospital admission) occurred. Little, if any, association was found between social isolation and hospital admission for a first coronary heart disease or stroke event (combined RR for both studies 1·01 [95% CI 0·98–1·04] for coronary heart disease and 1·13 [1·08–1·18] for stroke, when comparing the most isolated group with the least isolated group). However, the risk of death without an associated hospital admission was substantially higher in the most isolated group than the least isolated group for coronary heart disease (1·86 [1·63–2·12]) and stroke (1·91 [1·48–2·46]). For coronary heart disease or stroke death as the first event, RRs were substantially higher (test for heterogeneity, p=0·002) for participants living alone versus those not living alone (1·60 [1·46–1·75]) than for those with fewer versus more contact with family, friends, or groups (1·27 [1·16–1·38]). These findings did not differ greatly between studies, or by self-rated health.

Interpretation

Social isolation seems to have little direct effect on the risk of developing a first coronary heart disease or stroke. By contrast, social isolation substantially increases the risk that the first such event is fatal before reaching hospital, particularly among people who live alone, perhaps because of the absence of immediate help in responding to an acute heart attack or stroke.

Funding

UK Medical Research Council, Cancer Research UK.

中文翻译：

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社会隔离与心脏病和中风的风险：英国两项大型前瞻性研究的分析

 背景

社会隔离与冠心病和中风的风险增加有关。然而，尚不清楚致命事件和非致命事件之间的关联是否存在差异，或者是否因隔离类型（独居或社交接触很少）而存在差异。我们的目的是在英国的两个大型前瞻性队列中研究这些关联。

 方法

这项前瞻性分析纳入了百万女性研究和英国生物银行参与者，他们在 2010 年中位数（IQR 2009-2011）中提供了有关社会接触的数据，这些参与者以前没有冠心病或中风。通过与国家医院和死亡记录的电子链接，对参与者进行了随访至 2017 年中位数（2017-2017 年）。使用 Cox 回归计算首次冠心病和中风事件的风险比 (RR)（总体，以及分别将入院作为首次事件和将没有相关入院的死亡作为首次事件）按三个社会隔离水平（基于独居、与家人或朋友的接触以及团体参与）根据年龄、性别、学习、地区、贫困、吸烟、饮酒、体重指数、体力活动和自评健康进行调整。

 发现

我们的分析纳入了 938 558 名参与者（平均年龄 63 岁 [SD 9]）：来自百万女性研究的 481 946 名参与者（平均年龄 68 岁 [5]）和 456 612 名参与者（平均年龄 57 岁 [8]）英国生物银行。在平均 7 年 (2) 的随访期间，发生了 42 402 起首次冠心病事件（其中 1834 起死亡且未入院）和 19 999 起首次中风事件（其中 529 起死亡且未入院） ）发生。社会隔离与首次冠心病或中风事件入院之间几乎没有发现关联（如果有的话）（冠心病的两项研究的综合 RR 1·01 [95% CI 0·98–1·04] 和 1） ·13 [1·08–1·18] 对于中风，当比较最孤立的组和最不孤立的组时）。然而，在冠心病 (1·86 [1·63–2·12]) 和中风 (1·91 [1 ·48–2·46]）。对于冠心病或中风死亡作为首发事件，独居参与者的 RR 显着高于非独居参与者（异质性检验，p=0·002）（1·60 [1·46–1·75]）与那些与家人、朋友或团体接触较少或较多的人相比 (1·27 [1·16–1·38])。这些研究结果在研究之间或自评健康状况方面并没有太大差异。

 解释

社会隔离似乎对首次患冠心病或中风的风险几乎没有直接影响。相比之下，社会隔离大大增加了第一次此类事件在到达医院之前致命的风险，特别是对于独居者来说，这可能是因为在应对急性心脏病发作或中风时缺乏立即帮助。

 资金

英国医学研究委员会，英国癌症研究中心。