Bereavement in adulthood and risks of incident and recurrent cardiovascular diseases

Abstract: Bereavement, the loss of a family member or a loved one, is a severely stressful life event that may occur at least once in most individuals’ life. Bereaved persons are likely to be influenced by the loss in multiple aspects of their life, such as daily routines, financial security, or sleep quality. Furthermore, accumulating evidence suggests that bereaved individuals have increased risks of psychological and somatic morbidity, as well as death. The death of a partner in middle- and old age has been found in several studies to be related to increased risks of incident CVD and cardiovascular mortality. However, knowledge about the association between the death of a child, i.e., one of the most stressful life events, and the risk of CVD, is limited. Additionally, the question of whether bereavement could lead to poor prognosis in CVD has received very little attention. Therefore, in this thesis, we aimed to investigate the association between the death of a child and parental risk of CVD (studies Ⅰ and Ⅱ) and between the death of a close family member or friend and prognosis in acute myocardial infarction (AMI) (studies Ⅲ and Ⅳ). In studies Ⅰ and Ⅱ, we investigated whether bereaved parents had increased risks of ischemic heart diseases (IHD), AMI, and heart failure (HF). Studies Ⅰ and Ⅱ were bi-national population-based cohort studies including 6.7 million parents who had at least one child born during 1973-2016 in Denmark or during 1973-2014 in Sweden. We obtained information on children’s death, parental sociodemographic and health-related characteristics, and parental heart diseases from several Danish and Swedish nationwide registries. We observed modest associations between the death of a child and the risks of IHD (incidence rate ratio (IRR) [95% confidence intervals (CIs)]: 1.20 [1.18-1.23]), AMI (IRR [95% CIs]: 1.21 [1.17-1.25]), and HF (IRR [95% CIs]: 1.35 [1.29-1.41]). The associations were found irrespective of the child’s causes of death (due to CVD, other natural causes, or unnatural causes). There were U-shaped associations with the risks of IHD, AMI, and HF when we categorized exposure according to the age of the deceased child at loss. Bereaved parents who lost an infant or an adult child had higher risks of the studied heart diseases than those who lost a child aged 2-17 years. The relative risk of AMI was highest in the week immediately after the loss and persisted throughout the follow-up. The relative risk of HF did not differ substantially according to the time since the loss. In study Ⅲ, we investigated whether the loss of a family member or a close friend one year before the first AMI was associated with prognosis in AMI. We conducted a population-based cohort study involving 1732 first-AMI patients from the Stockholm Heart Epidemiology Program during 1992-1994 whom we followed for a median of 14 years. We retrieved information on bereavement and several other characteristics of study participants from questionnaires completed by patients or their family members during or shortly after the hospitalization, while information on outcomes (i.e., non-fatal recurrent AMI, death due to IHD, all-cause mortality, HF and stroke) was from national health and mortality registers. We found no association between any loss one year before the first AMI and the combination of non-fatal recurrent AMI and death due to IHD. However, the patients who lost their partner one year before the first AMI had an increased risk of non-fatal recurrent AMI or death due to IHD (hazard ratio [95% CIs]: 1.55 [1.06-2.27]). In study Ⅳ, we investigated further, using a larger sample, whether AMI patients had a poor prognosis if they experienced bereavement. This study included 266,651 patients with a first AMI recorded in the SWEDEHEART (acronym for Swedish Web-system for Enhancement and Development of Evidence-based care in Heart disease Evaluated According to Recommended Therapies) from 1991 to 2018. We collected information on bereavement as well as study participants’ characteristics and outcomes from several Swedish nationwide registers. We defined exposure as the death of a partner, child, grandchild, sibling, or parent one year before the first AMI or during the 4.4 years median follow-up. We found that bereaved AMI patients had a slightly increased risk of the combination of non-fatal recurrent AMI and death due to IHD. The association was strongest for the loss of a partner, followed by the loss of a child, grandchild, sibling, and parent, but was similar with respect to natural and unnatural deaths. The prognosis of AMI was poor during most of the periods when the loss occurred except for the year immediately after the first AMI. Similar associations were observed for all-cause mortality, HF, and stroke in relation to bereavement. In conclusion, the death of a child was associated with increased risks of IHD, AMI, and HF. Loss of a partner, child, grandchild, and sibling was associated with an increased risk of poor prognosis in AMI. If our findings are confirmed by future studies, support from family and society as well as attention from health care professionals would be beneficial for bereaved individuals’ cardiovascular health.