In this population-based study, we found that spousal bereavement was associated with an excess risk of mortality and with a wide range of negative health outcomes, especially among men. The effect of bereavement reached its peak immediately after the death of the spouse and weakened over time. We observed that the illness trajectory of the deceased spouse had a substantial modifying effect on this association. Notably, the risk of non-fatal adverse health outcomes increased already in the 0-6 months before spousal loss. Our results indicate that the provision of formal and informal bereavement support should start early after, if not before, spousal loss. These findings are of particular public health and clinical relevance in the context of the Covid-19 pandemic, which will unfortunately result in a substantial number of bereaved older adults over a short period of time.

The first major conclusion of the present study is that spousal bereavement in old age seems to have a substantial causal effect on mortality and on a wide range of poor health outcomes. Our finding of a 66% increase in the risk of death from any cause during the first year of follow-up is in the upper range of previously reported estimates, both in Sweden and in other countries.^3,4 The association between bereavement and acute cardiovascular events was similar in direction and magnitude to the findings of Carey and colleagues in the United Kingdom, despite a markedly higher rate of acute strokes among bereaved older adults in the present cohort.¹⁸ Not surprisingly, we found that the mortality and health disadvantage after spousal loss was greater among men than among women—with the notable exceptions of hip fractures and self-harm. Men have been shown to be more vulnerable to the acute health consequences of grief than women, most likely because of gender differences in social support, coping styles, and health behaviours around the time of bereavement.^49,50 However, contrary to a study that investigated the relative risk of suicide after the loss of a partner in 1994–1998 in Denmark,⁵¹ women were found to a greater excess risk of self-harm and suicide than men after spousal loss. This was, however, mostly explained by a higher baseline incidence of self-harm among married men in the matched control group. The dramatic increase in self-harm and suicides speaks of the seriousness of the psychological distress experienced by older adults facing the loss of a partner.

The second major conclusion is that the effect of bereavement reaches its peak immediately after the death of the spouse and weakens as time elapses. The existence of a time-dependent relationship has already been suggested by previous studies, albeit with conflicting evidence.^6,15,52–54 By using flexible parametric survival models, we were able to visualise the shape of the association between bereavement and negative health outcomes over time. Our results regarding mortality are well aligned with recent findings in Denmark, where the 2.5 times higher risk of death during the first month after spousal loss declined down to 38% six to twelve months later.⁵⁵ Additionally, the present study shows that while the risk of acute cardiovascular events, pneumonia, and non-elective hospitalisations also increased in a transient fashion, other outcomes such as hip fractures, injuries due to self-harm, and nursing home admissions remained elevated for longer periods of time. This has important implications for public health and clinical practice, as it means that bereavement support should be offered without delay to mitigate short-term decline and then maintained over a sufficiently long period of time.

The third major conclusion is that the detrimental effects of bereavement on the surviving spouses’ health vary substantially according to the illness trajectory of the deceased. Earlier work has shown that the negative health effects of bereavement varied according to the cause of death of the deceased spouse, but most of these studies used the cause of spousal loss as a way to test for selection bias ⁵⁶ or to separate expected from unexpected deaths.^57,58 To our knowledge, this is the first large cohort study that has examined the impact of bereavement across different and clinically meaningful illness trajectories. We found that the excess risk of mortality was highest among bereaved older adults whose spouse died suddenly and lowest among those whose spouse died after a trajectory of prolonged dwindling (often marked by the progression of dementia or other neurodegenerative diseases). However, the latter still experience substantially higher rates of death, acute cardiovascular events, hip fractures and self-harm than their married counterparts. In that respect, our findings contrast with the conclusion by Elwert and colleagues that the spouses of people who died from Alzheimer’s disease or Parkinson’s disease remained unaffected by the widowhood effect.⁵⁹ We also observed that bereaved older adults whose spouse died from organ failure experienced a particularly high excess risk of acute cardiovascular events and self-harm, and those whose spouse died from cancer had the highest excess risk of pneumonia after bereavement. Thus, although sudden spousal deaths expose surviving partners to especially high excess mortality, our findings suggest that longer and more predictable illness trajectories do not shield survivors from the adverse health consequences of bereavement.⁶⁰

The fourth major conclusion is that the risk of non-fatal adverse health outcomes starts increasing already during the 6-month period prior to spousal loss. Our results are consistent with previous work showing substantial changes in the risk of cardiovascular events and injuries during the months before bereavement.^19,61 In a cross-sectional analysis of the Health and Retirement Study, a nationally representative survey of Americans aged 50 years and older, researchers found that spouses nearing bereavement reported worse mobility, more impairments in instrumental activities of daily living, a greater burden of depressive symptoms and poorer working memory than continuously married individuals.²⁰ The finding that health outcomes start worsening before spousal death suggests that the observed association between bereavement and ill health is partly attributable to factors that precede widowhood. Thus, any hypothesis for the causal effect of spousal bereavement on health should also explain how the experience of the surviving spouses before the death of their partners contributes to exposing them to serious adverse events.

One such hypothesis is that the effect of bereavement is mediated by enhanced inflammatory responses to psychophysiological stress and depressive symptoms.^62–64 This exacerbated inflammation may be triggered not only by loss and grief after spousal loss, but also by ‘anticipatory grief’, namely that soon-to-be widows and widowers face substantial emotional and psychological distress before the death of their loved one actually occurs.⁶⁵ A second hypothesis is that the “widowhood effect” stems partly from a shared health disadvantage among spouses, which could be explained both by assortative mating and by unfavourable living conditions throughout adulthood such as insufficient material resources, poor housing quality, and high-risk diet. Hence, social scientists have suggested that the excess risk of negative health events around the time of bereavement is driven either by selection mechanisms (those who become widows and widowers tend to have a lower socioeconomic position) or by the substantial reduction in material resources already before spousal loss. Although our data shows that bereaved cases have, on average, a lower level of education and income and tend to live in more socially deprived areas compared with married controls, we found no evidence of a socioeconomic gradient in the association between bereavement and mortality. We acknowledge that this may very well be specific to the study population at hand, namely older people whose main source of income was retirement pensions rather than work-related earnings, in a country where the financial toll of widowhood is automatically compensated by a specific pension scheme. Finally, a third hypothesis is that the observed health disadvantage among bereaved relatives is partly due to the caregiving burden, which is well documented among spouses of older people with advanced illness (e.g. cancer, heart failure, dementia).^66,67 Caregiving burden is hypothesised to have a direct impact on mental health and cognition, and to affect physical health through poorer self-management of pre-existing diseases, including lower adherence to essential medicines, and postponing of routine clinical appointments.⁶⁸ In a large cohort of 12 722 older people with chronic cardiovascular conditions in the United Kingdom, Shah and colleagues showed that during the year prior to spousal loss there was a lower uptake of basic care processes (e.g. blood pressure and HbA1c measurements) among soon-to-be widows and widowers than among their continuously married counterparts.⁶⁹ Similarly, they found that adherence to statins, platelet antiaggregants and renin-angiotensin drugs started declining already during the months preceding spousal death. In the present study, we hypothesise that a large part of the observed increase in the risk of fall-related injuries already during the 6 months before spousal loss can be attributed to the use of sedatives, anxiolytics and hypnotics that are often prescribed to help relatives cope with the psychological stress of caring for someone at the end of life.^70,71 This suggests that palliative care services could have an important role in detecting high-risk caregivers, providing bereavement counselling already before spousal loss, and signposting to relevant health services (including GPs and other primary care professionals) to ensure adequate management of existing conditions.

A major strength of this study is that we used routinely collected administrative and healthcare data with nationwide coverage. This eliminates the potential for non-participation bias, and thus enhances the generalizability of our findings to older people at large, at least in countries socially, culturally and economically similar to Sweden. Moreover, the use of routinely collected data mitigates the risk of recall bias. The ascertainment of the date of spousal loss was made in two separate data sources and older spouses were linked together in a deterministic rather than probabilistic manner, which provides an unbiased classification of bereaved cases and non-bereaved controls. We were able to identify and measure a wide range of demographic, socioeconomic, and health-related baseline characteristics, thus allowing us to adjust our analyses for important confounders. Matching on sex and date of birth achieved good balance of measured covariates at baseline, which suggests strong empirical equipoise and supports our claim of a causal relationship between spousal bereavement and negative health outcomes. However, the lack of information with regard to important physical (e.g. body-mass index), functional (e.g. gait speed, ADL impairments), lifestyle (e.g. diet, smoking, alcohol use) or family-related factors (e.g. level of social support) represents a potential source of residual confounding, which could threaten the validity of our effect estimates. To alleviate this concern, we calculated E-values to evaluate how susceptible the observed associations were to unmeasured confounders. This sensitivity analysis showed that unmeasured confounders would need to be of substantial magnitude to fully explain the adjusted effect estimates. For instance, the observed incidence rate ratio for all-cause mortality (1.66, 95% CI 1.53–1.80) could only be moved to the null by an unmeasured confounder associated with both spousal loss and mortality by a risk ratio of at least 2.70 above and beyond measured confounders. The existence of such confounders is, to the best of our knowledge, highly unlikely. Negative control outcomes with presumed null effect sizes were used to assess the potential for residual systemic bias, which revealed no obvious prognostic imbalance at baseline. We also devised a cohort crossover design to measure within-individual change in the risk of experiencing adverse health outcomes before and after spousal loss among bereaved cases compared with the change among married controls. This approach offers the double advantage of eliminating between-person confounding (measured or otherwise) by using study subjects as their own controls while also attenuating the risk of bias due to left truncation and natural age-related trends. Another important strength of the present study is that all prespecified sensitivity analyses and non-prespecified post-hoc analyses are reported in a clear and transparent manner and explicitly linked to the corresponding hypotheses that we intended to test.

One obvious limitation of the present study stems from its observational nature; since spousal bereavement is, by definition, a non-randomizable exposure, we cannot completely rule out the presence of residual confounding. Another limitation is that the categorization of end-of-life illness trajectories of the deceased spouses is both an over-simplification of the actual trajectory of functional decline that these persons followed and an imperfect proxy for the burden of caregiving that the surviving spouses experienced during the final months and weeks before spousal loss. In the self-controlled cohort crossover design, we were unable to conduct subgroup analyses by illness trajectories due to a very low number of events during each hazard period for most outcomes. Moreover, outcomes were limited to serious health events related to somatic conditions. Although we recognize that endpoints related to the development of chronic diseases, quality of life, or mental health are very important to bereaved older adults and highly relevant for clinicians and policy makers, the lack of sufficiently detailed data from primary care practitioners and the risk of detection bias (whereby bereaved individuals would, for instance, be more likely to be reported as having depressive symptoms and worse quality of life) prevented us from including these aspects in the present study. Finally, we were unable to investigate the long-term health consequences of spousal bereavement.