Spousal bereavement, mortality and risk of negative health outcomes among older adults: a population-based study

Lucas Morin; Jonas W Wastesson; Stefan Fors; Neda Agahi; Kristina Johnell

In self-controlled studies, cases are used as their own controls to eliminate the risk of bias due to between-individual unmeasured confounders. 28-31 King and colleagues recently conducted a selfcontrolled case series analysis to examine the mortality risk after the loss of a partner compared with before. 32 However, since it can be argued that the experience of bereavement is not a transient exposure clearly defined in time, these methods can yield biased estimates. 33 Instead, we used a cohort crossover design combining the self-controlled and the cohort approaches to measure the within-individual change in the risk of experiencing adverse health outcomes before and after spousal loss. This approach has, for instance, been proposed to study the risk of aortic dissection during pregnancy 34 or to quantify the excess risk of injury during the period shortly before and after a diagnosis of cancer. 35 In our study, we defined a reference period from 18 until 12 months before spousal loss (T0), and we calculated the relative risk of adverse health outcomes from 1 year before until 1 year after spousal loss by dividing person time into four 6-month periods (182 days), from T1 to T4 (Figure 2 ). By design, the relative risk of fatal events during the pre-bereavement period cannot be calculated.