Regression models using parametric pseudo-observations.

Pseudo-observations based on the nonparametric Kaplan-Meier estimator of the survival function have been proposed as an alternative to the widely used Cox model for analyzing censored time-to-event data. Using a spline-based estimator of the survival has some potential benefits over the nonparametric approach in terms of less variability. We propose to define pseudo-observations based on a flexible parametric estimator and use these for analysis in regression models to estimate parameters related to the cumulative risk. We report the results of a simulation study that compares the empirical standard errors of estimates based on parametric and nonparametric pseudo-observations in various settings. Our simulations show that in some situations there is a substantial gain in terms of reduced variability using the proposed parametric pseudo-observations compared with the nonparametric pseudo-observations. The gain can be measured as a reduction of the empirical standard error by up to about one third; corresponding to an additional 125% larger sample size. We illustrate the use of the proposed method in a brief data example.

Risk of suicide, deliberate self-harm and psychiatric illness after the loss of a close relative: A nationwide cohort study.

The loss of a close relative is a common event, yet it is associated with increased risk of serious mental health conditions. No large-scale study has explored up to now the importance of the bereaved person's relation to the deceased while accounting for gender and age. We performed a nationwide Danish cohort study using register information from 1995 through 2013 on four sub-cohorts including all persons aged ≥18 years exposed to the loss of a child, spouse, sibling or parent. We identified 1,445,378 bereaved persons, and each was matched by gender, age and family composition to five non-bereaved persons. Cumulative incidence proportions were calculated to estimate absolute differences in suicide, deliberate self-harm and psychiatric illness. Cox proportional hazard regression was used to calculate hazard ratios while adjusting for potential confounders. Results revealed that the risk of suicide, deliberate self-harm and psychiatric illness was increased in the bereaved cohorts for at least 10 years after the loss, particularly during the first year. During that year, the risk difference was 18.9 events in 1,000 persons after loss of a child (95% CI: 17.6-20.1) and 16.0 events in 1,000 persons after loss of the spouse (95% CI: 15.4-16.6). Hazard ratios were generally highest after loss of a child, in younger persons, and after sudden loss by suicide, homicide or accident. One in three persons with a previous psychiatric diagnosis experienced suicide, deliberate self-harm or psychiatric illness within the first year of bereavement. In conclusion, this study shows that the risk of suicide, deliberate self-harm and psychiatric illness is high after the loss of a close relative, especially in susceptible subgroups. This suggests the need for early identification of high-risk persons displaying adjustment problems after loss of a close family member, in order to reduce the risk of serious mental health outcomes.