Morbidity and mortality in parents who lost a child: follow-up studies based on national registers in Denmark

This PhD dissertation was accepted by the Faculty of Health Sciences of the University of Aarhus, and defended on February 18, 2004.

Official opponents: Bente Nørgaard, Tores Theorell, Sweden, and Merete Nordentoft.

Supervisors: Jørn Olsen, Preben Bo Mortensen, and Dorthe Hansen Precht.

Correspondence: Jiong Li, The Danish Epidemiology Science Centre, University of Aarhus, Building 260, Vennelyst Boulevard 6, DK-8000 Århus C.

Dan Med Bull 2004;51:232.

ABSTRACT

The PhD study was carried out at the Danish Epidemiology Science Centre, at the Department of Epidemiology and Social Medicine, at the University of Aarhus.

Aim: To investigate and quantify specific health effects of the death of a child on physical and mental health of the bereaved parents.

Background: Parental bereavement is considered one of the most severe stressful events. Little is known, however, about its effect on clinical illness in bereaved parents.

Methods: The studies were based on follow-up of cohorts established from several nationwide registers. A total of 21,062 parents who lost a child under the age of 18 in Denmark during the period from 1980 to 1996 were enrolled into the exposed cohort, and 293,745 parents who did not lose a child were selected to the unexposed cohort. We followed the study population from the enrollment to the end of 1997 with a follow-up time of up to 18 years. The outcomes of interest were mortality, hospitalization due to myocardial infarction (MI), stroke, and multiple sclerosis (MS), as well as cancer incidence and survival in the two cohorts. Cox' proportional-hazards regression models were used to evaluate the relative risks (RRs).

In another study design, we established a cohort consisting of the 1,082,503 persons who were born in Denmark between 1952 and 1999 and had at least one child (under the age of 18) between 1970 and 1999. The follow-up period was from 1970 to 1999. Parents who lost a child were included into the exposed cohort from the day when the child died. The outcome was the first psychiatric admission. The relative risks were estimated with the log-linear Poisson regression.

Main results: We observed a significantly increased overall mortality risk in bereaved mothers (RR 1.43, 95% CI 1.24-1.64), but not in bereaved fathers (RR 1.09, 95% CI 0.95-1.23). The RRs of first MI event and MS were 1.28 (95% CI 1.08-1.51) and 1.56 (95% CI 1.05-2.31), respectively. We observed a slightly increased cancer risk (RR 1.09, 95% CI 0.99-1.20) in bereaved parents. The HR of dying from an incident cancer was 1.23 (95% CI 1.03-1.47). The risk of stroke in the bereaved parents was identical to that in the non-bereaved (RR 1.00, 95% CI 0.83-1.20). The RR of any first psychiatric hospitalisation was 1.67 (95% CI 1.53-1.83). Bereaved mothers had a higher RR (1.83, 95% CI 1.65-2.03) than bereaved fathers (RR 1.37, 95% CI 1.16-1.61).

Conclusions: We observed an increased mortality in bereaved mothers. The death of a child may lead to an increased risk of MI and MS, and may also play a role in the development and prognosis of cancer in bereaved parents. The loss of a child is not associated with the risk of stroke. The death of a child was associated with an increased risk of psychiatric admissions, especially in mothers.

Implications: Our data suggest that parents, especially mothers, who have been exposed to the stress of child loss, have a higher overall mortality and a higher morbidity from several diseases than unexposed parents.