Widowhood in old age increases mortality and adverse health effects, particularly depression and need for psychiatric care. The causes of this are poorly understood. To study risk factors and mechanisms, theories about what to study are needed. A qualitatively approach to widowhood from the widow/widower's perspective may uncover important knowledge.

To investigate risk factors of the adverse health effects associated with widowhood in old age from the perspective of the widower/widowers and to test the generalisability of the theories quantitatively.

This is a cross-country mixed methods study combining narrative interviews with Danish widows/widowers and a 50-year follow-up study from Sweden – The Lundby Study. Widows/widowers above 65 years of age referred to in- or outpatient treatment at the Department of Psychiatry at Odense or Aarhus University Hospital are included. Narrative interviews are conducted and analysed according to grounded theory. The qualitatively developed theories will then be tested quantitatively through the Lundby Study by comparing widows/widowers above 65 years with age-matched controls, who are still married.

In the Lundby Study, 597 persons above 65 years were identified in the latest follow-up: 176 (29.5%) were widow/widowers, 421 (70.5%) were married/cohabitating. Depending on the theories developed a total of 384 possible variables regarding physical health, mental health and general living circumstances are tested. Further results will be presented.

The causes of adverse health effects in widowhood are poorly understood. This study will potentially contribute to unravelling these by identifying possible risk factors.

The authors have not supplied their declaration of competing interest.