Public Defence: Siri Marie Solbakken

MD Siri Marie Solbakken at Institute of Health and Society will be defending the thesis “Hip fracture incidence and mortality: The impact of season, health status and urbanization” for the degree of PhD (Philosophiae Doctor).

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Photo: Jon Olav Bakke Nesvold

Trial Lecture – time and place

See Trial Lecture.

Adjudication committee

  • First opponent: Professor Daniel Prieto Alhambra, Oxford University
  • Second opponent: Professor Björn Rosengren, Lund University
  • Third member and chair of the evaluation committee: Professor Marit B. Veierød, University of Oslo

Chair of the Defence

Professor Morten Lindbæk, University of Oslo

Principal Supervisor

Associate Professor Tone Kristin Omsland, University of Oslo


Norway has one of the highest hip fracture rates in the world. Mortality is very high in hip fracture patients, and knowledge on explanatory factors is important when considering strategies to reduce the high post hip fracture mortality. The aims of this thesis were to investigate seasonal variation in hip fracture incidence and the impact of pre-fracture health status (based on body mass index (BMI), smoking status and self-perceived health) and urbanization on post hip fracture mortality.

In three large register-based cohort studies, national hip fracture data from the NOREPOS hip fracture database were combined with data from Cohort of Norway (a compilation of large population-based health surveys), the 2001 Population and Housing Census and data from the National Registry.

There was a distinct seasonal variation in hip fracture incidence by age, gender and comorbidity, with a higher risk of hip fracture in winter compared to summer. The seasonal variation was most pronounced in men and in the youngest and healthiest patients.

Information on self-perceived health, BMI and smoking status predicted excess mortality in hip fracture patients. Underweight patients who reported poor or not very good self-perceived health and daily smoking had a more than 6-fold increased mortality compared to persons without fracture. However, an excess mortality was present also in patients with the most favorable levels of these risk factors. Hip fracture patients living in urban areas had a higher mortality than their rural-dwelling counterparts, and the mortality differences were most pronounced during the first 1-2 years after hip fracture.

Our findings may partly explain the high hip fracture burden in Norway, and suggest that both pre-fracture health status and fracture-related factors contribute to the excess hip fracture mortality. In addition, hip fracture mortality varied by degree of urbanization in the municipalities.

Additional information

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Published Nov. 27, 2019 1:50 PM - Last modified Nov. 27, 2019 3:55 PM