Disputas – Cand.med. Rita Kral
Cand.med. Rita Kral disputerer for ph.d.-graden i helsevitenskap og vil offentlig forsvare avhandlingen:
«Cortical bone and fracture risk: The Tromsø Study»
Kort sammendrag av avhandlingen:
Background: The aim of this thesis was to explore the association of the cortical architecture of the proximal femoral shaft with non-vertebral fractures. We tested the hypotheses that: (i) cortical bone parameters are associated with fracture risk independent of Fracture Risk Assessment Tool (FRAX) or Garvan estimates, (ii) women with fractures that are unidentified by FRAX but identified by cortical porosity have a different patient profile that contributes to their fracture risk, and (iii) women with type-2 diabetes mellitus (T2DM) have lower bone turnover markers (BTMs) and lower cortical porosity than those without diabetes, and that higher serum glucose and body mass index (BMI) are associated with lower BTMs and cortical porosity. Methods: We quantified FRAX and Garvan estimates with femoral neck areal bone mineral density (FN aBMD) and femoral subtrochanteric architecture in postmenopausal women, with non-vertebral fractures and controls in a nested case-control and sub-study of the Tromsø Study. Results: Paper I: Cortical porosity and thickness were associated with fracture risk independent of FRAX and Garvan estimates. Cortical porosity but not cortical thickness improved the net reclassification of fracture cases compared with FRAX alone but not compared with Garvan. Paper II: Fracture cases unidentified by FRAX but identified by cortical porosity were younger, had a higher FN aBMD, a lower FRAX score, and fewer had a prior fracture, they had higher cortical porosity, thinner cortices, and a larger total bone size than those identified by FRAX alone. Paper III: Women with T2DM had a higher serum glucose, BMI, and subtrochanteric total volumetric BMD but a lower cortical porosity than nondiabetic women. Increasing serum glucose level was associated with lower BTMs and cortical porosity. Increasing BMI was associated with lower BTMs and thicker cortices. Conclusion: These results suggest that cortical porosity was the most important cortical parameter associated with fracture risk. Fracture cases unidentified by high FRAX score but identified by high cortical porosity alone had a different patient profile compared with those identified by FRAX alone. Women with T2DM had lower serum BTMs and a lower cortical porosity than women without diabetes. Further research is needed in larger prospective studies to determine whether cortical porosity predicts fractures independent of FRAX and can be useful in clinical practice and to examine why T2DM patients have increased risks for fracture.
Veiledere
Hovedveileder førsteamanuensis Åshild Bjørnerem, IKM, UiT Norges arktiske universitet
Biveileder førsteamanuensis Elin Richardsen, IMB, UiT Norges arktiske universitet
Bedømmelseskomiteen
1. opponent: professor Dan Mellström, Institutionen för medicin Göteborgs universitet
2. opponent: førsteamanuensis Alvilde Dhainaut, Norges teknisk-naturvitenskapelige universitet
Leder av komite: førsteamanuensis Marit Solbu, IKM, UiT Norges arktiske universitet
Disputasleder
Førsteamanuensis Sven Weum, IKM, UiT Norges arktiske universitet
Prøveforelesning over oppgitt emne holdes kl. 10.15, samme sted: “Norge og Sverige har verdens høyeste forekomst av frakturer i hofte og ryggvirvler. Mulige årsaker?”