Introduction: Osteoporosis (OP) is a systemic skeletal disease characterized
by a low bone mineral density (BMD) and a micro-architectural (MA) deterioration.
Clinical risk factors (CRF) are often used as a MA approximation. MA
is yet evaluable in daily practice by the Trabecular Bone Score (TBS) measure.
TBS is a novel grey-level texture measurement reflecting bone micro-architecture
based on the use of experimental variograms of 2D projection images.
TBS is very simple to obtain, by reanalyzing a lumbar DXA-scan. TBS has
proven to have diagnosis and prognosis value, partially independent of CRF
and BMD. The aim of the OsteoLaus cohort is to combine in daily practice the
CRF and the information given by DXA (BMD, TBS and vertebral fracture assessment
(VFA)) to better identify women at high fracture risk.
Method: The OsteoLaus cohort (1400 women 50 to 80 years living in Lausanne,
Switzerland) started in 2010.
This study is derived from the cohort COLAUS who started in Lausanne in
2003. The main goals of
COLAUS is to obtain information on the epidemiology and genetic determinants
of cardiovascular risk in 6700 men and women. CRF for OP, bone ultrasound
of the heel, lumbar spine and hip BMD,
VFA by DXA and MA evaluation by TBS are recorded in OsteoLaus. Preliminary
results are reported.
Results: We included 631 women: mean age 67.4±6.7 y, BMI 26.1±4.6, mean
lumbar spine BMD 0.943±0.168 (T-score -1.4 SD), TBS 1.271±0.103. As expected,
correlation between BMD and site matched TBS is low (r2=0.16).
Prevalence of VFx grade 2/3, major OP Fx and all OP Fx is 8.4%, 17.0% and
26.0% respectively. Age- and BMI-adjusted ORs (per SD decrease) are 1.8 (1.2-
2.5), 1.6 (1.2-2.1), 1.3 (1.1-1.6) for BMD for the different categories of fractures
and 2.0 (1.4-3.0), 1.9 (1.4-2.5), 1.4 (1.1-1.7) for TBS respectively. Only 32
to 37% of women with OP Fx have a BMD < -2.5 SD or a TBS < 1.200. If we
combine a BMD < -2.5 SD or a TBS < 1.200, 54 to 60% of women with an osteoporotic
Fx are identified.
Conclusion: As in the already published studies, these preliminary results
confirm the partial independence between BMD and TBS. More importantly, a
combination of TBS subsequent to BMD increases significantly the identification
of women with prevalent OP Fx which would have been miss-classified by
BMD alone. For the first time we are able to have complementary information
about fracture (VFA), density (BMD), micro- and macro architecture (TBS
& HAS) from a simple, low ionizing radiation and cheap device: DXA. Such
complementary information is very useful for the patient in the daily practice
and moreover will likely have an impact on cost effectiveness analysis.