Osteoporosis Diagnosis by DEXA and Ultrasound Measurement

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Osteoporosis Diagnosis by DEXA and Ultrasound
Measurement

• Dr. Suppasin Soontrapa
• Department of Orthopedics
• Khon Kaen University
• Khon Kaen
• Thailand
• 5 Mar 09

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Diagnostic criteria of skeletal osteoporosis
By using bone densitometry to measure BMD and
categorized the bone into 4 subgroups

• 1. Normal
• 2. Low bone mass (osteopenia)
• 3. Osteoporosis
• 4. Severe osteoporosis

WHO 1994
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Dual Energy X-Ray Absorptiometry (DEXA)

• Precision errors 1-2

• DPX-IQ, Lunar Corp, USA

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Average BMD in each age group
Peak bone mass (young adult reference mean)
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85
NORMAL
Normal BMD within 1 SD of the young adult
reference mean (T-scoregt -1)
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Low bone mass (osteopenia) BMD lt-1 SD of the
young adult mean but gt -2.5 SD (-1lt T-scoregt-2.5)
85
NORMAL
14.4
OSTEOPENIA
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Osteoporosis BMD lt -2.5 SD (T-scorelt-2.5)
85
NORMAL
14.4
OSTEOPENIA
0.6
OSTEOPOROSIS
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Severe osteoporosis BMDlt -2.5 SD with bony
fracture
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Guideline for diagnosing osteoporosis in Asia

• E.M.C. Lau, et al.
• APLAR Journal of Rheumatology 2006

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Indications for BMD measurement

• NOF recommends DXA measurement
• The elderly women age gt 65 yrs
• Postmenopausal women with previous history of
  fracture

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NOF recommends DXA measurement

• Postmenopausal women agelt 65 yrs and with gt 1
  additional risk factors for osteoporosis
• Parental history of hip fracture
• Current cigarette smoking
• BMI lt19 (for Asian women)
• Use of (or plan to use) oral corticosteroids for
  longer than 3 months
• Serious long-term conditions thought to increase
  fracture risk, such as hyperthyroidism or
  malabsorption

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Advantage Disadvantage of DEXA
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A Simple Tool to Identify Asian Women at
Increased Risk of Osteoporosis

• L.K.H. Koh et al.
• Osteoporos Int (2001) 12699-705

Osteoporosis Self Assessment Tool for Asians
(OSTA) Research Group
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OSTA index
Integer of (0.2 X (weight age))
Wt40, age 70 OSTA index -6
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Compared OSTA index with BMD of femoral neck

• By using OSTA index with cutoff value of -1 vs.
  Femoral neck BMD T-score lt -2.5
• Sensitivity 91
• Specificity 45
• PPV 20.88
• NPV 96.85

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Quantitative Ultrasound (QUS)
Heel QUS using a gel-coupled bone sonometer
Achillis Express (GE-Lunar, Madison, USA)
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Quantitative Ultrasound (QUS)

• Advantages
• Low cost
• Portability
• No radiation
• Easy to use

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Quantitative Ultrasound (QUS)

• Many studies showed QUS had low sensitivity and
  high specificity
• Suthee Panichkul, et al., (Phramongkutklao
  hospital) Obstet. Gynaecol. 2004
• QUS of the calcaneus (SI) vs. femoral neck BMD
  (using WHO criteria T-score lt -2.5)
• Sensitivity 39.25
• Specificity 91.71
• PPV 72.41
• NPV 73.14

SI (stiffness index)(0.67xBUA0.28xSOS-420)
Achillis express (Lunar, Madison, USA)
SI stiffness index
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Quantitative Ultrasound (QUS)

• Many studies showed QUS had low sensitivity and
  high specificity
• Vasi Naganathan, et al., (Royal North Shore
  hospital, Sydney) MJA 1999
• QUS of the calcaneus (BUA, VOS) vs. lumbar spine
  femoral neck BMD (using WHO criteria T-score lt
  -2.5)
• Sensitivity 9- 47 depending on the QUS
  parameters
• Specificity 88 - 100 depending on the QUS
  parameters

BUA Board band ultrasound attenuation VOS
velocity of sound
CUBA Mark II (McCue Ultrasonics, London, UK)
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Differences between OSTA and QUS
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The combination of OSTA index and quantitative
ultrasound to increase the efficacy and decrease
the cost in diagnosis of osteoporosis

• Dr.Suppasin Soontrapa, et al.
• Srinagarind Hospital
• Khon Kaen University
• Khon Kaen
• Thailand

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Research question

• Could sequential method of investigation
  (OSTAQUS) has diagnostic power on osteoporosis
  vs. gold standard DXA

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Objective

• To evaluate the efficacy of the combination of
  OSTA index and QUS in diagnosing osteoporosis in
  Thai elderly

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Methods

• First step
• Screening the participants by using OSTA index
  cutoff value of lt -1 (sen 91)
• Second step
• Measuring all participants who had OSTA index lt
  -1 by QUS (Achillis express) (spec 90) and
  DXA
• Comparing the T-score of QUS with T-score of DXA

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Results

• Total one hundred elderly women with OSTA index lt
  -1 were enrolled
• Average age 69.97 yrs (age range 60-89 yrs)
• Average weight 49.24 kg (weight range 30-81 kg)
• Average BMI 22.51 Kg/m2 (range 15.75-35.06)
• BMIlt19 19 cases
• BMI gt 19 81 cases

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Reliability and reproducibility of measurement
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Correlation between 1st and 2nd measurement of
1st observer
r0.973 plt0.001
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Correlation between 1st and 2nd measurement of
2nd observer
r0.976 plt0.001
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Correlation of the measurement between 1st and
2nd observers
r0.925 plt0.001
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Reliability or agreement of measurement

• Continuous value
• Limits of agreement of measurement
• X axis mean of measurement
• Y axis difference of measurement
• Test for significant difference
• One sample t-test with zero value
• Significant difference when p-valuelt0.05

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Mean SI 1 SI 2 2
Diff_SI SI1 SI2
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Limit agreement of SI between 1st and 2nd
measurement of 1st observer
One sample t-test test value 0 P-value 0.765
Mean diff. 0.12 SD 4
SI stiffness index
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Limit agreement of SI between 1st and 2nd
observer
Limit agreement of SI between 1st and 2nd
measurement of 2nd observer
One sample t-test test value 0 P-value 1
Mean diff. 0.00 SD 3.79
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Limit agreement of SI between 1st and 2nd
observer
One sample t-test test value 0 P-value 0.904
Mean diff. -0.08 SD 6.63
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conclusion

• Correlation coefficient (r) of both intra and
  interobserver showed strong correlation (gt0.9)
• Limits of agreement of both intra and
  interobserver showed no any significant
  difference from zero
• QUS has good reliability, reproducibility and
  easy to use

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Diagnostic characteristic of OSTA QUS vs. BMD
of spine L1-4 (T-score lt -2.5)
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Diagnostic characteristic of OSTA QUS vs. BMD
of femoral neck (T-score lt -2.5)
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Diagnostic characteristic of OSTA QUS vs. BMD
of total femur (T-score lt -2.5)
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Diagnostic characteristic of QUS T-score lt -4.5
VS BMD of spine and hip
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Site Of Measurement of DXA for osteoporosis
diagnosis

• WHO criteria (1994)
• No specific site
• WHO task force for Osteoporosis (1999)
• Femoral neck
• IOF (International Osteoporosis Foundation) year
  2000
• Total hip

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Diagnostic value of QUS T-score -4.5 for spine
and hip
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Conclusion

• OSTA index lt-1 and QUS T-score lt-4.5 performed
  well in diagnosis of osteoporosis (accuracy
  80-89 for hip BMD)
• Convenience to use
• Portability
• Cost effective

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Thank You for Your Attention