1. Rational Use of DXA-BMD
a Case based approach - Gregory Kline MD FRCPC

2. Disclosures (since 2009)
no relationships or conflicts to declare

3. Objectives
discussion of what BMD does and does not add to “screening/diagnosis” in osteoporosis
discuss indications for and limitations of serial BMD tests
review the related 2016 TOP Osteoporosis guidelines in clinical context
most important! Learn to think about what BMD might add BEFORE you order it.

4. Cases for discussion Case 1: when to do the “first” bone density
Case 2: serial “screening” bone density
Bonus material

5. Case 1: principles, not rules
the “first” BMD

6. Mrs. B
Mrs. B is a 50 year old healthy woman, no medications, no family history of hip fracture.
Height cm, weight 61 kg
She is concerned about developing osteoporosis and requests a “baseline” BMD
How do you respond and what reasons would you give either for or against?

7. Thinking it through What are we looking for with a “baseline” BMD?
remember: bone loss is universal with age - don’t need a test to prove ageing.
What will you do if it shows T score > -2.0?
What will you do if it shows T score -2.3?

8. Thinking it through: if the baseline BMD is “good”
A “baseline” measure implies that there will be a future measure which may be different than baseline AND
The rate of change between baseline and repeat measure is of relevance to management.
REALITY: the baseline BMD will simply reflect the time that has passed since menopause
REALITY: 100% chance that the next BMD will be lower
REALITY: management decisions will depend on the next BMD....no relevance to “baseline”

9. Thinking it through: what if the baseline BMD is “bad”?
What are the chances that a BMD, done now, in the absence of other risk factors, will be so low that it actually warrants medical therapy to be started right now?
Assume that medical therapy is warranted for a 10 year fracture risk of 20% or higher....
She would need to have a T-score of -4.5
The odds of that, in a healthy 50 year old < 1/10,000
And by the way, if she did have a T-score of -4.5 at age 50...she likely has some kind of metabolic bone disease…..

10. guidance

11. know the paradigm When we screen for osteoporosis:
we should NOT be screening to “find” low BMD
because many will not warrant treatment anyways
what is the point of screening for something that is a natural process of ageing and affects 100% of people
rather, appropriate osteoporosis screening should:
be designed to find people who are at such high fracture risk that drug intervention is warranted.

12. Practical meaning

13. how to think in practice
the idea is to “find” people who have at least 20% chance of fracture in the next 10 years
BMD is a tool that may help find some of those people

14. examples

15. exhibits
A) a 60 year old woman with polymyalgia rheumatica on prednisone 10 mg daily x 9 months. Smoker, height 168 cm weight 62 kg.
B) a 70 year old woman with mild kyphosis and maternal history of hip fracture. Height 165 cm, weight 59 kg.
C) a 59 year old female smoker with family history of hip fracture. Height 165 cm, weight 73 kg.
D) 62 year old healthy woman with no risk factors, height 166 cm, weight 75 kg.

16. exhibits
A) a 60 year old woman with polymyalgia rheumatica on prednisone 10 mg daily x 9 months, previous wrist fracture. Smoker, height 168 cm weight 62 kg. 10 year major OP # risk: 23% (FRAX score, no BMD)
B) a 70 year old woman with mild kyphosis and maternal history of hip fracture. Height 165 cm, weight 59 kg. 10 year major OP # risk: 31% (FRAX score, no BMD)
C) a 59 year old female smoker with family history of hip fracture. Height 165 cm, weight 73 kg. 10 year major OP # risk: 11.5% (FRAX score, no BMD)
D) 62 year old healthy woman with no risk factors, height 166 cm, weight 75 kg. 10 year major OP # risk: 7% (FRAX score, no BMD)

17. exhibits
A) a 60 year old woman with polymyalgia rheumatica on prednisone 10 mg daily x 9 months, previous wrist fracture. Smoker, height 168 cm weight 62 kg. 10 year major OP # risk: 23% (no BMD)
OP # risk with T-score -2.6: 26%
OP # risk with T-score - 1.5: 18%
B) a 70 year old woman with mild kyphosis and maternal history of hip fracture. Height 165 cm, weight 59 kg. 10 year major OP # risk: 31% (no BMD)
OP risk with T-score -2.6: 31%
OP # risk with T-score -1.5: 20%
C) a 59 year old female smoker with family history of hip fracture. Height 165 cm, weight 73 kg. 10 year major OP # risk: 11.5% (no BMD)
OP risk with T-score -2.6: 19%
OP risk with T-score -1.5: 12.5%
D) 62 year old healthy woman with no risk factors, height 166 cm, weight 75 kg. 10 year major OP # risk: 7% (no BMD)
OP # risk with T-score - 2.6: 11%
OP # risk with T-score -1.5: 7%

18. exhibits BMD changes nothing! BMD changes nothing!
A) a 60 year old woman with polymyalgia rheumatica on prednisone 10 mg daily x 9 months, previous wrist fracture. Smoker, height 168 cm weight 62 kg. 10 year major OP # risk: 23% (no BMD)
OP # risk with T-score -2.6: 26%
OP # risk with T-score - 1.5: 18%
B) a 70 year old woman with mild kyphosis and maternal history of hip fracture. Height 165 cm, weight 59 kg. 10 year major OP # risk: 31% (no BMD)
OP risk with T-score -2.6: 31%
OP # risk with T-score -1.5: 20%
C) a 59 year old female smoker with family history of hip fracture. Height 165 cm, weight 73 kg. 10 year major OP # risk: 11.5% (no BMD)
OP risk with T-score -2.6: 19%
OP risk with T-score -1.5: 12.5%
D) 62 year old healthy woman with no risk factors, height 166 cm, weight 75 kg. 10 year major OP # risk: 7% (no BMD)
OP # risk with T-score - 2.6: 11%
OP # risk with T-score -1.5: 7%
BMD changes nothing!
BMD changes nothing!
*BMD will be useful*
BMD changes nothing!

19. Guidelines in context

20. TOP guidelines Feb 2016 suggest screening BMD for women age > 65
because advanced age is a major risk factor
suggest screening BMD for men or women >50 with risk factors (long list)
memorize the list OR
use FRAX score without BMD

21. Case-based messages Case 1: the first bone density
“baseline” bone density concept is of no medical use and should be discouraged
bone density is an occasionally useful tool for fracture risk estimation in patients who are not obviously at very high (>20%) or very low (<10%) risk.
goal is to find people at high fracture risk
goal is not to find people with low BMD

22. Case 2 - serial “screening”
Mrs. C is 66 years old. She has no fracture risk factors. She had a screening BMD done last year, showing femoral neck T-score No specific therapy was started. She asks if she should have a repeat BMD this year to see if it has changed.
Will it have changed?
What is the chance she will have crossed a treatment threshold on the basis of bone loss in the past year?

23. guidance

25. interpretation They lack other risk factors OR
If a BMD is done (“rightly” or “wrongly”) and the patient is far away from an interventional threshold either because
They lack other risk factors OR
Their current risk factors + BMD still puts them at low risk
It will take somewhere between 2 and 15 years for even 10% of such persons to see enough BMD loss to actually cross an interventional threshold (all other risks being equal)

26. PRActical meaning

27. practical meaning
The value to annual or biannual BMD testing (all other risks being constant) is virtually zero since overall fracture risks (and therefore, distance to treatment threshold) changes minimally in less than 3-5 years.

28. examples

29. long term monitoring?
66 year old woman, height 170 cm, wt 73 kg, no risks, screening BMD T-score OP # risk 8.6%
67 years old, BMD T-score -1.9 OP # risk 9.5%
68 years old, BMD T-score -1.9 OP # risk 9.8%
69 years old, BMD T-score -2.2 OP # risk 11.4%
70 years old, BMD T-score -2.3 OP # risk 12.1%
71 years old, BMD T-score -2.6 OP # risk 14.3%

30. how much did it add? NOT VALUABLE NOT VALUABLE NOT VALUABLE
66 year old woman, height 170 cm, wt 73 kg, no risks, screening BMD T-score OP # risk 8.6%
67 years old, BMD T-score -1.9 OP # risk 9.5%
68 years old, BMD T-score -1.9 OP # risk 9.8%
69 years old, BMD T-score -2.2 OP # risk 11.4%
70 years old, BMD T-score -2.3 OP # risk 12.1%
71 years old, BMD T-score -2.6 OP # risk 14.3%
NOT VALUABLE
NOT VALUABLE
NOT VALUABLE
NOT VALUABLE
NOT VALUABLE?

31. maternal hip # reported
Thinking about what you might find first…
65 year old woman, height 170 cm, wt 73 kg, no risks, screening BMD T-score OP # risk 8.6%
Age
other risks
risk (no BMD)
risk (T-2.0)
risk (T-3.3) 66
8.6%
9.6%
17.5%*
highly unlikely! 67
maternal hip # reported
15.1%
17.2%*
most likely but
adds little
29%*
useful if the first BMD 68
15.3%
17.2%
29.8% 69
15.5%
17.1%
30.8%

32. how much does BMD add…?
if a prior BMD exists from the past 3-5 years, a repeat measure rarely adds to your updated FRAX assessment (use the old BMD result!)
if over age 50 and a new major risk factor acquired, consider new BMD if:
no prior BMD within 5 years AND
intervention not already obviously indicated by risk factors alone
General principle: before ordering BMD, consider whether it is likely to really change anything; FRAX calculation may help.

33. guidelines in context

34. TOP guidelines 2016
repeated BMD testing alone provides little value to decision-making in osteoporosis

35. Case-based messages (2)
Case 2: serial “screening” bone density
intervals for repeat screening depend upon fracture risk at last screening visit, not necessarily time-standardized.
fracture risk and BMD change very slowly
annual BMD almost never useful unless patient has also acquired new major risk factors as well
since goal is to find people who are at intervention threshold, serial screening need not necessarily be BMD- driven

36. bonus material

37. BMD measures “on therapy”
BMD “change” in either direction not really predictive of anything while on therapy
BMD / scoring systems on therapy not useful for fracture risk estimation
BMD - driven changes to therapy (medication switching) not supported by evidence
Undetermined role of BMD monitoring around bisphosphonate “holiday”

38. Monitoring Osteoporosis Therapy With Bone Densitometry
Misleading Changes and Regression to the Mean
JAMA. 2000;283(10): doi: /jama

39. examples
patient on alendronate, follow up BMD shows 2% decrease. Action: nothing.
patient on alendronate, follow up BMD shows 3% decrease. Action: probably obligated to repeat next year…..BMD no change….action: nothing.
patient on alendronate, follow up BMD shows no change. Action: nothing.
patient on alendronate, follow up BMD shows 10% decrease. Action:investigate……but very rare situation!
Controversy: is serial BMD broadly warranted to find very rare cases of occult metabolic bone disease / cancer?

40. exhibits (2)
patient on bisphosphonate has repeat BMD (no change), report says “high risk of fracture”
is this true? is this a surprise? does this change anything?

41. when does repeat BMD on therapy help?
little evidence to answer this question
possibly if suspected malabsorption of oral bisphosphonate
possibly during bisphosphonate holiday
and therefore, possibly at the “end” of bisphosphonate treatment, prior to bisphosphonate holiday

42. summary

43. BMD uses baseline BMD at menopause - discourage
choice to do BMD should FOLLOW, not precede, a review of risk factors
BMD is most useful in cases of indeterminate risk
…which usually means people with fracture risk factors or advanced age without risk factors
serial BMD in untreated patients should likely be years apart in order to be useful
serial BMD in treated patients is of very low value in most cases