AYR 5th Webinar Blackboard

CASE 1

A 78 year old Chinese lady came to see you with back pain. A plain lumbar spine x-ray showed lumbar spondylosis in L3, L4 and L5. There were no obvious vertebral fracture but the bones were reported as “osteopenic”. She had well-controlled hypertension on valsartan but was otherwise well with no history of fracture. You did a DXA for her and found her results showed osteoporosis. She was started on weekly alendronate with vitamin D3. After 5 years of treatment, she had another DXA. These are her results:

Which of the following statements are CORRECT, when comparing the 2 DXA results?

1. There has been no significant increase in her total hip BMD.
2. There has been a 5.9% reduction in her femoral neck T-score which suggests an adequate response to treatment.
3. There has been an 8.5% increase in her lumbar spine BMD suggestive of an adequate response to treatment.
4. There has been a 4.6% increase in femoral neck BMD suggestive of an inadequate response.
5. She has not been on the drug for long enough yet to assess if she has responded to the drug.

Your Answer is Incorrect

Answer with Detailed explanation

The correct answer is 1 & 3:
1. There has been no significant increase in her total hip BMD
3. There has been an 8.5% increase in her lumbar spine BMD suggestive of an adequate response to treatment.

When assessing whether there has been a significant change in BMD on treatment, remember the concept of “least significant change”, to determine if there has been a true interval change in BMD. For the spine, there has to be a change of at least 3-4%, 4-6% at the femoral neck and 2-3% at the wrist. Thus for statement 1, for total hip BMD, there was an increase of +2%, which is not a significant increase, thus TRUE. Similarly, for statement 3, an increase of +8.5% in lumbar spine BMD is an adequate response – TRUE. For statement 4, an increase of +4.6% in the femoral neck is adequate, thus it is FALSE. For statement 2, the least significant change is calculated on BMD, not T-scores, thus FALSE. For statement 5, we would expect that after 5 years, there would have been enough time to determine if the drug is working, thus FALSE. At the minimum, we would expect to see a response by 2 years.

By Dr Swan Sim Yeap, Consultant Rheumatologist, Subang Jaya Medical Centre, Selangor, Malaysia