Whom to Screen: Question Three
Your answer is incorrect. The correct answer is A.
If her hip DXA did not show osteoporosis, when would you screen her again?
- Option A In 2-5 years, depending on her T score and risk factors.
- Option B Follow up screening is not necessary because if she does not have osteoporosis by age 65, she most likely will never develop it.
- Option C In one year, as osteoporosis develops quickly after age 65.
What is the optimal interval for repeat screening for osteoporosis?
This area has not been well studied; no organizations recommend a specific screening frequency. The USPSTF states that "evidence is lacking about optimal intervals for repeat screening." (1) The National Osteoporosis Foundation guidelines suggest that repeat BMD testing might be indicated to monitor the effects of anti-resorptive therapy at 2 year intervals. (2) At least one study suggests that repeat testing added little to the predictive power over and above that of the first measurement.(3)
If repeat measurement is considered, the appropriate interval depends on the expected rate of bone loss and the precision/margin of error of the test; in the case of DXA this is =/-2-3%. The table below lists the expected rate of bone loss and screening interval in a variety of clinical conditions.
|Condition||Change||DXA Screening Interval|
|Natural Menopause||- 1-2%||2-5 years|
|Glucocorticoids||- 10-30%||3-12 months|
|Heart Transplant||- 8-10%||6-12 months|
|ChemoTx for Breast Ca||- 3-8%||12 months|
|BisPhos Treatment||+2-3%||2-5 years|
|Margin of Error DXA||+/- 2-3%|
Table source, see reference 4.
BOTTOM LINE: If repeat screening is deemed necessary, a screening interval of 2-5 years is reasonable for women without conditions associated with very rapid bone loss. This decision will ultimately depending on the previous DEXA results and the expected rate of bone loss. The age at which screening should be discontinued is unclear.
- Nelson HD, Haney EM, Dana T, Bougatsos C, Chou R. Screening for osteoporosis: an update for the U.S. Preventive Services Task Force. Ann Intern Med 2010; 153: 99-111 [PMID: 2062189].
- National Osteoporosis Foundation. Clinicians Guide to Prevention and Treatment of Osteoporosis 2010. 0000. Available online.
- Hillier TA, et al. Evaluating the value of repeat bone mineral density measurement and prediction of fractures in older women: the study of osteoporotic fractures. Arch Intern Med 2007; 167: 155-160.
- Sambrook P, et al. Corticosteroid effects on proximal femur bone loss. J Bone Min Res 1990; 59120: 1211-16.