1. Aetna considers bone mass measurement using the established techniques listed below medically necessary for members who meet any of the following criteria:
   
   
   1. Screening of women who have been determined to be estrogen-deficient (peri- or post-menopausal) and at clinical risk for osteoporosis, based on individual or family history (Note: covered for members with preventive services benefits only); or
   2. Individuals with vertebral abnormalities as demonstrated by an x-ray to be indicative of osteoporosis, osteopenia, or vertebral fracture; or
   3. Individuals receiving (or expected to receive) glucocorticoid (steroid) therapy equivalent to 5 mg of prednisone or greater, per day, for more than 3 months; or
   4. Individuals with primary hyperparathyroidism; or
   5. Individuals being monitored to assess the response to or efficacy of osteoporosis drug therapy (only dual-energy x-ray absorptiometry is considered medically necessary for this indication); or
   6. Non-traumatic (fragility) fractures; or
   7. Women with hyperthyroidism; or
   8. Women on long-term anti-convulsant therapy (e.g., phenytoin, and phenobarbital); or
   9. Individuals with celiac sprue; or
   10. Men with hypogonadism or receiving androgen deprivation treatment (e.g., leuprolide, and goserelin).

   Aetna considers bone mass measurement experimental and investigational for all other indications.

   Repeat bone mass measurements are usually not indicated more frequently than once every two years. More frequent bone mass measurements may be considered medically necessary in any of the following circumstances:

   1. Monitoring individuals on long-term glucocorticoid (steroid) therapy or anticonvulsant therapy of more than 3 months duration; or
   2. For a confirmatory baseline bone mass measurement to permit monitoring of individuals in the future if the initial bone mass test was performed with a technique that is different from the proposed testing method; or
   3. Monitoring of individuals with uncorrected primary hyperparathyroidism. 

   Repeat bone mass measurement has no proven value for other indications.
   

2. Aetna considers simultaneous axial (central) and appendicular (peripheral) bone mass measurements medically necessary only in the following limited circumstances:
   
   
   1. Member is diagnosed with uncorrected primary hyperparathyroidism; or
   2. Appendicular measurements are considered medically necessary when artifacts obscure measurement at the axial skeleton; or
   3. An axial scan is considered medically necessary to get a baseline measurement for monitoring if osteoporosis is identified with an appendicular scan.

   Simultaneous axial and appendicular bone mass measurements have no proven value for other indications.

   The following methods are established procedures of bone mass measurements of the axial or appendicular (peripheral) skeleton:

   1. Dual energy X-ray absorptiometry (DEXA or DXA);
   2. Single energy X-ray absorptiometry (SEXA);
   3. Radiographic absorptiometry (photodensitometry);
   4. Quantitative computed tomography (QCT);
   5. Ultrasound bone mineral density studies (e.g., Sahara, SoundScan, Achilles + Bone Sonometer).
      
      

3. Aetna considers bone mass measurement by dual photon absorptiometry (DPA) or single photon absorptiometry (SPA) experimental and investigational.

4. Aetna considers screening for vertebral fractures with dual energy x-ray absorptiometry (DEXA or DXA) (also known as morphometric x-ray absorptiometry) as an adjunct to bone mineral density measurement experimental and investigational.  There is a lack of clinical trial evidence showing that patients with vertebral fractures on DXA but with bone mineral density levels above treatment thresholds benefit from pharmacologic treatment (BCBSA, 2004; BCBSA, 2006).  Note: Examples of vertebral fracture assessment application packages that have received 510(k) marketing clearance are the Instant Vertebral Assessment (IVA) (Hologic, Inc.) and Dual Energy Vertebral Assessment (DVA) (previously known as Lateral Vertebral Assessment (LVA) (GE Lunar Medical Systems). 

See also CPB 039 - Weight Reduction Medications and Programs.

This policy is based upon guidelines for bone mineral density screening from the Centers for Medicare and Medicaid Services, National Institutes of Health, the American Association of Clinical Endocrinologists, and the American Gastroenterological Association.

Osteoporosis is a disease characterized by low bone density and increased bone fragility, which reduce bone strength.  Postmenopausal osteoporosis is due to rapid bone loss that occurs with the decline in endogenous estrogen following menopause.

Primary osteoporosis is an aged-related disease characterized by low bone mass, microarchitectural deterioration of bone tissue leading to enhanced bone fragility, and a consequent increase in fracture risk in the absence of other recognizable causes of bone loss.   Present intervention efforts are directed largely at identifying those perimenopausal women who are the most likely to be at risk for future fracture, and providing preventive bisphosphonate therapy along with adequate calcium intake and weight bearing exercise.  Secondary osteoporosis has an identifiable cause of bone loss.  Many, but not all, patients receiving long-term therapy with glucocorticoids have rapid loss of bone; those who do, need to be identified for consideration of medication adjustments.  Bone mass also is reduced in some patients with asymptomatic primary hyperparathyroidism, that has been diagnosed as a result of multiphasic screening tests.  Whether these latter patients undergo parathyroidectomy may depend on there being a progressive loss of bone, presumed to be parathyroid hormone-dependent, and treatable by correction of the hyperparathyroidism.  Lastly, since not all patients with vertebral abnormalities have significant osteoporosis, identifying those who do, enables the costs and risks of follow-up and therapy to be directed and limited to those that require more extensive intervention.

The rationale for densitometry lies in the assumption that the strength or resistance of a bone to fracture is closely related to the mass of the mineral present in the bone; the lower the bone density, the greater the fracture risk.   Although BMD can be measured by some multi-purpose imaging devices such as quantitative computed tomography (QCT) scanners, specific densitometry tests emit lower radiation and cost less.  Single-photon absorptiometry (SPA), dual-photon absorptiometry (DPA), and dual-energy radiographic (x-ray) absorptiometry, (DEXA, DXA, DER, DRA) all calculate bone mass on the basis of tissue absorption of photons derived from either a radionuclide or an x-ray tube.

In the past, SPA and DPA were the most commonly method of measurement. These methods have largely been replaced by DEXA. SPA measures the distal third of the radius which is composed mainly of cortical bone whereas most nontraumatic fractures occur in the axial skeleton (spine) and proximal femur (hip), which have a significant amount of trabecular bone.   Measuring trabecular bone mass in the ultradistal radius or calcaneus (heel) has been more difficult because of bone tapering and irregularities.

Dual photon absorptiometry measures trabecular bone but costs more, takes longer, and the patient must lie down; apparent changes in serial DPA results must be carefully interpreted because the aging of the Gd-153 source can result in an apparent increase in bone mineral content.  

DEXA, available since 1987, is the current standard of care for  bone mass measruement, DEXA uses an x-ray tube, instead of an isotope to generate dual energy photons, resulting in higher image resolution and greater speed than DPA.   DEXA has replaced DPA; previous DPA manufacturers have switched to producing DEXA scanners.

Some authorities have advocated annual bone mineral density screening. The International Society for Clinical Densitometry, an association of providers with an interest in bone density measurement, recommends annual testing to detect continued bone loss in patients receiving treatment.  The position statement included a series of recommendations, but did not provide analysis to support these recommendations.  In addition, the American College of Radiology has recommended annual testing in patients receiving treatment.

However, the clinical literature on the accuracy and precision of bone density measurement does not support a recommendation for annual screening.    Erlichman & Holohan (1996) reviewed the literature on commonly used bone densitometry techniques, including DEXA.  They found that, although reviews of recent studies report DEXA accuracy error from 3 to 6 percent, other data indicate that DEXA accuracy error of ashed bone specimens of 9 percent.  (Measurements obtained by densitometers are compared with an independent standard measurement of bone mass, such as ashed bone sections.  The accuracy error is determined by how much the measurement varies from this accepted or "true" value.)

DEXA scans of the femur have a precision error from 0.5 percent to 3 percent.  Precision error is the variability in the measurements occurring with repeated measurements of the same object.  A technique's precision is critical for serial measurements that correctly document bone loss over time.  Factors such as patient positioning, calibration and standardization procedures, and differences in operator technique can result in large measurement variations.  The precision of measurements is reduced outside of the controlled conditions of a clinical trial setting.

The requisite minimum intervals between measurements that are necessary to reliably detect a reduction in bone mass are related to the precision attainable with current instruments and the rate of bone mass loss, assuming that the accuracy of the instrument is invariable.  If one assumed a 1 percent precision error, an annual rate of bone loss of 3 percent would be required to reliably detect bone mass loss after 1 year.

But Erlichman & Holohan (1996) explained that it is unlikely that yearly densitometry would be clinically indicated given the fact that 1 percent precision error is rarely attained and that a 3 percent annual loss in bone mass would be distinctly uncommon.  Precision errors in the range of 2 to 3 percent and annual bone mass losses of 1 to 2 percent are parameters more representative of published data.  In those instances, the minimum interval between densitometry measures necessary to document bone mass loss would be between 3.7 and 6 years.

Furthermore, there are no clinical data that demonstrate improved outcomes in osteoporosis patients who are screened annually.  Clinical trials of the bisphosphonate alendronates for the treatment of osteoporosis have found that failure to respond to therapy is a rare event.