Official positions of the International Society for Clinical Densitometry.

Introduction

With the increasing use of bone density testing for diagnosing osteoporosis and establishing fracture risk, inconsistencies have arisen in the way in which bone densitometry is performed and the results interpreted. Differences in indications for bone mass testing, acquisition techniques, interpretation of results for different ages, genders, and ethnicity, quality assurance, reporting methods, and terminology may have adverse effects on patient care and the exchange of scientific information. For this reason the International Society for Clinical Densitometry (ISCD) periodically convenes Position Development Conferences (PDCs) at which panels of international experts in the field of bone densitometry consider these issues. Recommendations of the panel are then submitted to the ISCD Board of Directors for consideration, and those that are approved become official ISCD positions.

The ISCD is a not-for-profit multidisciplinary professional society with a mission to enhance knowledge and quality of bone densitometry among healthcare professionals, to provide continuing education courses for clinicians and technologists, to increase patient awareness and access to bone densitometry, and to support clinical and scientific advances in the field.

The most recent PDC was held in Cincinnati, Ohio, on July 25-27, 2003. This document summarizes the official positions of the ISCD resulting from this conference and the previous one held in 2001. The complete original papers with the background and rationale for each position are published in the Journal of Clinical Densitometry. (1-12)

Positions of the ISCD

Indications for bone mineral density (BMD) testing

* Women aged 65 and older.

* Postmenopausal women under age 65 with risk factors.

* Men aged 70 and older.

* Adults with a fragility fracture.

* Adults with a disease or condition associated with low bone mass or bone loss.

* Adults taking medications associated with low bone mass or bone loss.

* Anyone being considered for pharmacologic therapy.

* Anyone being treated, to monitor treatment effect.

* Anyone not receiving therapy in whom evidence of bone loss would lead to treatment.

Women discontinuing estrogen should be considered for bone density testing according to the indications listed above.

Reference database for t-scores

* Use a uniform Caucasian (non-race adjusted) female normative database for women of all ethnic groups.

* Use a uniform Caucasian (non-race adjusted) male normative database for men of all ethnic groups.

Central DXA for diagnosis

* Skeletal sites to measure

* Measure BMD at both PA spine and hip in all patients.

* Forearm BMD should be measured under the following circumstances:

* Hip and/or spine cannot be measured or interpreted.

* Hyperparathyroidism.

* Very obese patients (over the weight limit for DXA table).

* Spine Region of Interest

* Use PA L1-L4 for spine BMD measurement.

* Use all evaluable vertebrae and only exclude vertebrae that are affected by local structural change or artifact. Use three vertebrae if four cannot be used and two if three cannot be used.

* Lateral spine should not be used for diagnosis, but may have a role in monitoring.

* Hip Region of Interest

* Use total proximal femur, femoral neck, or trochanter, whichever is lowest.

* BMD may be measured at either hip.

* Do not use Ward's area for diagnosis.

* There are insufficient data to determine whether mean T-scores for bilateral hip BMD can be used for diagnosis.

* The mean hip BMD can be used for monitoring, with total hip being preferred.

* Forearm Region of Interest

* Use 33% radius (sometimes called one-third radius) of the non-dominant forearm for diagnosis. Other forearm regions of interest are not recommended.

Peripheral bone densitometry

* The World Health Organization (WHO) classification for diagnosis of osteoporosis and osteopenia should not be used with peripheral BMD measurement other than 33% radius.

* Peripheral measurements:

* Are useful for assessment of fracture risk.

* Theoretically can be used to identify patients unlikely to have osteoporosis and identify patients who should be treated; however, this cannot be applied in clinical practice until device-specific cut-points are established.

* Should not be used for monitoring.

Diagnosis in postmenopausal women

* The WHO classification (normal, T-score -1.0 or above; osteoporosis, T-score -2.5 or below; osteopenia, T-score between -1.0 and -2.5) should be used.

* The lowest T-score of PA spine, femoral neck, total hip, trochanter, or the 33% radius, if measured, should be selected.

Diagnosis in men (age 20 and older)

* The WHO classification should not be applied in its entirety to men.

* In men age 65 and older, T-scores should be used and osteoporosis diagnosed if the T-score is at or below -2.5.

* In men from age 50 to 64 years, T-scores may be used and osteoporosis diagnosed if both the T-score is at or below -2.5 and other risk factors for fracture are identified.

* Men at any age with secondary causes of low BMD (eg, glucocorticoid therapy, hypogonadism, hyperparathyroidism) may be diagnosed clinically with osteoporosis supported by findings of low BMD.

* The diagnosis of osteoporosis in men under age 50 years should not be made on the basis of densitometric criteria alone.

Diagnosis in premenopausal women (age 20 to menopause)

* The WHO classification should not be applied to healthy premenopausal women.

* Z-scores rather than T-scores should be used.

* Osteoporosis may be diagnosed if there is low BMD with secondary causes (eg, glucocorticoid therapy, hypogonadism, hyperparathyroidism) or with risk factors for fracture.

* The diagnosis of osteoporosis in premenopausal women should not be made on the basis of densitometric criteria alone.

Diagnosis in children (males or females less than age 20)

* The WHO classification should not be applied to children.

* T-scores should not be used in children; Z-scores should be used instead.

* T-scores should not appear in reports or on DXA printouts in children.

* The diagnosis of osteoporosis in children should not be made on the basis of densitometric criteria alone.

* Terminology such as "low bone density for chronologic age" may be used if the Z-score is below -2.0.

* Z-scores must be interpreted in the light of the best available pediatric databases of age-matched controls. The reference database should be cited in the report.

* Spine and total body are the preferred skeletal sites for measurement.

* The value of BMD to predict fractures in children is not clearly determined.

* There is no agreement on standards for adjusting BMD or bone mineral content (BMC) for factors such as bone size, pubertal stage, skeletal maturity, and body composition. If adjustments are made, they should be clearly stated in the report.

* Serial BMD studies should be done on the same machine using the same scanning mode, software and analysis when appropriate. Changes may be required with growth of the child.

* Any deviation from standard adult acquisition protocols, such as use of low-density software and manual adjustment of region of interest, should be stated in the report.

Serial BMD measurement

* Serial BMD testing can be used to determine whether treatment should be started on untreated patients, because significant loss may be an indication for treatment.

* Serial BMD testing can monitor response to therapy by finding an increase or stability of bone density.

* Serial BMD testing can evaluate individuals for non-response by finding loss of bone density, suggesting the need for reevaluation of treatment and evaluation for secondary causes of osteoporosis.

* Follow-up BMD testing should be done when the expected change in BMD equals or exceeds the least significant change (LSC).

* Intervals between BMD testing should be determined according to each patient's clinical status. Typically one year after initiation or change of therapy is appropriate, with longer intervals once therapeutic effect is established.

* In conditions associated with rapid bone loss, such as glucocorticoid therapy, testing more frequently is appropriate.

Phantom scanning and calibration

The Quality Control (QC) program at a DXA center should include adherence to manufacturer guidelines for system maintenance. In addition, if not recommended in the manufacturer protocol, the following QC procedures are advised:

* Perform periodic (at least once per week) phantom scans for any DXA system as an independent assessment of system calibration.

* Plot and review data from calibration and phantom scans.

* Verify the phantom mean BMD after any service performed on the densitometer.

* Establish and enforce corrective action thresholds that trigger a call for service.

* Maintain service logs.

* Comply with government inspections, radiation surveys and regulatory requirements.

Precision assessment

* Each DXA center should determine its precision error and calculate the LSC. The precision error supplied by the manufacturer should not be used.

* If a DXA center has more than one technologist, an average precision error, combining data from all technologists, should be used to establish precision error and LSC for the center, provided the precision error for each technologist is within a pre-established range of acceptable performance.

* At the present time, in the absence of an industry-wide competency threshold, the center's discretion must be used to define acceptable performance.

* An industry-wide competency threshold (expressed as the %CV) should be established to define the minimum skill level. This competency threshold could be used to verify that the skill level of different technologists is similar.

* Every technologist should perform an in vivo precision assessment using patients representative of the clinic's patient population.

* Each technologist should do one complete precision assessment after basic scanning skills have been learned (eg, manufacturer training) and after having performed approximately 100 patient scans.

* A repeat precision assessment should be done if a new DXA system is installed.

* A repeat precision assessment should be done if a technologist's skill level has changed.

* To perform a precision analysis:

* Measure 15 patients 3 times, or 30 patients 2 times, repositioning the patient after each scan.

* Calculate the root mean square standard deviation (RMS-SD) for the group.

* Calculate LSC for the group at 95% confidence interval.

* Precision assessment should be standard clinical practice. Precision assessment is not research and may potentially benefit patients. It should not require approval of an institutional review board. Adherence to local radiologic safety regulations is necessary. Performance of a precision assessment requires the consent of participating patients.

Cross-calibration of DXA systems

Until such time as DXA manufacturers develop practical standardized procedures for phantom and in vivo cross-calibration, it is necessary to reestablish the BMD baseline on the new DXA system and not rely on the baseline acquired with the old DXA or cross-calibration formulas.

Baseline DXA report: minimum requirements

* Demographics (name, medical record identifying number, date of birth, sex).

* Requesting provider.

* Indications for the test.

* Manufacturer and model of instrument used.

* Technical quality and limitations of the study, stating why a specific site or region of interest (ROI) is invalid or not included.

* BMD in g/c[m.sup.2] for each site.

* The skeletal sites, ROIs, and, if appropriate, the side, that were scanned.

* The T-score and/or Z-score where appropriate.

* WHO classification for diagnosis in postmenopausal females and in men over age 65 years or men 50 to 65 years with other risk factors.

* Risk factors including information regarding previous nontraumatic fractures.

* A statement about fracture risk. Any use of relative fracture risk must specify the population of comparison (eg, young adult or age-matched). The ISCD favors the use of absolute fracture risk prediction when such methodologies are established.

* A general statement that a medical evaluation for secondary causes of low BMD may be appropriate.

* Recommendations for the necessity and timing of the next BMD study.

Follow-up DXA report: minimum requirements

* Statement regarding which previous or baseline study and ROI is being used for comparison.

* Statement about the LSC at your center and the statistical significance of the comparison.

* Report significant change, if any, between the current and previous study or studies in g/c[m.sup.2] and percentage.

* Comments on any outside study including manufacturer and model on which previous studies were performed and the appropriateness of the comparison.

* Recommendations for the necessity and timing of the next BMD study.

DXA report: optional items

* Recommendation for further non-BMD testing, such as x-ray, magnetic resonance imaging, computed tomography, etc.

* Recommendations for pharmacological and nonpharmacological interventions.

* Addition of the percentage compared to a reference population.

* Specific recommendations for evaluation of secondary osteoporosis.

DXA report: items that should not be included

* A statement that there is bone loss without knowledge of previous bone density.

* Mention of "mild," "moderate" or "marked" osteopenia or osteoporosis.

* Separate diagnoses for different regions of interest (eg, osteopenia at the hip and osteoporosis at the spine).

* Expressions such as "She has the bones of an 80-year-old," if the patient is not 80 years old.

* Results from skeletal sites that are not technically valid.

* The change in BMD if it is not a significant change based on the precision error and LSC.

DXA nomenclature 

* DXA - not DEXA.

* T-score - not T score, t-score, or t score

* Z-score - not Z score, z-score, or z score

DXA decimal digits

Preferred number of decimal digits for DXA reporting:

* BMD: 3 digits (example, 0.927 g/c[m.sup.2])

* T-score: 1 digit (example, -2.3)

* Z-score: 1 digit (example, 1.7)

* BMC: 2 digits (example, 31.76 g)

* Area: 2 digits (example, 43.25 c[m.sup.2])

* % reference database: Integer (example, 82%)

For the International Society for Clinical Densitometry

Copyright [c] 2004 by The Southern Medical Association 0038-4348/04/9701-0107

References

(1.) Lenchik L, Leib ES, Hamdy RC, Binkley NC, Miller PD, Watts NB. 2002 Executive summary International Society for Clinical Densitometry position development conference Denver, Colorado July 20-22, 2001. J Clin Densitom. 5 Suppl:S1-3.

(2.) Lenchik L, Kiebzak GM, Blunt BA. 2002 What is the role of serial bone mineral density measurements in patient management? J Clin Densitom. 5 Suppl:S29-38.

(3.) Hamdy RC, Petak SM, Lenchik L. 2002 Which central dual X-ray absorptiometry skeletal sites and regions of interest should be used to determine the diagnosis of osteoporosis? J Clin Densitom. 5 Suppl:S11-18.

(4.) Binkley NC, Schmeer P, Wasnich RD, Lenchik L. 2002 What are the criteria by which a densitometric diagnosis of osteoporosis can be made in males and non-Caucasians? J Clin Densitom. 5 Suppl:S19-27.

(5.) Miller PD, Njeh CF, Jankowski LG, Lenchik L. 2002 What are the standards by which bone mass measurement at peripheral skeletal sites should be used in the diagnosis of osteoporosis? J Clin Densitom. 5 Suppl:S39-45.

(6.) Leib ES, Lenchik L, Bilezikian JP, Maricic MJ, Watts NB. 2002 Position statements of the International Society for Clinical Densitometry: methodology. J Clin Densitom. 5 Suppl:S5-10.

(7.) International Society for Clinical Densitometry Position Development Conference. Executive summary: Cincinnati Ohio, July 25-27, 2003. 2004 J Clin Densitom. 7:In press.

(8.) International Society for Clinical Densitometry Position Development Conference. Introduction, methods, and participants. 2004 J Clin Densitom. 7:In press.

(9.) International Society for Clinical Densitometry Position Development Conference. The diagnosis of osteoporosis in men, premenopausal women, and children. 2004 J Clin Densitom. 7:In press.

(10.) International Society for Clinical Densitometry Position Development Conference. Technical standardization for dual-energy x-ray absorptiometry. 2004 J Clin Densitom. 7:In press.

(11.) International Society for Clinical Densitometry Position Development Conference. Indications and reporting for dual-energy x-ray absorptiometry. 2004 J Clin Densitom. 7:In press.

(12.) International Society for Clinical Densitometry Position Development Conference. Nomenclature and decimal places in bone densitometry. 2004 J Clin Densitom. 7:In press.

Edward S. Leib, MD, E. Michael Lewiecki, MD, Neil Binkley, MD, and Ronald C. Hamdy, MD