When should medication be initiated based on Dual-Energy X-ray Absorptiometry (DEXA) scan results?

From the Guidelines

Medication should be initiated based on Dual-Energy X-ray Absorptiometry (DEXA) scan results when the T-score is -2.5 or lower, or when the T-score is between -1.0 and -2.5 with additional risk factors for fracture, as recommended by the most recent guidelines 1. The decision to start medication based on a DEXA scan depends on various factors, including the T-score, age, and presence of risk factors for fracture.

Key Considerations

• A T-score of -2.5 or lower indicates osteoporosis, and treatment is generally recommended in these cases.
• For individuals with a T-score between -1.0 and -2.5, additional risk factors such as previous fractures, family history of hip fracture, or use of medications that affect bone health should be considered when deciding whether to initiate treatment.
• The updated practice guideline for dual-energy x-ray absorptiometry (DXA) recommends considering DXA in all women at the age ≥ 65 years, men age > 70 years, and women and men age ≥ 50 years with risk factors for osteoporosis 1.

Treatment Options

• Common first-line medications include bisphosphonates like alendronate (Fosamax) 70mg weekly, risedronate (Actonel) 35mg weekly, or zoledronic acid (Reclast) 5mg IV yearly.
• For postmenopausal women, selective estrogen receptor modulators like raloxifane (Evista) 60mg daily may be an option.
• For severe cases or when other treatments fail, anabolic agents like teriparatide (Forteo) or abaloparatide (Tymlos) might be prescribed.

Additional Recommendations

• Regardless of medication choice, calcium (1000-1200mg daily) and vitamin D (800-1000 IU daily) supplements are typically recommended alongside weight-bearing exercise.
• Treatment duration varies but is often reassessed after 3-5 years to evaluate continued need based on fracture risk, as suggested by the guidelines 1.

From the FDA Drug Label

The efficacy and safety of Prolia in the treatment to increase bone mass in men with osteoporosis was demonstrated in a 1-year, randomized, double-blind, placebo-controlled trial. Enrolled men had a baseline BMD T-score between -2.0 and -3. 5 at the lumbar spine or femoral neck. Men with a BMD T-score between -1.0 and -3. 5 at the lumbar spine or femoral neck were also enrolled if there was a history of prior fragility fracture.

Enrolled patients ≥ 50 years of age who were in the glucocorticoid-continuing subpopulation were required to have a baseline BMD T-score of ≤ -2.0 at the lumbar spine, total hip, or femoral neck; or a BMD T-score ≤ -1. 0 at the lumbar spine, total hip, or femoral neck and a history of osteoporotic fracture.

Men less than 70 years of age had either a BMD T-score at the lumbar spine, total hip, or femoral neck between -1.0 and -4.0, or a history of an osteoporotic fracture.

Medication with denosumab (Prolia) should be initiated based on the following Dual-Energy X-ray Absorptiometry (DEXA) scan results:

• A BMD T-score between -2.0 and -3.5 at the lumbar spine or femoral neck
• A BMD T-score between -1.0 and -3.5 at the lumbar spine or femoral neck with a history of prior fragility fracture
• A BMD T-score of ≤ -2.0 at the lumbar spine, total hip, or femoral neck
• A BMD T-score of ≤ -1.0 at the lumbar spine, total hip, or femoral neck with a history of osteoporotic fracture
• A BMD T-score between -1.0 and -4.0 at the lumbar spine, total hip, or femoral neck for men with prostate cancer receiving androgen therapy 2

From the Research

Initiation of Medication Based on DEXA Scan Results

Medication for osteoporosis should be initiated based on the results of a Dual-Energy X-ray Absorptiometry (DEXA) scan, which measures bone mineral density (BMD) 3. The decision to start medication is typically made when the BMD T-score values at the lumbar spine, femoral neck, or total hip are at or below -2.5, confirming the diagnosis of osteoporosis 3.

Factors Influencing Medication Initiation

Several factors influence the initiation of medication, including:

• Age: Medication may be considered for individuals aged 65 and older, as the vast majority of these patients will have a T-score of -1.5 or below 3.
• Clinical risk factors: DEXA scans should be considered for patients with an increased risk of fracture based on clinical risk factors, such as long-term corticosteroid therapy, chronic inflammatory disease, malabsorption, and untreated premature menopause 3.
• Fracture risk: Patients at high risk of fracture should consider treatment with antiresorptive therapy, including bisphosphonates and denosumab 4.

DEXA Scan Results and Medication Initiation

The results of a DEXA scan can guide the initiation of medication, with the following considerations:

• T-score of -2.5 or less: Confirms the diagnosis of osteoporosis and indicates the need for medication [(3,4)].
• T-score of -1.5 or below: May indicate the need for medication, especially in patients with glucocorticoid-induced osteoporosis 3.
• BMD gain or loss: Monitoring BMD changes over time can help assess the response to treatment and guide adjustments to medication [(5,6,7)].