At what FRAX (Fracture Risk Assessment Tool) score would you start a bisphosphonate for an osteopenia patient?

Bisphosphonate Treatment Threshold for Osteopenia Patients

For an osteopenia patient with a FRAX score of 9% for major osteoporotic fracture, bisphosphonate therapy is not recommended as this falls below the established treatment threshold of ≥20% for major osteoporotic fracture or ≥3% for hip fracture.

Treatment Thresholds Based on FRAX Scores

The American College of Radiology and other major guidelines recommend initiating bisphosphonate therapy when:

• FRAX 10-year probability is ≥20% for major osteoporotic fracture OR
• FRAX 10-year probability is ≥3% for hip fracture, regardless of T-score 1

With a FRAX score of only 9% for major osteoporotic fracture, this patient falls significantly below the recommended treatment threshold, making bisphosphonate therapy inappropriate at this time.

Risk Stratification Approach

The decision to initiate bisphosphonate therapy should follow this algorithm:

1. High fracture risk (requiring treatment):

   • FRAX score ≥20% for major osteoporotic fracture OR
   • FRAX score ≥3% for hip fracture OR
   • T-score ≤-2.5 at any major site OR
   • Previous fragility fracture

2. Moderate fracture risk (consider treatment):

   • FRAX score 10-19% for major osteoporotic fracture
   • Significant risk factors not captured by FRAX

3. Low fracture risk (no pharmacologic treatment):

   • FRAX score <10% for major osteoporotic fracture
   • No significant additional risk factors

Important Considerations

Efficacy in Osteopenia

The efficacy of bisphosphonates in patients with T-scores in the osteopenic range (-2.5 to -1.0) is less well established than in those with osteoporosis. The number needed to treat (NNT) in osteopenic patients without other risk factors exceeds 100, compared to NNT of 10-20 in patients with fractures and T-scores below -2.5 2.

Treatment Failure Risk

Initiating treatment when not indicated may expose patients to unnecessary risks. Studies show that approximately 25.8% of postmenopausal women with primary osteoporosis experience bisphosphonate treatment failure despite good compliance 3. This highlights the importance of targeting therapy to appropriate candidates.

Risk-Benefit Assessment

For patients with FRAX scores below treatment thresholds, the potential risks of bisphosphonates (including gastrointestinal side effects, atypical femur fractures, and osteonecrosis of the jaw) outweigh the modest benefits in fracture reduction.

Alternative Management Approach

For this osteopenia patient with a FRAX score of 9%, focus on:

1. Calcium and vitamin D supplementation: 1,000-1,200 mg calcium and 800-1,000 IU vitamin D daily 1

2. Lifestyle modifications:

   • Weight-bearing exercise (30 minutes, 3 days/week)
   • Smoking cessation
   • Limiting alcohol consumption
   • Fall prevention strategies

3. Regular monitoring:

   • Reassess FRAX score every 1-2 years
   • Repeat BMD testing every 2-3 years
   • Monitor for height loss or new fractures

When to Reconsider Treatment

Bisphosphonate therapy should be initiated if:

• FRAX score increases to ≥20% for major osteoporotic fracture or ≥3% for hip fracture
• Patient experiences a fragility fracture
• BMD decreases significantly on follow-up testing
• Patient develops additional risk factors (e.g., starts corticosteroid therapy)

For patients on glucocorticoid therapy, the FRAX thresholds should be adjusted by increasing the risk by 1.15 for major osteoporotic fracture and 1.2 for hip fracture if the glucocorticoid dose is >7.5 mg/day 4.