What is the best method to estimate fracture risk in a patient with concerns about osteoporosis, considering factors such as age, sex, weight, height, family history of hip fracture, personal history of fracture, smoking, glucocorticoid use, and rheumatoid arthritis?

FRAX Score: The Gold Standard for Fracture Risk Assessment

Use the FRAX calculator (https://www.shef.ac.uk/FRAX/tool.jsp) to estimate 10-year fracture probability—this is the recommended method for fracture risk assessment in patients with osteoporosis concerns. 1

What FRAX Calculates

FRAX provides two critical outputs for patients aged 40-90 years 1:

• 10-year probability of hip fracture
• 10-year probability of major osteoporotic fracture (MOF) - includes hip, clinical spine, wrist, or humerus fractures 1

Required Input Variables

Enter the following clinical information into the FRAX calculator 1, 2, 3:

• Demographics: Age, sex, weight, height (or BMI)
• Femoral neck BMD T-score (optional but strongly recommended—improves prediction accuracy significantly) 1, 2
• Clinical risk factors (all dichotomous yes/no):
  • Prior fragility fracture
  • Parental history of hip fracture
  • Current smoking
  • Glucocorticoid use (oral steroids)
  • Rheumatoid arthritis
  • Secondary osteoporosis causes
  • Alcohol consumption ≥3 units/day 1, 2, 3

Treatment Thresholds: When to Intervene

Initiate pharmacologic treatment when FRAX indicates 4, 5:

• ≥3% 10-year hip fracture risk, OR
• ≥20% 10-year major osteoporotic fracture risk

These thresholds represent cost-effective intervention points in the United States and are endorsed across multiple guidelines 4, 5, 3.

Critical Adjustment for Glucocorticoid Users

For patients taking prednisone >7.5 mg/day, manually adjust the FRAX output 1, 4:

• Multiply the MOF risk by 1.15
• Multiply the hip fracture risk by 1.2

Example: If FRAX calculates 2.0% hip fracture risk, adjust to 2.4% for high-dose steroid users 1.

This adjustment is necessary because FRAX's default glucocorticoid calculation assumes prednisone 2.5-7.5 mg/day 1.

Risk Stratification for Treatment Selection

Once you have the adjusted FRAX score, categorize patients 4:

• Very high risk: MOF >30% OR hip fracture >4.5% → Consider anabolic therapy first (teriparatide, romosozumab)
• High risk: MOF ≥20% OR hip fracture ≥3% → Antiresorptive therapy (bisphosphonates, denosumab)
• Low-moderate risk: Below treatment thresholds → Non-pharmacologic interventions only

Screening Recommendations by Age and Sex

For postmenopausal women ≥65 years: Screen all patients with DXA ± FRAX, regardless of risk factors 1, 4.

For postmenopausal women 50-64 years: Calculate FRAX without BMD first 1, 2:

• If FRAX approaches or exceeds 9.3% MOF risk or 1.3% hip fracture risk (the baseline risk of a 65-year-old white woman), proceed to DXA screening 1, 4, 2
• This approach identifies younger women who warrant formal BMD assessment

For men ≥50 years: Apply the same FRAX-based approach as for women 1, 3.

Important Limitations and Clinical Pitfalls

Race-Specific Calculator Concerns

FRAX uses race-specific calculators that systematically predict lower fracture risk for Asian, Black, and Hispanic individuals compared to White individuals with identical clinical profiles 1, 4, 2. This may lead to undertreatment in non-White populations—use clinical judgment to adjust treatment decisions when this disparity seems inappropriate 2.

What FRAX Doesn't Capture

FRAX has significant blind spots 1, 4, 2:

• Dose-dependent glucocorticoid effects (only yes/no, not quantified dose)
• Fall history and frailty status
• Number of prior fractures (only yes/no for any fracture)
• Lumbar spine BMD (uses only femoral neck)
• Trabecular bone score
• Diabetes mellitus

When these additional risk factors are present, consider treatment even if FRAX is below standard thresholds 4, 2.

Validity in Treated Patients

FRAX is validated only for untreated patients 3. There is ongoing debate about the accuracy of FRAX estimates after initiating osteoporosis pharmacotherapy 1. Use caution when reassessing fracture risk in patients already on treatment.

Reassessment Intervals

For patients on glucocorticoids not receiving osteoporosis treatment: Repeat FRAX assessment every 1-3 years 1, 4.

For very high-dose glucocorticoid users: Consider earlier reassessment (annually) 1.

Special Population: Adults <40 Years

FRAX cannot be used in adults <40 years 1. For this population, designate as moderate-to-high risk if 1:

• History of osteoporotic fracture, OR
• Hip or spine BMD Z-score <-3, OR
• Rapid bone loss (≥10% at hip or spine over 1 year), OR
• Continuing glucocorticoid treatment ≥7.5 mg/day for ≥6 months

Predictive Accuracy

FRAX demonstrates moderate-to-good predictive accuracy 4:

• Hip fracture prediction: AUC 0.74-0.79 (with BMD)
• MOF prediction: AUC 0.67-0.71 (with BMD)

Screening with FRAX followed by DXA reduces 4:

• Hip fractures by 17% (RR 0.83,95% CI 0.73-0.93)
• Major osteoporotic fractures by 6% (RR 0.94,95% CI 0.88-0.99)

Treatment with bisphosphonates in high-risk patients reduces vertebral fractures by 49% and hip fractures by 33% 4.