Definition of Severe Osteoporosis
Severe osteoporosis is defined as a bone mineral density (BMD) T-score of -2.5 or lower plus the presence of one or more fragility fractures. 1
Diagnostic Criteria
Severe osteoporosis represents an advanced stage of bone disease characterized by:
- T-score ≤ -2.5 as measured by dual-energy x-ray absorptiometry (DXA) 2
- One or more fragility fractures 3
- A fragility fracture is defined as a fracture resulting from trauma equivalent to or less than a fall from standing height 2
This definition builds upon the World Health Organization (WHO) classification system for bone mineral density:
| Category | T-score |
|---|---|
| Normal BMD | ≥ -1.0 |
| Osteopenia/low bone mass | -1.0 to -2.5 |
| Osteoporosis | ≤ -2.5 |
| Severe osteoporosis | ≤ -2.5 plus fragility fracture |
Clinical Significance
The designation of "severe osteoporosis" has important clinical implications:
- Indicates substantially higher risk for subsequent fractures 4
- Patients with severe osteoporosis have a 5-fold increased risk for additional vertebral fractures 4
- They also have a 2-3 fold increased risk for fractures at other sites 4
- Represents a medical urgency requiring prompt intervention 3
Advanced Severe Osteoporosis
Some experts have proposed a concept of "advanced severe osteoporosis" for patients with even higher fracture risk, defined as:
- BMD T-score ≤ -2.5 PLUS
- Presence of proximal femur fragility fracture OR
- Two or more fragility fractures at any site 3
These patients may benefit from more aggressive management approaches, including consideration of anabolic agents rather than antiresorptive therapy as first-line treatment 3.
Treatment Implications
The diagnosis of severe osteoporosis typically warrants:
- More urgent and aggressive pharmacological intervention 3
- Consideration of anabolic agents (teriparatide, abaloparatide, romosozumab) as first-line therapy, particularly in very high-risk individuals 5
- More meticulous surgical approaches if fracture repair is needed 3
- Comprehensive fall prevention strategies 6
- Closer monitoring and follow-up 6
Clinical Pitfalls to Avoid
- Failing to recognize that a fragility fracture automatically indicates severe osteoporosis when the T-score is ≤ -2.5 1
- Overlooking that severe osteoporosis persists as a diagnosis even if subsequent treatment improves BMD above the -2.5 threshold 4
- Treating severe osteoporosis with the same approach as osteoporosis without fracture, when more aggressive therapy may be warranted 3
- Focusing solely on BMD improvement rather than fracture prevention 6
Understanding the definition and implications of severe osteoporosis is crucial for appropriate risk stratification and treatment selection to reduce the significant morbidity, mortality, and decreased quality of life associated with subsequent fractures.