Is T score the only criteria for choosing teriparatide (recombinant human parathyroid hormone) over bisphosphonates?

Is T-Score the Only Criteria to Choose Teriparatide Over Bisphosphonates?

No, T-score is not the only criterion—the decision to use teriparatide over bisphosphonates depends on multiple clinical factors including fracture history, surgical context, prior treatment failure, fracture risk level, and specific contraindications to bisphosphonates. 1, 2

Key Decision Criteria Beyond T-Score

Clinical Context Determines Choice

The selection between teriparatide and bisphosphonates requires assessment of:

• Fracture history and severity: Presence of one or more osteoporotic fractures, particularly multiple or moderate-to-severe vertebral fractures, favors teriparatide 2, 3
• Surgical planning: Patients undergoing spinal instrumentation should preferentially receive teriparatide to reduce screw loosening (7% vs 13% with bisphosphonates) and improve fusion rates (82% vs 68%) 1
• Prior treatment response: Inadequate response to bisphosphonates after 2 years (defined as new fractures despite treatment) indicates switching to teriparatide 2, 4
• Fracture risk stratification: Very high fracture risk patients (FRAX assessment, age <65 with T-score ≤-3.5) warrant teriparatide consideration regardless of prior treatment 2, 5

Guideline-Based Recommendations

The Congress of Neurological Surgeons (2021) provides Grade B evidence that clinicians should consider preoperative teriparatide in osteoporotic patients undergoing spinal instrumentation to decrease postoperative adverse events. 1 Conversely, there is insufficient evidence to support bisphosphonates alone in this surgical context 1.

The American College of Rheumatology conditionally recommends teriparatide over anti-resorptives only in patients at very high fracture risk 2. This represents a hierarchical approach where bisphosphonates remain first-line for most patients.

Specific Clinical Scenarios Favoring Teriparatide

Glucocorticoid-induced osteoporosis: Teriparatide is recommended after oral bisphosphonates when they are not appropriate, particularly in patients requiring long-term steroid treatment at very high fracture risk 2, 5, 6

Perioperative spine surgery: Level II evidence demonstrates teriparatide superiority over bisphosphonates for:

• Earlier fusion (8 months vs 10 months) 1
• Higher fusion rates at interim timepoints 1
• Reduced pedicle screw loosening 1
• Faster BMD recovery 1

Bisphosphonate intolerance or contraindication: When patients cannot tolerate bisphosphonates or raloxifene, teriparatide becomes the appropriate alternative 2, 4

Important Caveats and Pitfalls

Prior bisphosphonate treatment may blunt teriparatide response: Previous bisphosphonate exposure is likely to diminish the bone anabolic potential of teriparatide 3. However, in glucocorticoid-induced osteoporosis patients with prior bisphosphonate treatment, teriparatide still demonstrated significant BMD improvements (7.9% lumbar spine increase at 24 months) 6.

Concurrent therapy should be avoided: Bisphosphonates should not be combined with teriparatide during active treatment, as this reduces teriparatide's anabolic effects 5, 3, 4. Sequential therapy (teriparatide followed by bisphosphonates) is the recommended approach to consolidate skeletal benefits 5.

Treatment duration is limited: Teriparatide therapy should not exceed 18-24 months based on osteosarcoma concerns in rat models, though this risk is unlikely in humans 5, 3. Following teriparatide, antiresorptive medication should be prescribed to preserve bone mass gains 3.

Cost-Effectiveness Considerations

Teriparatide is significantly more expensive than bisphosphonates without demonstrated superior antifracture efficacy in all populations 5. Therefore, its use should be limited to:

• Severe osteoporosis with documented fractures 2, 3
• Very high fracture risk patients who have failed first-line therapies 2
• Patients requiring spinal instrumentation 1
• Glucocorticoid-induced osteoporosis at very high risk 2, 5

Practical Algorithm for Decision-Making

1. Assess T-score AND fracture history: T-score <-2.5 with ≥1 fracture suggests severe osteoporosis 1, 2
2. Evaluate surgical context: Planned spinal instrumentation favors teriparatide 1
3. Review prior treatment: Bisphosphonate failure (new fractures after 2 years) indicates teriparatide 2, 4
4. Calculate fracture risk: Use FRAX tool; very high risk favors teriparatide 2
5. Consider special populations: Glucocorticoid use, age <65 with T-score ≤-3.5 2, 5
6. Assess tolerability: Bisphosphonate intolerance necessitates alternative 2, 4

In summary, while T-score provides essential diagnostic information, the choice between teriparatide and bisphosphonates requires integrating fracture history, surgical planning, prior treatment response, overall fracture risk assessment, and patient-specific factors. 1, 2, 7