Bone and Metabolic
The fracture risk tools differ, the PHARMAC treatment thresholds don't map neatly to international frameworks, and denosumab has a cessation problem that most prescribers don't know about until it happens.
Scope: diagnosis and treatment of osteoporosis in non-pregnant adults in primary care, including post-fracture management. Does not cover glucocorticoid-induced osteoporosis (GIOP) as a primary topic, though it is referenced.
Where they agree
Where they diverge
Comparison
| Domain | NZ - BPAC / Osteoporosis NZ | AU - RACGP / Osteoporosis Australia | International - IOF / NOGG / AACE 2020 |
|---|---|---|---|
| When to investigate with DEXA | DEXA funded by PHARMAC for: all women ≥65, all men ≥70, any adult with prior low-trauma fracture, adults on systemic glucocorticoids ≥3 months, adults with conditions associated with bone loss (RA, malabsorption, CKD, early menopause, hypogonadism, anorexia). BPAC also recommends considering DEXA at younger ages for women with strong risk factors (family history of hip fracture, early menopause, BMI <19). VFA (vertebral fracture assessment) on DEXA scanner adds information about morphometric vertebral fractures.Funded | RACGP/Osteoporosis Australia: women ≥50 with risk factors, men ≥60 with risk factors, all ≥70 regardless of risk factors. DEXA funded via MBS (Medicare).MBS funded | IOF/ISCD: DEXA recommended for all women ≥65, men ≥70, and younger patients with significant risk factors. The IOF One Minute Osteoporosis Risk Test and FRAX can be used to identify who needs DEXA. |
| Fracture risk assessment tool | BPAC recommends the GARVAN Fracture Risk Calculator (garvan.org.au/bone-fracture-risk). Inputs: age, sex, weight, prior fractures, number of falls in past year, and optionally BMD. The falls input makes GARVAN more accurate for community-dwelling older adults than FRAX. Output: 5-year and 10-year risk of hip fracture and any fracture. Risk thresholds for treatment initiation: BPAC does not specify a single GARVAN threshold; treatment decision integrates GARVAN risk, DEXA T-score, PHARMAC SA criteria, and patient values.GARVAN preferred | Osteoporosis Australia recommends both GARVAN and FRAX as valid tools. GARVAN preferred for patients with falls history. Treatment threshold discussions are based on absolute risk estimates.GARVAN or FRAX | Uses FRAX-based intervention thresholds. 10-year major osteoporotic fracture risk ≥7.5% with femoral neck BMD: diagnostic assessment. ≥20% (or hip fracture risk ≥3%): treat. The IOF/NOF (US): 10-year hip fracture risk ≥3% or major osteoporotic fracture risk ≥20% (FRAX-based, US-specific). |
| First-line: alendronate | Alendronate 70 mg once weekly (or 10 mg daily) - PHARMAC-funded with Special Authority. SA criteria broadly: (a) T-score ≤-2.5 at femoral neck, total hip, or lumbar spine, or (b) prior low-trauma fracture (fragility fracture), or (c) on systemic glucocorticoids with T-score ≤-1.5. Take fasting with full glass of water, remain upright 30 minutes, no food for 30-60 minutes after. Contraindications: oesophageal abnormalities, inability to remain upright, eGFR <35.SA required | Alendronate PBS-listed. Same dosing and administration. Risedronate also PBS-listed (alternative for GI intolerance).PBS listed | Alendronate, risedronate, zoledronic acid as first-line. Choice depends on fracture risk, adherence, comorbidities. For very high fracture risk: consider anabolic agent first (teriparatide, romosozumab) then antiresorptive maintenance. |
| Alternative bisphosphonates and zoledronic acid | Risedronate 35 mg weekly or 150 mg monthly: PHARMAC-funded (SA, similar criteria to alendronate) for GI intolerance. Zoledronic acid 5 mg IV annually: PHARMAC-funded (SA) for oral intolerance or poor absorption. Transient flu-like illness 1-3 days post-infusion common. Post-hip fracture: HORIZON-PFT showed annual zoledronic acid reduced subsequent fractures and all-cause mortality by 28%.Funded | All three PBS-listed. Zoledronic acid widely used post-fracture.PBS listed | Consistent class. Zoledronic acid post-hip fracture has the strongest mortality evidence of any osteoporosis drug (HORIZON-PFT). |
| Denosumab - critical cessation issue | Denosumab 60 mg SC every 6 months: PHARMAC-funded with SA - criteria require severe osteoporosis (T-score ≤-2.5 with prior fracture, or T-score ≤-3.0) and inadequate response or intolerance to bisphosphonates. CRITICAL: denosumab MUST NOT be stopped without transition plan. Cessation without antiresorptive coverage causes rapid rebound BMD loss and elevated vertebral fracture risk in 12-18 months post-cessation. Transition: give zoledronic acid 5 mg IV approximately 6 months after last denosumab dose (when next dose would have been due). Do not allow denosumab to lapse due to prescription failure or patient non-attendance.Transition mandatory | PBS-listed. Cessation management consistent with international guidance. Same critical transition requirement.PBS listed | Effective and well-tolerated, superior to alendronate for BMD gains at some sites. However, cessation rebound is a class-specific problem. IOF/AACE strongly recommend automatic bisphosphonate transition (zoledronic acid preferred) when denosumab is stopped for any reason. This is the most important safety issue in osteoporosis pharmacotherapy in the last decade. |
| Anabolic agents: teriparatide and romosozumab | Teriparatide (Forteo) 20 mcg SC daily for 24 months: PHARMAC-funded with narrow SA - T-score ≤-3.0 with ≥2 prior low-trauma fractures, or specialist (endocrinologist or rheumatologist) initiation. After completion: MUST transition to antiresorptive (bisphosphonate) - BMD gains lost rapidly without maintenance. Romosozumab (Evenity): not funded in NZ.Limited access / not funded | Both teriparatide and romosozumab PBS-listed for high fracture risk with specific criteria. Broader access than NZ.PBS listed | For very high fracture risk (T-score ≤-2.5 with prior vertebral or hip fracture, or ≥2 prior fractures, or on glucocorticoids): anabolic agent first, then antiresorptive maintenance ("sequence matters"). Anabolic-first strategy produces greater BMD gains than antiresorptive-first. Romosozumab (anti-sclerostin): one year SC monthly, followed by antiresorptive; reduces vertebral fractures by ~70% vs placebo. Not funded in NZ. |
| Drug holidays from bisphosphonates | After 5 years oral bisphosphonate (or 3 years IV zoledronic acid): assess ongoing need. Low-risk patients (no interim fracture, T-score now >-2.5, no falls): may pause and monitor with DEXA at 2 years. Higher-risk patients: continue. Re-initiate if T-score drops or fracture occurs. No formal BPAC drug holiday protocol - use clinical judgement and specialist input where uncertain. | Consistent. Osteoporosis Australia 5-year review recommendation. | Drug holiday after 5 years oral bisphosphonate (or 3 years zoledronic acid) for moderate-risk patients. High-risk patients (prior hip or vertebral fracture, multiple fractures, T-score ≤-2.5, glucocorticoids): continue without holiday. Atypical femoral fracture risk increases with duration but is still rare (<1/10,000 patient-years) compared with hip fracture reduction. |
| Calcium and vitamin D supplementation | Target dietary calcium ≥1200 mg/day. Routine calcium supplementation in patients with adequate dietary intake is no longer recommended (Bolland 2010 meta-analysis raised concerns about cardiovascular risk with high-dose calcium supplements). Vitamin D: supplement with 800-1000 IU/day for older adults, housebound patients, and those with documented deficiency. PHARMAC funds colecalciferol (vitamin D3).D3 funded | Consistent approach. Dietary calcium preferred; supplement only if intake inadequate. Vitamin D supplementation for at-risk groups. | Dietary calcium preferred. Supplement only if dietary intake <1000 mg/day. Vitamin D: 800-1000 IU/day for at-risk older adults. Do not exceed 2000 IU/day without evidence of deficiency. |
NZ clinical context
PHARMAC criteria, the GARVAN tool, and the denosumab cessation problem
Any patient started on denosumab should be counselled that this is a medication that must not simply be stopped - it requires a planned transition. If a patient misses a dose, contact them urgently. If they are stopping for any reason (intolerance, moving overseas, patient preference), arrange zoledronic acid 5 mg IV approximately 6 months after the last denosumab dose. This is not optional and is now clearly recommended in international guidelines. It is a patient safety issue, not a preference.
The GARVAN calculator is available at garvan.org.au/bone-fracture-risk. Enter age, sex, weight, number of prior fractures (from age 50), number of falls in the past 12 months, and (optionally) BMD from DEXA. It takes 2 minutes and produces a more meaningful risk estimate for NZ patients than FRAX alone because falls are the proximate cause of most hip fractures. This is a significant practical advantage over FRAX.
Alendronate SA is straightforward and worth checking for any patient with T-score ≤-2.5 or prior low-trauma fracture who is not already on treatment. A significant number of patients who meet criteria for treatment are not receiving it - this is a known quality gap in NZ primary care. The post-fracture window (especially post-hip fracture or vertebral fracture) is a critical intervention opportunity. Consider using a Fracture Liaison Service if your DHB has one.
Routine calcium supplementation in patients with adequate dietary intake is no longer recommended. The Bolland meta-analysis (2010) raised concerns about cardiovascular risk with high-dose calcium supplements. Target dietary calcium ≥1200 mg/day. Ask patients about dietary intake: milk, yoghurt, cheese, fortified plant-based milks, leafy greens, and tinned fish with bones are good sources. Supplement only if dietary intake is clearly inadequate. Vitamin D: supplement with 800-1000 IU/day for older adults, housebound patients, and those with documented deficiency. PHARMAC funds colecalciferol (vitamin D3).
A low-trauma fracture (hip, vertebral, wrist, or humerus) in an older adult is a fracture risk assessment opportunity. Any patient with a new low-trauma fracture should have DEXA unless already done, and should be assessed for pharmacotherapy regardless of T-score if the fracture occurred with minimal trauma. Post-hip fracture: consider zoledronic acid IV rather than oral bisphosphonate - administration is reliable and HORIZON-PFT showed it reduces mortality by 28% compared with placebo. This is the strongest mortality evidence of any osteoporosis drug.
Bottom line for NZ practice
What this means in the consulting room
Sources