Genetic polymorphisms and other risk factors associated with bisphosphonate induced osteonecrosis of the jaw

Bisphosphonate induced osteonecrosis of the jaw (BONJ) is a complication in patients taking bisphosphonate (BP) that affects their quality of life and compliance. In this cohort study, patients with multiple myeloma (MM) on intravenous BP therapy were enrolled over 1 year. Demographic and clinical data and genotyping of 10 single nucleotide polymorphisms (SNPs) from seven candidate genes associated with drug or bone metabolism were determined. Of the 78 patients enrolled, 12 had BONJ. The median time to developing BONJ was 28 months. Univariate and multivariate analysis revealed a significant association between BONJ and smoking (p = 0.048) and type of BP treatment (p = 0.03). A trend for higher odds for BONJ was found for SNPs in five genes: COL1A1 (rs1800012), RANK (rs12458117), MMP2 (rs243865), OPG (rs2073618) and OPN (rs11730582). Considering all five SNPs together, patients with genotype scores ≥5 had a BONJ event rate of 57%; those with scores <5 had a rate of 10%. The adjusted odds ratio was 11.2 (95% confidence interval of 1.8-69.9; p value 0.0097). Smoking, type of BP and combined genotype score of COL1A1, RANK, MMP2, OPG and OPN were significantly associated with BONJ in MM patients undergoing BP therapy.     

Persistent bisphosphonate use and the risk of osteoporotic fractures in clinical practice: a database analysis study*

ABSTRACT

Objective: This study aimed to investigate the association between persistent use of bisphosphonates and the risk of osteoporotic fractures in clinical practice.

Methods: Data were obtained from the PHARMO Record Linkage System, which includes, among other databases, drug-dispensing records from community pharmacies linked to hospital discharge records of more than two million subjects in defined areas in the Netherlands. Persistence with bisphosphonate therapy was assessed during a period of 3 years. A nested matched case control study (cases:controls = 1:10) was performed to study the association between persistent bisphosphonate use and hospitalisation for osteoporotic fractures and analysed by conditional logistic regression analysis. The analyses were adjusted for patient characteristics such as previous hospitalisations for fractures, co-morbidity and co-medication.

Results: 14?760 new female users of bisphosphonates were identified of which 541 women had a hospitalisation for osteoporotic fracture after start of bisphosphonate treatment (1–3 years follow-up). One-year persistence rates increased from 33% with alendronate daily to 48% with alendronate weekly, an increase of 15%. Similar results were obtained with risedronate daily and weekly. One year persistent use of bisphosphonates resulted in a statistical significant 26% lower fracture rate (OR 0.74; 95%CI 0.57–0.95) whereas 2 year persistent use resulted in a 32% lower rate (OR 0.68; 95%CI 0.47–0.96).

Conclusions: Persistent use of bisphosphonates decreases the risk of osteoporotic fractures in clinical practice. Approximately 6% of fractures among users of bisphosphonates could be prevented if persistence was improved by 20%. However, current persistence with bisphosphonate therapy is suboptimal and strategies that further increase persistence are likely to further prevent the number of fractures.     

Cost-effectiveness of alternative treatments for women with osteoporosis in Canada

ABSTRACT

Background: During the years following menopause, estrogen levels decline leading to accelerated bone loss and an increased risk of osteoporosis and osteoporosis-related fractures.

Methods: Using a Markov model and decision analytic techniques, the long-term costs and outcomes of five treatment and secondary prevention strategies for osteoporosis were compared: ‘no intervention’, alendronate, etidronate, risedronate, and raloxifene. The base case analysis examined postmenopausal (65 year old) osteoporotic women without prior fracture. Probabilistic sensitivity analysis (PSA) was used to incorporate the impact of parameter uncertainty, and deterministic sensitivity analysis (DSA) was used to compare alternative patient populations and modeling assumptions. Life years and Quality Adjusted Life Years (QALYs) were used as measures of effectiveness.

Results: In the base case analysis, risedronate was dominated by etidronate and alendronate. Alendronate and etidronate were projected to have similar costs and QALYs, and the efficiency frontier was represented by ‘no intervention’, etidronate, alendronate, and raloxifene (Can$32?571, Can$38?623 and Can$114?070 per QALY respectively). Alternative assumptions of raloxifene's impact on CHD and breast cancer, alternative discount rates and alternative patient risk factors (e.g., starting age of therapy, CHD risk, and prior fracture risk) had significant impacts on the overall cost-effectiveness results for both the bisphosphonates and raloxifene.

Discussion: Using conventionally quoted benchmarks and compared to no therapy, alendronate, etidronate, and raloxifene would all be considered cost-effective alternatives for treating women with osteoporosis. Potential limitations of this study include the usual caveats and cautions associated with long-term projection models and the fact that not all inputs into the model are Canadian data sources.     

Changing trends in osteoporosis care from specialty to primary care physicians

Abstract

Background:

Inadequate treatment by non-specialty primary care physicians (PCPs) has been a concern in improving osteoporosis care. An increase in outpatient visits by older patients seeking osteoporosis care has been reported. But what percentages of these visits are made to PCPs are unknown. We investigated recent trends of outpatient visits and treatment for osteoporosis in older adults (>50 years) by physician type (PCPs vs. specialty care non-PCPs).     

Peripatetic intravenous service for metabolic bone disease: case study in patient centred-care for new NHS

Abstract

Objective:

To develop a ‘close to patient’ peripatetic intravenous service (PIVS) for delivery of specialist osteoporosis care in a community setting without increasing cost and with a reduced carbon footprint.     

Prevention of vertebral fractures in osteoporosis: mixed treatment comparison of bisphosphonate therapies

ABSTRACT

Objective: The objective was to compare the efficacy of bisphosphonates regarding the prevention of vertebral fractures in postmenopausal women with osteoporosis.

Methods: Seven randomized placebo controlled trials investigating the effects of zoledronic acid (one study), alendronate (three studies), ibandronate (one study), and risedronate (two studies) in terms of fractures with a follow-up of 3 years were identified with a systematic literature search. The endpoint of interest was vertebral fractures. Results of all trials were analyzed simultaneously with a Bayesian mixed treatment comparison (MTC). With MTC the relative treatment effect of one intervention to another can be obtained in the absence of head-to-head evidence. MTC can be considered a valid method when included studies are comparable regarding effect modifying baseline patient and study characteristics.

Results: There is a 98% probability that zoledronic acid shows the greatest reduction in vertebral fractures of all four bisphophonates compared. Zoledronic acid showed an OR of 0.28 (95% Credible Interval 0.22; 0.35) relative to placebo, an OR of 0.57 (0.36; 0.92) relative to ibandronate, an OR of 0.54 (0.39; 0.75) relative to alendronate, and an OR of 0.49 (0.34; 0.69) relative to risedronate. Alendronate, ibandronate, and risedronate showed comparable vertebral fracture reductions. Indirect comparisons using a conservative random effects model supported these findings.

Conclusion: An indirect comparison of findings from placebo controlled randomized studies indicates that zoledronic acid provides a greater vertebral fracture risk reduction in postmenopausal women with osteoporosis than ibandronate, alendronate, or risedronate.     

Relationship between duration of compliant bisphosphonate use and the risk of osteoporotic fractures

ABSTRACT

Objectives: To investigate the relationship between duration of compliant bisphosphonate use and the risk of osteoporotic fractures.

Methods: The PHARMO database was used to identify new female bisphosphonate users, aged ≥ 45 years or with diagnosed post-menopausal osteoporosis in the period of January 1996 – June 2004. Within this cohort a matched case–control study was performed. Cases were defined as patients who were hospitalized for an osteoporotic fracture and were matched to ten controls without a fracture by duration of follow-up. The duration of compliant bisphosphonate use (i.e., medication possession ratio ≥ 80%) preceding the outcome date was determined.

Results: Of 14 760 new female bisphosphonate users, 387 fracture patients fulfilled the inclusion criteria. These cases were matched to 3950 controls. Increasing duration of compliant bisphosphonate use was associated with a decreased risk of fracture (trend p < 0.01). Adjusted for several cofactors, 1–2 years of compliant bisphosphonate use and 3–4 years of compliant bisphosphonate use decreased fracture risk by 12% and 46%, respectively, compared to < 1 year of compliant bisphosphonate use (OR 0.88; 95% CI 0.66–1.18 and OR 0.54; 95% CI 0.35–0.84, respectively). Unexpectedly, 5–6 years of compliant bisphosphonate use was no longer associated with a decreased risk of fractures compared to < 1 year of compliant bisphosphonate use (OR 1.12, 95% CI 0.66–1.88).

Conclusions: These results show a direct link between duration of compliant bisphosphonate use and fracture risk, and confirm the importance of continuing the use of bisphosphonates to maintain optimal bone protection. However, this link is inconclusive for bisphosphonate use for more than 4 years.     

What is the optimal policy for osteoporosis management?

The fractures that result from osteoporosis create a huge burden for both individuals affected and for societies across the world. This is especially aggravated as population age. Optimal policy in the management of osteoporosis should provide alleviation of suffering by reducing fracture events. In most health systems the interest is in achieving this at manageable cost. An important initiative is the WHO programme to provide tools for the individualisation of fracture risk which would have similarities to the approach familiar to doctors in the management of coronary heart disease risk. With individualised fracture risk it should be possible to focus resources on fracture prevention in those people most at risk. It is then a matter for the healthcare system to provide policies which guide clinicians on how far down the gradient of risk the system care afford to resource. This is the basis for a cost-effective approach. The paper explores the factors that enable valid risk assessment to be made and the difficulties that result for clinicians if resources are limited and affect the level of intervention that might be preferred.     

Synthesis, stereochemistry and SAR of a series of minodronate analogues as RGGT inhibitors

Phosphonocarboxylate (PC) analogues of bisphosphonates are of interest due to their selective inhibition of a key enzyme in the mevalonate pathway, Rab geranylgeranyl transferase (RGGT). The dextrarotatory enantiomer of 2-hydroxy-3-(imidazo[1,2-a]pyridin-3-yl)-2-phosphonopropanoic acid (3-IPEHPC, 1) is the most potent PC-type RGGT inhibitor thus far identified. The absolute configuration of (+)-1 in the active site complex has remained unknown due to difficulties in obtaining RGGT inhibitor complex crystals suitable for X-ray diffraction analysis. However, we have now succeeded in crystallizing (−)-1 and here report its absolute configuration (AC) obtained by X-ray crystallography, thus also defining the AC of (+)-1. An Autodock Vina 1.1 computer modeling study of (+)-1 in the active site of modified RGGT binding GGPP (3DSV) identifies stereochemistry-dependent interactions that could account for the potency of (+)-1 and supports the hypothesis that this type of inhibitor binds at the TAG tunnel, inhibiting the second geranylgeranylation step. We also report a convenient ³¹P NMR method to determine enantiomeric excess of 1 and its pyridyl analogue 2, using α- and β-cyclodextrins as chiral solvating agents, and describe the synthesis of a small series of 1 α-X (X = H, F, Cl, Br; 7a-d) analogues to assess the contribution of the α-OH group to activity at enzyme and cellular levels. The IC₅₀ of 1 was 5-10× lower than 7a-d, and the LED for inhibition of Rab11 prenylation in vitro was 2-8× lower than for 7a-d. However, in a viability reduction assay with J774 cells, 1 and 7b had similar IC₅₀ values, ∼10× lower than those of 7a and 7c-d.