Poster Presentation ESA-SRB-ANZBMS 2024 in conjunction with ENSA

Utility of baseline bone turnover markers in predicting response to Zoledronic acid in patients with osteoporosis (#548)

Divia Mohandas 1 , Victoria Deacon 1 , Nick Green 1 , Minh Nguyen 2 , Nupa Gahatraj 1 , James Elhindi 3 , Angela Xun-Nan Chen 1 , Christian M Girgis 1
  1. Endocrinology, Westmead Hospital, Sydney, NSW, Australia
  2. Australian Digital Health Agency, Sydney, NSW, Australia
  3. Statistics, Western Sydney University, Sydney, NSW, Australia

Aims
Bisphosphonates are first-line agents in the treatment of osteoporosis, with established improvement in bone mineral density (BMD) and fracture risk reduction. Improvement in BMD is a surrogate marker for fracture risk reduction. However, data corelating changes in bone turnover markers (BTMs) - Procollagen type 1 N telopeptide (P1NP) and C-terminal telopeptide of Type 1 collagen (CTx) with fracture and BMD outcomes are unclear. We aimed to assess changes in BTMs in subjects receiving zoledronic acid and examined their ability to predict BMD changes on treatment.

 

Methods

We conducted a retrospective observational study of patients who attended the Osteoporosis and Refracture Prevention (ORP) clinic at Westmead hospital between 2019 and 2022. Data was obtained by review of medical records and ORP database and included patient demographics, fractures, menopause age, serial BMD and BTMs.
The association between changes in BTMs and BMD on treatment were assessed with a linear mixed effects model with fixed effects between the values of interest and a random effects structure for the repeated measurements over time. P1NP and CTX were log-transformed to comply with normality assumptions of the model.

 

Results

In our cohort of 86 patients (mean age 60.9 years [SD 10.03], 82.5% female), zoledronic acid 5 mg led to 47.7% reduction in P1NP (SD 35.5, 30.5% reduction in CTx (SD 117.9), improvement in spine BMD of 8.4% (SD 14.8) and hip BMD of 5.5% (SD 13.9) over mean of 24 months. Baseline levels and degree of suppression in BTMs correlated significantly with improvements in lumbar spine BMD although the magnitude of effect was small (r2 0.01, p<0.01, Table 1).

 

Conclusions
BTMs correlated with spinal BMD changes over 2 years in response to treatment with zoledronic acid. However, there is ongoing uncertainty regarding the clinical value.

 

Table 1

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