MO539: Use of FRAX® Scale to Estimate Bone Fracture Risk in Patients Undergoing Haemodialysis
Authors: Hernández Paúl , Sandino Pérez Justo , Aubert Lucia , González García Celia , Mérida Evangelina , Gutiérrez Elena , Pascual Julio 
Published: May 2022

Abstract

BACKGROUND AND AIMS
Decreased bone mineral density in patients undergoing haemodialysis (HD) is related to the development of fractures that lead to increased morbimortality.
There is limited evidence on fracture risk factors that would allow to identify patients at risk to prompt early treatment.
In this context, FRAX® (Fracture Risk Assessment scale, which is freely available online at https://www.sheffield.ac.uk/FRAX/tool.aspx?country=4) scale aids in the risk prediction (as a percentage over a 10-year span) of both major and hip osteoporotic fractures in specific populations, including patients with chronic kidney disease (CKD) [1]. However, the evidence of its utility in HD patients is scarce [2].
The aim of our study is to identify patients on HD with increased risk of fractures based on FRAX® scale, blood-test and densitometric parameters. Also, we aim to demonstrate a correlation between a higher risk of fractures as assessed by FRAX® scale and densitometry-established osteoporosis.

METHOD
This is a single-centre retrospective study including patients undergoing periodic intermittent haemodiafiltration.
Data regarding clinical and blood-test parameters were collected. FRAX® scale was used to estimate the risk of hip and major fractures.
Patients were divided accordingly into high and low fracture risk, with a threshold set at a 10-year 3% risk of hip fracture and 10% for other major fractures, according to definitions for the general population given by FRIDEX (Fracture RIsk factors and bone DEnsitometry type central dual X-ray) and FROCAT cohorts[3].
The relationship between clinical, blood-test parameters and the degree of osteopaenia and osteoporosis was evaluated. Osteopaenia was defined as a T-score between −1 and −2.5 in femoral neck densitometry. Osteoporosis was established as a T-score lower than −2.5. Qualitative parameters were analysed using Fisher's exact test, whilst Mann–Whitney U test was employed in the analysis of quantitative parameters.

RESULTS
A total of 54 patients (59.26% male) with a median age of 60 years [interquartile range (IQR), 50–72.25] were recruited. Six low intensity fractures were observed (11.1%), five of them occurred in high-risk-FRAX-scale-classified patients (P 0.095). The observed median FRAX score for our sample was 7.35% (IQR, 4.97–13.25) for major fractures and 1.70% (IQR, 0.78–6.13) for hip fractures.
Patients with a higher risk of major fracture, according to FRAX® scale (&gt;7.5%), were older (P &lt; 0.001) and had been on renal replacement therapy (RRT) for a longer period of time (P 0.008).
Furthermore, a significantly higher proportion of patients with prior kidney transplantation (0.012) and osteoporosis (0.002) was found in this group. No differences were observed in blood-test parameters, KtV and dialysate composition between low and high-risk patients.
Densitometry was performed in 26 patients (48.14%). In this subset, osteopaenia was observed in 14 patients (53.84%) and osteoporosis in 11 (42.31%). Patients with osteoporosis had a higher FRAX score for major fracture (21%, IQR 11.50–26.50; P 0.001) and hip fracture (7.80%, IQR 5.75–14.50; P &lt; 0.001).
No correlation was found between prior kidney transplantation or exposure to steroids and densitometry-established osteoporosis.

CONCLUSIONS
Despite not being validated yet in Spain, our results demonstrate that FRAX® scale significantly correlates with the degree of osteoporosis in patients undergoing HD, representing an effective tool for the identification of patients at high risk of suffering fractures, prompting early prevention and management.