Background/Purpose: The FRAX^® tool has been developed by WHO to evaluate fracture (Fx) risk of patients. It is based on individual patient models that integrate the risks associated with clinical risk factors as well as bone mineral density (BMD) at the femoral neck (FN). The output is a 10-year probability of hip Fx and of a major osteoporotic Fx (clinical spine, forearm, hip or shoulder Fx). The tool allows calculation of Fx risk with and without (±) BMD. Assessment of Fx risk in the individual patient without BMD may be an advantage in the busy emergency room dealing with patients with distal forearm Fxs. Differences between Fx risk assessed ±BMD has previously been evaluated on group level, but not on the individual patient level. There is no recommendation on which side to measure BMD. The purpose was to examine the agreement between the FRAX 10-year Fx risk calculated ±BMD in patients with a recent Fx of the distal forearm. Furthermore, to examine the influence of measurement side for Fx risk assessment.

Methods: BMD of the left and right FN and of the spine was measured in 140 Danish women with a recent Fx of the distal forearm using a Lunar DXA-scanner. Only patients eligible for bilateral hip measurements were included. None of the patients were or had been on antiresorptives or anabolic treatment. Information of clinical risk factors were collected by questionnairing the patients. Using the FRAX tool for Denmark, the 10-year risk of a major Fx and of a hip Fx was calculated ±BMD with BMD from both measurement sides. Student’s t-test was used for comparison of paired Fx risk assessments. The Bland-Altman method was used to examine agreement between the risk assessments. Differences between pairs of risk assessments were calculated. Agreement on the group level was expressed as the bias (mean value of individual differences) and on the individual level as the 95 % limits of agreement (LoA).

Results: Mean age, height and weight were 66±8 (range 51-85) years, 163±14 cm and 68±13 kg. Mean BMD and T-score of the left FN were 0.81±0.15 g/cm2 and -1.6±0.9 and of the spine 1.0±0.2 g/cm2 and -1.3±1.4. Fourteen (10%) patients had a parent with hip Fx, 28 (20%) were smokers, 4 (2.8%) had 3 or more alcohol units per day, 15 (11%) had conditions strongly associated with osteoporosis (predominantly early menopause), 1 (0.7%) had RA and 2 (1.4%) were on steroids. The 10-year risk of hip Fx and of a major Fx based on left hip BMD was 6.9±7.7% and 22.7±10.2%, respectively. The bias of hip Fx risk assessed without BMD was 4.2 (LoA -10.8; 19.2)% (p < 0.0001) and of a major Fx 5.3 (LoA -11.7; 22.3)% (p < 0.0001). The bias of the risk of a hip and of a major Fx assessed with the highest vs. the lowest BMD-value was -1.7 (LoA -6.1; 2.7)% (p < 0.0001) and -2.4 (LoA -7.4; 2.6)% (p < 0.0001), respectively.

Conclusion: The FRAX 10-year Fx risk calculated without BMD was averagely increased by 4-5% compared to assessment with BMD. In the individual patient, differences between risk assessments ±BMD approached 22%. Thus, Fx risk assessment without BMD should be used with caution when counselling individual patients with forearm fractures. The side of BMD measurement may also influence the risk assessment significantly, especially in individual patients.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/frax-10-year-fracture-risk-in-women-with-a-fracture-of-the-distal-forearm-agreement-between-assessments-with-and-without-bone-mineral-density-and-influence-of-measurement-side-in-individual-patients/