GIÁ TRỊ CỦA Z-SCORE TRONG TỐI ƯU HÓA ĐÁNH GIÁ MẬT ĐỘ XƯƠNG CHO NAM GIỚI DƯỚI 50 TUỔI TẠI VIỆT NAM

Abstract

Background: In the context where Z-score is recommended for diagnosis in men under 50 years of age, determining the appropriateness of the −2.0 threshold according to the ISCD (International Society for Clinical Densitometry) in interpreting bone mineral density (BMD) results in this population, compared with T-score, is of significant importance for providing evidence for clinical practice.

Methods: A cross-sectional study was conducted on 1,835 men under 50 years of age from 2018 to 2025 at Hanoi Medical University Hospital.

Results: When using T-score, the proportion of individuals at risk of overclassification ranged from 0–2.72% (T-score ≤ −2.5 and Z-score > −2.0), while the proportion at risk of underclassification ranged from 0.61–2.67% (T-score > −2.5 and Z-score ≤ −2.0), depending on anatomical site. In contrast, when using Z-score, the overclassification rate was negligible, ranging from 0–0.15% (Z-score ≤ −2.0 and T-score > −1.1), while the underclassification rate based on the T-score ≤ −2.5 threshold ranged from 0–2.72% (Z-score > −2.0 and T-score ≤ −2.5).

Conclusion: The use of Z-score reduces the risk of age-inappropriate and clinically inconsistent classification, aligning with international recommendations and the clinical context in Vietnam.