骨粗鬆症診断において，FRAX®は，骨密度測定部位による治療介入対象者の違いを補うことができるか？―1次スクリーニングを含めたFRAX®有効利用の検討

Can FRAX® Compensate for Differences in Bone Mineral Density Measurements in the Diagnosis of Osteoporosis that May Lead to Inconsistent Identification of Candidates for Therapeutic Intervention? Effective Use of FRAX® for Primary Screening and Other Purposes

　背景：同一人物でも測定部位により骨密度が違うため，治療介入対象者が変わることが予想される．

　対象と方法：本研究は①FRAX^®がこの違いを補えるか，②FRAX^®の健診への応用について検討した．対象は50～74歳，3部位の骨密度を測定した74人である．

　結果：治療介入要否の一致率は，腰椎と橈骨遠位1/3で79.7％，大腿骨頚部と橈骨遠位1/3で70.3％と違い，FRAX^®を加味しても一致率は上がらなかった．また，FRAX^®と腰椎骨密度を基準に治療介入要否の感度・特異度を検討した．カットオフ値は9.6％だが，約40％の要治療者が対象外となった．

　まとめ：健診で治療不要な人を約90％除外するためのカットオフ値は6.8％であった．

　Background：Bone density measurements sometimes vary from site to site even in the same person, and this variation may lead to inconsistent identification of candidates for therapeutic intervention.

　Methods：The objectives of this study were to determine whether FRAX^® could compensate for this difference in measurements, and to evaluate the usefulness of FRAX^® during health check-ups.　A total of 74 subjects aged 50-74 years who underwent bone density measurements were assessed.

　Results：The rate of agreement in regard to the need for therapeutic intervention based on the bone mineral density between the lumber spine and distal one/third of the radius and between the femoral neck and distal one/third of the radius was 79.7% and 70.3% respectively.　However, the addition of FRAX^® did not improve these rates.　The sensitivity and specificity of agreement in regard to the need for therapeutic intervention between a cut-off value using FRAX^® and the bone mineral density of the lumbar spine serving as the standard were evaluated.

　Conclusions：At a cut-off value of 9.6% about 40% of the patients who needed treatment were excluded, and a cut-off value of 6.8% during health check-ups was needed to exclude 90% of the patients who did not need treatment.