基于腰椎定量CT分析强直性脊柱炎合并肌少症危险因素

Risk factors of ankylosing spondylitis complicated with sarcopenia:Analysis of lumbar quantitative CT

目的基于腰椎定量CT(QCT)分析强直性脊柱炎(AS)合并肌少症的危险因素。方法前瞻性纳入100例AS患者(AS组)及100名健康体检者(对照组),行腰椎QCT检查;测量并计算腰椎骨密度(BMD)、L3骨骼肌面积(SMA)、椎后肌群肌肉面积(MA)、椎后肌群脂肪面积(FA)、椎后肌群脂肪浸润(MFI)程度及竖脊肌CT脂肪百分数(CTFF),根据L3骨骼肌指数(SMI)将AS组分为肌少症亚组(n=26)和非肌少症亚组(n=74)。以Pearson或Spearman相关分析观察AS组病程、体质量指数(BMI)、腰椎BMD、椎后肌群MFI及竖脊肌CTFF与L3 SMI的相关性;构建多因素logistic回归模型,分析影响AS合并肌少症的独立因素。结果AS组腰椎BMD、L3 SMI及椎后肌群MA均低于对照组(P均<0.05),而椎后肌群FA、MFI及竖脊肌CTFF均高于对照组(P均<0.05)。肌少症亚组BMI及腰椎BMD均低于非肌少症亚组(P均<0.05),而病程、椎后肌群MFI及竖脊肌CTFF均高于非肌少症亚组(P均<0.05)。AS组BMI及腰椎BMD均与L3 SMI呈正相关(r=0.42、0.22,P均<0.05);椎后肌群MFI及竖脊肌CTFF均与L3 SMI呈负相关(r=-0.45、-0.26,P均<0.05)。骨质疏松症是AS合并肌少症的独立危险因素(P<0.05),低BMI则为其保护因素(P<0.05)。结论基于腰椎QCT可见骨质疏松症是AS合并肌少症的独立危险因素。

Objective To analyze risk factors of ankylosing spondylitis(AS)complicated with sarcopenia using lumbar quantitative CT(QCT).Methods Totally 100 AS patients(AS group)and 100 healthy subjects(control group)were prospectively enrolled and underwent lumbar QCT.The bone mineral density(BMD)of lumbar spine,skeletal muscle area(SMA)of L3,muscle area(MA)of posterior muscle groups,fat area(FA)of posterior muscle groups,muscle fat infiltration(MFI)of posterior muscle groups and CT fat fraction(CTFF)of erector spinae muscle were measured and calculated.Patients in AS group were divided into sarcopenia subgroup(n=26)or non-sarcopenia subgroup(n=74)according to L3 skeletal muscle index(SMI).Pearson or Spearman correlation analysis were performed to observe the correlations of disease duration,body mass index(BMI),BMD of lumbar spine,MFI of posterior muscle groups,CTFF of erector spinae muscle and L3 SMI.Multivariate logistic regression model was established to screen independent factors of AS complicated with sarcopenia.Results BMD of lumbar spine,L3 SMI and MA of posterior muscle groups in AS group were all lower than those in control group(all P<0.05),while FA and MFI of posterior muscle groups and CTFF of erector spinae muscle in AS group were all higher than those in control group(all P<0.05).BMI and BMD of lumbar spine in sarcopenia subgroup were both lower than those in non-sarcopenia subgroup(both P<0.05),while disease duration,MFI of posterior muscle groups and CTFF of erector spinae muscle in sarcopenia subgroup were all greater than those in non-sarcopenia subgroup(all P<0.05).In AS group,BMI and BMD of lumbar spine were positively correlated with L3 SMI(r=0.42,0.22,both P<0.05),whereas MFI of posterior muscle groups and CTFF of erector spinae were negatively correlated with L3 SMI(r=-0.45,-0.26,both P<0.05).Osteoporosis was the independent risk factor(P<0.05),whereas low BMI was the protective factor of AS complicated with sarcopenia(P<0.05).Conclusion Osteoporosis was the independent risk factor of AS complicated with sarcopenia using lumbar QCT.