Impact of Low Muscle Mass and Bone Mineral Density on Long-Term Outcomes of Acute Ischemic Stroke: A prospective study.

Abstract

Background: Premorbid sarcopenia, osteoporosis, and obesity are epiphenomena that affect survival and functional outcomes in patients with acute ischemic stroke. The effects of preexisting sarcopenia and/or osteopenia on long-term outcome after ischemic stroke were herein prospectively studied.

Methods: Dual-energy x-ray absorptiometry (DeXA), bio-impedance analysis (BIA) and muscle ultrasonography (US) data were prospectively collected within the first 72 hours in 297 consecutive acute ischemic stroke patients (45.5% women, mean age: 67.8 years). Bone mineral density (BMD) and bone mineral content (BMC) were measured by DeXA for the lumbar spine, and hip (femoral neck and total). BIA was used to measure skeletal muscle mass indices (SMMI, normalized to height-squared, weight and body mass index - SMMI-height, SMMI-weight and SMMI-BMI, respectively) and phase angle. Vertical muscle thickness (MT, mm) for biceps brachii (BB), rectus femoris (RF), vastus lateralis (VL) and gastrocnemius medialis (GCM), cross-sectional area (CSA, cm²) for BB and RF, fascicle length (fL) and pennation angle (PeA) for VL and GCM were measured using muscle US. Multiple exploratory logistic regression models were constructed for detect predictors of mortality and unfavorable functional outcome (Modified Rankin score-mRS>1) at the end of the first year. The cut-off value determined by the Younden-J index, and the lower limit of the 95% confidence interval of the area under the receiver operating characteristic (ROC) curve (AUC) were reported.

Results: Independent predictors for one-year unfavorable prognosis were phase angle (cut-off ≤5^o; lower limit of 95%CI of ROC-AUC: 0.704); muscle thickness (AUCs were 0.677 for RF (≤9.29), 0.660 for GCM (≤13.38), 0.655 for R+VIM (vastus intermedius) (≤15.31), 0.605 for BB+brachialis (≤23.98) and 0.592 for VL (≤10.64), 0.619 for VL transverse MT (≤19.95 mm), and cross sectional areas (0.656 for RF (≤4.27 cm²) and 0.609 for BB (≤8.88 cm²). Independent predictors for 1-year mortality were phase angle (95% lower limit of AUC 0.746 for ≤3.7^o), BB+brachialis MT (0.625 for ≤23.98 mm), and BB MT (0.613 for ≤19.27).

Conclusions: Phase angle and ultrasonographic muscle-size parameters (thickness and cross-sectional area) obtained at admission are significant and independent predictors of long-term functional prognosis and mortality in acute ischemic stroke. Ultrasound parameters of muscle architecture (pennation angle, fiber length), DeXA (BMC and BMD), and BIA-derived SMMI have low independent prediction capability of long-term prognosis.