Skeletal muscle quality as assessed by CT-derived skeletal muscle density is associated with 6-month mortality in mechanically ventilated critically ill patients

Abstract

BackgroundMuscle quantity at intensive care unit (ICU) admission has been independently associated with mortality. In addition to quantity, muscle quality may be important for survival. Muscle quality is influenced by fatty infiltration or myosteatosis, which can be assessed on computed tomography (CT) scans by analysing skeletal muscle density (SMD) and the amount of intermuscular adipose tissue (IMAT). We investigated whether CT-derived low skeletal muscle quality at ICU admission is independently associated with 6-month mortality and other clinical outcomes.MethodsThis retrospective study included 491 mechanically ventilated critically ill adult patients with a CT scan of the abdomen made 1 day before to 4 days after ICU admission. Cox regression analysis was used to determine the association between SMD or IMAT and 6-month mortality, with adjustments for Acute Physiological, Age, and Chronic Health Evaluation (APACHE) II score, body mass index (BMI), and skeletal muscle area. Logistic and linear regression analyses were used for other clinical outcomes.ResultsMean APACHE II score was 24 ± 8 and 6-month mortality was 35.6%. Non-survivors had a lower SMD (25.1 vs. 31.4 Hounsfield Units (HU); p < 0.001), and more IMAT (17.1 vs. 13.3 cm2; p = 0.004). Higher SMD was associated with a lower 6-month mortality (hazard ratio (HR) per 10 HU, 0.640; 95% confidence interval (CI), 0.552–0.742; p < 0.001), and also after correction for APACHE II score, BMI, and skeletal muscle area (HR, 0.774; 95% CI, 0.643–0.931; p = 0.006). Higher IMAT was not significantly associated with higher 6-month mortality after adjustment for confounders. A 10 HU increase in SMD was associated with a 14% shorter hospital length of stay.ConclusionsLow skeletal muscle quality at ICU admission, as assessed by CT-derived skeletal muscle density, is independently associated with higher 6-month mortality in mechanically ventilated patients. Thus, muscle quality as well as muscle quantity are prognostic factors in the ICU.Trial registrationRetrospectively registered (initial release on 06/23/2016) at ClinicalTrials.gov: NCT02817646.

Low Muscularity as Assessed by Abdominal Computed Tomography on Intensive Care Unit Admission Is Associated With Mortality in a Critically Ill Asian Population

“…Our study showed that patients with LM have a significantly lower MRA compared with patients with normal muscularity (28.34 HU vs 37.23 HU). Looijaard et al had demonstrated that low skeletal muscle quality at ICU admission (lower muscle density/MRA) is independently associated with higher 6‐month mortality in mechanically ventilated patients . We found that low MRA is an independent predictor of hospital mortality in the overall sample and in male but not female patients (data not shown).…”

Determination of Nutrition Risk and Status in Critically Ill Patients: What Are Our Considerations?

“…The potential use of various technologies for the assessment of body composition such as computed tomography (CT), ultrasound, and bioelectrical impedance analysis has been explored in various studies in recent years . Skeletal muscle quality revealed by CT scan at the third lumbar vertebra was associated with mortality in critically ill patients . However, CT scans are costly, require transfer to a radiology unit, and involve a dose of radiation that limits its usage to patients for whom CT is ordered for other clinical reasons.…”

Muscle mass and physical recovery in ICU: innovations for targeting of nutrition and exercise

“…Baseline skeletal muscle mass[11] and quality[12]** are demonstrated to be predictive of mortality in ICU patients. Muscle wasting and weakness are also major contributors to PICS [4*, 13*].…”