Psoas Muscle Density Research Articles

Statin use, development of sarcopenia, and long-term survival after endovascular aortic repair

ObjectiveStatin therapy, associated with improved short-term survival after treatment of abdominal aortic aneurysms, may also predispose to muscle side effects. Evidence on statin-related sarcopenia is limited mainly to muscle function, and it is subject to several sources of bias. In the long term, postoperative development of sarcopenia is linked to mortality after endovascular repair (EVAR). We investigated statin use and long-term postoperative mortality after EVAR in relation to objective measurable markers of sarcopenia (psoas muscle surface area and density). MethodsAltogether 216 abdominal aortic aneurysm patients treated with EVAR between 2006 and 2014 at Tampere University Hospital (Finland) were retrospectively studied. Psoas muscle parameters at the L3 level were evaluated from baseline and mainly 1- to 3-year follow-up computed tomography studies. Cox regression was used to study the association between statin medication, psoas muscle changes, and all-cause mortality. ResultsThe majority of patients were male (87%), and the mean age was 77.7 years (standard deviation, 7.4). The median duration of follow-up was 6.3 years (interquartile range, 3.5) with a total mortality of 54.2% (n = 117). Regardless of a higher burden of comorbidities, statin users (n = 119) had lower mortality when compared with nonusers (multivariable hazard ratio [HR]: 0.69, 95% confidence interval: 0.48-0.99, P = .048). Furthermore, statin use was not associated with inferior muscle parameter values, and the relative change in psoas muscle area was actually lower in statin users compared with nonusers (−15.7% and −21.1%, P < .046). ConclusionsStatin use is associated with lower long-term mortality among patients undergoing EVAR without predisposing to increased sarcopenia.

Psoas Muscle Density Evaluated by Chest CT and Long-Term Mortality in COPD Patients

RationalePoor muscle quality in COPD patients relates to exercise intolerance and mortality. Muscle quality can be estimated on computed tomography (CT) by estimating psoas density (PsD). We tested the hypothesis that PsD is lower in COPD patients than in controls and relates to all-cause mortality. MethodsAt baseline, PsD was measured using axial low-dose chest CT images in 220 COPD patients, 80% men, who were 65±8 years old with mild to severe airflow limitation and in a control group of 58 subjects matched by age, sex, body mass index (BMI) and body surface area (BSA). COPD patients were prospectively followed for 76.5 (48–119) months. Anthropometrics, smoking history, BMI, dyspnoea, lung function, exercise capacity, BODE index and exacerbations history were recorded. Cox proportional risk analysis determined the factors more strongly associated with long-term mortality. ResultsPsD was lower in COPD patients than in controls (40.5 vs 42.5, p=0.045). During the follow-up, 54 (24.5%) deaths occurred in the COPD group. PsD as well as age, sex, pack-year history, FEV1%, 6MWD, mMRC, BODE index, were independently associated with mortality. Multivariate analysis showed that age (HR 1.06; 95% CI 1.02–1.12, p=0.006) and CT-assessed PsD (HR 0.97; 95%CI 0.94–0.99, p=0.023) were the variables independently associated with all-cause mortality. ConclusionsIn COPD patients with mild to severe airflow limitation, chest CT-assessed psoas muscle density was lower than in matched controls and independently associated with long-term mortality. Muscle quality using the easy to evaluate psoas muscle density from chest CT may provide clinicians with important prognostic information in COPD.

Muscle fat content is strongly associated with NASH: A longitudinal study in patients with morbid obesity

Studies exploring the relationship between muscle fat content and non-alcoholic fatty liver disease (NAFLD) are scarce. Herein, we aimed to evaluate the association of muscle mass and fatty infiltration with biopsy-assessed NAFLD in patients with obesity. At inclusion (n=184) and 12 months after a dietary intervention (n=15) or bariatric surgery (n=24), we evaluated NAFLD by liver biopsy, and skeletal muscle mass index (SMI) by CT (CT-SMI) or bioelectrical impedance analysis (BIA-SMI). We developed an index to evaluate absolute fat content in muscle (skeletal muscle fat index [SMFI]) from CT-based psoas muscle density (SMFIPsoas). Muscle mass was higher in patients with NAFLD than in those without (CT-SMI 56.8±9.9 vs. 47.4±6.5cm2/m2, p <0.0001). There was no association between sarcopenia and non-alcoholic steatohepatitis (NASH). SMFIPsoas was higher in NASH ≥F2 and early NASH F0-1 than in NAFL (78.5±23.6 and 73.1±15.6 vs. 61.2±12.6, p <0.001). A 1-point change in the score for any of the individual cardinal NASH features (i.e. steatosis, inflammation or ballooning) was associated with an increase in SMFIPsoas (all p <0.05). The association between SMFIPsoas and NASH was highly significant even after adjustment for multiple confounders (all p <0.025). After intervention (n=39), NASH improvement, defined by NAFLD activity score <3 or a 2-point score reduction, was achieved in more than 75% of patients (n=25 or n=27, respectively) that had pre-established NASH at inclusion (n=32) and was associated with a significant decrease in SMFIPsoas (p <0.001). Strikingly, all patients who had ≥11% reduction in SMFIPsoas achieved NASH improvement (14/14, p<0.05). Muscle fat content, but not muscle mass, is strongly and independently associated with NASH. All individuals who achieved a ≥11% decrease in SMFIPsoas after intervention improved their NASH. These data indicate that muscle fatty infiltration could be a potential marker for (and perhaps a pathophysiological contributor to) NASH. The fat content in skeletal muscles is highly reflective of the severity of non-alcoholic fatty liver disease (NAFLD) in patients with morbid obesity. In particular, muscle fat content is strongly associated with non-alcoholic steatohepatitis (NASH) and decreases upon NASH improvement. These data indicate that muscle fatty infiltration could be a marker and possible pathophysiological contributor to NASH.

AGEs accumulation is related to muscle degeneration and vascular calcification in peritoneal dialysis patients.

Background:Patients with chronic kidney disease (CKD) are affected by dynapenia, sarcopenia, and vascular calcification. Advanced glycation end products (AGEs) may accumulate in peritoneal dialysis (PD) patients and favor sarcopenia via changes in collagen cross-linking, muscle protein breakdown, and the calcification of arterial smooth muscle cells via p38-MAPK activation. The aim of this study is to explore the relationships between AGEs, muscle degeneration, and coronary artery calcification.Methods: This was a clinical observational study in patients with CKD undergoing PD, in which serum and skin AGEs (AGEs-sAF), cumulative glucose load, muscle strength and functional tests, muscle ultrasounds with elastography, coronary artery calcium (CAC) quantification, and muscle density by multislice computed tomography were measured.Results:27 patients aged 48±16 years, dialysis vintage of 27±17 months, had AGEs-sAF levels of 3.09±0.65 AU (elevated in 13 [87%] patients), grip strength levels of 26.2±9.2 kg (11 [42%] patients with dynapenia), gait speed of 1.04±0.3 m/s (abnormal in 14 [58%] patients) and "timed-up-and-go test" (TUG) of 10.5±2.2s (abnormal in 7 [26%] patients). Correlations between AGEs-sAF levels and femoral rectus elastography (R=-0.74; p=0.02), anterior-tibialis elastography (R= -0.68; p=0.04) and CAC (R=0.64; p=0.04) were detected. Cumulative glucose load correlated with femoral rectal elastography (R=-0.6; p=0.02), and serum glycated hemoglobin concentrations correlated with psoas muscle density (R= -0.58; p=0.04) and CAC correlated with psoas muscle density (R=0.57; p=0.01) and lumbar square muscle density (R=-0.63; p=0.005).Conclusions:The study revealed associations between AGEs accumulation and lower muscle stiffness/density. Associations that linked muscle degeneration parameters with vascular calcification were observed.

Myosteatosis as a novel prognostic biomarker after radical cystectomy for bladder cancer

This study aims to evaluate the influence of myosteatosis on survival of patients after radical cystectomy (RC) for bladder cancer. We retrospectively identified 230 patients who underwent RC for bladder cancer at our three institutions between 2009 and 2018. Digitized free-hand outlines of the left and right psoas muscles were made on axial non-contrast computed tomography images at level L3. To assess myosteatosis, average total psoas density (ATPD) in Hounsfield Units (HU) was also calculated as an average of bilateral psoas muscle density. We compared cancer-specific survival (CSS) between high ATPD and low ATPD groups and performed cox regression hazard analyses to identify the predictors of CSS. Median ATPD was 44 HU (quartile: 39–47 Hounsfield Units). Two-year CSS rate in overall patients was 76.6%. Patients with low ATPD (< 44 HU) had significantly lower CSS rate (P = 0.01) than patients with high ATPD (≥ 44 HU). According to multivariate analysis, significant independent predictors of poor CSS were: Eastern Cooperative Oncology Group performance status ≥ 1 (P = 0.03), decreasing ATPD (P = 0.03), non-urothelial carcinoma (P = 0.01), pT ≥ 3 (P < 0.01), and pN positive (P < 0.01). In conclusion, myosteatosis (low ATPD) could be a novel predictor of prognosis after RC for bladder cancer.

Are computed tomography-based measures of specific abdominal muscle groups predictive of adverse outcomes in older cancer patients?

PurposeIt is unknown whether computed tomography (CT)-based total abdominal muscle measures are representative of specific abdominal muscle groups and whether analysis of specific abdominal muscle groups are predictive of the risk of adverse outcomes in older cancer patients. MethodsRetrospective single-center cohort study in elective colon cancer patients aged ≥65 years. CT-based skeletal muscle (SM) surface area, muscle density and intermuscular adipose tissue (IMAT) surface area were determined for rectus abdominis; external- and internal oblique and transversus abdominis (lateral muscles); psoas; and erector spinae and quadratus lumborum (back muscles). Outcomes were defined as severe postoperative complications (Clavien-Dindo score >2) and long-term survival (median follow-up 5.2 years). Results254 older colon cancer patients were included (median 73.6 years, 62.2% males). Rectus abdominis showed the lowest SM surface area and muscle density and the back muscles showed the highest IMAT surface area. Psoas muscle density, and lateral muscle density and percentage IMAT were associated with severe postoperative complications independent of gender, age and cancer stage. ConclusionsCT-based total abdominal muscle quantity and quality do not represent the heterogeneity that exists between specific muscle groups. The potential added value of analysis of specific muscle groups in predicting adverse outcomes in older (colon) cancer patients should be further addressed in prospective studies.

Impact of sarcopenia in aortoiliac occlusive disease in Mediterranean population.

Background This study aims to validate the psoas muscle area and psoas muscle density as morphometric predictors in cardiovascular and cerebrovascular endpoints in patients with extensive aortoiliac peripheral arterial disease. Methods A total of 57 patients (55 males, 2 females; mean age 60±8.2 years; range, 35 to 83 years) with Trans-Atlantic Inter-Society Consensus type D lesions who underwent revascularization at two Portuguese tertiary hospitals between January 2013 and July 2019 were retrospectively analyzed. The patients with a recent (<6 months) computed tomography scan prior to the revascularization procedure were included in the study. Both centers offered to their patients open and endovascular repair of aortoiliac peripheral arterial disease. Major adverse cardiovascular and cerebrovascular events and major adverse limb events were evaluated. Results The median follow-up was 20 months. The mean survival rate was 93±3.4% at 30 days and 62.7±8.6% at 48 months. The discriminative thresholds found in this population were 2,175.8 mm2 for total psoas area and 51.75 Hounsfield unit for psoas muscle density. There was a statistically significant difference in the one-year survival rate (p=0.003 and p=0.291, respectively) and major adverse cardiovascular and cerebrovascular events (p=0.005 and p=0.206, respectively) for total psoas area compared to psoas muscle density. Conclusion Total psoas area shows a prognostic value for survival and major adverse cardiovascular and cerebrovascular events in this patient population.

Morphometric parameters of muscle and bone in critically ill patients : Post hoc analysis of the VITdAL-ICU trial.

SummaryBackgroundSarcopenia, defined as loss of muscle mass, quality and function, is a part of the frailty syndrome. In critical illness, sarcopenia has rarely been evaluated regarding clinical outcomes. Therefore, we evaluated the association of sarcopenia with both hospital length of stay (HLOS) and 6‑month mortality in critically ill patients using abdominal computed tomography (CT) scans.MethodsIn a post hoc analysis from the high dose vitamin D3 vs. placebo in adult vitamin D deficient patients (VITdAL-ICU) trial, we retrospectively reviewed all available abdominal CT scans (18 women, 19 men). We measured and calculated total psoas area (TPA), psoas muscle density (PMD), skeletal muscle index (SMI) and bone mineral density (BMD) and analyzed the relation of these endpoints with HLOS and mortality. Defining sarcopenia we used cut-off values for TPA as 642.1 mm2/m2 in women and 784 mm2/m2 in men and PMD as 31.1 Hounsfield units (HU) in women and 33.3 HU in men, both measured at the level of L3, as well as for SMI (38.5 cm2/m2 in women and 52.4 cm2/m2 in men). Likely osteoporosis was defined by L1 trabecular attenuation of ≤110 HU. Values for TPA, PMD and SMI could not be obtained in 11 patients and BMD in 1 patient.ResultsMean adjusted TPA was lower in women versus men (478 vs. 749 mm2/m2) as well as PMD (34.6 vs. 41.3 HU), SMI (62.36 vs. 76.81 cm2/m2) and BMD (141.1 vs. 157.2 HU). No significant influence on hospital length of stay and on 6‑month mortality was found, irrespective of the morphometric parameter used (TPA, PMD, SMI, BMD; p > 0.05). Survivors showed statistically nonsignificantly better values than nonsurvivors: TPA: 652 vs. 530 mm2/m2 (p = 0.27); PMD: 38.4 vs. 37.4 HU (p = 0.85); SMI: 70.32 vs. 69.54 cm2/m2 (p = 0.91); BMD: 156 vs. 145.8 HU (p = 0.81).ConclusionAlthough the study is limited by the small sample size, our data do not support a strong predictive value for TPA/PMD/SMI or BMD for HLOS or mortality in critically ill patients with vitamin D deficiency.

The psoas muscle density as a predictor of postoperative complications and 30-day mortality for acute mesenteric ischemia patients.

Low muscle mass and quality is associated with poor surgical outcomes. Psoas muscle density (PMD)is a validated surrogate for muscle quality that can be easily measured from a clinical computed tomography (CT) scan. The objective of this study was to investigate the association between PMD and short-term postoperative outcomes in patients with acute mesenteric ischemia (AMI). From April 2006 and September 2019, the clinical data of all patients who underwent surgical intervention with a preoperative diagnosis of AMI and had preoperative non-contrast CT images available were retrospectively reviewed. PMD was measured by CT at the third lumbar vertebra. The lowest quartile of PMD for men and women in all patients was used as sex-specific cut-off values for low PMD. Univariate and multivariate analyses evaluating risk factors of postoperative complications and 30-day mortality were performed. The cohort consisted of 88 patients with a mean age of 58.8 ± 16.2years, of whom 21 (23.9%) patients had low PMD based on the diagnostic cut-off values (40.5 HU for men and 28.4 HU for women), 35 (39.8%) patients developed complications within 30days of the operation, and 10 (11.3%) patients died within 30days of surgery. Low PMD patients had a higher risk of postoperative complications and 30-day mortality than patients without low PMD patients. In a multivariate analysis, low PMD and low psoas muscle area (PMA) were independent predictors of postoperative complications. However, only low PMD remained an independent risk factor for 30-day mortality. Preoperative assessment of the PMD on CT can be a practical method for identifying AMI patients at risk for postoperative complications and 30-day mortality.

A lower psoas muscle index predicts a poorer prognosis in metastatic hormone-naïve prostate cancer.

IntroductionA recent investigation revealed that sarcopenia was associated with a poorer prognosis in some solid malignancies, including prostate cancer. In most reports, sarcopenia was defined as a low psoas volume on CT. This study investigated the association of sarcopenia, determined according to the psoas muscle volume and density on CT, with the prognosis in patients with metastatic hormone‐naïve prostate cancer (mHNPC).MethodsA total of 66 patients initially diagnosed with mHNPC were enrolled in this study. Skeletal muscle was evaluated according to the psoas muscle index density (PMID) on computed tomography scans. The psoas muscle volume was calculated at the level of L3 and CT density was evaluated as the mean CT density at the psoas muscle area. We divided the patients into higher and lower PMID groups.ResultsThe lower PMID group (on both sides) showed a poorer overall survival than the higher PMID group (Right: 32.5 vs 99.0 months in Rt PMID, P = .014; Left: 36.0 vs 100.0 months in Lt PMID, P = .029). The lower PMID group (on both sides) showed a shorter time to CRPC (Right: 9.0 vs 42.0 months in Rt PMID, P = .006; Left: 9.0 vs 31.0 months in Lt PMID, P = .005). A multivariate analysis showed that lower Rt PMID and Lt PMID were independent risk factors for poorer OS (HR:2.02, 95%CI: 1.04‐3.90, P = .037, HR:2.29, 95%CI: 1.18‐4.47, P = .015, respectively). For CRPC, both Rt and Lt lower PMID also showed independent risk factors for shorter time to CRPC (HR:2.39, 95%CI: 1.23‐4.62, P = .010, HR:2.43, 95%CI: 1.23‐4.78, P = .010, respectively).ConclusionsAmong mHNPC patients, both lower PMID groups showed a poorer overall survival and shorter time to CRPC than the higher PMID groups.

Computed Tomography-Measured Psoas Muscle Density as a Predictive Factor for Hypophosphatemia Associated With Refeeding.

Initiation of parenteral nutrition (PN) after a period of starvation can be complicated by refeeding syndrome (RFS). RFS is associated with electrolyte abnormalities including hypomagnesemia, hyponatremia, and hypophosphatemia. Risk factors include recent weight loss, low body mass index, and electrolyte deficiencies; however, these associations are not strong. We hypothesized that a validated measure of nutrition risk, computed tomography (CT)-measured psoas muscle density, can be used to predict the development of hypophosphatemia associated with RFS. A retrospective analysis of surgical patients initiated on PN with an abdominal CT scan within the past 3 months was conducted. CT-measured psoas muscle density was assessed as a predictive variable for the development of electrolyte abnormalities. Daily electrolyte and clinical outcome measures were recorded. One hundred nine patients were stratified based on Hounsfield unit average calculation (HUAC). The lowest 25th percentile of patients had HUAC <25. Low HUAC was associated with a significant percent decrease in phosphate levels from baseline to PN day 3 (P < .01) and significant difference in serum phosphate value on PN day 3 (P < .01). The low muscle density quartile also experienced longer days on the mechanical ventilator (P = .01) compared with patients with a higher psoas muscle density. Psoas muscle density predicted the development of hypophosphatemia in patients initiated on PN. This measurement may aid in identifying patients at highest risk of experiencing RFS. Amean psoas HU <25 may prompt additional precautions, including additional phosphate replacement and slower initiation of PN.

Total Psoas Area Index is Valuable to Assess Sarcopenia, Sarcopenic Overweight/Obesity and Predict Outcomes in Patients Undergoing Open Pancreatoduodenectomy.

Background and AimSarcopenia has been proven to be a risk factor after pancreatoduodenectomy (PD). We aimed to evaluate if decreased psoas muscle area and density shown in CT scan, as measures for sarcopenia, were associated with postoperative major complications and adverse outcomes in patients who underwent PD.Patients and MethodsWe analyzed 152 consecutive patients who underwent open PD. Total psoas area and muscle attenuation were measured on CT images at the level of the third lumbar vertebra. Total psoas area index (TPAI) was calculated, the cut-off values of TPAI were estimated and validated. The relationship between radiographic characters and outcomes was analyzed.ResultsThe optimal cut-off values of TPAI were 4.78 cm2/m2 for males and 3.46 cm2/m2 for females. The values were validated by outcomes with significant differences in the rate of major complications, re-operation, length of stay, and total cost. The prevalence of TPAI-defined sarcopenia and sarcopenic overweight/obesity was 38.8% and 17.1% in total. In multivariate logistic regression, rate of major complications was associated with TPAI [OR=0.605, 95% CI (0.414, 0.883), P=0.009], TPAI-defined sarcopenia [OR=8.256, 95% CI (2.890, 23.583), P=0.000] and sarcopenic overweight/obesity [OR=7.462, 95% CI (2.084, 26.724), P=0.002]; meanwhile, NRS2002-defined nutritional risk and GLIM-defined malnutrition did not show relationship with major complications.ConclusionBoth sarcopenia and sarcopenic overweight/obesity determined by new TPAI cut-off values were associated with a higher rate of major complications and adverse outcomes in Chinese patients undergoing open PD whereas usual nutritional assessment was not.

Editorial Comment: 2019 Musculoskeletal Infection Society Proceedings

Editorial Comment: 2019 Musculoskeletal Infection Society Proceedings

Impact of the preoperative body composition indexes on intraoperative blood loss in patients undergoing pancreatoduodenectomy.

This study sought to identify any significant predictors of blood loss during pancreatoduodenectomy (PD) among preoperative variables, including the body composition indexes. The preoperative data of patients undergoing PD were retrospectively reviewed. The objective variable was the percentage of blood loss during PD to the estimated circulating blood volume (proportional blood loss: PBL). The circulating blood volume was estimated using Nadler's formula. The total psoas area, average Hounsfield units of psoas area (psoas muscle density: PMD), and visceral to subcutaneous adipose tissue area ratio (VSR) were measured at the third vertebra using preoperative plain computed tomography images. A univariate analysis and multiple linear regression analysis for PBL were conducted using the preoperative variables. A total of 415 patients were analyzed. The median PBL was 24.5%. The PMD (coefficient -0.267; 95% CI -0.518, -0.015), VSR (coefficient 2.719; 95% CI 0.238, 5.201), serum albumin level (coefficient -8.458; 95% CI -13.02, -3.898), neoadjuvant therapy (coefficient 9.605; 95% CI 1.722, 17.49), and prothrombin time-international normalized ratio (PT-INR, coefficient 38.63; 95% CI 10.94, 66.31) were independently associated with PBL. The preoperative PMD, VSR, serum albumin level, neoadjuvant therapy, and PT-INR independently affected PBL. These factors could therefore be potential targets to reduce blood loss during PD.

Defining Sarcopenia in the Indian Population—a Step Forward

Decline in muscle mass and function has been associated with frailty syndrome and other chronic medical conditions. Poor outcomes following treatment have been reported in various gastrointestinal malignancies in sarcopenic patients. The Asian Working Group of Sarcopenia has suggested 2 standard deviation below the mean muscle mass of a young reference group, as the cut-off point for defining this entity. However, values vary according to ethnicities, and no study has previously assessed muscle indices in the Indian population. The study aims to access muscle area and density as markers of sarcopenia and to define sex specific cut off points for the Indian population. This is a prospective study conducted at the Medanta Hospital from May 2016 to March 2018. Prospective organ donors, in age group of 18 to 65 years, were enrolled in this study. Computed tomography scan of the abdomen (used for preoperative evaluation) was used to evaluate psoas muscle area and density at the level of transverse processes of the third and fourth lumbar vertebrae. Plain scan images with 3 mm cuts were used for calculations. Psoas area was normalized for height, and density was normalized for weight. Mean of psoas area (acquired at L3 and L4 levels) was normalized for height, and values less than 2 standard deviation (SD) below the mean were calculated. Similar calculations were done for psoas density. Values using 1.64SD below the mean, 5th percentile and 10th percentile were calculated as well. There were 457 healthy donors who were enrolled in the study, but 26 were excluded from the analysis as they belonged to non-Indian ethnicities. Sex-specific values were calculated. Values at 2SD below the mean, 1.64SD below the mean, 5th percentile and 10th percentile for the male population were 173.8 mm2/m2, 210.7 mm2/m2, 220.7 mm2/m2 and 239.05 mm2/m2, respectively, for psoas area. Similar values for psoas density were 0.48, 0.53, 0.56 and 0.575 Hounsfield units/kg, respectively. For the female cohort, values at 2SD below the mean, 1.64SD below the mean, 5th percentile and 10th percentile, for psoas density, were 101.2 mm2/m2, 128.7 mm2/m2, 149.5 mm2/m2 and 173.80 mm2/m2, respectively. Values for psoas density were 0.26, 0.36, 0.53 and 0.59 Hounsfield units/kg, respectively. 5th percentile values and values at 1.64SD below the mean were found to be more concordant, and we have decided to take 5th percentile values as the cut-off point to define sarcopenia for further studies. We defined sarcopenia at 5th percentile, with sex-specific cut-off points for psoas area and density. Defining this parameter is important as there has been a substantial increase in the elderly population. Studies have shown poor outcomes in patients with sarcopenia, when managing them for chronic illnesses and malignancy.

Associations between psoas muscle area (PMA) and density (PMD) with phase I oncology clinical trial outcomes.

7007 Background: Malnutrition and cancer cachexia can lead to loss of muscle mass (sarcopenia) and are associated with poor outcomes. Muscle status can be evaluated by computed tomography (CT)-based radiographic measures, specifically at the L3 vertebrae where the psoas and other core muscles reside. We previously found that baseline malnutrition was associated with worse phase 1 clinical trial outcomes including increased toxicity and reduced survival (Jain et al. Oncologist, 2019). We sought to evaluate the relationship between muscle status and phase 1 trial outcomes. Methods: CT-based psoas muscle area (PMA) and psoas muscle density (PMD) were evaluated in 83 patients who enrolled in a phase 1 trial. We localized the L3 vertebral body on axial imaging and manually outlined the psoas muscle to calculate PMA (standardized to height) and PMD. Two reviewers independently conducted the analyses. We stratified patients by having a PMA or PMD above or below the group’s median. We evaluated for associations between PMA/PMD and the following clinical trial outcomes: rates of grade ≥ 3 toxicity, frequency of dose reductions/interruptions, hospitalizations, tumor response, duration on study (DOS), and overall survival (OS). We also evaluated for correlations between PMA/PMD and a validated measure of nutritional status, the PG-SGA. Chi-square analysis was used to determine statistical significance between groups. Kaplan-Meier curves were used to compare DOS and OS. Results: 83 patients were included (38 male, 45 female), with a median age of 60 (range 28-85). The most common cancer type was gastrointestinal (33%). Mean PMA was 2.89 cm2/m2 (range 1.41-5.72) and mean PMD 37.77 Hounsfield units (range 13.27-56.18). PMA above the median was associated with a reduced risk of grade ≥ 3 toxicity (32.5% vs 67.4%, p = 0.001). There was no association between PMD and grade ≥ 3 toxicity, or between PMA/PMD and other phase 1 trial outcomes. There was a significant correlation between nutritional status and PMA (r = -0.278, p = 0.01) but not PMD. Conclusions: PMA and PMD are readily available CT-based measures of muscle status. In oncology phase 1 clinical trial participants, lower baseline PMA was associated with a two-fold increased risk of grade ≥ 3 toxicity. Baseline PMA was moderately correlated with nutritional status which was previously shown to be associated with poor trial outcomes. More research is necessary to further understand the specific mechanisms by which nutritional status and muscle mass may influence toxicity risk in this population.

Risk Factors for Surgical Site Infection after Operative Fixation of Acetabular Fractures: Is Psoas Density a Useful Metric?

Surgical site infection (SSI) occurs in 5% to 7% of patients undergoing operative fixation of acetabular fractures, with reported risk factors including longer operative duration, increased blood loss, pelvic artery embolization, and concurrent abdominal organ injury, among others. Psoas muscle density is a measure of muscle quality and, as a metric for sarcopenia and/or nutrition status, has been associated with poor outcomes such as mortality across multiple surgical specialties. To date, psoas muscle density has not been explored for its associations with SSI in acetabular fracture patients.Questions/purposes (1) Is decreased psoas muscle density, as measured by Hounsfield units, associated with an increased SSI risk after acetabular fracture fixation? (2) What patient, operative, and hospital variables are associated with an increased SSI risk after acetabular fracture fixation? Between 2012 to 2017, surgeons performed 684 acetabular ORIF procedures at one level I trauma center. Of those, 8% (56 of 684) did not meet inclusion criteria, leaving 92% (n = 628) for analysis in this study. The median (range) follow-up duration was 12 months (0.5-77). Patient demographics, comorbidities, operative and in-hospital variables, and psoas muscle density measured using preoperative pelvic CT images-acquired for all operative acetabular fracture patients-were analyzed. SSI was defined by positive culture results obtained during irrigation and débridement. Overall, 7% (42 of 628) of patients had an SSI. A multivariable regression analysis was performed to identify independent risk factors. Sensitivity analysis was performed with minimum follow-up set at 3 months and 6 months. There was no difference in the mean psoas muscle density between patients with SSI (50.9 ± 10.2 Hounsfield units [HUs]) and those who did not have an SSI within 1 year of open reduction and internal fixation (51.4 ± 8.1 HUs) (mean difference: 0.5 [95% confidence interval -2.34 to 3.32]; p = 0.69). Four variables were independently associated with an increased risk of SSI: increased operative time (1.04 [95% CI 1.00 to 1.07]; p = 0.03), estimated blood loss (1.08 [95% CI 1.02 to 1.14]; p = 0.01), female sex (2.34 [95% CI 1.19 to 4.60]; p = 0.01), and intravenous drug use (3.95 [95% CI 1.51 to 10.33]; p = 0.01). Sensitivity analysis showed no change in results using either 3-month or 6-month minimum follow-up. Risk factors for SSI after acetabular fixation include female sex, intravenous drug use, prolonged operative times, and increased intraoperative blood loss. Although the density of the psoas muscle may be a surrogate for nutritional markers, it was not associated with SSI in our patients with acetabular fractures. Thus, it is not useful for risk assessment of SSI in the general population with acetabular fracture; however, future studies with larger sample sizes of patients older than 60 years may re-investigate this marker for SSI risk. Contrary to the results of previous studies, pelvic artery embolization, intraoperative blood transfusion, and intensive care unit stay did not increase the risk of SSI; however, we may have been underpowered to detect differences in these secondary endpoints. Future large, multisite studies may be needed to address these conflicting results more definitively. Level III, therapeutic study.

Abstract P462: Myosteatosis: Differences in Association With Type 2 Diabetes by Anatomical Location

Background: CT-derived muscle density (MD) reflects the degree of adiposity in muscle (i.e., myosteatosis) with lower MD indicating greater adiposity. Previous research indicates lower MD is associated with increased risk of type 2 diabetes (T2D). However, few studies have compared the association of simultaneously measured MD by anatomic location. The relationship between myosteatosis and cardiometabolic health may differ by body site and influence which location(s) is most useful for risk assessment. We investigated potential differential relationships between T2D and MD of the locomotor muscles of the abdomen (psoas), thigh, and calf among 539 African Caribbean men from Tobago. Methods: Men were aged 50-91 years (mean 64.4 years, mean BMI 27.5 kg/m 2 ). Calf MD was measured at 66% of calf length using peripheral quantitative CT; calf MD was defined as the ratio of muscle mass to cross-sectional muscle area. Psoas MD was measured in the abdomen (between L3/L4) and thigh MD was measured in the mid-thigh using CT; for these, MD was defined as the average muscle attenuation across each site. MDs were converted to per-SD units for comparability. T2D was defined as a fasting serum glucose level of ≥126 mg/dL or currently taking antidiabetic medication. Results: Psoas and thigh MDs were more highly correlated (r = 0.70) than psoas and calf (r = 0.33) or thigh and calf (r = 0.53) MDs, and calf MD was moderately correlated with BMI (r = -0.38) compared to lower BMI correlations for thigh (r = -0.18) or psoas (r = -0.16) MDs (all significant p &lt; 0.05). After age and lifestyle factor adjustment (Table), a 1-SD lower MD of the thigh or calf was significantly associated with higher odds of T2D. Additional adjustment for BMI completely attenuated the association with T2D for thigh MD, but not calf MD. Conclusion: In our study of African Ancestry men, only calf MD was associated with higher odds of T2D independent of BMI and other muscle groups. Longitudinal studies are needed to better characterize specific muscle myosteatosis and metabolic abnormalities.

Preoperative Psoas Muscle Size and Radiodensity Predict Mid-term Survival and Quality of Life After Fenestrated-branched Endovascular Aortic Repair

Introduction: Age alone is a relatively poor predictor of survival due to the discrepancy between biological and chronological age. We need better predictors of clinical outcomes and life expectancy in elderly patients considered for endovascular repair of complex aortic aneurysms. Sarcopenia may be a key determinant of survival in elderly people. Psoas muscle area (PMA) measured at L3-level has been shown to be a reproducible and reliable surrogate for sarcopenia. However, the association of PMA with survival has been inconsistent in previous studies involving patients treated for infrarenal abdominal aortic aneurysms (1-7). PMA alone does not take the muscle quality over quantity into account. Decreased radiodensity, on the other hand, could indicate fatty infiltration of skeletal muscle (myesteatosis) that is associated with frailty and sarcopenia. The aim of this study was to investigate the association of PMA and psoas muscle density (PMD) with survival and quality of life (QOL) after fenestrated-branched endovascular aortic repair (F-BEVAR) of pararenal and thoracoabdominal aortic aneurysms. Methods: The study included 244 consecutive patients enrolled in a prospective study to investigate outcomes of F-BEVAR. Preoperative computed tomography angiography was used to measure PMA (cm2) and PMD (Hounsfield unit, HU) from a single axial slice at L3-level. Lean psoas muscle area (LPMA) was calculated (LPMA = PMA×PMD). Patients were divided into two groups using LPMA cut-point based on Cox hazard model (Figure 1). Group A was defined as LPMA ≥ 350 (n=79) and group B as LPMA < 350 cm2×HU (n=165). QOL was assessed at baseline and 12 months using SF-36 survey. Results: Patients in Group A were younger (mean age, 72±8 vs 76±7 years, P< .001), more often males (95% vs 59%, P< .001) and had higher body mass index (30±6 vs 27±5 kg/m2, P=.001). There were no major differences in comorbidities, aneurysm extent and procedural measures between the groups. Thirty-day mortality (0% vs 0.6%, P=1.00) and major adverse event rates (15% vs 24%, P=.18) were similar in Group A and B. At 3 years, patient survival was 94±3% in Group A and 75±4% in Group B (hazard ratio [HR] 0.20, 95% confidence interval [CI] 0.07-0.56, P=.002, Figure 2). The 3-year survival difference was even more prominent in patients aged ≥75 years: 100% for Group A and 72±5% for Group B (HR 0.12, 95% CI 0.02-0.86, P=.035). Group A patients had significantly higher QOL scores at baseline and 12 months. Out of all preoperative variables, LPMA was the strongest independent predictor of survival during the follow-up in multivariable analysis (adjusted HR 0.59 per one standard deviation, 95% CI 0.40-0.87, P=.008), whereas PMA alone was not a significant predictor. Conclusion: A high LPMA was independently and strongly associated with better mid-term survival and quality of life after F-BEVAR. LPMA can be used to identify suitable candidates for F-BEVAR among elderly patients. The measurement of psoas muscle radiodensity should be included in future studies assessing CT parameters as predictors of survival in patients undergoing vascular surgical procedures.Figure 2Kaplan-Meier survival estimates, dotted line adjusted for age, gender and BMI.View Large Image Figure ViewerDownload Hi-res image Download (PPT) Disclosure: The last author has received consulting fees and grants from Cook Medical, W. L. Gore, and GE Healthcare (all paid to the affiliated institution with no personal income).

Pre-operative Psoas Muscle Size Combined With Radiodensity Predicts Mid-Term Survival and Quality of Life After Fenestrated-Branched Endovascular Aortic Repair

To investigate the association between psoas muscle area (PMA) and density (PMD) with survival and quality of life (QoL) after fenestrated-branched endovascular aortic repair (F-BEVAR). The study included 244 consecutive patients enrolled in a prospective study to investigate outcomes of F-BEVAR. Pre-operative computed tomography angiography was used to measure PMA (cm2) and PMD (Hounsfield unit [HU]) at the L3 level. Lean PMA (LPMA) was calculated (PMA×PMD). Patients were divided into two groups using the LPMA cut off point based on a Cox hazard model. Group A was defined as LPMA ≥350 (n=79) and group B as LPMA<350cm2×HU (n=165). QoL was assessed at baseline and at 12 months using the Short Form-36. Patients in group A were younger (mean age 72±8 vs. 76±7 years; p<.001), more often male (95% vs. 59%; p<.001), and had higher body mass index (30±6 vs. 27±5kg/m2; p=.001). There were no major differences in comorbidities, aneurysm extent, or procedural measures between the groups. Thirty day mortality (0% vs. 0.6%; p=1.0) and major adverse event rates (15% vs. 24%; p=.18) were similar in groups A and B. At three years, patient survival was 94%±3% in group A and 75%±4% in group B (hazard ratio [HR] 0.20, 95% confidence interval [CI] 0.07-0.56; p=.002). The three-year survival difference was even more prominent in patients aged ≥75 years: 100% for group A and 72%±5% for group B (HR 0.12, 95% CI 0.02-0.86; p=.035). Patients in group A had significantly higher QoL scores at baseline and at 12 months. LPMA was the strongest independent predictor of survival during follow up in multivariable analysis (adjusted HR 0.59 per 1 standard deviation, 95% CI 0.40-0.87; p=.008). A high LPMA was independently and strongly associated with better mid term survival and QoL after F-BEVAR. LPMA may help to identify the best candidates for F-BEVAR among elderly patients.