P017 Sarcopenia Defined by Psoas Muscle Thickness is Not a Predictor of Post-Operative Outcomes in IBD Patients

P017 Sarcopenia Defined by Psoas Muscle Thickness is Not a Predictor of Post-Operative Outcomes in IBD Patients

 

Lee Vivian1, Alipour Omeed2, Tejura Tapas1, Wilson Melissa1, Memel Zoe3, Cologne Kyle1, Hwang Caroline4, Shao Ling1
1 University of Southern California Keck School of Medicine, Los Angeles, United States, 2 University of Washington School of Medicine, Seattle, United States, 3 Massachusetts General Hospital, Harvard Medical School, Boston, United States, 4 Hoag Hospital, Newport Beach, United States

BACKGROUND: Sarcopenia, or muscle mass loss, has been associated with post-operative complications in inflammatory bowel disease (IBD). It is commonly diagnosed by skeletal muscle index (SMI), which is computed by specialized software using several cross-sectional muscle areas at the L3 vertebral body level and is labor intensive. In contrast, psoas muscle thickness normalized to height (PMTH) is calculated quickly without specific software and has potential for routine community use. PMTH is a potential surrogate of SMI and sarcopenia in cirrhosis and chronic pancreatitis. Our aim was to investigate whether sarcopenia defined by PMTH has utility in a predictive model for post-operative complications in IBD.

METHODS: We performed a retrospective study of adults undergoing IBD related surgical resections from 2009 to 2019 at two hospitals. Patients with MRI or CT scans within 90 days preoperatively to 7 days postoperatively were included. Sarcopenia was defined by sex-specific PMTH at the level of the umbilicus on MRI or CT images using a 50th percentile median cutoff (17.8 mm/m in males, 14.8 mm/m in females). Predictive models were created using variables (BMI, age, gender, smoking status, albumin level, INR, platelet count, hemoglobin level, hypertension, diabetes, coronary artery disease, steroid/immunomodulator/biologic use) associated with complications (defined as mortality within 30 days, reoperation within 30 days, readmission within 90 days, RBC transfusion, ICU admission, sepsis, any infection, or DVT/PE). Additional predictive models were created incorporating sarcopenia for comparison. P-values were obtained using univariate logistic regression with P < 0.05 significant. True area under the curve (AUC) was estimated to be within 0.7 to 0.9, with 0.8 as a cut point for clinical relevance.

RESULTS: A total of 85 patients (66% Crohn's disease, 34% Ulcerative colitis, 48 male, 37 female) with mean age 42.5 ± 14.6 were included. Eighty-four patients were on at least one medication for IBD, including 52.4% on steroids, 23.8% on immunomodulators, and 23.8% on biologics. Albumin level (OR = 0.52, p=0.039) and biologic use (OR=5.92, p=0.006) were significantly associated with post-operative complications. The predictive models incorporating sarcopenia, either as a dichotomous variable or PMTH as a continuous variable, were not significantly different from a model with hypoalbuminemia and biologic use (p=0.73). Sarcopenia on univariate analysis was only significantly associated with lower rate of 30-day reoperation (p=0.04).

CONCLUSION(S): While PMTH as a surrogate marker for sarcopenia was not a predictor of post-operative outcomes, hypoalbuminemia and biologic use were. An unexpected association between sarcopenia and lower 30-day reoperation rates may be due to hesitancy to take sarcopenic patients back to the operating room. Sarcopenia defined by PMTH may have a role in decision making with nutritional markers, however larger studies that compare PMTH with accepted radiographic surrogates for sarcopenia and risk assessment in IBD patients are needed.