The relationship between sarcopenia in inflammatory bowel disease and its clinical activation and prognostic impact

OBJECTİVE: Inflammatory Bowel Diseases (IBD) are characterized by chronic, recurrent inflammation of the gastrointestinal system, encompassing Crohn's Disease, Ulcerative Colitis, and Indeterminate Colitis. A decrease in skeletal muscle mass, referred to as sarcopenia, has been increasingly reported in patients with IBD. Despite studies on IBD and sarcopenia, the relationship between reduced skeletal muscle mass and the prognosis of IBD remains not fully elucidated. Neutrophil-lymphocyte ratio (NLR), Platelet-lymphocyte ratio (PLR), and Serum LDH/Albumin ratio (LAR) are biomarkers used as indicators of systemic inflammatory response. There is no previous study on the relationship between sarcopenia in IBD and these mentioned biomarkers. Therefore, the primary aim of our study is to investigate the impact of certain systemic biomarkers and demographic characteristics on sarcopenia in patients diagnosed with IBD and to identify factors that determine the risk of developing sarcopenia. MATERİALS AND METHODS: Our study is a retrospective, cross-sectional cohort study. A total of 261 patients, aged >18, who presented to the IBD outpatient clinic of Dokuz Eylül University Faculty of Medicine's Division of Gastroenterology with diagnoses of Ulcerative Colitis and Crohn's Disease and had undergone abdominal CT scans for any reason between 01/01/2010- 01/01/2023 were included. Demographic and clinical data, abdominal CT dates, received treatments, surgical history, and laboratory values from the date of the abdominal CT or the nearest date were retrospectively recorded. From these parameters, Systemic Immune- Inflammation Index (SII), Body Mass Index (BMI), Prognostic Nutritional Index (PNI), NLR, PLR, and LDH/Albumin Ratio were calculated. The diagnosis and degree of sarcopenia were determined using abdominal CT images. The third lumbar disc plane (L3) was selected for imaging, and L3 Skeletal Muscle Index (SMI, cm/m2) was calculated by taking the average value of the cross-sectional area and dividing it by the square of the patient's height. The impact of the obtained data on sarcopenia was investigated. RESULTS: In our study, the average age of 261 patients (134 female, 127 male) was determined as 50.0±14.7 years. The BMI averages were calculated as 25.8±4.8. A smoking history was present in 65.5% of the patients, and the most frequently observed comorbidity was hypertension (HT) with 21.8%. Crohn's disease was diagnosed in 65.5% of the patients, while 34.5% had Ulcerative Colitis. The most common Crohn's involvement site was the ileocolonic region (45.6%), and the most common Crohn's type was the inflammatory type (65.5%). Leftsided colitis (38.9%) was the most common involvement in Ulcerative Colitis. The rate of extraintestinal involvement was 28.7%. The most common treatment for Crohn's patients was Biological Agent + AZT (29.8%), and for Ulcerative Colitis patients, it was 5-ASA treatment (46.7%). Active Anti-TNF treatment was received by 34.5% of the patients. The rate of patients with a surgical history was 19.9%, with the most frequently applied surgical treatment being stricture resection (36.5%). Sarcopenia was detected in 19.9% of the patients. The average age of patients diagnosed with sarcopenia was higher (p=0.075). A borderline statistical significance was found in the age of IBD diagnosis (p=0.056). There was no significant difference in gender distribution. BMI was lower in the sarcopenia group (p<0.001). While there was a borderline statistical significance in the smoking rate, the rate of HT among comorbidities was significantly lower in the group with sarcopenia (p=0.045). The rate of sarcopenia was determined as 20.5% in Crohn's disease and 18.9% in Ulcerative Colitis. There was no statistically significant difference among Crohn's involvement sites, Crohn's types, and Ulcerative Colitis involvement sites. When comparing the rates of active treatment, types of medical treatment, types of biological agents used, rates of surgical treatment, and types of surgical treatment between the sarcopenia and non-sarcopenia groups, no statistically significant difference was found. Among the immune-inflammatory markers, the median value of PNI was lower in the group with sarcopenia (p=0.006), while SII and PLR values were higher in the sarcopenia group (p=0.012 and p=0.001, respectively). There was no statistically significant difference in NLR and LDH/Albumin ratio between the two groups. CONCLUSİON:Our study demonstrates the impact of certain systemic biomarkers and demographic characteristics on sarcopenia in patients diagnosed with IBD. Sarcopenia has been increasingly reported in patients with IBD in recent years, emphasizing the importance of early diagnosis and treatment. In our study, the prevalence of sarcopenia was found to be 19.9%. Sarcopenia increases with age, but gender does not have an effect on the development of sarcopenia. Patients with lower BMI, smokers, and those without hypertension are at a higher risk of developing sarcopenia. Sarcopenia is more prevalent in Crohn's disease compared to Ulcerative Colitis. However, Crohn's involvement site and type, as well as Ulcerative Colitis involvement site, do not affect the risk of developing sarcopenia. The types of medical treatment, types of biological agents used, and types of surgical treatment do not have an impact on sarcopenia. Sarcopenia develops more in patients with high inflammatory activity. There is currently no study related to biomarkers in sarcopenia in IBD patients and the determinative role of NLR and LDH/Albumin ratio in sarcopenia has not been established. However, PNI, SII, and PLR values can be used as markers for assessing the risk of sarcopenia in newly diagnosed IBD patients. These markers can serve as non-invasive methods for the early detection of sarcopenia. KEYWORDS: Inflammatory Bowel Disease, Sarcopenia, Ulcerative Colitis, Crohn's Disease