Investigation of Respiratory Muscle Sarcopenia in Patients with Systemic Sclerosis

Sarcopenia is a generalized and progressive loss of skeletal muscles and is characterized by a decrease in muscle strength, muscle mass and physical performance. It usually occurs in older people, but can also occur in people with certain diseases or who lead a very sedentary lifestyle. The European Working Group on Sarcopenia in Older People (EWGSOP) has developed guidelines for diagnosing sarcopenia and determining its severity. EWGSOP defined three conceptual stages of sarcopenia. Pre-sarcopenia is characterized by low muscle mass that does not affect muscle strength or physical performance. Sarcopenia is characterized by low muscle mass and decreased muscle strength or reduced physical performance. Severe sarcopenia is characterized when all criteria are met. Respiratory muscle sarcopenia is defined as a condition of muscle fiber atrophy and weakness that also occurs in respiratory muscles. The Japanese Respiratory Sarcopenia Study Group defined respiratory muscle sarcopenia as "whole body sarcopenia and low respiratory muscle mass with low respiratory muscle strength and/or low respiratory function". Respiratory muscle sarcopenia was also defined by Kera et al. based on peak expiratory flow rate. However, whole body sarcopenia and respiratory muscle strength are also important to define and diagnose respiratory muscle sarcopenia. The incidence of respiratory muscle sarcopenia is higher in the presence of sarcopenia. Sarcopenic respiratory failure is diagnosed when there is sarcopenia with functional impairment. Cases of respiratory sarcopenia without functional impairment are diagnosed as "at risk of sarcopenic respiratory failure". When the literature is reviewed, it is seen that there is no study on respiratory muscle sarcopenia in patients with systemic sclerosis. Therefore, the aim of this study is to examine respiratory muscle sarcopenia in patients with systemic sclerosis.

The smallest sample size of the study was 85 people with 90% power at 95% confidence interval. Data will be analyzed using IBM® SPSS® Statistics for Windows (ver. 25.0; IBM Corp, New York, USA) software. Values will be expressed as mean ± standard deviation and median (25-75 quartiles) for continuous variables and frequencies will be reported for categorical variables. Shapiro-Wilk test and histograms will be used to assess the normality distribution of the data. Pearson correlation coefficient will be used to evaluate the parameters associated with respiratory muscle strength. Binary Logistic Regression Analysis, which is used to estimate whether the dependent variable belongs to two categorical classes, will be used to determine the risk factors for respiratory muscle sarcopenia.