Di̇scussi̇on
In this study, we assessed the presence of sarcopenia and probable sarcopenia in patients with SLE, using HGS and SMMI (BMI). The percentage of probable sarcopenia according to HGS was 51.2%, while the percentage of sarcopenia according to HGS and SMMI (BMI) together was 12.9%. A meta-analysis conducted in 2023 included 11 studies that evaluated muscle strength in patients with lupus. HGS was assessed in patients with SLE and it was found that muscle strength was lower than in healthy controls. In this meta-analysis, HGS in patients with lupus was calculated to be 21.74 kg.8 The muscle strength in patients with SLE in our study was similar (21.7±4.9) and was found to be significantly lower than in the healthy control group.
Our data show a higher prevalence of probable sarcopenia and sarcopenia in patients with SLE than expected for this age group. The higher prevalence of patients with probable sarcopenia in our study may be attributed to the use of sarcopenia indices defined by Bahat et al from the EWGSOP Study group in the Turkish population, which differ from those recommended by the EWGSOP.
The prevalence of sarcopenia in systemic sclerosis is 22.5%, which is consistent with other rheumatic diseases such as rheumatoid arthritis (20.8%), psoriatic arthritis (20%) and ankylosing spondylitis (22.7%).2 9 10 However, there are no studies on the prevalence of sarcopenia in patients with lupus. Sumantri et al conducted the only study on the Asian study group based on the HGS cut-off. The group of patients defined as having low HGS was found to be 44%, and the sarcopenia quality of life indices were reported to be lower in the low HGS group.11 The relationship between sarcopenia and disease markers has been extensively studied in other rheumatic diseases such as osteoarthritis, rheumatoid arthritis, systemic sclerosis, Sjögren’s syndrome and ankylosing spondylitis. However, little is known about the relationship between SLE-specific markers and sarcopenia. This study focused on demographic, clinical and immunological variables to investigate the relationship between sarcopenia and SLE.
There were no significant differences in SMMI (BMI), PGA and SLEDAI-2K scores between patients with and without probable sarcopenia. The frequency of organ involvement was also not significantly different between the groups. Mahran et al found a correlation between HGS and disease activity, while Keramiotou et al did not.12 13 In particular, patients defined as having probable sarcopenia had lower anti-dsDNA levels and higher complement levels. This suggests that the immunological burden of the disease is not associated with sarcopenia. When regression analysis was performed with the significant variables in our study, height and anti-dsDNA antibody levels were found to be independent predictors of sarcopenia in these patients.
Balsamo et al showed increased fatigue, decreased functional performance and poorer quality of life with lower dynamic muscle strength in 25 premenopausal patients with SLE with low disease activity compared with 25 controls matched for age, physical characteristics and physical activity level.14 Another study from our centre demonstrated worse hand functions in 46 patients with SLE (all women), but reported that it was better compared with 51 patients with rheumatoid arthritis.15 Stockton et al found that muscle strength was decreased in 24 patients with SLE compared with the control group.16 In the study conducted by Keramiotou et al, it was found that arthritis was reported by 18% of the participants, while joint pain was indicated by 48% of them.13 We believe that such a high rate is related to the presence of arthritis and arthralgia in about half of the group. The grip strength of the lupus low disease activity state (LLDAS) group was higher than that of the non-LLDAS group. In the model constructed according to compressive strength, increasing age, female sex, painful joints and use of immunosuppressants were statistically significant, but no relationship was shown with disease activity scores. In our study, no significant association was found between low-dose steroid use and the probable sarcopenia.
Sarcopenia, characterised by the loss of skeletal muscle mass and strength, is greatly influenced by non-disease-related factors, particularly physical exercise. Structured and consistent exercise programmes are crucial for preventing and managing sarcopenia, enhancing mobility and improving overall quality of life. Systematic reviews highlight that aerobic exercises boost cardiovascular health, while resistance training enhances physical function in patients, including those with SLE. Exercise also effectively reduces fatigue and depressive symptoms, which contributes to improved aerobic capacity and overall physical functioning.17 Considering the diverse effects of SLE on various organ systems and physical functions, personalised physical activity recommendations are vital for effective disease management. According to Blaess et al, integrating safe and specific exercises tailored to the patient’s disease severity, comorbidities and overall health can significantly improve health outcomes, helping patients with SLE to lead an active and healthier life.18
The strengths of this study include the availability of a large and well-characterised population with SLE and the detailed use of sarcopenia and clinical features, immunological parameters and demographic data. However, our study has several limitations. First, we were not able to assess all our patients by BIA due to the restrictions imposed by the pandemic. Second, all our patients were Turkish, as SLE is a predominantly female disease due to the gender trend, which may limit the applicability of the findings to male patients with SLE of other ethnicities. The study was cross-sectional; SLEDAI-2K was analysed, but given that sarcopenia is a progressive disease, it would have been better to look at Systemic Lupus International Collaborating Clinics Damage Index. Furthermore, although we believe that nutritional parameters and physical activity may have an effect on sarcopenia, it is not easy to collect such information in a standardised way, so this could not be done in this study. Evaluation of the same parameters in a larger group of patients from multiple centres is necessary to confirm our findings.
This observational study emphasises that probable sarcopenia is a common and often underestimated complication in patients with SLE. Clinicians should be aware that, according to our findings, probable sarcopenia and sarcopenia may start at a young age in patients with lupus.
Importantly, this study points to significant gaps in current research, particularly in longitudinal studies assessing sarcopenia’s progression in patients with SLE and the effectiveness of integrated treatment protocols. Future research should aim at elucidating the precise molecular mechanisms linking SLE and sarcopenia, exploring novel therapeutic targets and developing standardised assessment tools for sarcopenia in the context of autoimmune diseases. By fostering a multidisciplinary approach that integrates rheumatology, geriatrics and physical therapy, we can enhance patient care, improve quality of life and potentially extend disease-free survival in individuals with SLE. Thus, this study not only broadens our understanding of sarcopenia’s impact on autoimmune diseases but also sets the stage for innovative research and clinical practice paradigms aimed at addressing this complex challenge.
Conclusions
Our results suggest that sarcopenia is a prevalent condition among patients with SLE. The frequency of probable sarcopenia was 51.2%, and sarcopenia was 12.9% in our patients with lupus. Even if BIA cannot be performed, HGS may be an indicator for the possibility of sarcopenia in patients with lupus. Therefore, we think it is important to evaluate it. Since anti-dsDNA is a predictive factor of probable sarcopenia, physicians should pay attention when evaluating the findings of patients. In addition, the HGS showed low muscle strength in almost half of the patients. Despite this, probable sarcopenia was not found to be associated with any clinical parameters.