The MUnich SArcopenia Registry (MUSAR)

The MUSAR aims to enhance awareness of sarcopenia. In the long term we seek to establish a database for studying modifiable risk factors and the underlying pathophysiology of sarcopenia. The first data shown here exemplarily investigate whether there are significant differences in comorbidities, functional impairments or quality of life among patients with different stages of sarcopenia or those at risk of developing it.

The sarcopenia registry (Project title: Identification of ICD-based SARcopenia, I(C)DSAR, The MUnich SArcopenia Registry (MUSAR) ethical vote no. 17-874) was founded in July 2018 at the Department of Medicine IV, LMU University Hospital Munich, Germany under consideration of the European General Data Protection Regulation (EuGDPR), enforceable beginning 25 May 2018.

In our case, patients are recruited during their hospital stay. This results in different time intervals between assessments. Figure 1 shows an overview of possible assessment timelines for different participants.

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A web-based open-source database with expandable modules for deep phenotyping was established using LibreClinica by ReliaTec© (ReliaTec GmbH, Munich, Germany) and was validated for further clinical trials.

Data quality parameters will be continuously assessed and quantified. This quality control can be ensured through a sampling framework with predefined study variables, documentation of the frequency and distribution of missing data as well as checking for range value violations and follows existing frameworks and data quality guidelines [12].

From July 2018 onwards patients with sarcopenia or with a risk of sarcopenia have been recruited from the outpatient and inpatient facilities of the geriatric department of the Ludwig Maximilians University (LMU) Hospital in Munich, Germany. There are no exclusion criteria regarding primary or secondary sarcopenia or whether patients are already undergoing treatment. The only requirement is that patients must be at least 65 years old and capable of giving informed consent.

To provide initial insights into the cohort that we will continue to investigate in the future, we analyzed 30 complete patient data sets for each syndrome stage. This includes patients identified as at risk of sarcopenia, defined by a SARC‑F score of 4 or higher and those with probable sarcopenia, characterized by normal muscle mass but impaired muscle function (defined as handgrip strength below 16 kg for women and below 27 kg for men, and/or a chair rising test time exceeding 15 s for both sexes) and patients diagnosed with sarcopenia, marked by reduced muscle mass (with cut-off thresholds for skeletal muscle mass indexes of less than 5.5 kg/m² for women and less than 7.0 kg/m² for men) in addition to impaired muscle function [8]. Patients were subsequently divided into subgroups. In total data from 90 patients collected between July 2018 and August 2024 were analyzed using ANOVA and χ²-tests (IBM SPSS v.29.0, IBM Corp, Armonk, NY, USA).

Lewis et al. labelled the rise of age-associated musculoskeletal syndromes and diseases, due to higher life expectancy, change in lifestyle and insufficient interventions as a main burden of the twenty-first century healthcare system. They also note that other medical conditions are commonly aggravated, and psychological distress is worsened by musculoskeletal disorders [13]. The broad negative impact of sarcopenia, beyond its purely functional aspects, is also evident in our sample (Table 1).

In addition to the high burden imposed by the syndrome itself, the significant knowledge gap further complicates patient care. The lack of awareness among practicing physicians, as highlighted in the introduction, underlines the need to raise awareness and build expertise. A reason for this gap could be the lack of consensus on diagnostic criteria, which has also made the design and implementation of treatment trials on sarcopenia very challenging in the past [11, 14].

It is imperative to state that the cohort of older adults is underrepresented in clinical research and trials [15]. This gap in representation becomes even more consequential when one considers the development of evidence-based medical guidelines intended to guide treatment decisions for a broad patient spectrum. Paradoxically, these guidelines frequently omit adequate representation of older individuals. Consequently, older adult patients may not experience the intended benefits of treatment, or worse, could face unnecessary harm [15]. Challenges in research on geriatric patients often arise from recruitment issues, such as cognitive impairment and comorbidities. Maintaining follow-up with older patients presents its own set of difficulties. Many may encounter transportation barriers or experience fluctuations in their health.

Every registry design follows its purpose. Administrative registries collect the least amount of data and are predominantly used to measure the prevalence of certain diseases or syndromes [16].

Clinical registries aim to not only identify patients but also to learn as much as possible about them, their disease, progression, intervention and outcomes [16]. Gliklich et al. differentiated clinical registries further, between product registries, where patients are exposed to a specific medication or medical product and outcomes and safety are examined; next to this health service registries, where patients undergo a particular procedure and lastly, disease or condition registries, where the presence of a specific condition serves as an inclusion criterion [17].

The MUSAR fits the latter category and therefore offers a much broader perspective on patients and syndromes compared to conventional predefined study protocols. As patients are recruited from the acute geriatric ward and geriatric day clinic, the study cohort can be considered representative of a wide spectrum of geriatric treatment settings. Moreover, the cohort is even more representative as it includes not only patients suffering from sarcopenia but also those classified as at risk of sarcopenia through the SARC‑F assessment or classified as having probable sarcopenia. This can help identify early risk factors for the development or aggravation of sarcopenia. In this context longitudinal observations will help to identify new prognostic and modifiable factors, including harmful and beneficial medications for syndrome progression and muscle loss in geriatrics, as has already been done in other medical fields [18]. Due to the infrequent assessment and diagnosis of sarcopenia, recruitment of patients of eligible cohorts through traditional sources remains a challenge. Consequently, past studies have struggled to reach the recruitment goals [19, 20]. While registries do not replace randomized controlled trials (RCT), they can help identify subgroups, questions and hypotheses for further examination in RCTs [21, 22]. A potential avenue for future clinical practice, therefore, involves RCTs based on registries [18, 22]. By utilizing the frequent hospitalizations of geriatric patients, data collection is easily carried out during their stays. As the registry currently includes over 400 datasets and continues to grow daily, we anticipate that further recruitment will lead to an even larger dataset, ultimately helping to mitigate the naturally high drop-out rates among advanced-aged patients.

In 2018 Sanchez-Rodriguez et al. finally proposed the establishment of an international registry on sarcopenia to provide a long-term source of data and patient cohort [23]. This initiative was not successful. The reasons are not published. They may have stemmed from various factors, such as potentially low participation or a data collection design that no longer aligned with the changed European data protection laws.

Additionally, technical difficulties may have contributed to the lack of success; therefore, our registry is also equipped with adjustments in this area. Our registry has a user-friendly interface and can be easily navigated. After instruction, researchers from different medical backgrounds can generate datasets. Accessible remotely, it enables a wide range of users to engage anytime at any place, while following the new European data protection laws [24]. This benefits future cooperation on a national and international basis and lines up with the launch of several cross-border initiatives that have recently been initiated in the EU region [25, 26]. The modular structure of our registry is in this collaboration context also advantageous. Future upcoming cooperation partners can incorporate their data and adapt the structure and finally, comprehensive research initiatives would also be highly welcomed by those affected. The results of a pilot study in the UK exploring the establishment of a patient registry for sarcopenia revealed a significant patient interest in further research participation. Remarkably, 98% of the recruited pilot participants expressed their willingness to be recruited for future studies [20].

Incomplete and invalid data are undoubtedly among the most significant challenges in every patient registry [18, 27]. Variability in input from different individuals at different times can compromise data quality, potentially leading to distortions and erroneous conclusions. To mitigate these concerns, we conduct regular quality control assessments involving all stakeholders [27]. Another possible limitation is the recruitment of patients during their hospital stay. Although this eases the recruitment of participants, it also poses a challenge to data quality, as acute illness, multiple different chronic diseases and exacerbation of comorbidities might influence their status at the time of assessment. No patient is in a “normal” state and this might potentially distort the accuracy and representativeness of the results. Next to this, the absence of fixed follow-up time points might also be a limitation. This leads to considerable variability in the assessment intervals (Fig. 1) and again, given the advanced age of the patients, the risk of drop-out due to patient death is also very high.

Another inherent disadvantage of our recruitment approach during hospital stays is also that we are unable to capture the time when the patient is not present. This prevents us from capturing potential factors that may influence subsequent assessments, such as changes during rehabilitation stays or social events in the patient’s life. Nonetheless, we can provide real-world data, in which certain variables and inconsistencies naturally affect outcomes or can create bias and errors in measurements [18]. The current single-center design can also be counted as a minor drawback but the integration of new collaborative partners in the future can address this issue.