Background: The Sarcopenia & Quality of Life (SarQoL) questionnaire is a patient-reported outcome measure designed for assessing health-related quality of life in individuals with sarcopenia. Despite its wide acceptance in the scientific literature, its content validity has only been partially demonstrated so far. Aims: To enhance the evidence supporting the content validity of the SarQoL questionnaire. Methods: Following COSMIN methodology, semi-structured interviews were conducted with 17 Belgian older adults who met the EWGSOP2 criteria for the diagnosis of sarcopenia and 11 experts in sarcopenia, with clinical or research background. Comprehensiveness, relevance and comprehensibility of SarQoL content were assessed through individual transcripts and were qualitatively analyzed thematically according to the seven dimensions of SarQoL. Results: The majority of the concepts elicited during the semi-structured interviews fitted within existing SarQoL dimensions. Importantly, the different domains of SarQoL were consensually considered as relevant by patients and experts. Some new emergent concepts were identified by the participants. While many of them could be considered as enrichments of existing dimensions or sub-concepts, other new concepts (i.e. self-fulfilment, acceptance of the reduced condition, adaptation/use of strategies, depression) may highlight two potential dimensions not covered by SarQoL, i.e. patient empowerment and depression. Cognitive interviews also highlighted that SarQoL items and instructions were clear and comprehensible. Conclusions: SarQoL, in its current form, demonstrates good evidence of content validity for assessing health-related quality of life in patients with sarcopenia. We do not recommend adding new items or dimensions to SarQoL. Instead, for researchers or clinicians who aim to specifically address self-empowerment or depression of sarcopenic populations, we suggest completing the assessment of quality of life by concurrently using additional validated scales of patient empowerment or depression.

Background: The vitamin D metabolite ratio (VMR) has recently been identified as a potentially better indicator of vitamin D deficiency than 25-hydroxyvitamin D (25(OH)D) alone. This study aims to validate these findings by demonstrating that VMR is more strongly correlated with parathyroid hormone (PTH) levels than 25(OH)D and 24,25-dihydroxyvitamin D (24,25(OH)₂D). In addition, the study investigates VMR as a more effective predictor of mortality than 25(OH)D and 24,25(OH)₂D. Methods: The SarcoPhAge cohort is a Belgian cohort of community-dwelling older adults. Levels of 25(OH)D and 24,25(OH)₂D were measured in 204 serum samples collected at the second year of follow-up using liquid chromatography–tandem mass spectrometry (LC–MS/MS), and VMR was calculated using the formula: VMR = (24,25(OH)D/25(OH)D) × 100. Vitamin D deficiency cut-offs were defined at 25(OH)D < 20 ng/mL, 24,25(OH)₂D < 1.2 ng/mL, or VMR < 4% according to previously proposed cut-offs. Participants were followed for up to 9 years. Results: A total of 35 individuals (17.2%) had 25(OH)D < 20 ng/mL, 40 individuals (19.6%) had 24,25(OH)₂D < 1.2 ng/mL, and 14 individuals (7.0%) had VMR < 4%. All three markers, 25(OH)D, 24,25(OH)₂D, and VMR, were independently associated with PTH levels, with VMR showing the strongest correlation (rho: −0.292; p < 0.0001). When categorized into quartiles, only 24,25(OH)2D and VMR showed significant increases in PTH levels across quartiles (p = 0.002 and p < 0.0001, respectively). When cut-offs for low vitamin D status were applied, patients with low VMR had the highest rate of all-cause mortality. However, in a Cox proportional hazard regression model, both low VMR profile and low 25(OH)D profile were risk factors for all-cause mortality. Conclusions: This study confirms that VMR is an efficient biomarker for assessing functional vitamin D deficiency.

COVID-19 vaccination raised concerns about its potential effects on physical performance. To assess the impact of COVID-19 vaccination on the perceived change in physical performance, we conducted an online survey among elite athletes from Belgium, Canada, France and Luxembourg, with questions about socio-demographics, COVID-19 vaccination, perceived impact on physical performance and perceived pressure to get vaccinated. Full vaccination was defined as two doses of mRNA or vector vaccine or a heterologous vaccine scheme. Among 1106 eligible athletes contacted, 306 athletes answered the survey and were included in this study. Of these, 72% perceived no change in their physical performance, 4% an improvement and 24% a negative impact following full COVID-19 vaccination. For 82% of the included athletes, the duration of the negative vaccine reactions was ≤3 days. After adjustment for potential confounding variables, practicing an individual sport, a duration of vaccine reactions longer than 3 days, a high level of vaccine reaction and the perceived pressure to get vaccinated were independently associated with a perceived negative impact on physical performance of more than 3 days after the vaccination. The perceived pressure to get vaccinated appears to be a parameter associated with the negative perceived change in the physical performance and deserves further consideration.

Background: The Sarcopenia and Quality of Life (SarQoL) questionnaire is recognized as the only disease‐specific patient‐reported outcome measure (PROM) for assessing sarcopenia‐related HRQoL. This systematic review and meta‐analysis aimed to provide a quantitative summary of all evidence reported on the reliability, validity, responsiveness and floor/ceiling effects of SarQoL in older adults. Methods: Following PRISMA‐COSMIN guidelines, a systematic search for studies evaluating the psychometric properties of SarQoL (i.e., reliability, validity, responsiveness and floor and ceiling effects) in older people was conducted on MEDLINE (via OVID), PsycINFO, Scopus and EMBASE. Studies published between 2013 and November 2024 using a consensual definition of sarcopenia were included. Study selection and data extraction were made by two independent reviewers. A random‐effects model meta‐analysis was applied. PROSPERO registration: CRD42024546880. Results: From 411 studies identified by the search strategy, 25 fulfilled the inclusion criteria, including 4585 community‐dwelling individuals, of which 1311 were diagnosed as sarcopenic. SarQoL demonstrated high reliability (pooled Cronbach's alpha values consistently exceeding 0.80) and excellent test–retest reliability (pooled ICC = 0.98). Construct validity was confirmed with strong convergent correlations (pooled r > 0.54) with related dimensions of generic SF‐36 and EQ‐5D and weaker divergent correlations (pooled r < 0.47). Responsiveness, evaluated in two studies using different methodologies, supported the ability of SarQoL to detect meaningful changes in HRQoL. The certainty of evidence was rated as high for reliability, validity and responsiveness. Conclusion: This meta‐analysis consolidates a decade of evidence and confirms the strong psychometric properties of SarQoL, with a high level of evidence.